mingw: add a helper function to attach GDB to the current process

When debugging Git, the criss-cross spawning of processes can make
things quite a bit difficult, especially when a Unix shell script is
thrown in the mix that calls a `git.exe` that then segfaults.

To help debugging such things, we introduce the `open_in_gdb()` function
which can be called at a code location where the segfault happens (or as
close as one can get); This will open a new MinTTY window with a GDB
that already attached to the current process.

Inspired by Derrick Stolee.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/compat/mingw.h b/compat/mingw.h
index 04ca731a6b..88c07c4520 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -592,6 +592,16 @@ int wmain(int argc, const wchar_t **w_argv);
 int main(int argc, const char **argv);
 
 /*
+ * For debugging: if a problem occurs, say, in a Git process that is spawned
+ * from another Git process which in turn is spawned from yet another Git
+ * process, it can be quite daunting to figure out what is going on.
+ *
+ * Call this function to open a new MinTTY (this assumes you are in Git for
+ * Windows' SDK) with a GDB that attaches to the current process right away.
+ */
+extern void open_in_gdb(void);
+
+/*
  * Used by Pthread API implementation for Windows
  */
 int err_win_to_posix(DWORD winerr);