From 21e66f807cc0b502522f67c8cce61b8381241c0a Mon Sep 17 00:00:00 2001
From: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Date: Sun, 4 Feb 2024 13:37:53 -0500
Subject: [PATCH] enable -Wthread-safety for clang

---
 Makefile.am  |  4 ++++
 configure.ac | 13 +++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/Makefile.am b/Makefile.am
index 0cde401..6aec8c0 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -28,6 +28,10 @@ if HAVE_SIZED_DEALLOCATION
 AM_CXXFLAGS += -fsized-deallocation
 endif HAVE_SIZED_DEALLOCATION
 
+if ENABLE_W_THREAD_SAFETY
+AM_CXXFLAGS += -Wthread-safety
+endif ENABLE_W_THREAD_SAFETY
+
 # The -no-undefined flag allows libtool to generate shared libraries for
 # Cygwin and MinGW.
 AM_LDFLAGS = -no-undefined
diff --git a/configure.ac b/configure.ac
index 702174a..58f9de4 100644
--- a/configure.ac
+++ b/configure.ac
@@ -234,6 +234,19 @@ AC_CACHE_CHECK(
    CXXFLAGS="$OLD_CXXFLAGS"])
 AM_CONDITIONAL(ENABLE_FP_FLAGS, [test "x$ac_cv_frame_pointer_cflags" = "xyes"])
 
+# Clang-only (so far?) -Wthread-safety is a useful thing. We want.
+AC_CACHE_CHECK(
+  [compiler and target supports -Wthread-safety],
+  [ac_cv_w_thread_safety],
+  [OLD_CXXFLAGS="$CXXFLAGS"
+   CXXFLAGS="$CXXFLAGS -Wthread-safety"
+   AC_COMPILE_IFELSE(
+     [AC_LANG_PROGRAM([], [])],
+     [ac_cv_w_thread_safety=yes],
+     [ac_cv_w_thread_safety=no])
+   CXXFLAGS="$OLD_CXXFLAGS"])
+AM_CONDITIONAL(ENABLE_W_THREAD_SAFETY, [test "x$ac_cv_w_thread_safety" = "xyes"])
+
 AX_C___ATTRIBUTE__
 
 AC_MSG_CHECKING(for __attribute__((aligned(N))) on functions)