Modules: Use new SOURCES_FROM_* try_compile (1/2)

Modify some modules that ship with CMake to use the new SOURCES_FROM_*
arguments to try_compile / try_run as added by commits cb14ae2b87
(try_compile: Add SOURCE_FROM_{ARG,VAR}, 2022-09-21) and 611d801790
(try_compile: Add SOURCE_FROM_FILE, 2022-09-22). This covers users which
previously either used an existing file (but sometimes needed to rename
it), or which wrote out their source in entirety. It does NOT cover
users that actually need configure_file functionality, as those will be
more involved to update and will thus be tackled in part 2.

Modules/Internal/CheckSourceCompiles.cmake

@@ -86,14 +86,13 @@ function(CMAKE_CHECK_SOURCE_COMPILES _lang _source _var)
     else()
       set(CHECK_${LANG}_SOURCE_COMPILES_ADD_INCLUDES)
     endif()
-    file(WRITE "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/src.${_SRC_EXT}"
-      "${_source}\n")
 
     if(NOT CMAKE_REQUIRED_QUIET)
       message(CHECK_START "Performing Test ${_var}")
     endif()
+    string(APPEND _source "\n")
     try_compile(${_var}
-      SOURCES ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/src.${_SRC_EXT}
+      SOURCE_FROM_VAR "src.${_SRC_EXT}" _source
       COMPILE_DEFINITIONS -D${_var} ${CMAKE_REQUIRED_DEFINITIONS}
       ${CHECK_${LANG}_SOURCE_COMPILES_ADD_LINK_OPTIONS}
       ${CHECK_${LANG}_SOURCE_COMPILES_ADD_LIBRARIES}

Modules/Internal/CheckSourceRuns.cmake

@@ -85,14 +85,13 @@ function(CMAKE_CHECK_SOURCE_RUNS _lang _source _var)
     else()
       set(CHECK_${_lang}_SOURCE_COMPILES_ADD_INCLUDES)
     endif()
-    file(WRITE "${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/src.${_SRC_EXT}"
-      "${_source}\n")
 
     if(NOT CMAKE_REQUIRED_QUIET)
       message(CHECK_START "Performing Test ${_var}")
     endif()
+    string(APPEND _source "\n")
     try_run(${_var}_EXITCODE ${_var}_COMPILED
-      SOURCES ${CMAKE_BINARY_DIR}${CMAKE_FILES_DIRECTORY}/CMakeTmp/src.${_SRC_EXT}
+      SOURCE_FROM_VAR "src.${_SRC_EXT}" _source
       COMPILE_DEFINITIONS -D${_var} ${CMAKE_REQUIRED_DEFINITIONS}
       ${CHECK_${_lang}_SOURCE_COMPILES_ADD_LINK_OPTIONS}
       ${CHECK_${_lang}_SOURCE_COMPILES_ADD_LIBRARIES}

Modules/Internal/FeatureTesting.cmake

@@ -4,7 +4,7 @@ macro(_record_compiler_features lang compile_flags feature_list)
 
   string(TOLOWER ${lang} lang_lc)
   file(REMOVE "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.bin")
-  file(WRITE "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.${lang_lc}" "
+  set(_content "
   const char features[] = {\"\\n\"\n")
 
   get_property(known_features GLOBAL PROPERTY CMAKE_${lang}_KNOWN_FEATURES)
@@ -16,10 +16,11 @@ macro(_record_compiler_features lang compile_flags feature_list)
       else()
         set(_feature_condition "#if ${_cmake_feature_test_${feature}}\n\"1\"\n#else\n\"0\"\n#endif\n")
       endif()
-      file(APPEND "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.${lang_lc}" "\"${lang}_FEATURE:\"\n${_feature_condition}\"${feature}\\n\"\n")
+      string(APPEND _content
+        "\"${lang}_FEATURE:\"\n${_feature_condition}\"${feature}\\n\"\n")
     endif()
   endforeach()
-  file(APPEND "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.${lang_lc}"
+  string(APPEND _content
     "\n};\n\nint main(int argc, char** argv) { (void)argv; return features[argc]; }\n")
 
   if(CMAKE_${lang}_LINK_WITH_STANDARD_COMPILE_OPTION)
@@ -31,7 +32,7 @@ macro(_record_compiler_features lang compile_flags feature_list)
   endif()
 
   try_compile(CMAKE_${lang}_FEATURE_TEST
-    SOURCES "${CMAKE_BINARY_DIR}/CMakeFiles/feature_tests.${lang_lc}"
+    SOURCE_FROM_VAR "feature_tests.${lang_lc}" _content
     COMPILE_DEFINITIONS "${compile_flags}"
     LINK_LIBRARIES "${compile_flags_for_link}"
     OUTPUT_VARIABLE _output