Merge branch 'master' into jgrpp

# Conflicts:
#	.gitignore
#	CMakeLists.txt
#	src/3rdparty/optional/optional.hpp
#	src/group_cmd.cpp
#	src/industry_cmd.cpp
#	src/misc_gui.cpp
#	src/video/sdl2_v.cpp

.github/workflows/ci-build.yml

@@ -10,6 +10,55 @@ env:
   CTEST_OUTPUT_ON_FAILURE: 1
 
 jobs:
+  emscripten:
+    name: Emscripten
+
+    runs-on: ubuntu-20.04
+    container:
+      # If you change this version, change the number in the cache step too.
+      image: emscripten/emsdk:2.0.10
+
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+
+    - name: Setup cache
+      uses: actions/cache@v2
+      with:
+        path: /emsdk/upstream/emscripten/cache
+        key: 2.0.10-${{ runner.os }}
+
+    - name: Build (host tools)
+      run: |
+        mkdir build-host
+        cd build-host
+
+        echo "::group::CMake"
+        cmake .. -DOPTION_TOOLS_ONLY=ON
+        echo "::endgroup::"
+
+        echo "::group::Build"
+        echo "Running on $(nproc) cores"
+        make -j$(nproc) tools
+        echo "::endgroup::"
+
+    - name: Install GCC problem matcher
+      uses: ammaraskar/gcc-problem-matcher@master
+
+    - name: Build
+      run: |
+        mkdir build
+        cd build
+
+        echo "::group::CMake"
+        emcmake cmake .. -DHOST_BINARY_DIR=../build-host
+        echo "::endgroup::"
+
+        echo "::group::Build"
+        echo "Running on $(nproc) cores"
+        emmake make -j$(nproc)
+        echo "::endgroup::"
+
   linux:
     name: Linux
 

.github/workflows/preview_build.yml

@@ -0,0 +1,133 @@
+name: Preview build
+
+on:
+  repository_dispatch:
+    types:
+    - Preview*
+
+jobs:
+  preview:
+    name: Build preview
+
+    runs-on: ubuntu-20.04
+    container:
+      # If you change this version, change the number in the cache step too.
+      image: emscripten/emsdk:2.0.10
+      # uid=1001(runner) gid=121(docker)
+      options: -u 1001:121
+
+    steps:
+    - name: Update deployment status to in progress
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/{owner}/{repo}/deployments/{deployment_id}/statuses
+        mediaType: |
+          previews:
+          - ant-man
+          - flash
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        deployment_id: ${{ github.event.client_payload.deployment_id }}
+        state: in_progress
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - name: Checkout
+      uses: actions/checkout@v2
+      with:
+        ref: ${{ github.event.client_payload.sha }}
+
+    - name: Name branch
+      run: |
+        name=$(echo "${{ github.event.client_payload.folder }}")
+        git checkout -b ${name}
+
+    - name: Setup cache
+      uses: actions/cache@v2
+      with:
+        path: /emsdk/upstream/emscripten/cache
+        key: 2.0.10-${{ runner.os }}
+
+    - name: Build (host tools)
+      run: |
+        mkdir build-host
+        cd build-host
+
+        echo "::group::CMake"
+        cmake .. -DOPTION_TOOLS_ONLY=ON
+        echo "::endgroup::"
+
+        echo "::group::Build"
+        echo "Running on $(nproc) cores"
+        make -j$(nproc) tools
+        echo "::endgroup::"
+
+    - name: Install GCC problem matcher
+      uses: ammaraskar/gcc-problem-matcher@master
+
+    - name: Build
+      run: |
+        mkdir build
+        cd build
+
+        echo "::group::CMake"
+        emcmake cmake .. \
+          -DHOST_BINARY_DIR=../build-host \
+          -DCMAKE_BUILD_TYPE=RelWithDebInfo \
+          # EOF
+        echo "::endgroup::"
+
+        echo "::group::Build"
+        echo "Running on $(nproc) cores"
+        emmake make -j$(nproc)
+        echo "::endgroup::"
+
+    - name: Publish preview
+      run: |
+        # setuptools is missing in this Docker image, which breaks installing
+        # awscli. So we need to do this in two steps to recover sanity.
+        pip3 install setuptools
+        pip3 install awscli
+
+        ~/.local/bin/aws s3 cp --only-show-errors build/openttd.data s3://${{ secrets.PREVIEW_S3_BUCKET }}/${{ github.event.client_payload.folder }}/
+        ~/.local/bin/aws s3 cp --only-show-errors build/openttd.html s3://${{ secrets.PREVIEW_S3_BUCKET }}/${{ github.event.client_payload.folder }}/
+        ~/.local/bin/aws s3 cp --only-show-errors build/openttd.js s3://${{ secrets.PREVIEW_S3_BUCKET }}/${{ github.event.client_payload.folder }}/
+        ~/.local/bin/aws s3 cp --only-show-errors build/openttd.wasm s3://${{ secrets.PREVIEW_S3_BUCKET }}/${{ github.event.client_payload.folder }}/
+
+        # Invalidate the cache of the CloudFront distribution
+        ~/.local/bin/aws cloudfront create-invalidation --distribution-id ${{ secrets.PREVIEW_CF_DISTRIBUTION_ID }} --paths "/${{ github.event.client_payload.folder }}/*"
+      env:
+        AWS_ACCESS_KEY_ID: ${{ secrets.AWS_ACCESS_KEY_ID }}
+        AWS_SECRET_ACCESS_KEY: ${{ secrets.AWS_SECRET_ACCESS_KEY }}
+
+    - name: Update deployment status to success
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/{owner}/{repo}/deployments/{deployment_id}/statuses
+        mediaType: |
+          previews:
+          - ant-man
+          - flash
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        deployment_id: ${{ github.event.client_payload.deployment_id }}
+        state: success
+        environment_url: https://preview.openttd.org/${{ github.event.client_payload.folder }}/
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: failure()
+      name: Update deployment status to failure
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/{owner}/{repo}/deployments/{deployment_id}/statuses
+        mediaType: |
+          previews:
+          - ant-man
+          - flash
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        deployment_id: ${{ github.event.client_payload.deployment_id }}
+        state: failure
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}

.github/workflows/preview_label.yml

@@ -0,0 +1,66 @@
+name: Preview label
+
+on:
+  pull_request_target:
+    types:
+    - labeled
+
+env:
+  TEAM_CORE_DEVELOPER: core-developers
+
+jobs:
+  check_preview_label:
+    name: Check for preview label
+    if: github.event.action == 'labeled' && github.event.label.name == 'preview'
+
+    runs-on: ubuntu-20.04
+
+    steps:
+    - name: Check if label was added by core developer
+      id: core_developer
+      continue-on-error: true
+      uses: octokit/request-action@v2.x
+      with:
+        route: GET /orgs/OpenTTD/teams/${{ env.TEAM_CORE_DEVELOPER }}/memberships/${{ github.event.sender.login }}
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: steps.core_developer.outcome == 'failure'
+      name: Remove preview label if not core developer
+      uses: octokit/request-action@v2.x
+      with:
+        route: DELETE /repos/{owner}/{repo}/issues/{issue_number}/labels/preview
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        issue_number: ${{ github.event.number }}
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: steps.core_developer.outcome == 'success'
+      name: Create deployment
+      id: deployment
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/{owner}/{repo}/deployments
+        mediaType: |
+          previews:
+          - ant-man
+          - flash
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        ref: ${{ github.event.pull_request.head.sha }}
+        task: deploy:preview
+        auto_merge: false
+        required_contexts: "[]"
+        environment: preview-pr-${{ github.event.number }}
+        description: "Preview for Pull Request #${{ github.event.number }}"
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: steps.core_developer.outcome == 'success'
+      name: Trigger 'preview build'
+      uses: peter-evans/repository-dispatch@v1
+      with:
+        token: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+        event-type: "Preview build #${{ github.event.number }}"
+        client-payload: '{"folder": "pr${{ github.event.number }}", "sha": "${{ github.event.pull_request.head.sha }}", "deployment_id": "${{ fromJson(steps.deployment.outputs.data).id }}"}'

.github/workflows/preview_push.yml

@@ -0,0 +1,66 @@
+name: Preview push
+
+on:
+  pull_request_target:
+    types:
+    - synchronize
+
+jobs:
+  check_new_preview:
+    name: Check preview needs update
+
+    runs-on: ubuntu-20.04
+
+    steps:
+    - name: Check if earlier preview exists
+      id: earlier_preview
+      uses: octokit/request-action@v2.x
+      with:
+        route: GET /repos/{owner}/{repo}/deployments
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        environment: preview-pr-${{ github.event.number }}
+        per_page: 1
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: toJson(fromJson(steps.earlier_preview.outputs.data)) != '[]'
+      name: Check for preview label
+      id: preview_label
+      uses: octokit/request-action@v2.x
+      with:
+        route: GET /repos/{owner}/{repo}/issues/{issue_number}/labels
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        issue_number: ${{ github.event.number }}
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: toJson(fromJson(steps.earlier_preview.outputs.data)) != '[]' && contains(fromJson(steps.preview_label.outputs.data).*.name, 'preview')
+      name: Create deployment
+      id: deployment
+      uses: octokit/request-action@v2.x
+      with:
+        route: POST /repos/{owner}/{repo}/deployments
+        mediaType: |
+          previews:
+          - ant-man
+          - flash
+        owner: ${{ github.event.repository.owner.login }}
+        repo: ${{ github.event.repository.name }}
+        ref: ${{ github.event.pull_request.head.sha }}
+        task: deploy:preview
+        auto_merge: false
+        required_contexts: "[]"
+        environment: preview-pr-${{ github.event.number }}
+        description: "Preview for Pull Request #${{ github.event.number }}"
+      env:
+        GITHUB_TOKEN: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+
+    - if: toJson(fromJson(steps.earlier_preview.outputs.data)) != '[]' && contains(fromJson(steps.preview_label.outputs.data).*.name, 'preview')
+      name: Trigger 'preview build'
+      uses: peter-evans/repository-dispatch@v1
+      with:
+        token: ${{ secrets.PREVIEW_GITHUB_TOKEN }}
+        event-type: "Preview build #${{ github.event.number }}"
+        client-payload: '{"folder": "pr${{ github.event.number }}", "sha": "${{ github.event.pull_request.head.sha }}", "deployment_id": "${{ fromJson(steps.deployment.outputs.data).id }}"}'

.gitignore

@@ -1,5 +1,5 @@
 /.vs
-/build*/
+/build*
 CMakeSettings.json
 docs/aidocs/*
 docs/gamedocs/*

CMakeLists.txt

@@ -10,6 +10,10 @@ if(CMAKE_SOURCE_DIR STREQUAL CMAKE_BINARY_DIR)
     message(FATAL_ERROR "In-source builds not allowed. Please run \"cmake ..\" from the bin directory")
 endif()
 
+if (EMSCRIPTEN)
+    set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/os/emscripten/cmake")
+endif()
+
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/cmake")
 set(CMAKE_OSX_DEPLOYMENT_TARGET 10.9)
 
@@ -27,6 +31,61 @@ set_directory_options()
 include(Static)
 set_static_if_needed()
 
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED YES)
+set(CMAKE_CXX_EXTENSIONS NO)
+
+set(CMAKE_EXPORT_COMPILE_COMMANDS YES)
+
+# An empty target for the tools
+add_custom_target(tools)
+
+include(Endian)
+add_endian_definition()
+
+include(CompileFlags)
+compile_flags()
+
+if(APPLE OR UNIX)
+    add_definitions(-DUNIX)
+endif()
+
+if(UNIX)
+    find_package(Doxygen)
+endif()
+
+list(APPEND GENERATED_SOURCE_FILES "${CMAKE_BINARY_DIR}/generated/rev.cpp")
+if(WIN32)
+    list(APPEND GENERATED_SOURCE_FILES "${CMAKE_BINARY_DIR}/generated/ottdres.rc")
+endif()
+
+# Documentation
+if(DOXYGEN_EXECUTABLE)
+    add_custom_target(docs)
+    add_custom_target(docs_source
+        ${CMAKE_COMMAND} -E make_directory ${CMAKE_BINARY_DIR}/docs
+        COMMAND ${DOXYGEN_EXECUTABLE} ${CMAKE_BINARY_DIR}/Doxyfile
+        WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+        COMMENT "Generating documentation for source"
+    )
+    add_dependencies(docs_source
+        find_version
+    )
+    add_dependencies(docs
+        docs_source
+    )
+endif()
+
+include(AddCustomXXXTimestamp)
+
+if(OPTION_TOOLS_ONLY)
+    if(HOST_BINARY_DIR)
+        unset(HOST_BINARY_DIR CACHE)
+    endif()
+    add_subdirectory(${CMAKE_SOURCE_DIR}/src)
+    return()
+endif()
+
 # Prefer -pthread over -lpthread, which is often the better option of the two.
 set(CMAKE_THREAD_PREFER_PTHREAD YES)
 # Make sure we have Threads available.
@@ -98,10 +157,6 @@ find_package(Xaudio2)
 
 find_package(Grfcodec)
 
-if(UNIX)
-    find_package(Doxygen)
-endif()
-
 # IPO is only properly supported from CMake 3.9. Despite the fact we are
 # CMake 3.5, still enable IPO if we detect we are 3.9+.
 if(POLICY CMP0069)
@@ -129,47 +184,7 @@ if(APPLE)
     endif()
 endif()
 
-if(MSVC)
-    # C++17 for MSVC
-    set(CMAKE_CXX_STANDARD 17)
-else()
-    # C++11 for all other targets
-    set(CMAKE_CXX_STANDARD 11)
-endif()
-
-set(CMAKE_CXX_STANDARD_REQUIRED YES)
-set(CMAKE_CXX_EXTENSIONS NO)
-
-set(CMAKE_EXPORT_COMPILE_COMMANDS YES)
-
-list(APPEND GENERATED_SOURCE_FILES "${CMAKE_BINARY_DIR}/generated/rev.cpp")
-if(WIN32)
-    list(APPEND GENERATED_SOURCE_FILES "${CMAKE_BINARY_DIR}/generated/ottdres.rc")
-endif()
-
-# An empty target for the tools
-add_custom_target(tools)
-
-# Documentation
-if(DOXYGEN_EXECUTABLE)
-    add_custom_target(docs)
-    add_custom_target(docs_source
-        ${CMAKE_COMMAND} -E make_directory ${CMAKE_BINARY_DIR}/docs
-        COMMAND ${DOXYGEN_EXECUTABLE} ${CMAKE_BINARY_DIR}/Doxyfile
-        WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
-        COMMENT "Generating documentation for source"
-    )
-    add_dependencies(docs_source
-        find_version
-    )
-    add_dependencies(docs
-        docs_source
-    )
-endif()
-
 include(SourceList)
-include(Endian)
-add_endian_definition()
 
 # Needed by rev.cpp
 include_directories(${CMAKE_SOURCE_DIR}/src)
@@ -178,9 +193,6 @@ include_directories(${CMAKE_SOURCE_DIR}/src/3rdparty/squirrel/include)
 
 include(MSVCFilters)
 
-include(CompileFlags)
-compile_flags()
-
 add_executable(openttd WIN32 ${GENERATED_SOURCE_FILES})
 set_target_properties(openttd PROPERTIES OUTPUT_NAME "${BINARY_NAME}")
 # All other files are added via target_sources()
@@ -215,7 +227,6 @@ else()
     )
 endif()
 
-include(AddCustomXXXTimestamp)
 add_subdirectory(${CMAKE_SOURCE_DIR}/src)
 add_subdirectory(${CMAKE_SOURCE_DIR}/media/baseset)
 add_subdirectory(${CMAKE_SOURCE_DIR}/bin)
@@ -248,10 +259,6 @@ endif()
 set_target_properties(openttd PROPERTIES VS_DEBUGGER_WORKING_DIRECTORY "${CMAKE_SOURCE_DIR}/bin")
 process_compile_flags()
 
-if(APPLE OR UNIX)
-    add_definitions(-DUNIX)
-endif()
-
 include(LinkPackage)
 link_package(PNG TARGET PNG::PNG ENCOURAGED)
 link_package(ZLIB TARGET ZLIB::ZLIB ENCOURAGED)
@@ -288,6 +295,39 @@ if(APPLE)
     )
 endif()
 
+if(EMSCRIPTEN)
+    add_library(WASM::WASM INTERFACE IMPORTED)
+
+    # Allow heap-growth, and start with a bigger memory size.
+    target_link_libraries(WASM::WASM INTERFACE "-s ALLOW_MEMORY_GROWTH=1")
+    target_link_libraries(WASM::WASM INTERFACE "-s INITIAL_MEMORY=33554432")
+
+    # Export functions to Javascript.
+    target_link_libraries(WASM::WASM INTERFACE "-s EXPORTED_FUNCTIONS='[\"_main\", \"_em_openttd_add_server\"]' -s EXTRA_EXPORTED_RUNTIME_METHODS='[\"cwrap\"]'")
+
+    # Preload all the files we generate during build.
+    # As we do not compile with FreeType / FontConfig, we also have no way to
+    # render several languages (like Chinese, ..), so where do you draw the
+    # line what languages to include and which not? In the end, especially as
+    # the more languages you add the slower downloading becomes, we decided to
+    # only ship the English language.
+    target_link_libraries(WASM::WASM INTERFACE "--preload-file ${CMAKE_BINARY_DIR}/baseset@/baseset")
+    target_link_libraries(WASM::WASM INTERFACE "--preload-file ${CMAKE_BINARY_DIR}/lang/english.lng@/lang/english.lng")
+    target_link_libraries(WASM::WASM INTERFACE "--preload-file ${CMAKE_SOURCE_DIR}/bin/ai@/ai")
+    target_link_libraries(WASM::WASM INTERFACE "--preload-file ${CMAKE_SOURCE_DIR}/bin/game@/game")
+
+    # We use IDBFS for persistent storage.
+    target_link_libraries(WASM::WASM INTERFACE "-lidbfs.js")
+
+    # Use custom pre-js and shell.html.
+    target_link_libraries(WASM::WASM INTERFACE "--pre-js ${CMAKE_SOURCE_DIR}/os/emscripten/pre.js")
+    target_link_libraries(WASM::WASM INTERFACE "--shell-file ${CMAKE_SOURCE_DIR}/os/emscripten/shell.html")
+
+    # Build the .html (which builds the .js, .wasm, and .data too).
+    set_target_properties(openttd PROPERTIES SUFFIX ".html")
+    target_link_libraries(openttd WASM::WASM)
+endif()
+
 if(NOT PERSONAL_DIR STREQUAL "(not set)")
     add_definitions(
         -DWITH_PERSONAL_DIR

COMPILING.md

@@ -83,9 +83,9 @@ make
 
 ## Supported compilers
 
-Every compiler that is supported by CMake and supports C++11, should be
+Every compiler that is supported by CMake and supports C++17, should be
 able to compile OpenTTD. As the exact list of compilers changes constantly,
-we refer to the compiler manual to see if it supports C++11, and to CMake
+we refer to the compiler manual to see if it supports C++17, and to CMake
 to see if it supports your compiler.
 
 ## Compilation of base sets

cmake/Options.cmake

@@ -55,8 +55,20 @@ function(set_options)
     option(OPTION_DEDICATED "Build dedicated server only (no GUI)" OFF)
     option(OPTION_INSTALL_FHS "Install with Filesystem Hierarchy Standard folders" ${DEFAULT_OPTION_INSTALL_FHS})
     option(OPTION_USE_ASSERTS "Use assertions; leave enabled for nightlies, betas, and RCs" ON)
+    if(EMSCRIPTEN)
+        # Although pthreads is supported, it is not in a way yet that is
+        # useful for us.
+        option(OPTION_USE_THREADS "Use threads" OFF)
+    else()
         option(OPTION_USE_THREADS "Use threads" ON)
+    endif()
     option(OPTION_USE_NSIS "Use NSIS to create windows installer; enable only for stable releases" OFF)
+    option(OPTION_TOOLS_ONLY "Build only tools target" OFF)
+    option(OPTION_DOCS_ONLY "Build only docs target" OFF)
+
+    if (OPTION_DOCS_ONLY)
+        set(OPTION_TOOLS_ONLY ON PARENT_SCOPE)
+    endif()
 endfunction()
 
 # Show the values of the generic options.

cmake/PackageBundle.cmake

@@ -5,6 +5,7 @@ set(CPACK_BUNDLE_ICON "${CMAKE_SOURCE_DIR}/os/macosx/openttd.icns")
 set(CPACK_BUNDLE_PLIST "${CMAKE_CURRENT_BINARY_DIR}/Info.plist")
 set(CPACK_BUNDLE_STARTUP_COMMAND "${CMAKE_SOURCE_DIR}/os/macosx/launch.sh")
 set(CPACK_DMG_BACKGROUND_IMAGE "${CMAKE_SOURCE_DIR}/os/macosx/splash.png")
+set(CPACK_DMG_FORMAT "UDBZ")
 
 # Create a temporary Info.plist.in, where we will fill in the version via
 # CPackProperties.cmake.in. This because at this point in time the version

os/emscripten/Dockerfile

@@ -0,0 +1,4 @@
+FROM emscripten/emsdk
+
+COPY emsdk-liblzma.patch /
+RUN cd /emsdk/upstream/emscripten && patch -p1 < /emsdk-liblzma.patch

os/emscripten/README.md

@@ -0,0 +1,40 @@
+## How to build with Emscripten
+
+Building with Emscripten works with emsdk 2.0.10 and above.
+
+Currently there is no LibLZMA support upstream; for this we suggest to apply
+the provided patch in this folder to your emsdk installation.
+
+For convenience, a Dockerfile is supplied that does this patches for you
+against upstream emsdk docker. Best way to use it:
+
+Build the docker image:
+```
+  docker build -t emsdk-lzma .
+```
+
+Build the host tools first:
+```
+  mkdir build-host
+  docker run -it --rm -v $(pwd):$(pwd) -u $(id -u):$(id -g) --workdir $(pwd)/build-host emsdk-lzma cmake .. -DOPTION_TOOLS_ONLY=ON
+  docker run -it --rm -v $(pwd):$(pwd) -u $(id -u):$(id -g) --workdir $(pwd)/build-host emsdk-lzma make -j5 tools
+```
+
+Next, build the game with emscripten:
+
+```
+  mkdir build
+  docker run -it --rm -v $(pwd):$(pwd) -u $(id -u):$(id -g) --workdir $(pwd)/build emsdk-lzma emcmake cmake .. -DHOST_BINARY_DIR=$(pwd)/build-host -DCMAKE_BUILD_TYPE=RelWithDebInfo -DOPTION_USE_ASSERTS=OFF
+  docker run -it --rm -v $(pwd):$(pwd) -u $(id -u):$(id -g) --workdir $(pwd)/build emsdk-lzma emmake make -j5
+```
+
+And now you have in your build folder files like "openttd.html".
+
+To run it locally, you would have to start a local webserver, like:
+
+```
+  cd build
+  python3 -m http.server
+````
+
+Now you can play the game via http://127.0.0.1:8000/openttd.html .

os/emscripten/cmake/FindLibLZMA.cmake

@@ -0,0 +1,20 @@
+# LibLZMA is a recent addition to the emscripten SDK, so it is possible
+# someone hasn't updated his SDK yet. Test out if the SDK supports LibLZMA.
+include(CheckCXXSourceCompiles)
+set(CMAKE_REQUIRED_FLAGS "-sUSE_LIBLZMA=1")
+
+check_cxx_source_compiles("
+    #include <lzma.h>
+    int main() { return 0; }"
+    LIBLZMA_FOUND
+)
+
+if (LIBLZMA_FOUND)
+        add_library(LibLZMA::LibLZMA INTERFACE IMPORTED)
+        set_target_properties(LibLZMA::LibLZMA PROPERTIES
+                INTERFACE_COMPILE_OPTIONS "-sUSE_LIBLZMA=1"
+                INTERFACE_LINK_LIBRARIES "-sUSE_LIBLZMA=1"
+        )
+else()
+        message(WARNING "You are using an emscripten SDK without LibLZMA support. Many savegames won't be able to load in OpenTTD. Please apply 'emsdk-liblzma.patch' to your local emsdk installation.")
+endif()

os/emscripten/cmake/FindPNG.cmake

@@ -0,0 +1,7 @@
+add_library(PNG::PNG INTERFACE IMPORTED)
+set_target_properties(PNG::PNG PROPERTIES
+        INTERFACE_COMPILE_OPTIONS "-sUSE_LIBPNG=1"
+        INTERFACE_LINK_LIBRARIES "-sUSE_LIBPNG=1"
+)
+
+set(PNG_FOUND on)

os/emscripten/cmake/FindSDL2.cmake

@@ -0,0 +1,7 @@
+add_library(SDL2::SDL2 INTERFACE IMPORTED)
+set_target_properties(SDL2::SDL2 PROPERTIES
+        INTERFACE_COMPILE_OPTIONS "-sUSE_SDL=2"
+        INTERFACE_LINK_LIBRARIES "-sUSE_SDL=2"
+)
+
+set(SDL2_FOUND on)

os/emscripten/cmake/FindZLIB.cmake

@@ -0,0 +1,7 @@
+add_library(ZLIB::ZLIB INTERFACE IMPORTED)
+set_target_properties(ZLIB::ZLIB PROPERTIES
+        INTERFACE_COMPILE_OPTIONS "-sUSE_ZLIB=1"
+        INTERFACE_LINK_LIBRARIES "-sUSE_ZLIB=1"
+)
+
+set(ZLIB_FOUND on)

os/emscripten/emsdk-liblzma.patch

@@ -0,0 +1,213 @@
+From 90dd4d4c6b1cedec338ff5b375fffca93700f7bc Mon Sep 17 00:00:00 2001
+From: milek7 <me@milek7.pl>
+Date: Tue, 8 Dec 2020 01:03:31 +0100
+Subject: [PATCH] Add liblzma port
+
+---
+Source: https://github.com/emscripten-core/emscripten/pull/12990
+
+Modifed by OpenTTD to have the bare minimum needed to work. Otherwise there
+are constantly conflicts when trying to apply this patch to different versions
+of emsdk.
+
+diff --git a/embuilder.py b/embuilder.py
+index 818262190ed..ab7d5adb7b2 100755
+--- a/embuilder.py
++++ b/embuilder.py
+@@ -60,6 +60,7 @@
+     'harfbuzz',
+     'icu',
+     'libjpeg',
++    'liblzma',
+     'libpng',
+     'ogg',
+     'regal',
+@@ -197,6 +198,8 @@ def main():
+       build_port('ogg', libname('libogg'))
+     elif what == 'libjpeg':
+       build_port('libjpeg', libname('libjpeg'))
++    elif what == 'liblzma':
++      build_port('liblzma', libname('liblzma'))
+     elif what == 'libpng':
+       build_port('libpng', libname('libpng'))
+     elif what == 'sdl2':
+diff --git a/src/settings.js b/src/settings.js
+index 61cd98939ba..be6fcb678c6 100644
+--- a/src/settings.js
++++ b/src/settings.js
+@@ -1197,6 +1197,9 @@ var USE_BZIP2 = 0;
+ // 1 = use libjpeg from emscripten-ports
+ var USE_LIBJPEG = 0;
+
++// 1 = use liblzma from emscripten-ports
++var USE_LIBLZMA = 0;
++
+ // 1 = use libpng from emscripten-ports
+ var USE_LIBPNG = 0;
+
+diff --git a/tools/ports/liblzma.py b/tools/ports/liblzma.py
+new file mode 100644
+index 00000000000..e9567ef36ff
+--- /dev/null
++++ b/tools/ports/liblzma.py
+@@ -0,0 +1,160 @@
++# Copyright 2020 The Emscripten Authors.  All rights reserved.
++# Emscripten is available under two separate licenses, the MIT license and the
++# University of Illinois/NCSA Open Source License.  Both these licenses can be
++# found in the LICENSE file.
++
++import os
++import shutil
++
++VERSION = '5.2.5'
++HASH = '7443674247deda2935220fbc4dfc7665e5bb5a260be8ad858c8bd7d7b9f0f868f04ea45e62eb17c0a5e6a2de7c7500ad2d201e2d668c48ca29bd9eea5a73a3ce'
++
++
++def needed(settings):
++  return settings.USE_LIBLZMA
++
++
++def get(ports, settings, shared):
++  libname = ports.get_lib_name('liblzma')
++  ports.fetch_project('liblzma', 'https://tukaani.org/xz/xz-' + VERSION + '.tar.gz', 'xz-' + VERSION, sha512hash=HASH)
++
++  def create():
++    ports.clear_project_build('liblzma')
++
++    source_path = os.path.join(ports.get_dir(), 'liblzma', 'xz-' + VERSION)
++    dest_path = os.path.join(ports.get_build_dir(), 'liblzma')
++
++    shared.try_delete(dest_path)
++    os.makedirs(dest_path)
++    shutil.rmtree(dest_path, ignore_errors=True)
++    shutil.copytree(source_path, dest_path)
++
++    build_flags = ['-DHAVE_CONFIG_H', '-DTUKLIB_SYMBOL_PREFIX=lzma_', '-fvisibility=hidden']
++    exclude_dirs = ['xzdec', 'xz', 'lzmainfo']
++    exclude_files = ['crc32_small.c', 'crc64_small.c', 'crc32_tablegen.c', 'crc64_tablegen.c', 'price_tablegen.c', 'fastpos_tablegen.c'
++                     'tuklib_exit.c', 'tuklib_mbstr_fw.c', 'tuklib_mbstr_width.c', 'tuklib_open_stdxxx.c', 'tuklib_progname.c']
++    include_dirs_rel = ['../common', 'api', 'common', 'check', 'lz', 'rangecoder', 'lzma', 'delta', 'simple']
++
++    open(os.path.join(dest_path, 'src', 'config.h'), 'w').write(config_h)
++
++    final = os.path.join(dest_path, libname)
++    include_dirs = [os.path.join(dest_path, 'src', 'liblzma', p) for p in include_dirs_rel]
++    ports.build_port(os.path.join(dest_path, 'src'), final, flags=build_flags, exclude_dirs=exclude_dirs, exclude_files=exclude_files, includes=include_dirs)
++
++    ports.install_headers(os.path.join(dest_path, 'src', 'liblzma', 'api'), 'lzma.h')
++    ports.install_headers(os.path.join(dest_path, 'src', 'liblzma', 'api', 'lzma'), '*.h', 'lzma')
++
++    return final
++
++  return [shared.Cache.get(libname, create, what='port')]
++
++
++def clear(ports, settings, shared):
++  shared.Cache.erase_file(ports.get_lib_name('liblzma'))
++
++
++def process_args(ports):
++  return []
++
++
++def show():
++  return 'liblzma (USE_LIBLZMA=1; public domain)'
++
++
++config_h = r'''
++#define ASSUME_RAM 128
++#define ENABLE_NLS 1
++#define HAVE_CHECK_CRC32 1
++#define HAVE_CHECK_CRC64 1
++#define HAVE_CHECK_SHA256 1
++#define HAVE_CLOCK_GETTIME 1
++#define HAVE_DCGETTEXT 1
++#define HAVE_DECL_CLOCK_MONOTONIC 1
++#define HAVE_DECL_PROGRAM_INVOCATION_NAME 1
++#define HAVE_DECODERS 1
++#define HAVE_DECODER_ARM 1
++#define HAVE_DECODER_ARMTHUMB 1
++#define HAVE_DECODER_DELTA 1
++#define HAVE_DECODER_IA64 1
++#define HAVE_DECODER_LZMA1 1
++#define HAVE_DECODER_LZMA2 1
++#define HAVE_DECODER_POWERPC 1
++#define HAVE_DECODER_SPARC 1
++#define HAVE_DECODER_X86 1
++#define HAVE_DLFCN_H 1
++#define HAVE_ENCODERS 1
++#define HAVE_ENCODER_ARM 1
++#define HAVE_ENCODER_ARMTHUMB 1
++#define HAVE_ENCODER_DELTA 1
++#define HAVE_ENCODER_IA64 1
++#define HAVE_ENCODER_LZMA1 1
++#define HAVE_ENCODER_LZMA2 1
++#define HAVE_ENCODER_POWERPC 1
++#define HAVE_ENCODER_SPARC 1
++#define HAVE_ENCODER_X86 1
++#define HAVE_FCNTL_H 1
++#define HAVE_FUTIMENS 1
++#define HAVE_GETOPT_H 1
++#define HAVE_GETOPT_LONG 1
++#define HAVE_GETTEXT 1
++#define HAVE_IMMINTRIN_H 1
++#define HAVE_INTTYPES_H 1
++#define HAVE_LIMITS_H 1
++#define HAVE_MBRTOWC 1
++#define HAVE_MEMORY_H 1
++#define HAVE_MF_BT2 1
++#define HAVE_MF_BT3 1
++#define HAVE_MF_BT4 1
++#define HAVE_MF_HC3 1
++#define HAVE_MF_HC4 1
++#define HAVE_OPTRESET 1
++#define HAVE_POSIX_FADVISE 1
++#define HAVE_PTHREAD_CONDATTR_SETCLOCK 1
++#define HAVE_PTHREAD_PRIO_INHERIT 1
++#define HAVE_STDBOOL_H 1
++#define HAVE_STDINT_H 1
++#define HAVE_STDLIB_H 1
++#define HAVE_STRINGS_H 1
++#define HAVE_STRING_H 1
++#define HAVE_STRUCT_STAT_ST_ATIM_TV_NSEC 1
++#define HAVE_SYS_PARAM_H 1
++#define HAVE_SYS_STAT_H 1
++#define HAVE_SYS_TIME_H 1
++#define HAVE_SYS_TYPES_H 1
++#define HAVE_UINTPTR_T 1
++#define HAVE_UNISTD_H 1
++#define HAVE_VISIBILITY 1
++#define HAVE_WCWIDTH 1
++#define HAVE__BOOL 1
++#define HAVE___BUILTIN_ASSUME_ALIGNED 1
++#define HAVE___BUILTIN_BSWAPXX 1
++#define MYTHREAD_POSIX 1
++#define NDEBUG 1
++#define PACKAGE "xz"
++#define PACKAGE_BUGREPORT "lasse.collin@tukaani.org"
++#define PACKAGE_NAME "XZ Utils"
++#define PACKAGE_STRING "XZ Utils 5.2.5"
++#define PACKAGE_TARNAME "xz"
++#define PACKAGE_VERSION "5.2.5"
++#define SIZEOF_SIZE_T 4
++#define STDC_HEADERS 1
++#define TUKLIB_CPUCORES_SYSCONF 1
++#define TUKLIB_FAST_UNALIGNED_ACCESS 1
++#define TUKLIB_PHYSMEM_SYSCONF 1
++#ifndef _ALL_SOURCE
++# define _ALL_SOURCE 1
++#endif
++#ifndef _GNU_SOURCE
++# define _GNU_SOURCE 1
++#endif
++#ifndef _POSIX_PTHREAD_SEMANTICS
++# define _POSIX_PTHREAD_SEMANTICS 1
++#endif
++#ifndef _TANDEM_SOURCE
++# define _TANDEM_SOURCE 1
++#endif
++#ifndef __EXTENSIONS__
++# define __EXTENSIONS__ 1
++#endif
++#define VERSION "5.2.5"
++'''

os/emscripten/pre.js

@@ -0,0 +1,93 @@
+Module.arguments.push('-mnull', '-snull', '-vsdl:relative_mode');
+Module['websocket'] = { url: function(host, port, proto) {
+    /* openttd.org hosts a WebSocket proxy for the content service. */
+    if (host == "content.openttd.org" && port == 3978 && proto == "tcp") {
+        return "wss://content.openttd.org/";
+    }
+
+    /* Everything else just tries to make a default WebSocket connection.
+     * If you run your own server you can setup your own WebSocket proxy in
+     * front of it and let people connect to your server via the proxy. You
+     * are best to add another "if" statement as above for this. */
+    return null;
+} };
+
+Module.preRun.push(function() {
+    personal_dir = '/home/web_user/.openttd';
+    content_download_dir = personal_dir + '/content_download'
+
+    /* Because of the "-c" above, all user-data is stored in /user_data. */
+    FS.mkdir(personal_dir);
+    FS.mount(IDBFS, {}, personal_dir);
+
+    Module.addRunDependency('syncfs');
+    FS.syncfs(true, function (err) {
+        /* FS.mkdir() tends to fail if parent folders do not exist. */
+        if (!FS.analyzePath(content_download_dir).exists) {
+            FS.mkdir(content_download_dir);
+        }
+        if (!FS.analyzePath(content_download_dir + '/baseset').exists) {
+            FS.mkdir(content_download_dir + '/baseset');
+        }
+
+        /* Check if the OpenGFX baseset is already downloaded. */
+        if (!FS.analyzePath(content_download_dir + '/baseset/opengfx-0.6.0.tar').exists) {
+            window.openttd_downloaded_opengfx = true;
+            FS.createPreloadedFile(content_download_dir + '/baseset', 'opengfx-0.6.0.tar', 'https://installer.cdn.openttd.org/emscripten/opengfx-0.6.0.tar', true, true);
+        } else {
+            /* Fake dependency increase, so the counter is stable. */
+            Module.addRunDependency('opengfx');
+            Module.removeRunDependency('opengfx');
+        }
+
+        Module.removeRunDependency('syncfs');
+    });
+
+    window.openttd_syncfs_shown_warning = false;
+    window.openttd_syncfs = function() {
+        /* Copy the virtual FS to the persistent storage. */
+        FS.syncfs(false, function (err) { });
+
+        /* On first time, warn the user about the volatile behaviour of
+         * persistent storage. */
+        if (!window.openttd_syncfs_shown_warning) {
+            window.openttd_syncfs_shown_warning = true;
+            Module.onWarningFs();
+        }
+    }
+
+    window.openttd_exit = function() {
+        Module.onExit();
+    }
+
+    window.openttd_abort = function() {
+        Module.onAbort();
+    }
+
+    window.openttd_server_list = function() {
+        add_server = Module.cwrap("em_openttd_add_server", null, ["string", "number"]);
+
+        /* Add servers that support WebSocket here. Example:
+         *  add_server("localhost", 3979); */
+    }
+
+    /* https://github.com/emscripten-core/emscripten/pull/12995 implements this
+    * properly. Till that time, we use a polyfill. */
+   SOCKFS.websocket_sock_ops.createPeer_ = SOCKFS.websocket_sock_ops.createPeer;
+   SOCKFS.websocket_sock_ops.createPeer = function(sock, addr, port)
+   {
+       let func = Module['websocket']['url'];
+       Module['websocket']['url'] = func(addr, port, (sock.type == 2) ? 'udp' : 'tcp');
+       let ret = SOCKFS.websocket_sock_ops.createPeer_(sock, addr, port);
+       Module['websocket']['url'] = func;
+       return ret;
+   }
+});
+
+Module.postRun.push(function() {
+    /* Check if we downloaded OpenGFX; if so, sync the virtual FS back to the
+     * IDBFS so OpenGFX is stored persistent. */
+    if (window['openttd_downloaded_opengfx']) {
+        FS.syncfs(false, function (err) { });
+    }
+});

regression/regression/result.txt

@@ -9075,7 +9075,7 @@ ERROR: IsEnd() is invalid as Begin() is never called
   --Accounting--
     GetCosts():         -5947
     Should be:          -5947
-  GetName():            Road Vehicle 1
+  GetName():            Road Vehicle #1
   SetName():            true
   GetName():            MyVehicleName
   CloneVehicle():       13

src/3rdparty/optional/LICENSE_1_0.txt

@@ -1,23 +0,0 @@
-Boost Software License - Version 1.0 - August 17th, 2003
-
-Permission is hereby granted, free of charge, to any person or organization
-obtaining a copy of the software and accompanying documentation covered by
-this license (the "Software") to use, reproduce, display, distribute,
-execute, and transmit the Software, and to prepare derivative works of the
-Software, and to permit third-parties to whom the Software is furnished to
-do so, all subject to the following:
-
-The copyright notices in the Software and this entire statement, including
-the above license grant, this restriction and the following disclaimer,
-must be included in all copies of the Software, in whole or in part, and
-all derivative works of the Software, unless such copies or derivative
-works are solely in the form of machine-executable object code generated by
-a source language processor.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
-SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
-FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
-ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
-DEALINGS IN THE SOFTWARE.

src/3rdparty/optional/ottd_optional.h

@@ -1,33 +0,0 @@
-/*
- * This file is part of OpenTTD.
- * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
- * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
- */
-
-/** @file ottd_optional.h Header to select between native. */
-
-#ifndef OTTD_OPTIONAL_H
-#define OTTD_OPTIONAL_H
-
-#if defined(__has_include)
-#	if __has_include(<version>)
-#		include <version>
-#	endif
-#endif
-
-#if (__cplusplus >= 201703L) || (defined(__cpp_lib_optional) && __cpp_lib_optional >= 201606L)
-
-/* Native std::optional. */
-#include <optional>
-namespace opt = std;
-
-#else
-
-/* No std::optional, use local copy instead. */
-#include "optional.hpp"
-namespace opt = std::experimental;
-
-#endif
-
-#endif /* OTTD_OPTIONAL_H */

src/CMakeLists.txt

@@ -1,3 +1,11 @@
+add_subdirectory(script)
+add_subdirectory(settingsgen)
+add_subdirectory(strgen)
+
+if(OPTION_TOOLS_ONLY)
+    return()
+endif()
+
 add_subdirectory(3rdparty)
 add_subdirectory(ai)
 add_subdirectory(blitter)
@@ -11,11 +19,8 @@ add_subdirectory(network)
 add_subdirectory(os)
 add_subdirectory(pathfinder)
 add_subdirectory(saveload)
-add_subdirectory(script)
-add_subdirectory(settingsgen)
 add_subdirectory(sound)
 add_subdirectory(spriteloader)
-add_subdirectory(strgen)
 add_subdirectory(table)
 add_subdirectory(video)
 add_subdirectory(widgets)

src/base_media_func.h

@@ -55,15 +55,15 @@ bool BaseSet<T, Tnum_files, Tsearch_in_tars>::FillSetDetails(IniFile *ini, const
 	}
 
 	fetch_metadata("shortname");
-	for (uint i = 0; item->value.value()[i] != '\0' && i < 4; i++) {
+	for (uint i = 0; (*item->value)[i] != '\0' && i < 4; i++) {
-		this->shortname |= ((uint8)item->value.value()[i]) << (i * 8);
+		this->shortname |= ((uint8)(*item->value)[i]) << (i * 8);
 	}
 
 	fetch_metadata("version");
 	this->version = atoi(item->value->c_str());
 
 	item = metadata->GetItem("fallback", false);
-	this->fallback = (item != nullptr && item->value && item->value.value() != "0" && item->value.value() != "false");
+	this->fallback = (item != nullptr && item->value && *item->value != "0" && *item->value != "false");
 
 	/* For each of the file types we want to find the file, MD5 checksums and warning messages. */
 	IniGroup *files  = ini->GetGroup("files");

src/bridge_gui.cpp

@@ -442,8 +442,7 @@ void ShowBuildBridgeWindow(TileIndex start, TileIndex end, TransportType transpo
 				/* Re-check bridge building possibility is initial bridge builindg query indicated a bridge type dependent failure */
 				if (query_per_bridge_type && DoCommand(end, start, type | brd_type, CommandFlagsToDCFlags(GetCommandFlags(CMD_BUILD_BRIDGE)) | DC_QUERY_COST, CMD_BUILD_BRIDGE).Failed()) continue;
 				/* bridge is accepted, add to list */
-				/*C++17: BuildBridgeData &item = */ bl->emplace_back();
+				BuildBridgeData &item = bl->emplace_back();
-				BuildBridgeData &item = bl->back();
 				item.index = brd_type;
 				item.spec = GetBridgeSpec(brd_type);
 				/* Add to terraforming & bulldozing costs the cost of the

src/core/smallmap_type.hpp

@@ -142,8 +142,7 @@ struct SmallMap : std::vector<std::pair<T, U> > {
 		for (uint i = 0; i < std::vector<Pair>::size(); i++) {
 			if (key == std::vector<Pair>::operator[](i).first) return std::vector<Pair>::operator[](i).second;
 		}
-		/*C++17: Pair &n = */ std::vector<Pair>::emplace_back();
+		Pair &n = std::vector<Pair>::emplace_back();
-		Pair &n = std::vector<Pair>::back();
 		n.first = key;
 		return n.second;
 	}

src/currency.cpp

@@ -26,14 +26,14 @@
 	 *   |   |    |          |              |                |  | */
 /** The original currency specifications. */
 static const CurrencySpec origin_currency_specs[CURRENCY_END] = {
-	{    1, "", CF_NOEURO, "\xC2\xA3",     "",               0, STR_GAME_OPTIONS_CURRENCY_GBP    }, ///< british pound
+	{    1, "", CF_NOEURO, u8"\u00a3",     "",               0, STR_GAME_OPTIONS_CURRENCY_GBP    }, ///< british pound
 	{    2, "", CF_NOEURO, "$",            "",               0, STR_GAME_OPTIONS_CURRENCY_USD    }, ///< american dollar
-	{    2, "", CF_ISEURO, "\xE2\x82\xAC", "",               0, STR_GAME_OPTIONS_CURRENCY_EUR    }, ///< euro
+	{    2, "", CF_ISEURO, u8"\u20ac",     "",               0, STR_GAME_OPTIONS_CURRENCY_EUR    }, ///< euro
-	{  220, "", CF_NOEURO, "\xC2\xA5",     "",               0, STR_GAME_OPTIONS_CURRENCY_JPY    }, ///< japanese yen
+	{  220, "", CF_NOEURO, u8"\u00a5",     "",               0, STR_GAME_OPTIONS_CURRENCY_JPY    }, ///< japanese yen
 	{   27, "", 2002,      "",             NBSP "S.",        1, STR_GAME_OPTIONS_CURRENCY_ATS    }, ///< austrian schilling
 	{   81, "", 2002,      "BEF" NBSP,     "",               0, STR_GAME_OPTIONS_CURRENCY_BEF    }, ///< belgian franc
 	{    2, "", CF_NOEURO, "CHF" NBSP,     "",               0, STR_GAME_OPTIONS_CURRENCY_CHF    }, ///< swiss franc
-	{   41, "", CF_NOEURO, "",             NBSP "K\xC4\x8D", 1, STR_GAME_OPTIONS_CURRENCY_CZK    }, ///< czech koruna
+	{   41, "", CF_NOEURO, "",             NBSP u8"K\u010d", 1, STR_GAME_OPTIONS_CURRENCY_CZK    }, ///< czech koruna
 	{    4, "", 2002,      "DM" NBSP,      "",               0, STR_GAME_OPTIONS_CURRENCY_DEM    }, ///< deutsche mark
 	{   11, "", CF_NOEURO, "",             NBSP "kr",        1, STR_GAME_OPTIONS_CURRENCY_DKK    }, ///< danish krone
 	{  333, "", 2002,      "Pts" NBSP,     "",               0, STR_GAME_OPTIONS_CURRENCY_ESP    }, ///< spanish peseta
@@ -45,7 +45,7 @@ static const CurrencySpec origin_currency_specs[CURRENCY_END] = {
 	{ 3873, "", 2002,      "",             NBSP "L.",        1, STR_GAME_OPTIONS_CURRENCY_ITL    }, ///< italian lira
 	{    4, "", 2002,      "NLG" NBSP,     "",               0, STR_GAME_OPTIONS_CURRENCY_NLG    }, ///< dutch gulden
 	{   12, "", CF_NOEURO, "",             NBSP "Kr",        1, STR_GAME_OPTIONS_CURRENCY_NOK    }, ///< norwegian krone
-	{    6, "", CF_NOEURO, "",             NBSP "z\xC5\x82", 1, STR_GAME_OPTIONS_CURRENCY_PLN    }, ///< polish zloty
+	{    6, "", CF_NOEURO, "",             NBSP u8"z\u0142", 1, STR_GAME_OPTIONS_CURRENCY_PLN    }, ///< polish zloty
 	{    5, "", CF_NOEURO, "",             NBSP "Lei",       1, STR_GAME_OPTIONS_CURRENCY_RON    }, ///< romanian leu
 	{   50, "", CF_NOEURO, "",             NBSP "p",         1, STR_GAME_OPTIONS_CURRENCY_RUR    }, ///< russian rouble
 	{  479, "", 2007,      "",             NBSP "SIT",       1, STR_GAME_OPTIONS_CURRENCY_SIT    }, ///< slovenian tolar
@@ -55,7 +55,7 @@ static const CurrencySpec origin_currency_specs[CURRENCY_END] = {
 	{    4, "", CF_NOEURO, "R$" NBSP,      "",               0, STR_GAME_OPTIONS_CURRENCY_BRL    }, ///< brazil real
 	{   31, "", 2011,      "",             NBSP "EEK",       1, STR_GAME_OPTIONS_CURRENCY_EEK    }, ///< estonian krooni
 	{    4, "", 2015,      "",             NBSP "Lt",        1, STR_GAME_OPTIONS_CURRENCY_LTL    }, ///< lithuanian litas
-	{ 1850, "", CF_NOEURO, "\xE2\x82\xA9", "",               0, STR_GAME_OPTIONS_CURRENCY_KRW    }, ///< south korean won
+	{ 1850, "", CF_NOEURO, u8"\u20a9",     "",               0, STR_GAME_OPTIONS_CURRENCY_KRW    }, ///< south korean won
 	{   13, "", CF_NOEURO, "R" NBSP,       "",               0, STR_GAME_OPTIONS_CURRENCY_ZAR    }, ///< south african rand
 	{    1, "", CF_NOEURO, "",             "",               2, STR_GAME_OPTIONS_CURRENCY_CUSTOM }, ///< custom currency (add further languages below)
 	{    3, "", CF_NOEURO, "",             NBSP "GEL",       1, STR_GAME_OPTIONS_CURRENCY_GEL    }, ///< Georgian Lari
@@ -63,9 +63,9 @@ static const CurrencySpec origin_currency_specs[CURRENCY_END] = {
 	{   80, "", CF_NOEURO, "",             NBSP "rub",       1, STR_GAME_OPTIONS_CURRENCY_RUB    }, ///< New Russian Ruble
 	{   24, "", CF_NOEURO, "$",            "",               0, STR_GAME_OPTIONS_CURRENCY_MXN    }, ///< Mexican peso
 	{   40, "", CF_NOEURO, "NTD" NBSP,     "",               0, STR_GAME_OPTIONS_CURRENCY_NTD    }, ///< new taiwan dollar
-	{    8, "", CF_NOEURO, "\xC2\xA5",     "",               0, STR_GAME_OPTIONS_CURRENCY_CNY    }, ///< chinese renminbi
+	{    8, "", CF_NOEURO, u8"\u00a5",     "",               0, STR_GAME_OPTIONS_CURRENCY_CNY    }, ///< chinese renminbi
 	{   10, "", CF_NOEURO, "HKD" NBSP,     "",               0, STR_GAME_OPTIONS_CURRENCY_HKD    }, ///< hong kong dollar
-	{   90, "", CF_NOEURO, "\xE2\x82\xB9", "",               0, STR_GAME_OPTIONS_CURRENCY_INR    }, ///< Indian Rupee
+	{   90, "", CF_NOEURO, u8"\u20b9",     "",               0, STR_GAME_OPTIONS_CURRENCY_INR    }, ///< Indian Rupee
 };
 
 /** Array of currencies used by the system */

src/engine.cpp

@@ -496,8 +496,7 @@ void EngineOverrideManager::ResetToDefaultMapping()
 	this->clear();
 	for (VehicleType type = VEH_TRAIN; type <= VEH_AIRCRAFT; type++) {
 		for (uint internal_id = 0; internal_id < _engine_counts[type]; internal_id++) {
-			/*C++17: EngineIDMapping &eid = */ this->emplace_back();
+			EngineIDMapping &eid = this->emplace_back();
-			EngineIDMapping &eid = this->back();
 			eid.type            = type;
 			eid.grfid           = INVALID_GRFID;
 			eid.internal_id     = internal_id;

src/fios.h

@@ -126,8 +126,7 @@ public:
 	 */
 	inline FiosItem *Append()
 	{
-		/*C++17: return &*/ this->files.emplace_back();
+		return &this->files.emplace_back();
-		return &this->files.back();
 	}
 
 	/**

src/fontcache.cpp

@@ -26,7 +26,6 @@
 #include "safeguards.h"
 
 static const int ASCII_LETTERSTART = 32; ///< First printable ASCII letter.
-static const int MAX_FONT_SIZE     = 72; ///< Maximum font size.
 
 /** Default heights for the different sizes of fonts. */
 static const int _default_font_height[FS_END]   = {10, 6, 18, 10};
@@ -200,6 +199,8 @@ void UpdateFontHeightCache()
 
 FreeTypeSettings _freetype;
 
+static const int MAX_FONT_SIZE = 72; ///< Maximum font size.
+
 static const byte FACE_COLOUR = 1;
 static const byte SHADOW_COLOUR = 2;
 

src/gfx.cpp

@@ -2090,6 +2090,30 @@ void SetAnimatedMouseCursor(const AnimCursor *table)
 	SwitchAnimatedCursor();
 }
 
+/**
+ * Update cursor position on mouse movement for relative modes.
+ * @param delta_x How much change in the X position.
+ * @param delta_y How much change in the Y position.
+ */
+void CursorVars::UpdateCursorPositionRelative(int delta_x, int delta_y)
+{
+	if (this->fix_at) {
+		this->delta.x = delta_x;
+		this->delta.y = delta_y;
+	} else {
+		int last_position_x = this->pos.x;
+		int last_position_y = this->pos.y;
+
+		this->pos.x = Clamp(this->pos.x + delta_x, 0, _cur_resolution.width - 1);
+		this->pos.y = Clamp(this->pos.y + delta_y, 0, _cur_resolution.height - 1);
+
+		this->delta.x = last_position_x - this->pos.x;
+		this->delta.y = last_position_y - this->pos.y;
+
+		this->dirty = true;
+	}
+}
+
 /**
  * Update cursor position on mouse movement.
  * @param x New X position.

src/gfx_type.h

@@ -144,6 +144,7 @@ struct CursorVars {
 	/* Drag data */
 	bool vehchain;                ///< vehicle chain is dragged
 
+	void UpdateCursorPositionRelative(int delta_x, int delta_y);
 	bool UpdateCursorPosition(int x, int y, bool queued_warp);
 
 private:
@@ -163,7 +164,9 @@ struct DrawPixelInfo {
 union Colour {
 	uint32 data; ///< Conversion of the channel information to a 32 bit number.
 	struct {
-#if TTD_ENDIAN == TTD_BIG_ENDIAN
+#if defined(__EMSCRIPTEN__)
+		uint8 r, g, b, a;  ///< colour channels as used in browsers
+#elif TTD_ENDIAN == TTD_BIG_ENDIAN
 		uint8 a, r, g, b; ///< colour channels in BE order
 #else
 		uint8 b, g, r, a; ///< colour channels in LE order
@@ -178,7 +181,9 @@ union Colour {
 	 * @param a The channel for the alpha/transparency.
 	 */
 	Colour(uint8 r, uint8 g, uint8 b, uint8 a = 0xFF) :
-#if TTD_ENDIAN == TTD_BIG_ENDIAN
+#if defined(__EMSCRIPTEN__)
+		r(r), g(g), b(b), a(a)
+#elif TTD_ENDIAN == TTD_BIG_ENDIAN
 		a(a), r(r), g(g), b(b)
 #else
 		b(b), g(g), r(r), a(a)

src/gfxinit.cpp

@@ -504,11 +504,11 @@ bool GraphicsSet::FillSetDetails(IniFile *ini, const char *path, const char *ful
 		IniItem *item;
 
 		fetch_metadata("palette");
-		this->palette = (item->value.value()[0] == 'D' || item->value.value()[0] == 'd') ? PAL_DOS : PAL_WINDOWS;
+		this->palette = ((*item->value)[0] == 'D' || (*item->value)[0] == 'd') ? PAL_DOS : PAL_WINDOWS;
 
 		/* Get optional blitter information. */
 		item = metadata->GetItem("blitter", false);
-		this->blitter = (item != nullptr && item->value.value()[0] == '3') ? BLT_32BPP : BLT_8BPP;
+		this->blitter = (item != nullptr && (*item->value)[0] == '3') ? BLT_32BPP : BLT_8BPP;
 	}
 	return ret;
 }

src/group_cmd.cpp

@@ -473,6 +473,8 @@ CommandCost CmdAlterGroup(TileIndex tile, DoCommandFlag flags, uint32 p1, uint32
 		InvalidateWindowData(WC_REPLACE_VEHICLE, g->vehicle_type, 1);
 		InvalidateWindowData(GetWindowClassForVehicleType(g->vehicle_type), VehicleListIdentifier(VL_GROUP_LIST, g->vehicle_type, _current_company).Pack());
 		InvalidateWindowData(WC_COMPANY_COLOUR, g->owner, g->vehicle_type);
+		InvalidateWindowClassesData(WC_VEHICLE_VIEW);
+		InvalidateWindowClassesData(WC_VEHICLE_DETAILS);
 		InvalidateWindowData(WC_TEMPLATEGUI_MAIN, 0, 0, 0);
 	}
 
@@ -609,6 +611,8 @@ CommandCost CmdAddVehicleGroup(TileIndex tile, DoCommandFlag flags, uint32 p1, u
 		SetWindowDirty(WC_VEHICLE_VIEW, v->index);
 		SetWindowDirty(WC_VEHICLE_DETAILS, v->index);
 		InvalidateWindowData(GetWindowClassForVehicleType(v->type), VehicleListIdentifier(VL_GROUP_LIST, v->type, _current_company).Pack());
+		InvalidateWindowData(WC_VEHICLE_VIEW, v->index);
+		InvalidateWindowData(WC_VEHICLE_DETAILS, v->index);
 	}
 
 	return CommandCost();

src/industry_gui.cpp

@@ -2633,8 +2633,7 @@ struct IndustryCargoesWindow : public Window {
 		_displayed_industries.set(it);
 
 		this->fields.clear();
-		/*C++17: CargoesRow &row = */ this->fields.emplace_back();
+		CargoesRow &row = this->fields.emplace_back();
-		CargoesRow &row = this->fields.back();
 		row.columns[0].MakeHeader(STR_INDUSTRY_CARGOES_PRODUCERS);
 		row.columns[1].MakeEmpty(CFT_SMALL_EMPTY);
 		row.columns[2].MakeEmpty(CFT_SMALL_EMPTY);
@@ -2649,8 +2648,7 @@ struct IndustryCargoesWindow : public Window {
 		int num_cust = CountMatchingAcceptingIndustries(central_sp->produced_cargo, lengthof(central_sp->produced_cargo)) + houses_accept;
 		int num_indrows = max(3, max(num_supp, num_cust)); // One is needed for the 'it' industry, and 2 for the cargo labels.
 		for (int i = 0; i < num_indrows; i++) {
-			/*C++17: CargoesRow &row = */ this->fields.emplace_back();
+			CargoesRow &row = this->fields.emplace_back();
-			CargoesRow &row = this->fields.back();
 			row.columns[0].MakeEmpty(CFT_EMPTY);
 			row.columns[1].MakeCargo(central_sp->accepts_cargo, lengthof(central_sp->accepts_cargo));
 			row.columns[2].MakeEmpty(CFT_EMPTY);
@@ -2713,8 +2711,7 @@ struct IndustryCargoesWindow : public Window {
 		_displayed_industries.reset();
 
 		this->fields.clear();
-		/*C++17: CargoesRow &row = */ this->fields.emplace_back();
+		CargoesRow &row = this->fields.emplace_back();
-		CargoesRow &row = this->fields.back();
 		row.columns[0].MakeHeader(STR_INDUSTRY_CARGOES_PRODUCERS);
 		row.columns[1].MakeEmpty(CFT_SMALL_EMPTY);
 		row.columns[2].MakeHeader(STR_INDUSTRY_CARGOES_CUSTOMERS);
@@ -2727,8 +2724,7 @@ struct IndustryCargoesWindow : public Window {
 		int num_cust = CountMatchingAcceptingIndustries(&cid, 1) + houses_accept;
 		int num_indrows = max(num_supp, num_cust);
 		for (int i = 0; i < num_indrows; i++) {
-			/*C++17: CargoesRow &row = */ this->fields.emplace_back();
+			CargoesRow &row = this->fields.emplace_back();
-			CargoesRow &row = this->fields.back();
 			row.columns[0].MakeEmpty(CFT_EMPTY);
 			row.columns[1].MakeCargo(&cid, 1);
 			row.columns[2].MakeEmpty(CFT_EMPTY);

src/ini.cpp

@@ -13,6 +13,9 @@
 #include "string_func.h"
 #include "fileio_func.h"
 #include <fstream>
+#ifdef __EMSCRIPTEN__
+#	include <emscripten.h>
+#endif
 
 #if (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 199309L) || (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 500)
 # include <unistd.h>
@@ -115,6 +118,10 @@ bool IniFile::SaveToDisk(const char *filename)
 	}
 #endif
 
+#ifdef __EMSCRIPTEN__
+	EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
+#endif
+
 	return true;
 }
 

src/ini_type.h

@@ -12,7 +12,7 @@
 
 #include "fileio_type.h"
 #include <string>
-#include "3rdparty/optional/ottd_optional.h"
+#include <optional>
 
 #include <string>
 
@@ -27,7 +27,7 @@ enum IniGroupType {
 struct IniItem {
 	IniItem *next;                    ///< The next item in this group
 	std::string name;                 ///< The name of this item
-	opt::optional<std::string> value; ///< The value of this item
+	std::optional<std::string> value; ///< The value of this item
 	std::string comment;              ///< The comment associated with this item
 
 	IniItem(struct IniGroup *parent, const std::string &name);

src/lang/english.txt

@@ -5825,10 +5825,10 @@ STR_INDUSTRY_NAME_SUGAR_MINE                                    :Sugar Mine
 ##id 0x6000
 STR_SV_EMPTY                                                    :
 STR_SV_UNNAMED                                                  :Unnamed
-STR_SV_TRAIN_NAME                                               :Train {COMMA}
+STR_SV_TRAIN_NAME                                               :Train #{COMMA}
-STR_SV_ROAD_VEHICLE_NAME                                        :Road Vehicle {COMMA}
+STR_SV_ROAD_VEHICLE_NAME                                        :Road Vehicle #{COMMA}
-STR_SV_SHIP_NAME                                                :Ship {COMMA}
+STR_SV_SHIP_NAME                                                :Ship #{COMMA}
-STR_SV_AIRCRAFT_NAME                                            :Aircraft {COMMA}
+STR_SV_AIRCRAFT_NAME                                            :Aircraft #{COMMA}
 
 STR_SV_STNAME                                                   :{STRING1}
 STR_SV_STNAME_NORTH                                             :{STRING1} North
@@ -6135,6 +6135,7 @@ STR_FORMAT_BUOY_NAME                                            :{TOWN} Buoy
 STR_FORMAT_BUOY_NAME_SERIAL                                     :{TOWN} Buoy #{COMMA}
 STR_FORMAT_COMPANY_NUM                                          :(Company {COMMA})
 STR_FORMAT_GROUP_NAME                                           :Group {COMMA}
+STR_FORMAT_GROUP_VEHICLE_NAME                                   :{GROUP} #{COMMA}
 STR_FORMAT_INDUSTRY_NAME                                        :{TOWN} {STRING}
 STR_FORMAT_WAYPOINT_NAME                                        :{TOWN} Waypoint
 STR_FORMAT_WAYPOINT_NAME_SERIAL                                 :{TOWN} Waypoint #{COMMA}

src/misc_gui.cpp

@@ -450,73 +450,73 @@ static WindowDesc _about_desc(
 );
 
 static const char * const _credits[] = {
-	"Original design by Chris Sawyer",
+	u8"Original design by Chris Sawyer",
-	"Original graphics by Simon Foster",
+	u8"Original graphics by Simon Foster",
-	"",
+	u8"",
-	"The OpenTTD team (in alphabetical order):",
+	u8"The OpenTTD team (in alphabetical order):",
-	"  Grzegorz Duczy\xC5\x84ski (adf88) - General coding (since 1.7.2)",
+	u8"  Grzegorz Duczy\u0144ski (adf88) - General coding (since 1.7.2)",
-	"  Albert Hofkamp (Alberth) - GUI expert (since 0.7)",
+	u8"  Albert Hofkamp (Alberth) - GUI expert (since 0.7)",
-	"  Matthijs Kooijman (blathijs) - Pathfinder-guru, Debian port (since 0.3)",
+	u8"  Matthijs Kooijman (blathijs) - Pathfinder-guru, Debian port (since 0.3)",
-	"  Ulf Hermann (fonsinchen) - Cargo Distribution (since 1.3)",
+	u8"  Ulf Hermann (fonsinchen) - Cargo Distribution (since 1.3)",
-	"  Christoph Elsenhans (frosch) - General coding (since 0.6)",
+	u8"  Christoph Elsenhans (frosch) - General coding (since 0.6)",
-	"  Lo\xC3\xAF""c Guilloux (glx) - General / Windows Expert (since 0.4.5)",
+	u8"  Lo\u00efc Guilloux (glx) - General / Windows Expert (since 0.4.5)",
-	"  Charles Pigott (LordAro) - General / Correctness police (since 1.9)",
+	u8"  Charles Pigott (LordAro) - General / Correctness police (since 1.9)",
-	"  Michael Lutz (michi_cc) - Path based signals (since 0.7)",
+	u8"  Michael Lutz (michi_cc) - Path based signals (since 0.7)",
-	"  Niels Martin Hansen (nielsm) - Music system, general coding (since 1.9)",
+	u8"  Niels Martin Hansen (nielsm) - Music system, general coding (since 1.9)",
-	"  Owen Rudge (orudge) - Forum host, OS/2 port (since 0.1)",
+	u8"  Owen Rudge (orudge) - Forum host, OS/2 port (since 0.1)",
-	"  Peter Nelson (peter1138) - Spiritual descendant from NewGRF gods (since 0.4.5)",
+	u8"  Peter Nelson (peter1138) - Spiritual descendant from NewGRF gods (since 0.4.5)",
-	"  Ingo von Borstel (planetmaker) - General, Support (since 1.1)",
+	u8"  Ingo von Borstel (planetmaker) - General, Support (since 1.1)",
-	"  Remko Bijker (Rubidium) - Lead coder and way more (since 0.4.5)",
+	u8"  Remko Bijker (Rubidium) - Lead coder and way more (since 0.4.5)",
-	"  Jos\xC3\xA9 Soler (Terkhen) - General coding (since 1.0)",
+	u8"  Jos\u00e9 Soler (Terkhen) - General coding (since 1.0)",
-	"  Leif Linse (Zuu) - AI/Game Script (since 1.2)",
+	u8"  Leif Linse (Zuu) - AI/Game Script (since 1.2)",
-	"",
+	u8"",
-	"Inactive Developers:",
+	u8"Inactive Developers:",
-	"  Jean-Fran\xC3\xA7ois Claeys (Belugas) - GUI, NewGRF and more (0.4.5 - 1.0)",
+	u8"  Jean-Fran\u00e7ois Claeys (Belugas) - GUI, NewGRF and more (0.4.5 - 1.0)",
-	"  Bjarni Corfitzen (Bjarni) - MacOSX port, coder and vehicles (0.3 - 0.7)",
+	u8"  Bjarni Corfitzen (Bjarni) - MacOSX port, coder and vehicles (0.3 - 0.7)",
-	"  Victor Fischer (Celestar) - Programming everywhere you need him to (0.3 - 0.6)",
+	u8"  Victor Fischer (Celestar) - Programming everywhere you need him to (0.3 - 0.6)",
-	"  Jaroslav Mazanec (KUDr) - YAPG (Yet Another Pathfinder God) ;) (0.4.5 - 0.6)",
+	u8"  Jaroslav Mazanec (KUDr) - YAPG (Yet Another Pathfinder God) ;) (0.4.5 - 0.6)",
-	"  Jonathan Coome (Maedhros) - High priest of the NewGRF Temple (0.5 - 0.6)",
+	u8"  Jonathan Coome (Maedhros) - High priest of the NewGRF Temple (0.5 - 0.6)",
-	"  Attila B\xC3\xA1n (MiHaMiX) - Developer WebTranslator 1 and 2 (0.3 - 0.5)",
+	u8"  Attila B\u00e1n (MiHaMiX) - Developer WebTranslator 1 and 2 (0.3 - 0.5)",
-	"  Zden\xC4\x9Bk Sojka (SmatZ) - Bug finder and fixer (0.6 - 1.3)",
+	u8"  Zden\u011bk Sojka (SmatZ) - Bug finder and fixer (0.6 - 1.3)",
-	"  Christoph Mallon (Tron) - Programmer, code correctness police (0.3 - 0.5)",
+	u8"  Christoph Mallon (Tron) - Programmer, code correctness police (0.3 - 0.5)",
-	"  Patric Stout (TrueBrain) - NoAI, NoGo, Network (0.3 - 1.2), sys op (active)",
+	u8"  Patric Stout (TrueBrain) - NoAI, NoGo, Network (0.3 - 1.2), sys op (active)",
-	"  Thijs Marinussen (Yexo) - AI Framework, General (0.6 - 1.3)",
+	u8"  Thijs Marinussen (Yexo) - AI Framework, General (0.6 - 1.3)",
-	"",
+	u8"",
-	"Retired Developers:",
+	u8"Retired Developers:",
-	"  Tam\xC3\xA1s Farag\xC3\xB3 (Darkvater) - Ex-Lead coder (0.3 - 0.5)",
+	u8"  Tam\u00e1s Farag\u00f3 (Darkvater) - Ex-Lead coder (0.3 - 0.5)",
-	"  Dominik Scherer (dominik81) - Lead programmer, GUI expert (0.3 - 0.3)",
+	u8"  Dominik Scherer (dominik81) - Lead programmer, GUI expert (0.3 - 0.3)",
-	"  Emil Djupfeld (egladil) - MacOSX (0.4.5 - 0.6)",
+	u8"  Emil Djupfeld (egladil) - MacOSX (0.4.5 - 0.6)",
-	"  Simon Sasburg (HackyKid) - Many bugfixes (0.4 - 0.4.5)",
+	u8"  Simon Sasburg (HackyKid) - Many bugfixes (0.4 - 0.4.5)",
-	"  Ludvig Strigeus (ludde) - Original author of OpenTTD, main coder (0.1 - 0.3)",
+	u8"  Ludvig Strigeus (ludde) - Original author of OpenTTD, main coder (0.1 - 0.3)",
-	"  Cian Duffy (MYOB) - BeOS port / manual writing (0.1 - 0.3)",
+	u8"  Cian Duffy (MYOB) - BeOS port / manual writing (0.1 - 0.3)",
-	"  Petr Baudi\xC5\xA1 (pasky) - Many patches, NewGRF support (0.3 - 0.3)",
+	u8"  Petr Baudi\u0161 (pasky) - Many patches, NewGRF support (0.3 - 0.3)",
-	"  Benedikt Br\xC3\xBCggemeier (skidd13) - Bug fixer and code reworker (0.6 - 0.7)",
+	u8"  Benedikt Br\u00fcggemeier (skidd13) - Bug fixer and code reworker (0.6 - 0.7)",
-	"  Serge Paquet (vurlix) - 2nd contributor after ludde (0.1 - 0.3)",
+	u8"  Serge Paquet (vurlix) - 2nd contributor after ludde (0.1 - 0.3)",
-	"",
+	u8"",
-	"Special thanks go out to:",
+	u8"Special thanks go out to:",
-	"  Josef Drexler - For his great work on TTDPatch",
+	u8"  Josef Drexler - For his great work on TTDPatch",
-	"  Marcin Grzegorczyk - Track foundations and for describing TTD internals",
+	u8"  Marcin Grzegorczyk - Track foundations and for describing TTD internals",
-	"  Stefan Mei\xC3\x9Fner (sign_de) - For his work on the console",
+	u8"  Stefan Mei\u00dfner (sign_de) - For his work on the console",
-	"  Mike Ragsdale - OpenTTD installer",
+	u8"  Mike Ragsdale - OpenTTD installer",
-	"  Christian Rosentreter (tokai) - MorphOS / AmigaOS port",
+	u8"  Christian Rosentreter (tokai) - MorphOS / AmigaOS port",
-	"  Richard Kempton (richK) - additional airports, initial TGP implementation",
+	u8"  Richard Kempton (richK) - additional airports, initial TGP implementation",
-	"",
+	u8"",
-	"  Alberto Demichelis - Squirrel scripting language \xC2\xA9 2003-2008",
+	u8"  Alberto Demichelis - Squirrel scripting language \u00a9 2003-2008",
-	"  L. Peter Deutsch - MD5 implementation \xC2\xA9 1999, 2000, 2002",
+	u8"  L. Peter Deutsch - MD5 implementation \u00a9 1999, 2000, 2002",
-	"  Michael Blunck - Pre-signals and semaphores \xC2\xA9 2003",
+	u8"  Michael Blunck - Pre-signals and semaphores \u00a9 2003",
-	"  George - Canal/Lock graphics \xC2\xA9 2003-2004",
+	u8"  George - Canal/Lock graphics \u00a9 2003-2004",
-	"  Andrew Parkhouse (andythenorth) - River graphics",
+	u8"  Andrew Parkhouse (andythenorth) - River graphics",
-	"  David Dallaston (Pikka) - Tram tracks",
+	u8"  David Dallaston (Pikka) - Tram tracks",
-	"  All Translators - Who made OpenTTD a truly international game",
+	u8"  All Translators - Who made OpenTTD a truly international game",
-	"  Bug Reporters - Without whom OpenTTD would still be full of bugs!",
+	u8"  Bug Reporters - Without whom OpenTTD would still be full of bugs!",
-	"",
+	u8"",
-	"",
+	u8"",
-	"Developer of this patchpack:",
+	u8"Developer of this patchpack:",
-	"  Jonathan G. Rennison (JGR)",
+	u8"  Jonathan G. Rennison (JGR)",
-	"",
+	u8"",
-	"",
+	u8"",
-	"And last but not least:",
+	u8"And last but not least:",
-	"  Chris Sawyer - For an amazing game!"
+	u8"  Chris Sawyer - For an amazing game!"
 };
 
 struct AboutWindow : public Window {

src/network/core/address.cpp

@@ -265,6 +265,18 @@ SOCKET NetworkAddress::Resolve(int family, int socktype, int flags, SocketList *
 			this->address_length = (int)runp->ai_addrlen;
 			assert(sizeof(this->address) >= runp->ai_addrlen);
 			memcpy(&this->address, runp->ai_addr, runp->ai_addrlen);
+#ifdef __EMSCRIPTEN__
+			/* Emscripten doesn't zero sin_zero, but as we compare addresses
+			 * to see if they are the same address, we need them to be zero'd.
+			 * Emscripten is, as far as we know, the only OS not doing this.
+			 *
+			 * https://github.com/emscripten-core/emscripten/issues/12998
+			 */
+			if (this->address.ss_family == AF_INET) {
+				sockaddr_in *address_ipv4 = (sockaddr_in *)&this->address;
+				memset(address_ipv4->sin_zero, 0, sizeof(address_ipv4->sin_zero));
+			}
+#endif
 			break;
 		}
 
@@ -297,7 +309,15 @@ static SOCKET ConnectLoopProc(addrinfo *runp)
 
 	if (!SetNoDelay(sock)) DEBUG(net, 1, "[%s] setting TCP_NODELAY failed", type);
 
-	if (connect(sock, runp->ai_addr, (int)runp->ai_addrlen) != 0) {
+	int err = connect(sock, runp->ai_addr, (int)runp->ai_addrlen);
+#ifdef __EMSCRIPTEN__
+	/* Emscripten is asynchronous, and as such a connect() is still in
+	 * progress by the time the call returns. */
+	if (err != 0 && errno != EINPROGRESS)
+#else
+	if (err != 0)
+#endif
+	{
 		DEBUG(net, 1, "[%s] could not connect %s socket: %s", type, family, strerror(errno));
 		closesocket(sock);
 		return INVALID_SOCKET;

src/network/core/os_abstraction.h

@@ -99,6 +99,16 @@ typedef unsigned long in_addr_t;
 #	include <errno.h>
 #	include <sys/time.h>
 #	include <netdb.h>
+
+#   if defined(__EMSCRIPTEN__)
+/* Emscripten doesn't support AI_ADDRCONFIG and errors out on it. */
+#		undef AI_ADDRCONFIG
+#		define AI_ADDRCONFIG 0
+/* Emscripten says it supports FD_SETSIZE fds, but it really only supports 64.
+ * https://github.com/emscripten-core/emscripten/issues/1711 */
+#		undef FD_SETSIZE
+#		define FD_SETSIZE 64
+#   endif
 #endif /* UNIX */
 
 /* OS/2 stuff */
@@ -160,6 +170,28 @@ typedef unsigned long in_addr_t;
 
 #endif /* OS/2 */
 
+#ifdef __EMSCRIPTEN__
+/**
+ * Emscripten doesn't set 'addrlen' for accept(), getsockname(), getpeername()
+ * and recvfrom(), which confuses other functions and causes them to crash.
+ * This function needs to be called after these four functions to make sure
+ * 'addrlen' is patched up.
+ *
+ * https://github.com/emscripten-core/emscripten/issues/12996
+ *
+ * @param address The address returned by those four functions.
+ * @return The correct value for addrlen.
+ */
+static inline socklen_t FixAddrLenForEmscripten(struct sockaddr_storage &address)
+{
+	switch (address.ss_family) {
+		case AF_INET6: return sizeof(struct sockaddr_in6);
+		case AF_INET: return sizeof(struct sockaddr_in);
+		default: NOT_REACHED();
+	}
+}
+#endif
+
 /**
  * Try to set the socket into non-blocking mode.
  * @param d The socket to set the non-blocking more for.
@@ -167,12 +199,16 @@ typedef unsigned long in_addr_t;
  */
 static inline bool SetNonBlocking(SOCKET d)
 {
-#ifdef _WIN32
+#ifdef __EMSCRIPTEN__
-	u_long nonblocking = 1;
+	return true;
 #else
+#	ifdef _WIN32
+	u_long nonblocking = 1;
+#	else
 	int nonblocking = 1;
-#endif
+#	endif
 	return ioctlsocket(d, FIONBIO, &nonblocking) == 0;
+#endif
 }
 
 /**
@@ -197,10 +233,14 @@ static inline bool SetBlocking(SOCKET d)
  */
 static inline bool SetNoDelay(SOCKET d)
 {
+#ifdef __EMSCRIPTEN__
+	return true;
+#else
 	/* XXX should this be done at all? */
 	int b = 1;
 	/* The (const char*) cast is needed for windows */
 	return setsockopt(d, IPPROTO_TCP, TCP_NODELAY, (const char*)&b, sizeof(b)) == 0;
+#endif
 }
 
 

src/network/core/tcp_listen.h

@@ -42,6 +42,9 @@ public:
 			socklen_t sin_len = sizeof(sin);
 			SOCKET s = accept(ls, (struct sockaddr*)&sin, &sin_len);
 			if (s == INVALID_SOCKET) return;
+#ifdef __EMSCRIPTEN__
+			sin_len = FixAddrLenForEmscripten(sin);
+#endif
 
 			SetNonBlocking(s); // XXX error handling?
 

src/network/core/udp.cpp

@@ -164,6 +164,9 @@ void NetworkUDPSocketHandler::ReceivePackets()
 			/* Did we get the bytes for the base header of the packet? */
 			if (nbytes <= 0) break;    // No data, i.e. no packet
 			if (nbytes <= 2) continue; // Invalid data; try next packet
+#ifdef __EMSCRIPTEN__
+			client_len = FixAddrLenForEmscripten(client_addr);
+#endif
 
 			NetworkAddress address(client_addr, client_len);
 			p.PrepareToRead();

src/network/network.cpp

@@ -1122,3 +1122,14 @@ bool IsNetworkCompatibleVersion(const char *other, bool extended)
 {
 	return strncmp(_openttd_revision, other, (extended ? NETWORK_LONG_REVISION_LENGTH : NETWORK_REVISION_LENGTH) - 1) == 0;
 }
+
+#ifdef __EMSCRIPTEN__
+extern "C" {
+
+void CDECL em_openttd_add_server(const char *host, int port)
+{
+	NetworkUDPQueryServer(NetworkAddress(host, port), true);
+}
+
+}
+#endif

src/network/network_content.cpp

@@ -23,6 +23,10 @@
 #include <zlib.h>
 #endif
 
+#ifdef __EMSCRIPTEN__
+#	include <emscripten.h>
+#endif
+
 #include "../safeguards.h"
 
 extern bool HasScenario(const ContentInfo *ci, bool md5sum);
@@ -296,6 +300,13 @@ void ClientNetworkContentSocketHandler::DownloadSelectedContent(uint &files, uin
 {
 	bytes = 0;
 
+#ifdef __EMSCRIPTEN__
+	/* Emscripten is loaded via an HTTPS connection. As such, it is very
+	 * difficult to make HTTP connections. So always use the TCP method of
+	 * downloading content. */
+	fallback = true;
+#endif
+
 	ContentIDList content;
 	for (const ContentInfo *ci : this->infos) {
 		if (!ci->IsSelected() || ci->state == ContentInfo::ALREADY_HERE) continue;
@@ -542,6 +553,10 @@ void ClientNetworkContentSocketHandler::AfterDownload()
 			unlink(GetFullFilename(this->curInfo, false));
 		}
 
+#ifdef __EMSCRIPTEN__
+		EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
+#endif
+
 		this->OnDownloadComplete(this->curInfo->id);
 	} else {
 		ShowErrorMessage(STR_CONTENT_ERROR_COULD_NOT_EXTRACT, INVALID_STRING_ID, WL_ERROR);

src/network/network_gui.cpp

@@ -41,6 +41,9 @@
 
 #include "../safeguards.h"
 
+#ifdef __EMSCRIPTEN__
+#	include <emscripten.h>
+#endif
 
 static void ShowNetworkStartServerWindow();
 static void ShowNetworkLobbyWindow(NetworkGameList *ngl);
@@ -490,6 +493,14 @@ public:
 		this->filter_editbox.cancel_button = QueryString::ACTION_CLEAR;
 		this->SetFocusedWidget(WID_NG_FILTER);
 
+		/* As the master-server doesn't support "websocket" servers yet, we
+		 * let "os/emscripten/pre.js" hardcode a list of servers people can
+		 * join. This means the serverlist is curated for now, but it is the
+		 * best we can offer. */
+#ifdef __EMSCRIPTEN__
+		EM_ASM(if (window["openttd_server_list"]) openttd_server_list());
+#endif
+
 		this->last_joined = NetworkGameListAddItem(NetworkAddress(_settings_client.network.last_host, _settings_client.network.last_port));
 		this->server = this->last_joined;
 		if (this->last_joined != nullptr) NetworkUDPQueryServer(this->last_joined->address);
@@ -630,6 +641,12 @@ public:
 		this->GetWidget<NWidgetStacked>(WID_NG_NEWGRF_SEL)->SetDisplayedPlane(sel == nullptr || !sel->online || sel->info.grfconfig == nullptr);
 		this->GetWidget<NWidgetStacked>(WID_NG_NEWGRF_MISSING_SEL)->SetDisplayedPlane(sel == nullptr || !sel->online || sel->info.grfconfig == nullptr || !sel->info.version_compatible || sel->info.compatible);
 
+#ifdef __EMSCRIPTEN__
+		this->SetWidgetDisabledState(WID_NG_FIND, true);
+		this->SetWidgetDisabledState(WID_NG_ADD, true);
+		this->SetWidgetDisabledState(WID_NG_START, true);
+#endif
+
 		this->DrawWidgets();
 	}
 

src/newgrf.cpp

@@ -1951,8 +1951,7 @@ static ChangeInfoResult StationChangeInfo(uint stid, int numinfo, int prop, cons
 					tmp_layout.clear();
 					for (;;) {
 						/* no relative bounding box support */
-						/*C++17: DrawTileSeqStruct &dtss = */ tmp_layout.emplace_back();
+						DrawTileSeqStruct &dtss = tmp_layout.emplace_back();
-						DrawTileSeqStruct &dtss = tmp_layout.back();
 						MemSetT(&dtss, 0);
 
 						dtss.delta_x = buf->ReadByte();
@@ -5159,8 +5158,7 @@ static void NewSpriteGroup(ByteReader *buf)
 			/* Loop through the var adjusts. Unfortunately we don't know how many we have
 			 * from the outset, so we shall have to keep reallocing. */
 			do {
-				/*C++17: DeterministicSpriteGroupAdjust &adjust = */ adjusts.emplace_back();
+				DeterministicSpriteGroupAdjust &adjust = adjusts.emplace_back();
-				DeterministicSpriteGroupAdjust &adjust = adjusts.back();
 
 				/* The first var adjust doesn't have an operation specified, so we set it to add. */
 				adjust.operation = adjusts.size() == 1 ? DSGA_OP_ADD : (DeterministicSpriteGroupAdjustOperation)buf->ReadByte();

src/newgrf_commons.cpp

@@ -664,8 +664,7 @@ uint32 NewGRFSpriteLayout::PrepareLayout(uint32 orig_offset, uint32 newgrf_groun
 
 	/* Create a copy of the spritelayout, so we can modify some values.
 	 * Also include the groundsprite into the sequence for easier processing. */
-	/*C++17: DrawTileSeqStruct *result = &*/ result_seq.emplace_back();
+	DrawTileSeqStruct *result = &result_seq.emplace_back();
-	DrawTileSeqStruct *result = &result_seq.back();
 	result->image = ground;
 	result->delta_x = 0;
 	result->delta_y = 0;
@@ -675,8 +674,7 @@ uint32 NewGRFSpriteLayout::PrepareLayout(uint32 orig_offset, uint32 newgrf_groun
 	foreach_draw_tile_seq(dtss, this->seq) {
 		result_seq.push_back(*dtss);
 	}
-	result_seq.emplace_back() /*C++17: .MakeTerminator()*/;
+	result_seq.emplace_back().MakeTerminator();
-	result_seq.back().MakeTerminator();
 	/* Determine the var10 values the action-1-2-3 chains needs to be resolved for,
 	 * and apply the default sprite offsets (unless disabled). */
 	const TileLayoutRegisters *regs = this->registers;

src/openttd.cpp

@@ -87,6 +87,11 @@
 
 #include "safeguards.h"
 
+#ifdef __EMSCRIPTEN__
+#	include <emscripten.h>
+#	include <emscripten/html5.h>
+#endif
+
 void CallLandscapeTick();
 void IncreaseDate();
 void MusicLoop();
@@ -123,6 +128,15 @@ void CDECL usererror(const char *s, ...)
 	ShowOSErrorBox(buf, false);
 	if (VideoDriver::GetInstance() != nullptr) VideoDriver::GetInstance()->Stop();
 
+#ifdef __EMSCRIPTEN__
+	emscripten_exit_pointerlock();
+	/* In effect, the game ends here. As emscripten_set_main_loop() caused
+	 * the stack to be unwound, the code after MainLoop() in
+	 * openttd_main() is never executed. */
+	EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
+	EM_ASM(if (window["openttd_abort"]) openttd_abort());
+#endif
+
 	exit(1);
 }
 

src/saveload/afterload.cpp

@@ -3293,8 +3293,7 @@ bool AfterLoadGame()
 					cur_skip = prev_tile_skip;
 				}
 
-				/*C++17: uint &this_skip = */ skip_frames.push_back(prev_tile_skip);
+				uint &this_skip = skip_frames.emplace_back(prev_tile_skip);
-				uint &this_skip = skip_frames.back();
 
 				/* The following 3 curves now take longer than before */
 				switch (u->state) {

src/saveload/engine_sl.cpp

@@ -191,8 +191,7 @@ static void Load_EIDS()
 	_engine_mngr.clear();
 
 	while (SlIterateArray() != -1) {
-		/*C++17: EngineIDMapping *eid = &*/ _engine_mngr.emplace_back();
+		EngineIDMapping *eid = &_engine_mngr.emplace_back();
-		EngineIDMapping *eid = &_engine_mngr.back();
 		SlObject(eid, _engine_id_mapping_desc);
 	}
 }

src/saveload/saveload.cpp

@@ -46,6 +46,9 @@
 #include "../scope.h"
 #include <atomic>
 #include <string>
+#ifdef __EMSCRIPTEN__
+#	include <emscripten.h>
+#endif
 
 #include "../tbtr_template_vehicle.h"
 
@@ -2928,6 +2931,10 @@ static void SaveFileDone()
 
 	InvalidateWindowData(WC_STATUS_BAR, 0, SBI_SAVELOAD_FINISH);
 	_sl.saveinprogress = false;
+
+#ifdef __EMSCRIPTEN__
+	EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
+#endif
 }
 
 /** Set the error message from outside of the actual loading/saving of the game (AfterLoadGame and friends) */

src/saveload/waypoint_sl.cpp

@@ -192,8 +192,7 @@ static void Load_WAYP()
 	int index;
 
 	while ((index = SlIterateArray()) != -1) {
-		/*C++17: OldWaypoint *wp = &*/ _old_waypoints.emplace_back();
+		OldWaypoint *wp = &_old_waypoints.emplace_back();
-		OldWaypoint *wp = &_old_waypoints.back();
 
 		wp->index = index;
 		SlObject(wp, _old_waypoint_desc);

src/script/CMakeLists.txt

@@ -1,5 +1,9 @@
 add_subdirectory(api)
 
+if(OPTION_TOOLS_ONLY)
+    return()
+endif()
+
 add_files(
     script_config.cpp
     script_config.hpp

src/script/api/CMakeLists.txt

@@ -131,6 +131,10 @@ foreach(API "ai;AI" "game;GS" "template;Template")
     )
 endforeach()
 
+if(OPTION_TOOLS_ONLY)
+    return()
+endif()
+
 add_library(openttd::script_api ALIAS script_api)
 
 

src/settingsgen/settingsgen.cpp

@@ -118,8 +118,7 @@ public:
 			text += stored_size;
 		}
 		while (length > 0) {
-			/*C++17: OutputBuffer &block =*/ this->output_buffer.emplace_back();
+			OutputBuffer &block = this->output_buffer.emplace_back();
-			OutputBuffer &block = this->output_buffer.back();
 			block.Clear(); // Initialize the new block.
 			size_t stored_size = block.Add(text, length);
 			length -= stored_size;

src/strgen/CMakeLists.txt

@@ -22,6 +22,10 @@ if (NOT HOST_BINARY_DIR)
     add_dependencies(tools strgen)
 endif()
 
+if(OPTION_TOOLS_ONLY)
+    return()
+endif()
+
 # Source Files
 add_files(strgen_base.cpp)
 

src/string_type.h

@@ -15,10 +15,10 @@
 #include <string>
 
 /** A non-breaking space. */
-#define NBSP "\xC2\xA0"
+#define NBSP u8"\u00a0"
 
 /** A left-to-right marker, marks the next character as left-to-right. */
-#define LRM "\xE2\x80\x8E"
+#define LRM u8"\u200e"
 
 /**
  * Valid filter types for IsValidChar.

src/stringfilter.cpp

@@ -74,8 +74,7 @@ void StringFilter::SetFilterTerm(const char *str)
 
 		/* Add to word */
 		if (word == nullptr) {
-			/*C++17: word = &*/ this->word_index.push_back({dest, false});
+			word = &this->word_index.emplace_back(WordState{ dest, false });
-			word = &this->word_index.back();
 		}
 
 		memcpy(dest, pos, len);

src/strings.cpp

@@ -1758,6 +1758,11 @@ static char *FormatString(char *buff, const char *str_arg, StringParameters *arg
 					int64 args_array[] = {(int64)(size_t)v->name.c_str()};
 					StringParameters tmp_params(args_array);
 					buff = GetStringWithArgs(buff, STR_JUST_RAW_STRING, &tmp_params, last);
+				} else if (v->group_id != DEFAULT_GROUP) {
+					/* The vehicle has no name, but is member of a group, so print group name */
+					int64 args_array[] = {v->group_id, v->unitnumber};
+					StringParameters tmp_params(args_array);
+					buff = GetStringWithArgs(buff, STR_FORMAT_GROUP_VEHICLE_NAME, &tmp_params, last);
 				} else {
 					int64 args_array[] = {v->unitnumber};
 					StringParameters tmp_params(args_array);

src/textfile_gui.cpp

@@ -359,7 +359,7 @@ static void Xunzip(byte **bufp, size_t *sizep)
 	}
 
 	/* Check for the byte-order-mark, and skip it if needed. */
-	char *p = this->text + (strncmp("\xEF\xBB\xBF", this->text, 3) == 0 ? 3 : 0);
+	char *p = this->text + (strncmp(u8"\ufeff", this->text, 3) == 0 ? 3 : 0);
 
 	/* Make sure the string is a valid UTF-8 sequence. */
 	str_validate(p, this->text + filesize, SVS_REPLACE_WITH_QUESTION_MARK | SVS_ALLOW_NEWLINE);

src/townname.cpp

@@ -505,7 +505,7 @@ static char *MakeFinnishTownName(char *buf, const char *last, uint32 seed)
 				strstr(orig, "A") != nullptr || strstr(orig, "O") != nullptr || strstr(orig, "U")  != nullptr) {
 			buf = strecpy(buf, "la", last);
 		} else {
-			buf = strecpy(buf, "l\xC3\xA4", last);
+			buf = strecpy(buf, u8"l\u00e4", last);
 		}
 		return buf;
 	}

src/tunnelbridge_cmd.cpp

@@ -1013,8 +1013,7 @@ CommandCost CmdBuildTunnel(TileIndex start_tile, DoCommandFlag flags, uint32 p1,
 		 * Do this for all tiles (like trees), not only objects. */
 		ClearedObjectArea *coa = FindClearedObject(end_tile);
 		if (coa == nullptr) {
-			/*C++17: coa = &*/ _cleared_object_areas.push_back({end_tile, TileArea(end_tile, 1, 1)});
+			coa = &_cleared_object_areas.emplace_back(ClearedObjectArea{ end_tile, TileArea(end_tile, 1, 1) });
-			coa = &_cleared_object_areas.back();
 		}
 
 		/* Hide the tile from the terraforming command */

src/video/sdl2_v.cpp

@@ -31,6 +31,10 @@
 #include "../3rdparty/mingw-std-threads/mingw.mutex.h"
 #include "../3rdparty/mingw-std-threads/mingw.condition_variable.h"
 #endif
+#ifdef __EMSCRIPTEN__
+#	include <emscripten.h>
+#	include <emscripten/html5.h>
+#endif
 
 #if defined(WITH_FCITX)
 #include <fcitx/frontend.h>
@@ -61,6 +65,11 @@ static volatile bool _draw_continue;
 static Palette _local_palette;
 static SDL_Palette *_sdl_palette;
 
+#ifdef __EMSCRIPTEN__
+/** Whether we just had a window-enter event. */
+static bool _cursor_new_in_window = false;
+#endif
+
 #define MAX_DIRTY_RECTS 100
 static SDL_Rect _dirty_rects[MAX_DIRTY_RECTS];
 static int _num_dirty_rects;
@@ -578,6 +587,9 @@ bool VideoDriver_SDL::CreateMainSurface(uint w, uint h, bool resize)
 bool VideoDriver_SDL::ClaimMousePointer()
 {
 	SDL_ShowCursor(0);
+#ifdef __EMSCRIPTEN__
+	SDL_SetRelativeMouseMode(SDL_TRUE);
+#endif
 	return true;
 }
 
@@ -796,9 +808,27 @@ int VideoDriver_SDL::PollEvent()
 
 	switch (ev.type) {
 		case SDL_MOUSEMOTION:
+#ifdef __EMSCRIPTEN__
+			if (_cursor_new_in_window) {
+				/* The cursor just moved into the window; this means we don't
+				* know the absolutely position yet to move relative from.
+				* Before this time, SDL didn't know it either, and this is
+				* why we postpone it till now. Update the absolute position
+				* for this once, and work relative after. */
+				_cursor.pos.x = ev.motion.x;
+				_cursor.pos.y = ev.motion.y;
+				_cursor.dirty = true;
+
+				_cursor_new_in_window = false;
+				SDL_SetRelativeMouseMode(SDL_TRUE);
+			} else {
+				_cursor.UpdateCursorPositionRelative(ev.motion.xrel, ev.motion.yrel);
+			}
+#else
 			if (_cursor.UpdateCursorPosition(ev.motion.x, ev.motion.y, true)) {
 				SDL_WarpMouseInWindow(_sdl_window, _cursor.pos.x, _cursor.pos.y);
 			}
+#endif
 			HandleMouseEvents();
 			break;
 
@@ -932,6 +962,12 @@ int VideoDriver_SDL::PollEvent()
 			} else if (ev.window.event == SDL_WINDOWEVENT_ENTER) {
 				// mouse entered the window, enable cursor
 				_cursor.in_window = true;
+#ifdef __EMSCRIPTEN__
+				/* Disable relative mouse mode for the first mouse motion,
+				 * so we can pick up the absolutely position again. */
+				_cursor_new_in_window = true;
+				SDL_SetRelativeMouseMode(SDL_FALSE);
+#endif
 			} else if (ev.window.event == SDL_WINDOWEVENT_LEAVE) {
 				// mouse left the window, undraw cursor
 				UndrawMouseCursor();
@@ -968,7 +1004,8 @@ const char *VideoDriver_SDL::Start(const StringList &parm)
 	/* Explicitly disable hardware acceleration. Enabling this causes
 	 * UpdateWindowSurface() to update the window's texture instead of
 	 * its surface. */
-	SDL_SetHint(SDL_HINT_FRAMEBUFFER_ACCELERATION , "0");
+	SDL_SetHint(SDL_HINT_FRAMEBUFFER_ACCELERATION, "0");
+	SDL_SetHint(SDL_HINT_MOUSE_RELATIVE_MODE_WARP, "1");
 
 	/* Just on the offchance the audio subsystem started before the video system,
 	 * check whether any part of SDL has been initialised before getting here.
@@ -1012,55 +1049,28 @@ void VideoDriver_SDL::Stop()
 	}
 }
 
-void VideoDriver_SDL::MainLoop()
+void VideoDriver_SDL::LoopOnce()
 {
-	uint32 cur_ticks = SDL_GetTicks();
-	uint32 last_cur_ticks = cur_ticks;
-	uint32 next_tick = cur_ticks + MILLISECONDS_PER_TICK;
 	uint32 mod;
 	int numkeys;
 	const Uint8 *keys;
-
-	CheckPaletteAnim();
-
-	std::thread draw_thread;
-	std::unique_lock<std::recursive_mutex> draw_lock;
-	if (_draw_threaded) {
-		/* Initialise the mutex first, because that's the thing we *need*
-		 * directly in the newly created thread. */
-		_draw_mutex = new std::recursive_mutex();
-		if (_draw_mutex == nullptr) {
-			_draw_threaded = false;
-		} else {
-			draw_lock = std::unique_lock<std::recursive_mutex>(*_draw_mutex);
-			_draw_signal = new std::condition_variable_any();
-			_draw_continue = true;
-
-			_draw_threaded = StartNewThread(&draw_thread, "ottd:draw-sdl", &DrawSurfaceToScreenThread);
-
-			/* Free the mutex if we won't be able to use it. */
-			if (!_draw_threaded) {
-				draw_lock.unlock();
-				draw_lock.release();
-				delete _draw_mutex;
-				delete _draw_signal;
-				_draw_mutex = nullptr;
-				_draw_signal = nullptr;
-			} else {
-				/* Wait till the draw mutex has started itself. */
-				_draw_signal->wait(*_draw_mutex);
-			}
-		}
-	}
-
-	DEBUG(driver, 1, "SDL2: using %sthreads", _draw_threaded ? "" : "no ");
-
-	for (;;) {
 	uint32 prev_cur_ticks = cur_ticks; // to check for wrapping
 	InteractiveRandom(); // randomness
 
 	while (PollEvent() == -1) {}
-		if (_exit_game) break;
+	if (_exit_game) {
+#ifdef __EMSCRIPTEN__
+		/* Emscripten is event-driven, and as such the main loop is inside
+		 * the browser. So if _exit_game goes true, the main loop ends (the
+		 * cancel call), but we still have to call the cleanup that is
+		 * normally done at the end of the main loop for non-Emscripten.
+		 * After that, Emscripten just halts, and the HTML shows a nice
+		 * "bye, see you next time" message. */
+		emscripten_cancel_main_loop();
+		MainLoopCleanup();
+#endif
+		return;
+	}
 
 	mod = SDL_GetModState();
 	keys = SDL_GetKeyboardState(&numkeys);
@@ -1113,9 +1123,17 @@ void VideoDriver_SDL::MainLoop()
 		_local_palette = _cur_palette;
 	} else {
 		/* Release the thread while sleeping */
-			if (_draw_mutex != nullptr) draw_lock.unlock();
+		if (_draw_mutex != nullptr) {
+			draw_lock.unlock();
 			CSleep(1);
-			if (_draw_mutex != nullptr) draw_lock.lock();
+			draw_lock.lock();
+		} else {
+/* Emscripten is running an event-based mainloop; there is already some
+ * downtime between each iteration, so no need to sleep. */
+#ifndef __EMSCRIPTEN__
+			CSleep(1);
+#endif
+		}
 
 		NetworkDrawChatMessage();
 		DrawMouseCursor();
@@ -1129,8 +1147,60 @@ void VideoDriver_SDL::MainLoop()
 		CheckPaletteAnim();
 		DrawSurfaceToScreen();
 	}
+}
+
+void VideoDriver_SDL::MainLoop()
+{
+	cur_ticks = SDL_GetTicks();
+	last_cur_ticks = cur_ticks;
+	next_tick = cur_ticks + MILLISECONDS_PER_TICK;
+
+	CheckPaletteAnim();
+
+	if (_draw_threaded) {
+		/* Initialise the mutex first, because that's the thing we *need*
+		 * directly in the newly created thread. */
+		_draw_mutex = new std::recursive_mutex();
+		if (_draw_mutex == nullptr) {
+			_draw_threaded = false;
+		} else {
+			draw_lock = std::unique_lock<std::recursive_mutex>(*_draw_mutex);
+			_draw_signal = new std::condition_variable_any();
+			_draw_continue = true;
+
+			_draw_threaded = StartNewThread(&draw_thread, "ottd:draw-sdl", &DrawSurfaceToScreenThread);
+
+			/* Free the mutex if we won't be able to use it. */
+			if (!_draw_threaded) {
+				draw_lock.unlock();
+				draw_lock.release();
+				delete _draw_mutex;
+				delete _draw_signal;
+				_draw_mutex = nullptr;
+				_draw_signal = nullptr;
+			} else {
+				/* Wait till the draw mutex has started itself. */
+				_draw_signal->wait(*_draw_mutex);
+			}
+		}
 	}
 
+	DEBUG(driver, 1, "SDL2: using %sthreads", _draw_threaded ? "" : "no ");
+
+#ifdef __EMSCRIPTEN__
+	/* Run the main loop event-driven, based on RequestAnimationFrame. */
+	emscripten_set_main_loop_arg(&this->EmscriptenLoop, this, 0, 1);
+#else
+	while (!_exit_game) {
+		LoopOnce();
+	}
+
+	MainLoopCleanup();
+#endif
+}
+
+void VideoDriver_SDL::MainLoopCleanup()
+{
 	if (_draw_mutex != nullptr) {
 		_draw_continue = false;
 		/* Sending signal if there is no thread blocked
@@ -1146,6 +1216,15 @@ void VideoDriver_SDL::MainLoop()
 		_draw_mutex = nullptr;
 		_draw_signal = nullptr;
 	}
+
+#ifdef __EMSCRIPTEN__
+	emscripten_exit_pointerlock();
+	/* In effect, the game ends here. As emscripten_set_main_loop() caused
+	 * the stack to be unwound, the code after MainLoop() in
+	 * openttd_main() is never executed. */
+	EM_ASM(if (window["openttd_syncfs"]) openttd_syncfs());
+	EM_ASM(if (window["openttd_exit"]) openttd_exit());
+#endif
 }
 
 bool VideoDriver_SDL::ChangeResolution(int w, int h)

src/video/sdl2_v.h

@@ -42,12 +42,26 @@ public:
 	const char *GetName() const override { return "sdl"; }
 private:
 	int PollEvent();
+	void LoopOnce();
+	void MainLoopCleanup();
 	bool CreateMainSurface(uint w, uint h, bool resize);
 
+#ifdef __EMSCRIPTEN__
+	/* Convert a constant pointer back to a non-constant pointer to a member function. */
+	static void EmscriptenLoop(void *self) { ((VideoDriver_SDL *)self)->LoopOnce(); }
+#endif
+
 	/**
 	 * This is true to indicate that keyboard input is in text input mode, and SDL_TEXTINPUT events are enabled.
 	 */
 	bool edit_box_focused;
+
+	uint32 cur_ticks;
+	uint32 last_cur_ticks;
+	uint32 next_tick;
+
+	std::thread draw_thread;
+	std::unique_lock<std::recursive_mutex> draw_lock;
 };
 
 /** Factory for the SDL video driver. */

src/viewport.cpp

@@ -816,8 +816,7 @@ static void AddTileSpriteToDraw(SpriteID image, PaletteID pal, int32 x, int32 y,
 {
 	assert((image & SPRITE_MASK) < MAX_SPRITES);
 
-	/*C++17: TileSpriteToDraw &ts = */ _vd.tile_sprites_to_draw.emplace_back();
+	TileSpriteToDraw &ts = _vd.tile_sprites_to_draw.emplace_back();
-	TileSpriteToDraw &ts = _vd.tile_sprites_to_draw.back();
 	ts.image = image;
 	ts.pal = pal;
 	ts.sub = sub;
@@ -1038,8 +1037,7 @@ void AddSortableSpriteToDraw(SpriteID image, PaletteID pal, int x, int y, int w,
 		return;
 	}
 
-	/*C++17: ParentSpriteToDraw &ps = */ _vd.parent_sprites_to_draw.emplace_back();
+	ParentSpriteToDraw &ps = _vd.parent_sprites_to_draw.emplace_back();
-	ParentSpriteToDraw &ps = _vd.parent_sprites_to_draw.back();
 	ps.x = tmp_x;
 	ps.y = tmp_y;
 
@@ -1180,8 +1178,7 @@ void AddChildSpriteScreen(SpriteID image, PaletteID pal, int x, int y, bool tran
 
 	*_vd.last_child = (uint)_vd.child_screen_sprites_to_draw.size();
 
-	/*C++17: ChildScreenSpriteToDraw &cs = */ _vd.child_screen_sprites_to_draw.emplace_back();
+	ChildScreenSpriteToDraw &cs = _vd.child_screen_sprites_to_draw.emplace_back();
-	ChildScreenSpriteToDraw &cs = _vd.child_screen_sprites_to_draw.back();
 	cs.image = image;
 	cs.pal = pal;
 	cs.sub = sub;
@@ -1201,8 +1198,7 @@ void AddChildSpriteScreen(SpriteID image, PaletteID pal, int x, int y, bool tran
 static void AddStringToDraw(int x, int y, StringID string, uint64 params_1, uint64 params_2, Colours colour, uint16 width)
 {
 	assert(width != 0);
-	/*C++17: StringSpriteToDraw &ss = */ _vd.string_sprites_to_draw.emplace_back();
+	StringSpriteToDraw &ss = _vd.string_sprites_to_draw.emplace_back();
-	StringSpriteToDraw &ss = _vd.string_sprites_to_draw.back();
 	ss.string = string;
 	ss.x = x;
 	ss.y = y;