[compiler-rt] [sanitizer_common] Suppress warning of cast from SignalHandlerType to sa_sigaction_t (PR #86046)

[Thurston Dang via llvm-commits]

https://github.com/thurstond created https://github.com/llvm/llvm-project/pull/86046

Some buildbots have recently started complaining about "cast from 'SignalHandlerType' (aka 'void (*)(int, void *, void *)') to 'sa_sigaction_t' (aka 'void (*)(int, siginfo_t *, void *)') converts to incompatible function type [-Werror,-Wcast-function-type-strict]"
  219 |   sigact.sa_sigaction = (sa_sigaction_t)handler;
This patch does an intermediate cast to '(void (*) (void))' to suppress the warning.

N.B. SignalHandlerType has 'void*' instead of 'siginfo_t*' because it is typedef'ed in sanitizer_common/sanitizer_common.h, which does not have access to the header (signal.h) that defines siginfo_t; we therefore cannot fix SignalHandlerType.


>From 9d79589e7c8b728a592a4b6b3dee53ac471d7946 Mon Sep 17 00:00:00 2001
From: Thurston Dang <thurston at google.com>
Date: Wed, 20 Mar 2024 23:52:02 +0000
Subject: [PATCH] [sanitizer_common] Suppress warning of cast from
 SignalHandlerType to sa_sigaction_t

Some buildbots have recently started complaining about "cast from 'SignalHandlerType' (aka 'void (*)(int, void *, void *)') to 'sa_sigaction_t' (aka 'void (*)(int, siginfo_t *, void *)') converts to incompatible function type [-Werror,-Wcast-function-type-strict]"
  219 |   sigact.sa_sigaction = (sa_sigaction_t)handler;
This patch does an intermediate cast to '(void (*) (void))' to suppress the warning.

N.B. SignalHandlerType has 'void*' instead of 'siginfo_t*' because it is typedef'ed in sanitizer_common/sanitizer_common.h, which does not have access to the header (signal.h) that defines siginfo_t; we therefore cannot fix SignalHandlerType.
---
 compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp
index ece2d7d63dd619..48daa2ed25c144 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp
@@ -216,7 +216,7 @@ static void MaybeInstallSigaction(int signum,
 
   struct sigaction sigact;
   internal_memset(&sigact, 0, sizeof(sigact));
-  sigact.sa_sigaction = (sa_sigaction_t)handler;
+  sigact.sa_sigaction = (sa_sigaction_t)(void (*)(void))handler;
   // Do not block the signal from being received in that signal's handler.
   // Clients are responsible for handling this correctly.
   sigact.sa_flags = SA_SIGINFO | SA_NODEFER;