From 460e28bff13d99cbf0a5763e9ddc966338a750d4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Micha=C5=82=20Janiszewski?= <janisozaur@gmail.com>
Date: Fri, 12 Jul 2019 22:16:42 +0200
Subject: [PATCH] Add -latomic when required

Some platforms ship with atomic builtins packaged in their own library
which needs to be linked in order to make use of them.

This patch, based on
https://github.com/WebPlatformForEmbedded/meta-wpe/issues/210 adds a
configure-time check to verify if the library is needed and adds it when
necessary.
---
 CMakeLists.txt | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index c0e8ec6..560a55f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -139,6 +139,19 @@ target_link_libraries(${PROJECT_NAME}
   PRIVATE ${ZLIB_LIBRARIES}
   )
 
+# Check if libatomic is needed in order to use std::atomic, and add
+# it to the list of JavaScriptCore libraries.
+file(WRITE ${CMAKE_BINARY_DIR}/test_atomic.cpp
+     "#include <atomic>\n"
+     "int main() { std::atomic<int64_t> i(0); i++; return 0; }\n")
+try_compile(ATOMIC_BUILD_SUCCEEDED ${CMAKE_BINARY_DIR} ${CMAKE_BINARY_DIR}/test_atomic.cpp)
+if (NOT ATOMIC_BUILD_SUCCEEDED)
+  target_link_libraries(${PROJECT_NAME}
+    PRIVATE -latomic
+  )
+endif ()
+file(REMOVE ${CMAKE_BINARY_DIR}/test_atomic.cpp)
+
 if(LINK_LIBCRYPTO EQUAL 1)
   target_link_libraries(${PROJECT_NAME}
     PRIVATE ${Libcrypto_LIBRARIES}