Windows: Win32 threads should be used when compiling with clang #2362
Description
Problem:
currently for MinGW environment pthreads are assumed. mostly clang based on MinGW is built with Win32 threading model because of better LLVM support. winpthread is just a wrapper around Win32 threads, but such wrapping is slower anyway.
this causes a build issue when compiling aws-lc-rs based packages with clang, because aws-lc links pthread functions, but resulting binaries are compiled without linking pthread
Relevant details
AWS-LC commit: recent
currently in MSYS2 we use this patch, but this a workaround and not an actual fix:
workaround to make clang based builds work
diff --git a/CMakeLists.txt b/CMakeLists.txt
index fcb8c928e..d283a6ed4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -399,7 +399,7 @@ if(GCC OR CLANG)
set(C_CXX_FLAGS "${C_CXX_FLAGS} -Wno-deprecated-declarations")
else()
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wextra")
- set(C_CXX_FLAGS "${C_CXX_FLAGS} -Wall -fvisibility=hidden -fno-common")
+ set(C_CXX_FLAGS "${C_CXX_FLAGS} -Wall -fvisibility=hidden -fno-common -fms-extensions")
set(CMAKE_ASM_FLAGS "${CMAKE_ASM_FLAGS} -Wno-newline-eof")
endif()
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wunused -Wcomment -Wchar-subscripts -Wuninitialized -Wshadow")
diff --git a/crypto/internal.h b/crypto/internal.h
index 4e42bb5b5..cb74fac23 100644
--- a/crypto/internal.h
+++ b/crypto/internal.h
@@ -141,7 +141,7 @@
#endif
#if defined(OPENSSL_THREADS) && \
- (!defined(OPENSSL_WINDOWS) || defined(__MINGW32__))
+ (!defined(OPENSSL_WINDOWS) || defined(__MINGW32__) && !defined(__clang__))
#include <pthread.h>
#define OPENSSL_PTHREADS
#endif
diff --git a/crypto/thread_win.c b/crypto/thread_win.c
index 9a1f8045e..0606e6db0 100644
--- a/crypto/thread_win.c
+++ b/crypto/thread_win.c
@@ -146,6 +146,7 @@ static void NTAPI thread_local_destructor(PVOID module, DWORD reason,
// optimization from discarding the variable.
//
// Note, in the prefixed build, |p_thread_callback_boringssl| may be a macro.
+#ifdef _MSC_VER
#define STRINGIFY(x) #x
#define EXPAND_AND_STRINGIFY(x) STRINGIFY(x)
#ifdef _WIN64
@@ -157,6 +158,7 @@ __pragma(comment(linker, "/INCLUDE:__tls_used"))
__pragma(comment(
linker, "/INCLUDE:_" EXPAND_AND_STRINGIFY(p_thread_callback_boringssl)))
#endif
+#endif
// .CRT$XLA to .CRT$XLZ is an array of PIMAGE_TLS_CALLBACK pointers that are
// called automatically by the OS loader code (not the CRT) when the module ishow to make workaround be a fix: apply -fms-extensions compile flag only if a C compiler is Clang and we're under Windows; ungate code with #define STRINGIFY(x) and so on and make it work for clang compiler (because current code is MSVC/link.exe specific)
Build log:
simple errors of pthread_* symbols being undefined