[sanitizer_common] Suppress warning of cast from SignalHandlerType to sa_sigaction_t

[thurstond]

Some buildbots (e.g., https://lab.llvm.org/buildbot/#/builders/18/builds/16061/steps/10/logs/stdio) 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.

[llvmbot]

@llvm/pr-subscribers-compiler-rt-sanitizer

Author: Thurston Dang (thurstond)

Changes

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.

---

Full diff: https://github.com/llvm/llvm-project/pull/86046.diff

1 Files Affected:

• (modified) compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp (+1-1)

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;

[thurstond]

I reverted it in 0e3fbfd because it didn't actually suppress the warning

"Split -Wcast-function-type into a separate group" (by AaronBallman; #86131) will prevent the warning, though we should figure out a way to fix the cast in the longer term.