Win32: offer to restart application on fatal errors.

This changes the assertion failure behavior to be the same in debug
and release builds: to show the complete failure message, and
to offer to restart the application or defer to Windows Error
Reporting to generate a backtrace. Contrary to popular belief,
WER is not useless, and since SolveSpace publishes pdb files,
WER-generated reports can be symbolized.

This commit also addresses the long-standing problem where showing
a dialog on fatal error would re-enter the application code, thus
causing another error or a crash that is more fatal than the current
one.

src/platform/platform.h

@@ -9,6 +9,13 @@
 
 namespace Platform {
 
+// Handling fatal errors.
+#if defined(__GNUC__)
+__attribute__((noreturn))
+#endif
+void FatalError(std::string message);
+extern bool handlingFatalError;
+
 // UTF-8 ⟷ UTF-16 conversion, for Windows.
 #if defined(WIN32)
 std::string Narrow(const wchar_t *s);

src/platform/unixutil.cpp

@@ -27,10 +27,10 @@ void dbp(const char *str, ...)
     fputc('\n', stderr);
 }
 
-void assert_failure(const char *file, unsigned line, const char *function,
-                    const char *condition, const char *message) {
-    fprintf(stderr, "File %s, line %u, function %s:\n", file, line, function);
-    fprintf(stderr, "Assertion '%s' failed: ((%s) == false).\n", message, condition);
+namespace Platform {
+
+void FatalError(std::string message) {
+    fprintf(stderr, "%s", message.c_str());
 
 #if !defined(LIBRARY) && defined(HAVE_BACKTRACE)
     static void *ptrs[1024] = {};
@@ -54,6 +54,8 @@ void assert_failure(const char *file, unsigned line, const char *function,
     abort();
 }
 
+}
+
 //-----------------------------------------------------------------------------
 // A separate heap, on which we allocate expressions. Maybe a bit faster,
 // since fragmentation is less of a concern, and it also makes it possible

src/platform/w32main.cpp

@@ -559,6 +559,8 @@ static void MouseWheel(int thisDelta) {
 
 LRESULT CALLBACK TextWndProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
 {
+    if(Platform::handlingFatalError) return 1;
+
     switch (msg) {
         case WM_ERASEBKGND:
             break;
@@ -955,6 +957,8 @@ bool SolveSpace::GraphicsEditControlIsVisible()
 LRESULT CALLBACK GraphicsWndProc(HWND hwnd, UINT msg, WPARAM wParam,
                                                             LPARAM lParam)
 {
+    if(Platform::handlingFatalError) return 1;
+
     switch (msg) {
         case WM_ERASEBKGND:
             break;

src/platform/w32util.cpp

@@ -35,15 +35,33 @@ void dbp(const char *str, ...)
 #endif
 }
 
-void assert_failure(const char *file, unsigned line, const char *function,
-                    const char *condition, const char *message) {
-    dbp("File %s, line %u, function %s:", file, line, function);
-    dbp("Assertion '%s' failed: ((%s) == false).", message, condition);
-#ifdef NDEBUG
-    _exit(1);
-#else
-    abort();
-#endif
+namespace Platform {
+
+bool handlingFatalError = false;
+
+void FatalError(std::string message) {
+    // Indicate that we're handling a fatal error, to avoid re-entering application code
+    // and potentially crashing even harder.
+    handlingFatalError = true;
+
+    message += "\nGenerate debug report?";
+    switch(MessageBoxW(NULL, Platform::Widen(message).c_str(),
+                       L"Fatal error — SolveSpace",
+                       MB_ICONERROR|MB_TASKMODAL|MB_SETFOREGROUND|MB_TOPMOST|
+                       MB_OKCANCEL|MB_DEFBUTTON2)) {
+        case IDOK:
+            abort();
+
+        case IDCANCEL:
+        default: {
+            WCHAR appPath[MAX_PATH] = {};
+            GetModuleFileNameW(NULL, appPath, sizeof(appPath));
+            ShellExecuteW(NULL, L"open", appPath, NULL, NULL, SW_SHOW);
+            _exit(1);
+        }
+    }
+}
+
 }
 
 //-----------------------------------------------------------------------------
@@ -85,15 +103,9 @@ void vl() {
 }
 
 std::vector<std::string> InitPlatform(int argc, char **argv) {
-    // Create the heap used for long-lived stuff (that gets freed piecewise).
-    PermHeap = HeapCreate(HEAP_NO_SERIALIZE, 1024*1024*20, 0);
-    // Create the heap that we use to store Exprs and other temp stuff.
-    FreeAllTemporary();
-
 #if !defined(LIBRARY) && defined(_MSC_VER)
-    // Don't display the abort message; it is aggravating in CLI binaries
-    // and results in infinite WndProc recursion in GUI binaries.
-    _set_abort_behavior(0, _WRITE_ABORT_MSG);
+    // We display our own message on abort; just call ReportFault.
+    _set_abort_behavior(_CALL_REPORTFAULT, _WRITE_ABORT_MSG|_CALL_REPORTFAULT);
     int crtReportTypes[] = {_CRT_WARN, _CRT_ERROR, _CRT_ASSERT};
     for(int crtReportType : crtReportTypes) {
         _CrtSetReportMode(crtReportType, _CRTDBG_MODE_FILE | _CRTDBG_MODE_DEBUG);
@@ -101,6 +113,11 @@ std::vector<std::string> InitPlatform(int argc, char **argv) {
     }
 #endif
 
+    // Create the heap used for long-lived stuff (that gets freed piecewise).
+    PermHeap = HeapCreate(HEAP_NO_SERIALIZE, 1024*1024*20, 0);
+    // Create the heap that we use to store Exprs and other temp stuff.
+    FreeAllTemporary();
+
     // Extract the command-line arguments; the ones from main() are ignored,
     // since they are in the OEM encoding.
     int argcW;

src/solvespace.h

@@ -56,7 +56,7 @@ typedef struct _cairo cairo_t;
 #define ssassert(condition, message) \
     do { \
         if(__builtin_expect((condition), true) == false) { \
-            SolveSpace::assert_failure(__FILE__, __LINE__, __func__, #condition, message); \
+            SolveSpace::AssertFailure(__FILE__, __LINE__, __func__, #condition, message); \
             __builtin_unreachable(); \
         } \
     } while(0)
@@ -64,7 +64,7 @@ typedef struct _cairo cairo_t;
 #define ssassert(condition, message) \
     do { \
         if((condition) == false) { \
-            SolveSpace::assert_failure(__FILE__, __LINE__, __func__, #condition, message); \
+            SolveSpace::AssertFailure(__FILE__, __LINE__, __func__, #condition, message); \
             abort(); \
         } \
     } while(0)
@@ -83,8 +83,8 @@ using std::swap;
 #if defined(__GNUC__)
 __attribute__((noreturn))
 #endif
-void assert_failure(const char *file, unsigned line, const char *function,
-                    const char *condition, const char *message);
+void AssertFailure(const char *file, unsigned line, const char *function,
+                   const char *condition, const char *message);
 
 #if defined(__GNUC__)
 __attribute__((__format__ (__printf__, 1, 2)))

src/util.cpp

@@ -6,6 +6,15 @@
 //-----------------------------------------------------------------------------
 #include "solvespace.h"
 
+void SolveSpace::AssertFailure(const char *file, unsigned line, const char *function,
+                               const char *condition, const char *message) {
+    std::string formattedMsg;
+    formattedMsg += ssprintf("File %s, line %u, function %s:\n", file, line, function);
+    formattedMsg += ssprintf("Assertion failed: %s.\n", condition);
+    formattedMsg += ssprintf("Message: %s.\n", message);
+    SolveSpace::Platform::FatalError(formattedMsg);
+}
+
 std::string SolveSpace::ssprintf(const char *fmt, ...)
 {
     va_list va;