From 579cc9ad2e2db6c3f1670b9f42c2cfe67bc5722c Mon Sep 17 00:00:00 2001
From: Mehdi Amini <joker.eph@gmail.com>
Date: Fri, 16 Jul 2021 03:32:59 +0000
Subject: [PATCH] Build libSupport with -Werror=global-constructors (NFC)
Ensure that libSupport does not carry any static global initializer.
libSupport can be embedded in use cases where we don't want to load all
cl::opt unless we want to parse the command line.
ManagedStatic can be used to enable lazy-initialization of globals.
---
llvm/lib/Support/CMakeLists.txt | 20 ++++++++++++++++++++
1 file changed, 20 insertions(+)
diff --git a/llvm/lib/Support/CMakeLists.txt b/llvm/lib/Support/CMakeLists.txt
index 2242b0ec60ab..94d1b02076b0 100644
--- a/llvm/lib/Support/CMakeLists.txt
+++ b/llvm/lib/Support/CMakeLists.txt
@@ -1,5 +1,25 @@
include(GetLibraryName)
+# Ensure that libSupport does not carry any static global initializer.
+# libSupport can be embedded in use cases where we don't want to load all
+# cl::opt unless we want to parse the command line.
+# ManagedStatic can be used to enable lazy-initialization of globals.
+# We don't use `add_flag_if_supported` as instead of compiling an empty file we
+# check if the current platform is able to compile global std::mutex with this
+# flag (Linux can, Darwin can't for example).
+SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Werror=global-constructors")
+SET(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Werror=global-constructors")
+CHECK_CXX_SOURCE_COMPILES("
+ #include <mutex>
+ static std::mutex TestGlobalCtorDtor;
+ static std::recursive_mutex TestGlobalCtorDtor2;
+ int main() { (void)TestGlobalCtorDtor; (void)TestGlobalCtorDtor2; return 0;}
+ " LLVM_HAS_NOGLOBAL_CTOR_MUTEX)
+if (NOT LLVM_HAS_NOGLOBAL_CTOR_MUTEX)
+ string(REPLACE "-Werror=global-constructors" "" CMAKE_CXX_FLAGS ${CMAKE_CXX_FLAGS})
+ string(REPLACE "-Werror=global-constructors" "" CMAKE_CXX_FLAGS ${CMAKE_C_FLAGS})
+endif()
+
if(LLVM_ENABLE_ZLIB)
set(imported_libs ZLIB::ZLIB)
endif()
--
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