From 211a9deac1d4144c7d7ce18ecb6c5d21c4854eaa Mon Sep 17 00:00:00 2001
From: "Klein, Thorsten (BSH)" <thorsten.klein@bshg.com>
Date: Mon, 28 Mar 2022 13:01:08 +0200
Subject: Preserve CMAKE_${lang}_COMPILER_ARG1 from existing CMakeCache.txt

`CMAKE_<LANG>_COMPILER` may be a list if it was defined by a toolchain
file.  In this case we move the args to `CMAKE_<LANG>_COMPILER_ARG1`.
If `CMAKE_<LANG>_COMPILER` is not a list, then it might have been cached
by a previous run that split the `CC` or `CXX` environment variable into
`CMAKE_<LANG>_COMPILER` and `CMAKE_<LANG>_COMPILER_ARG1`.  In this
latter case, avoid clobbering `CMAKE_<LANG>_COMPILER_ARG1`.

Fixes: #23358
---
 Modules/CMakeDetermineCompiler.cmake | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

(limited to 'Modules/CMakeDetermineCompiler.cmake')

diff --git a/Modules/CMakeDetermineCompiler.cmake b/Modules/CMakeDetermineCompiler.cmake
index aec86d92c7..ec2a86515f 100644
--- a/Modules/CMakeDetermineCompiler.cmake
+++ b/Modules/CMakeDetermineCompiler.cmake
@@ -119,9 +119,15 @@ macro(_cmake_find_compiler_path lang)
     # (e.g. via ctest) or set in CMAKE_TOOLCHAIN_FILE
     # if CMAKE_${lang}_COMPILER is a list, use the first item as
     # CMAKE_${lang}_COMPILER and the rest as CMAKE_${lang}_COMPILER_ARG1
-    set(CMAKE_${lang}_COMPILER_ARG1 "${CMAKE_${lang}_COMPILER}")
-    list(POP_FRONT CMAKE_${lang}_COMPILER_ARG1 CMAKE_${lang}_COMPILER)
-    list(JOIN CMAKE_${lang}_COMPILER_ARG1 " " CMAKE_${lang}_COMPILER_ARG1)
+    # Otherwise, preserve any existing CMAKE_${lang}_COMPILER_ARG1 that might
+    # have been saved by CMakeDetermine${lang}Compiler in a previous run.
+    list(LENGTH CMAKE_${lang}_COMPILER _CMAKE_${lang}_COMPILER_LENGTH)
+    if(_CMAKE_${lang}_COMPILER_LENGTH GREATER 1)
+      set(CMAKE_${lang}_COMPILER_ARG1 "${CMAKE_${lang}_COMPILER}")
+      list(POP_FRONT CMAKE_${lang}_COMPILER_ARG1 CMAKE_${lang}_COMPILER)
+      list(JOIN CMAKE_${lang}_COMPILER_ARG1 " " CMAKE_${lang}_COMPILER_ARG1)
+    endif()
+    unset(_CMAKE_${lang}_COMPILER_LENGTH)
 
     # find the compiler in the PATH if necessary
     # if compiler (and arguments) comes from cache then synchronize cache with updated CMAKE_<LANG>_COMPILER
-- 
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