From d66858c8e42c8a07a8bbc15559c21eb917866f46 Mon Sep 17 00:00:00 2001
From: Luthaf <luthaf@luthaf.fr>
Date: Mon, 5 Oct 2020 23:28:46 +0200
Subject: CheckCompilerFlag: Update the regex used to detect invalid options
 for GCC 10

The warning emmitted by GCC for invalid options have been updated to
read "command-line option XXX is valid ..." instead of "command line
option XXX is valid ...".  Update the regex to make it valid with both
the old and new warning message.

Fixes: #21275
---
 Modules/CheckCompilerFlag.cmake                           | 10 +++++-----
 Tests/RunCMake/CheckCompilerFlag/CheckCCompilerFlag.cmake |  7 +++++++
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/Modules/CheckCompilerFlag.cmake b/Modules/CheckCompilerFlag.cmake
index 9223009..0339225 100644
--- a/Modules/CheckCompilerFlag.cmake
+++ b/Modules/CheckCompilerFlag.cmake
@@ -45,20 +45,20 @@ function(CHECK_COMPILER_FLAG _lang _flag _var)
 
   if(_lang STREQUAL C)
     set(_lang_src "int main(void) { return 0; }")
-    set(_lang_fail_regex FAIL_REGEX "command line option .* is valid for .* but not for C")
+    set(_lang_fail_regex FAIL_REGEX "command[ -]line option .* is valid for .* but not for C")
   elseif(_lang STREQUAL CXX)
     set(_lang_src "int main() { return 0; }")
-    set(_lang_fail_regex FAIL_REGEX "command line option .* is valid for .* but not for C\\+\\+")
+    set(_lang_fail_regex FAIL_REGEX "command[ -]line option .* is valid for .* but not for C\\+\\+")
   elseif(_lang STREQUAL Fortran)
     set(_lang_src "       program test\n       stop\n       end program")
-    set(_lang_fail_regex FAIL_REGEX "command line option .* is valid for .* but not for Fortran")
+    set(_lang_fail_regex FAIL_REGEX "command[ -]line option .* is valid for .* but not for Fortran")
   elseif(_lang STREQUAL OBJC)
     set(_lang_src [=[
 #ifndef __OBJC__
 #  error "Not an Objective-C compiler"
 #endif
 int main(void) { return 0; }]=])
-    set(_lang_fail_regex FAIL_REGEX "command line option .* is valid for .* but not for Objective-C" # GNU
+    set(_lang_fail_regex FAIL_REGEX "command[ -]line option .* is valid for .* but not for Objective-C" # GNU
                          FAIL_REGEX "argument unused during compilation: .*") # Clang
   elseif(_lang STREQUAL OBJCXX)
     set(_lang_src [=[
@@ -66,7 +66,7 @@ int main(void) { return 0; }]=])
 #  error "Not an Objective-C++ compiler"
 #endif
 int main(void) { return 0; }]=])
-    set(_lang_fail_regex FAIL_REGEX "command line option .* is valid for .* but not for Objective-C\\+\\+" # GNU
+    set(_lang_fail_regex FAIL_REGEX "command[ -]line option .* is valid for .* but not for Objective-C\\+\\+" # GNU
                          FAIL_REGEX "argument unused during compilation: .*") # Clang
   else()
     message (SEND_ERROR "check_compiler_flag: ${_lang}: unknown language.")
diff --git a/Tests/RunCMake/CheckCompilerFlag/CheckCCompilerFlag.cmake b/Tests/RunCMake/CheckCompilerFlag/CheckCCompilerFlag.cmake
index d268ed2..095fd54 100644
--- a/Tests/RunCMake/CheckCompilerFlag/CheckCCompilerFlag.cmake
+++ b/Tests/RunCMake/CheckCompilerFlag/CheckCCompilerFlag.cmake
@@ -13,3 +13,10 @@ if(CMAKE_C_COMPILER_ID MATCHES "GNU|Clang" AND NOT "x${CMAKE_C_SIMULATE_ID}" STR
     message(SEND_ERROR "${CMAKE_C_COMPILER_ID} compiler flag '-x c' check failed")
   endif()
 endif()
+
+if(CMAKE_C_COMPILER_ID STREQUAL "GNU")
+  check_compiler_flag(C "-frtti" SHOULD_FAIL_RTTI)
+  if(SHOULD_FAIL_RTTI)
+    message(SEND_ERROR "${CMAKE_C_COMPILER_ID} compiler flag '-frtti' check passed but should have failed")
+  endif()
+endif()
-- 
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