Define a few variables of obscure types to aid debugging exceptions on Windows.

 src/w32.c (PEXCEPTION_POINTERS, PEXCEPTION_RECORD, PCONTEXT): Define
 variables of these types so that GDB would know about them, as aid
 for debugging fatal exceptions.  (Bug#15024)  See also
 http://sourceware.org/ml/gdb/2013-08/msg00010.html for related
 discussions.

2 files changed, 23 insertions, 0 deletions

diff --git a/src/ChangeLog b/src/ChangeLog
index d57086f7141..aa424d2ec06 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,11 @@
+2013-08-09  Eli Zaretskii  <eliz@gnu.org>
+
+        * w32.c (PEXCEPTION_POINTERS, PEXCEPTION_RECORD, PCONTEXT): Define
+        variables of these types so that GDB would know about them, as aid
+        for debugging fatal exceptions.  (Bug#15024)  See also
+        http://sourceware.org/ml/gdb/2013-08/msg00010.html for related
+        discussions.
+
 2013-08-08  Jan Djärv  <jan.h.d@swipnet.se>
 
         * nsterm.m (ns_update_begin): Don't change clip path if it would be
diff --git a/src/w32.c b/src/w32.c
index bb2f0acd99a..9b87cfc8faa 100644
--- a/src/w32.c
+++ b/src/w32.c
@@ -89,6 +89,21 @@ typedef struct _MEMORY_STATUS_EX {
   DWORDLONG ullAvailExtendedVirtual;
 } MEMORY_STATUS_EX,*LPMEMORY_STATUS_EX;
 
+/* These are here so that GDB would know about these data types.  This
+   allows to attach GDB to Emacs when a fatal exception is triggered
+   and Windows pops up the "application needs to be closed" dialog.
+   At that point, _gnu_exception_handler, the top-level exception
+   handler installed by the MinGW startup code, is somewhere on the
+   call-stack of the main thread, so going to that call frame and
+   looking at the argument to _gnu_exception_handler, which is a
+   PEXCEPTION_POINTERS pointer, can reveal the exception code
+   (excptr->ExceptionRecord->ExceptionCode) and the address where the
+   exception happened (excptr->ExceptionRecord->ExceptionAddress), as
+   well as some additional information specific to the exception.  */
+PEXCEPTION_POINTERS excptr;
+PEXCEPTION_RECORD excprec;
+PCONTEXT ctxrec;
+
 #include <lmcons.h>
 #include <shlobj.h>