From 5fb109989dc044bfda18909e308f126819cec6a1 Mon Sep 17 00:00:00 2001
From: Urs Fleisch <ufleisch@users.sourceforge.net>
Date: Mon, 19 Oct 2026 17:37:18 +0200
Subject: [PATCH] Check if libatomic is needed for 64-bit atomic operations
 (#1465)

---
 ConfigureChecks.cmake | 28 ++++++++++++++++++++++++++++
 taglib/CMakeLists.txt |  1 +
 2 files changed, 29 insertions(+)

diff --git a/ConfigureChecks.cmake b/ConfigureChecks.cmake
index acffa3fb..c9d44bc6 100644
--- a/ConfigureChecks.cmake
+++ b/ConfigureChecks.cmake
@@ -107,3 +107,31 @@ check_cxx_source_compiles("
 if(CMAKE_SYSTEM_NAME STREQUAL "WindowsStore")
   set(PLATFORM_WINRT 1)
 endif()
+
+# Check if 64-bit atomics require -latomic
+
+set(_CMAKE_REQUIRED_LIBRARIES_TMP ${CMAKE_REQUIRED_LIBRARIES})
+set(CMAKE_REQUIRED_LIBRARIES "")
+check_cxx_source_compiles("
+  #include <atomic>
+  #include <cstdint>
+  std::atomic<uint64_t> x;
+  int main() {
+    x.fetch_add(1, std::memory_order_relaxed);
+    return 0;
+  }
+" HAVE_CXX_ATOMICS_WITHOUT_LIB)
+
+if(NOT HAVE_CXX_ATOMICS_WITHOUT_LIB)
+  set(CMAKE_REQUIRED_LIBRARIES "atomic")
+  check_cxx_source_compiles("
+    #include <atomic>
+    #include <cstdint>
+    std::atomic<uint64_t> x;
+    int main() {
+      x.fetch_add(1, std::memory_order_relaxed);
+      return 0;
+    }
+  " HAVE_CXX_ATOMICS_WITH_LIBATOMIC)
+endif()
+set(CMAKE_REQUIRED_LIBRARIES ${_CMAKE_REQUIRED_LIBRARIES_TMP})
diff --git a/taglib/CMakeLists.txt b/taglib/CMakeLists.txt
index f2689a88..15c2b944 100644
--- a/taglib/CMakeLists.txt
+++ b/taglib/CMakeLists.txt
@@ -542,6 +542,7 @@ target_include_directories(tag INTERFACE
 target_link_libraries(tag
   PRIVATE $<IF:$<TARGET_EXISTS:utf8::cpp>,utf8::cpp,$<$<TARGET_EXISTS:utf8cpp>:utf8cpp>>
           $<$<TARGET_EXISTS:ZLIB::ZLIB>:ZLIB::ZLIB>
+          $<$<BOOL:${HAVE_CXX_ATOMICS_WITH_LIBATOMIC}>:atomic>
 )
 
 set_target_properties(tag PROPERTIES