Initial implementation of scope guard logging for including in crash logs.

This adds a mechanism to create scope guards with an associated std::function
which is called to output diagnostic info in the event of a crash.
Add a macro to make it easy to efficiently capture variables on the stack
and output a formatted message.
Requires C++11, #ifdefed out for legacy compilers.

src/scope_info.cpp

@@ -0,0 +1,72 @@
+/* $Id$ */
+
+/*
+ * 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 scope_info.cpp Scope info debug functions. */
+
+#include "stdafx.h"
+#include "scope_info.h"
+#include "string_func.h"
+#include "strings_func.h"
+#include "company_base.h"
+#include "vehicle_base.h"
+#include "table/strings.h"
+
+#include "safeguards.h"
+
+#ifdef USE_SCOPE_INFO
+
+std::vector<std::function<int(char *, const char *)>> _scope_stack;
+
+int WriteScopeLog(char *buf, const char *last)
+{
+	char *b = buf;
+	if (!_scope_stack.empty()) {
+		b += seprintf(b, last, "Within context:");
+		int depth = 0;
+		for (auto it = _scope_stack.rbegin(); it != _scope_stack.rend(); ++it, depth++) {
+			b += seprintf(b, last, "\n    %2d: ", depth);
+			b += (*it)(b, last);
+		}
+		b += seprintf(b, last, "\n\n");
+	}
+	return b - buf;
+}
+
+// helper functions
+char *DumpCompanyInfo(int company_id)
+{
+	char buf[256];
+	char *b = buf + seprintf(buf, lastof(buf), "%d (", company_id);
+	SetDParam(0, company_id);
+	b = GetString(b, STR_COMPANY_NAME, lastof(buf));
+	b += seprintf(b, lastof(buf), ")");
+	return stredup(buf, lastof(buf));
+}
+
+char *DumpVehicleInfo(const Vehicle *v)
+{
+	char buf[256];
+	char *b = buf;
+	if (v) {
+		b += seprintf(b, lastof(buf), "veh: %u: (", v->index);
+		SetDParam(0, v->index);
+		b = GetString(b, STR_VEHICLE_NAME, lastof(buf));
+		if (v->First() && v->First() != v) {
+			b += seprintf(b, lastof(buf), "), front: %u: (", v->First()->index);
+			SetDParam(0, v->First()->index);
+			b = GetString(b, STR_VEHICLE_NAME, lastof(buf));
+		}
+		b += seprintf(b, lastof(buf), ")");
+	} else {
+		b += seprintf(b, lastof(buf), "veh: NULL");
+	}
+	return stredup(buf, lastof(buf));
+}
+
+#endif