Check*: Tolerate variables set with names of languages

Fix the language checks added by commit 90dead024c (CheckCompilerFlag:
unified way to check compiler flags per language, 2020-09-25,
v3.19.0-rc1~88^2), commit 10ae907de0 (CheckSoureCompiles: Add a unified
way to check if a source compiles, 2020-09-14, v3.19.0-rc1~118^2~1), and
commit 357e2ef429 (CheckSoureRuns: Add a unified way to check if a
source runs, 2020-09-14, v3.19.0-rc1~118^2) to work when variables of
the language names are set.

Fixes: #21500

21 files changed, 56 insertions, 20 deletions

diff --git a/Modules/Internal/CheckCompilerFlag.cmake b/Modules/Internal/CheckCompilerFlag.cmake
index f790d87..6b2a11e 100644
--- a/Modules/Internal/CheckCompilerFlag.cmake
+++ b/Modules/Internal/CheckCompilerFlag.cmake
@@ -11,20 +11,20 @@ cmake_policy(SET CMP0057 NEW) # if() supports IN_LIST
 
 function(CMAKE_CHECK_COMPILER_FLAG _lang _flag _var)
 
-  if(_lang STREQUAL C)
+  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")
-  elseif(_lang STREQUAL CXX)
+  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\\+\\+")
-    elseif(_lang STREQUAL CUDA)
+  elseif(_lang STREQUAL "CUDA")
     set(_lang_src "__host__ int main() { return 0; }")
     set(_lang_fail_regex FAIL_REGEX "command[ -]line option .* is valid for .* but not for C\\+\\+" # Host GNU
                          FAIL_REGEX "argument unused during compilation: .*") # Clang
-  elseif(_lang STREQUAL Fortran)
+  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")
-  elseif(_lang STREQUAL OBJC)
+  elseif(_lang STREQUAL "OBJC")
     set(_lang_src [=[
 #ifndef __OBJC__
 #  error "Not an Objective-C compiler"
@@ -32,7 +32,7 @@ function(CMAKE_CHECK_COMPILER_FLAG _lang _flag _var)
 int main(void) { return 0; }]=])
     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)
+  elseif(_lang STREQUAL "OBJCXX")
     set(_lang_src [=[
 #ifndef __OBJC__
 #  error "Not an Objective-C++ compiler"
@@ -40,7 +40,7 @@ int main(void) { return 0; }]=])
 int main(void) { return 0; }]=])
     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 ISPC)
+  elseif(_lang STREQUAL "ISPC")
     set(_lang_src "float func(uniform int32, float a) { return a / 2.25; }")
   else()
     message (SEND_ERROR "check_compiler_flag: ${_lang}: unknown language.")
diff --git a/Modules/Internal/CheckSourceCompiles.cmake b/Modules/Internal/CheckSourceCompiles.cmake
index 91c8964..3b2152a 100644
--- a/Modules/Internal/CheckSourceCompiles.cmake
+++ b/Modules/Internal/CheckSourceCompiles.cmake
@@ -10,25 +10,25 @@ cmake_policy(SET CMP0057 NEW) # if() supports IN_LIST
 function(CMAKE_CHECK_SOURCE_COMPILES _lang _source _var)
   if(NOT DEFINED "${_var}")
 
-    if(_lang STREQUAL C)
+    if(_lang STREQUAL "C")
       set(_lang_textual "C")
       set(_lang_ext "c")
-    elseif(_lang STREQUAL CXX)
+    elseif(_lang STREQUAL "CXX")
       set(_lang_textual "C++")
       set(_lang_ext "cxx")
-    elseif(_lang STREQUAL CUDA)
+    elseif(_lang STREQUAL "CUDA")
       set(_lang_textual "CUDA")
       set(_lang_ext "cu")
-    elseif(_lang STREQUAL Fortran)
+    elseif(_lang STREQUAL "Fortran")
       set(_lang_textual "Fortran")
       set(_lang_ext "F90")
-    elseif(_lang STREQUAL ISPC)
+    elseif(_lang STREQUAL "ISPC")
       set(_lang_textual "ISPC")
       set(_lang_ext "ispc")
-    elseif(_lang STREQUAL OBJC)
+    elseif(_lang STREQUAL "OBJC")
       set(_lang_textual "Objective-C")
       set(_lang_ext "m")
-    elseif(_lang STREQUAL OBJCXX)
+    elseif(_lang STREQUAL "OBJCXX")
       set(_lang_textual "Objective-C++")
       set(_lang_ext "mm")
     else()
diff --git a/Modules/Internal/CheckSourceRuns.cmake b/Modules/Internal/CheckSourceRuns.cmake
index 3a4b758..676f3d0 100644
--- a/Modules/Internal/CheckSourceRuns.cmake
+++ b/Modules/Internal/CheckSourceRuns.cmake
@@ -10,22 +10,22 @@ cmake_policy(SET CMP0057 NEW) # if() supports IN_LIST
 function(CMAKE_CHECK_SOURCE_RUNS _lang _source _var)
   if(NOT DEFINED "${_var}")
 
-    if(_lang STREQUAL C)
+    if(_lang STREQUAL "C")
       set(_lang_textual "C")
       set(_lang_ext "c")
-    elseif(_lang STREQUAL CXX)
+    elseif(_lang STREQUAL "CXX")
       set(_lang_textual "C++")
       set(_lang_ext "cxx")
-    elseif(_lang STREQUAL CUDA)
+    elseif(_lang STREQUAL "CUDA")
       set(_lang_textual "CUDA")
       set(_lang_ext "cu")
-    elseif(_lang STREQUAL Fortran)
+    elseif(_lang STREQUAL "Fortran")
       set(_lang_textual "Fortran")
       set(_lang_ext "F90")
-    elseif(_lang STREQUAL OBJC)
+    elseif(_lang STREQUAL "OBJC")
       set(_lang_textual "Objective-C")
       set(_lang_ext "m")
-    elseif(_lang STREQUAL OBJCXX)
+    elseif(_lang STREQUAL "OBJCXX")
       set(_lang_textual "Objective-C++")
       set(_lang_ext "mm")
     else()
diff --git a/Tests/RunCMake/CheckCompilerFlag/CheckCCompilerFlag.cmake b/Tests/RunCMake/CheckCompilerFlag/CheckCCompilerFlag.cmake
index 095fd54..6483f11 100644
--- a/Tests/RunCMake/CheckCompilerFlag/CheckCCompilerFlag.cmake
+++ b/Tests/RunCMake/CheckCompilerFlag/CheckCCompilerFlag.cmake
@@ -2,6 +2,8 @@
 enable_language (C)
 include(CheckCompilerFlag)
 
+set(C 1) # test that this is tolerated
+
 check_compiler_flag(C "-_this_is_not_a_flag_" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "invalid C compile flag didn't fail.")
diff --git a/Tests/RunCMake/CheckCompilerFlag/CheckCUDACompilerFlag.cmake b/Tests/RunCMake/CheckCompilerFlag/CheckCUDACompilerFlag.cmake
index a40699c..681a546 100644
--- a/Tests/RunCMake/CheckCompilerFlag/CheckCUDACompilerFlag.cmake
+++ b/Tests/RunCMake/CheckCompilerFlag/CheckCUDACompilerFlag.cmake
@@ -2,6 +2,8 @@
 enable_language (CUDA)
 include(CheckCompilerFlag)
 
+set(CUDA 1) # test that this is tolerated
+
 check_compiler_flag(CUDA "-_this_is_not_a_flag_" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "invalid CUDA compile flag didn't fail.")
diff --git a/Tests/RunCMake/CheckCompilerFlag/CheckCXXCompilerFlag.cmake b/Tests/RunCMake/CheckCompilerFlag/CheckCXXCompilerFlag.cmake
index bbc104e..60e9755 100644
--- a/Tests/RunCMake/CheckCompilerFlag/CheckCXXCompilerFlag.cmake
+++ b/Tests/RunCMake/CheckCompilerFlag/CheckCXXCompilerFlag.cmake
@@ -2,6 +2,8 @@
 enable_language (CXX)
 include(CheckCompilerFlag)
 
+set(CXX 1) # test that this is tolerated
+
 check_compiler_flag(CXX "-_this_is_not_a_flag_" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "invalid CXX compile flag didn't fail.")
diff --git a/Tests/RunCMake/CheckCompilerFlag/CheckFortranCompilerFlag.cmake b/Tests/RunCMake/CheckCompilerFlag/CheckFortranCompilerFlag.cmake
index 220ee29..7bb88b1 100644
--- a/Tests/RunCMake/CheckCompilerFlag/CheckFortranCompilerFlag.cmake
+++ b/Tests/RunCMake/CheckCompilerFlag/CheckFortranCompilerFlag.cmake
@@ -1,6 +1,8 @@
 enable_language (Fortran)
 include(CheckCompilerFlag)
 
+set(Fortran 1) # test that this is tolerated
+
 check_compiler_flag(Fortran "-_this_is_not_a_flag_" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "invalid Fortran compile flag didn't fail.")
diff --git a/Tests/RunCMake/CheckCompilerFlag/CheckOBJCCompilerFlag.cmake b/Tests/RunCMake/CheckCompilerFlag/CheckOBJCCompilerFlag.cmake
index e9344ca..f250f8d 100644
--- a/Tests/RunCMake/CheckCompilerFlag/CheckOBJCCompilerFlag.cmake
+++ b/Tests/RunCMake/CheckCompilerFlag/CheckOBJCCompilerFlag.cmake
@@ -1,6 +1,8 @@
 enable_language (OBJC)
 include(CheckCompilerFlag)
 
+set(OBJC 1) # test that this is tolerated
+
 check_compiler_flag(OBJC "-_this_is_not_a_flag_" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "invalid OBJC compile flag didn't fail.")
diff --git a/Tests/RunCMake/CheckCompilerFlag/CheckOBJCXXCompilerFlag.cmake b/Tests/RunCMake/CheckCompilerFlag/CheckOBJCXXCompilerFlag.cmake
index 503a1de..bc940a6 100644
--- a/Tests/RunCMake/CheckCompilerFlag/CheckOBJCXXCompilerFlag.cmake
+++ b/Tests/RunCMake/CheckCompilerFlag/CheckOBJCXXCompilerFlag.cmake
@@ -1,6 +1,8 @@
 enable_language (OBJCXX)
 include(CheckCompilerFlag)
 
+set(OBJCXX 1) # test that this is tolerated
+
 check_compiler_flag(OBJCXX "-_this_is_not_a_flag_" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "invalid OBJCXX compile flag didn't fail.")
diff --git a/Tests/RunCMake/CheckSourceCompiles/CheckCSourceCompiles.cmake b/Tests/RunCMake/CheckSourceCompiles/CheckCSourceCompiles.cmake
index cf46189..4f73622 100644
--- a/Tests/RunCMake/CheckSourceCompiles/CheckCSourceCompiles.cmake
+++ b/Tests/RunCMake/CheckSourceCompiles/CheckCSourceCompiles.cmake
@@ -2,6 +2,8 @@
 enable_language (C)
 include(CheckSourceCompiles)
 
+set(C 1) # test that this is tolerated
+
 check_source_compiles(C "I don't build" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "invalid C source didn't fail.")
diff --git a/Tests/RunCMake/CheckSourceCompiles/CheckCUDASourceCompiles.cmake b/Tests/RunCMake/CheckSourceCompiles/CheckCUDASourceCompiles.cmake
index 1e6e6b2..2190649 100644
--- a/Tests/RunCMake/CheckSourceCompiles/CheckCUDASourceCompiles.cmake
+++ b/Tests/RunCMake/CheckSourceCompiles/CheckCUDASourceCompiles.cmake
@@ -2,6 +2,8 @@
 enable_language (CUDA)
 include(CheckSourceCompiles)
 
+set(CUDA 1) # test that this is tolerated
+
 check_source_compiles(CUDA "I don't build" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "invalid CUDA source didn't fail.")
diff --git a/Tests/RunCMake/CheckSourceCompiles/CheckCXXSourceCompiles.cmake b/Tests/RunCMake/CheckSourceCompiles/CheckCXXSourceCompiles.cmake
index ec01d42..97c9c30 100644
--- a/Tests/RunCMake/CheckSourceCompiles/CheckCXXSourceCompiles.cmake
+++ b/Tests/RunCMake/CheckSourceCompiles/CheckCXXSourceCompiles.cmake
@@ -2,6 +2,8 @@
 enable_language (CXX)
 include(CheckSourceCompiles)
 
+set(CXX 1) # test that this is tolerated
+
 check_source_compiles(CXX "I don't build" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "invalid CXX source didn't fail.")
diff --git a/Tests/RunCMake/CheckSourceCompiles/CheckFortranSourceCompiles.cmake b/Tests/RunCMake/CheckSourceCompiles/CheckFortranSourceCompiles.cmake
index 1d4e16d..48dc525 100644
--- a/Tests/RunCMake/CheckSourceCompiles/CheckFortranSourceCompiles.cmake
+++ b/Tests/RunCMake/CheckSourceCompiles/CheckFortranSourceCompiles.cmake
@@ -3,6 +3,8 @@
 enable_language (Fortran)
 include(CheckSourceCompiles)
 
+set(Fortran 1) # test that this is tolerated
+
 check_source_compiles(Fortran [=[
       PROGRAM TEST_HAVE_PRINT
         PRINT *, 'Hello'
diff --git a/Tests/RunCMake/CheckSourceCompiles/CheckOBJCSourceCompiles.cmake b/Tests/RunCMake/CheckSourceCompiles/CheckOBJCSourceCompiles.cmake
index 2f53cfc4..76a5009 100644
--- a/Tests/RunCMake/CheckSourceCompiles/CheckOBJCSourceCompiles.cmake
+++ b/Tests/RunCMake/CheckSourceCompiles/CheckOBJCSourceCompiles.cmake
@@ -1,6 +1,8 @@
 enable_language (OBJC)
 include(CheckSourceCompiles)
 
+set(OBJC 1) # test that this is tolerated
+
 check_source_compiles(OBJC [[
   #import <Foundation/Foundation.h>
   int main() {
diff --git a/Tests/RunCMake/CheckSourceCompiles/CheckOBJCXXSourceCompiles.cmake b/Tests/RunCMake/CheckSourceCompiles/CheckOBJCXXSourceCompiles.cmake
index 805d513..814237e 100644
--- a/Tests/RunCMake/CheckSourceCompiles/CheckOBJCXXSourceCompiles.cmake
+++ b/Tests/RunCMake/CheckSourceCompiles/CheckOBJCXXSourceCompiles.cmake
@@ -1,6 +1,8 @@
 enable_language (OBJCXX)
 include(CheckSourceCompiles)
 
+set(OBJCXX 1) # test that this is tolerated
+
 check_source_compiles(OBJCXX [[
   #include <vector>
   #import <Foundation/Foundation.h>
diff --git a/Tests/RunCMake/CheckSourceRuns/CheckCSourceRuns.cmake b/Tests/RunCMake/CheckSourceRuns/CheckCSourceRuns.cmake
index 3029ac2..96a1027 100644
--- a/Tests/RunCMake/CheckSourceRuns/CheckCSourceRuns.cmake
+++ b/Tests/RunCMake/CheckSourceRuns/CheckCSourceRuns.cmake
@@ -2,6 +2,8 @@
 enable_language (C)
 include(CheckSourceRuns)
 
+set(C 1) # test that this is tolerated
+
 check_source_runs(C "int main() {return 2;}" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "C check_source_runs succeeded, but should have failed.")
diff --git a/Tests/RunCMake/CheckSourceRuns/CheckCUDASourceRuns.cmake b/Tests/RunCMake/CheckSourceRuns/CheckCUDASourceRuns.cmake
index 01e5ac8..ea5f4f9 100644
--- a/Tests/RunCMake/CheckSourceRuns/CheckCUDASourceRuns.cmake
+++ b/Tests/RunCMake/CheckSourceRuns/CheckCUDASourceRuns.cmake
@@ -2,6 +2,8 @@
 enable_language (CUDA)
 include(CheckSourceRuns)
 
+set(CUDA 1) # test that this is tolerated
+
 check_source_runs(CUDA "int main() {return 2;}" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "CUDA check_source_runs succeeded, but should have failed.")
diff --git a/Tests/RunCMake/CheckSourceRuns/CheckCXXSourceRuns.cmake b/Tests/RunCMake/CheckSourceRuns/CheckCXXSourceRuns.cmake
index d47ddda..c4bef6e 100644
--- a/Tests/RunCMake/CheckSourceRuns/CheckCXXSourceRuns.cmake
+++ b/Tests/RunCMake/CheckSourceRuns/CheckCXXSourceRuns.cmake
@@ -2,6 +2,8 @@
 enable_language (CXX)
 include(CheckSourceRuns)
 
+set(CXX 1) # test that this is tolerated
+
 check_source_runs(CXX "int main() {return 2;}" SHOULD_FAIL)
 if(SHOULD_FAIL)
   message(SEND_ERROR "CXX check_source_runs succeeded, but should have failed.")
diff --git a/Tests/RunCMake/CheckSourceRuns/CheckFortranSourceRuns.cmake b/Tests/RunCMake/CheckSourceRuns/CheckFortranSourceRuns.cmake
index 2a1fdfe..50e8ec8 100644
--- a/Tests/RunCMake/CheckSourceRuns/CheckFortranSourceRuns.cmake
+++ b/Tests/RunCMake/CheckSourceRuns/CheckFortranSourceRuns.cmake
@@ -3,6 +3,8 @@
 enable_language (Fortran)
 include(CheckSourceRuns)
 
+set(Fortran 1) # test that this is tolerated
+
 check_source_runs(Fortran [=[
       PROGRAM TEST_HAVE_PRINT
         PRINT *, 'Hello'
diff --git a/Tests/RunCMake/CheckSourceRuns/CheckOBJCSourceRuns.cmake b/Tests/RunCMake/CheckSourceRuns/CheckOBJCSourceRuns.cmake
index 55f28f3..b828352 100644
--- a/Tests/RunCMake/CheckSourceRuns/CheckOBJCSourceRuns.cmake
+++ b/Tests/RunCMake/CheckSourceRuns/CheckOBJCSourceRuns.cmake
@@ -1,6 +1,8 @@
 enable_language (OBJC)
 include(CheckSourceRuns)
 
+set(OBJC 1) # test that this is tolerated
+
 check_source_runs(OBJC [[
   #import <Foundation/Foundation.h>
   int main() {
diff --git a/Tests/RunCMake/CheckSourceRuns/CheckOBJCXXSourceRuns.cmake b/Tests/RunCMake/CheckSourceRuns/CheckOBJCXXSourceRuns.cmake
index a218acd..8a56f13 100644
--- a/Tests/RunCMake/CheckSourceRuns/CheckOBJCXXSourceRuns.cmake
+++ b/Tests/RunCMake/CheckSourceRuns/CheckOBJCXXSourceRuns.cmake
@@ -1,6 +1,8 @@
 enable_language (OBJCXX)
 include(CheckSourceRuns)
 
+set(OBJCXX 1) # test that this is tolerated
+
 check_source_runs(OBJCXX [[
   #include <vector>
   #import <Foundation/Foundation.h>