From 89df8efba47ac33fd9951d3a2dde8eb64dc1b8f5 Mon Sep 17 00:00:00 2001
From: Oleg Derevenetz <oleg-derevenetz@yandex.ru>
Date: Wed, 23 Apr 2025 20:37:34 +0300
Subject: [PATCH] CheckLanguage: Bias compiler selection using already-enabled
 languages

In a project that has enabled C or CXX, we bias ASM and Fortran compiler
selection to match.  Propagate this bias into the `check_language` test
project so that if it succeeds, we will select the same compiler when
enabling the tested language in the calling project.

Fixes: #19350
---
 Modules/CMakeDetermineCompiler.cmake |  6 +++++-
 Modules/CheckLanguage.cmake          | 13 +++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/Modules/CMakeDetermineCompiler.cmake b/Modules/CMakeDetermineCompiler.cmake
index 06e8bedc51..16c5554fef 100644
--- a/Modules/CMakeDetermineCompiler.cmake
+++ b/Modules/CMakeDetermineCompiler.cmake
@@ -4,7 +4,11 @@
 
 macro(_cmake_find_compiler lang)
   # Use already-enabled languages for reference.
-  get_property(_languages GLOBAL PROPERTY ENABLED_LANGUAGES)
+  if(DEFINED _CMAKE_CHECK_ENABLED_LANGUAGES)
+    set(_languages "${_CMAKE_CHECK_ENABLED_LANGUAGES}")
+  else()
+    get_property(_languages GLOBAL PROPERTY ENABLED_LANGUAGES)
+  endif()
   list(REMOVE_ITEM _languages "${lang}")
 
   if(CMAKE_${lang}_COMPILER_INIT)
diff --git a/Modules/CheckLanguage.cmake b/Modules/CheckLanguage.cmake
index e2165ad589..ac61d7019c 100644
--- a/Modules/CheckLanguage.cmake
+++ b/Modules/CheckLanguage.cmake
@@ -78,6 +78,19 @@ macro(check_language lang)
     file(REMOVE_RECURSE ${CMAKE_CURRENT_BINARY_DIR}/CMakeFiles/Check${lang})
 
     set(_input_variables "set(CMAKE_MODULE_PATH \"${CMAKE_MODULE_PATH}\")\n")
+    get_property(_languages GLOBAL PROPERTY ENABLED_LANGUAGES)
+    list(REMOVE_ITEM _languages "NONE")
+    if(NOT _languages STREQUAL "")
+      string(APPEND _input_variables "set(_CMAKE_CHECK_ENABLED_LANGUAGES \"${_languages}\")\n")
+      foreach(l IN LISTS _languages)
+        string(APPEND _input_variables
+          "set(CMAKE_${l}_COMPILER \"${CMAKE_${l}_COMPILER}\")\n"
+          "set(CMAKE_${l}_COMPILER_ID \"${CMAKE_${l}_COMPILER_ID}\")\n"
+          "set(CMAKE_${l}_COMPILER_LOADED ${CMAKE_${l}_COMPILER_LOADED})\n"
+          "set(CMAKE_${l}_COMPILER_VERSION \"${CMAKE_${l}_COMPILER_VERSION}\")\n"
+        )
+      endforeach()
+    endif()
 
     set(_output_variables "set(CMAKE_${lang}_COMPILER \\\"\${CMAKE_${lang}_COMPILER}\\\")\n")
     if("${lang}" MATCHES "^(CUDA|HIP)$" AND NOT CMAKE_GENERATOR MATCHES "Visual Studio")