Merge topic 'CheckCompilerFlags-revert-linker-warnings'

4941887d7d CheckCompilerFlags: Revert "Catch linker warning about ignored flags"
c2341ece47 CheckLinkerFlag: Catch linker warning when the checked flag is ignored

Acked-by: Kitware Robot <[email protected]>
Tested-by: buildbot <[email protected]>
Merge-request: !7190

Modules/CMakeCheckCompilerFlagCommonPatterns.cmake

@@ -13,7 +13,6 @@ macro (CHECK_COMPILER_FLAG_COMMON_PATTERNS _VAR)
     FAIL_REGEX "unknown .*option"                          # Clang
     FAIL_REGEX "optimization flag .* not supported"        # Clang
     FAIL_REGEX "unknown argument ignored"                  # Clang (cl)
-    FAIL_REGEX "warning: .* ignored"                       # Clang (linker)
     FAIL_REGEX "ignoring unknown option"                   # MSVC, Intel
     FAIL_REGEX "warning D9002"                             # MSVC, any lang
     FAIL_REGEX "option.*not supported"                     # Intel

Modules/Internal/CheckLinkerFlag.cmake

@@ -25,6 +25,15 @@ function(CMAKE_CHECK_LINKER_FLAG _lang _flag _var)
   set(CMAKE_REQUIRED_LINK_OPTIONS "${_flag}")
 
   check_compiler_flag_common_patterns(_common_patterns)
+
+  # Match linker warnings if the exact flag is ignored.
+  foreach(flag IN LISTS _flag)
+    string(REGEX REPLACE "([][+.*?()^$])" [[\\\1]] _flag_regex "${flag}")
+    list(APPEND _common_patterns
+      FAIL_REGEX "warning: .*${_flag_regex}.* ignored"
+      )
+  endforeach()
+
   cmake_check_source_compiles(${_lang}
     "${_lang_src}"
     ${_var}