[newlib-cygwin/main] Cygwin: Do not show Error dialogs by default

[Corinna Vinschen]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=07ea90a5d223ea0d30f54acd87d17343b1c35680

commit 07ea90a5d223ea0d30f54acd87d17343b1c35680
Author:     Johannes Schindelin <johannes.schindelin@gmx.de>
AuthorDate: Wed Mar 31 11:38:41 2021 +0200
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Sat Feb 3 19:54:50 2024 +0100

    Cygwin: Do not show Error dialogs by default
    
    ...in a non-Cygwin child process.  Backported from MSYS2.
    Downstream commit message follows.
    
    In https://github.com/msys2/msys2-runtime/pull/18, we discussed a change
    that would allow default Windows error handling of spawned processes to
    kick in (such as registered JIT debuggers). We even agreed that it would
    make sense to hide this functionality behind a flag, `winjitdebug`.
    
    However, when this got upstreamed as 21ec498d7f (cygwin: use
    CREATE_DEFAULT_ERROR_MODE in spawn, 2020-12-09), that flag was deemed
    unnecessary.
    
    But it would appear that it _is_ necessary: As reported in
    https://github.com/msys2/MSYS2-packages/pull/2414#issuecomment-810841296
    this new behavior is pretty disruptive e.g. in CI scenarios.
    
    So let's introduce that `winjitdebug` flag (settable via the environment
    variable `MSYS`) at long last.
    
    Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/environ.cc | 1 +
 winsup/cygwin/globals.cc | 1 +
 winsup/cygwin/spawn.cc   | 2 +-
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/winsup/cygwin/environ.cc b/winsup/cygwin/environ.cc
index dca5c5db056b..d35b9564b622 100644
--- a/winsup/cygwin/environ.cc
+++ b/winsup/cygwin/environ.cc
@@ -122,6 +122,7 @@ static struct parse_thing
   {"wincmdln", {&wincmdln}, setbool, NULL, {{false}, {true}}},
   {"winsymlinks", {func: set_winsymlinks}, isfunc, NULL, {{0}, {0}}},
   {"disable_pcon", {&disable_pcon}, setbool, NULL, {{false}, {true}}},
+  {"winjitdebug", {&winjitdebug}, setbool, NULL, {{false}, {true}}},
   {NULL, {0}, setdword, 0, {{0}, {0}}}
 };
 
diff --git a/winsup/cygwin/globals.cc b/winsup/cygwin/globals.cc
index 885ada85e7b8..d8e058f1915d 100644
--- a/winsup/cygwin/globals.cc
+++ b/winsup/cygwin/globals.cc
@@ -72,6 +72,7 @@ bool reset_com;
 bool wincmdln;
 winsym_t allow_winsymlinks = WSYM_default;
 bool disable_pcon;
+bool winjitdebug = false;
 
 /* Taken from BSD libc:
    This variable is zero until a process has created a pthread.  It is used
diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index 8a2db5cf72e2..71d75bbf4e91 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -405,7 +405,7 @@ child_info_spawn::worker (const char *prog_arg, const char *const *argv,
 	 get the default error mode instead of inheriting the mode Cygwin
 	 uses.  This allows things like Windows Error Reporting/JIT debugging
 	 to work with processes launched from a Cygwin shell. */
-      if (!real_path.iscygexec ())
+      if (winjitdebug && !real_path.iscygexec ())
 	c_flags |= CREATE_DEFAULT_ERROR_MODE;
 
       /* We're adding the CREATE_BREAKAWAY_FROM_JOB flag here to workaround