From ae294a42f001a0fe8191f20627f22ddd0e8358ed Mon Sep 17 00:00:00 2001
From: Joerg Bornemann <joerg.bornemann@qt.io>
Date: Tue, 4 Jan 2022 10:30:04 +0100
Subject: [PATCH] CMake: Add C/C++ compiler options to C/C++ sources only

When compiling CUDA sources in a user project, the Qt6::Platform target
would pull in C/C++ related compiler flags, leading to compiler errors.

Make sure that we only add those flags to C/C++ source files.

Pick-to: 6.2 6.3
Fixes: QTBUG-99548
Change-Id: Idbccd65fe8f66abd1da3fce95e563065d1ed3cc6
Reviewed-by: Kai Koehne <kai.koehne@qt.io>
---
 cmake/QtFlagHandlingHelpers.cmake | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/cmake/QtFlagHandlingHelpers.cmake b/cmake/QtFlagHandlingHelpers.cmake
index 9c5aee5d90..b36f6cff0c 100644
--- a/cmake/QtFlagHandlingHelpers.cmake
+++ b/cmake/QtFlagHandlingHelpers.cmake
@@ -235,7 +235,8 @@ function(qt_set_msvc_cplusplus_options target visibility)
     # For MSVC we need to explicitly pass -Zc:__cplusplus to get correct __cplusplus.
     # Check qt_config_compile_test for more info.
     if(MSVC AND MSVC_VERSION GREATER_EQUAL 1913)
-        target_compile_options("${target}" ${visibility} "-Zc:__cplusplus" "-permissive-")
+        set(flags "-Zc:__cplusplus" "-permissive-")
+        target_compile_options("${target}" ${visibility} "$<$<COMPILE_LANGUAGE:CXX>:${flags}>")
     endif()
 endfunction()
 
@@ -247,7 +248,11 @@ function(qt_enable_utf8_sources target)
 
     if(utf8_flags)
         # Allow opting out by specifying the QT_NO_UTF8_SOURCE target property.
-        set(genex_condition "$<NOT:$<BOOL:$<TARGET_PROPERTY:QT_NO_UTF8_SOURCE>>>")
+        set(opt_out_condition "$<NOT:$<BOOL:$<TARGET_PROPERTY:QT_NO_UTF8_SOURCE>>>")
+        # Only set the compiler option for C and C++.
+        set(language_condition "$<COMPILE_LANGUAGE:C,CXX>")
+        # Compose the full condition.
+        set(genex_condition "$<AND:${opt_out_condition},${language_condition}>")
         set(utf8_flags "$<${genex_condition}:${utf8_flags}>")
         target_compile_options("${target}" INTERFACE "${utf8_flags}")
     endif()