use CMAKE_C_STANDARD to set C standard

Author: QuietMisdreavus

api_test/CMakeLists.txt

@@ -30,9 +30,12 @@ elseif(CMAKE_COMPILER_IS_GNUCC OR "${CMAKE_C_COMPILER_ID}" STREQUAL "Clang")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -std=c99 -pedantic")
 endif()
 
-# On MSVC 15.0 and newer, compile with C11 standard
-if (MSVC AND MSVC_VERSION GREATER_EQUAL 1910)
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /std:c11")
+# set a required C standard so we can load stdbool.h
+if(MSVC)
+  set(CMAKE_C_STANDARD 11)
+else()
+  set(CMAKE_C_STANDARD 99)
 endif()
+set(CMAKE_C_STANDARD_REQUIRED YES)
 
 set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -DCMARK_USE_CMAKE_HEADERS")

extensions/CMakeLists.txt

@@ -124,10 +124,13 @@ if(MSVC AND MSVC_VERSION LESS 1800)
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /TP")
 endif()
 
-# On MSVC 15.0 and newer, compile with C11 standard
-if (MSVC AND MSVC_VERSION GREATER_EQUAL 1910)
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /std:c11")
+# set a required C standard so we can load stdbool.h
+if(MSVC)
+  set(CMAKE_C_STANDARD 11)
+else()
+  set(CMAKE_C_STANDARD 99)
 endif()
+set(CMAKE_C_STANDARD_REQUIRED YES)
 
 if(CMAKE_BUILD_TYPE STREQUAL "Ubsan")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=undefined")

src/CMakeLists.txt

@@ -195,10 +195,13 @@ if(MSVC AND MSVC_VERSION LESS 1800)
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /TP")
 endif()
 
-# On MSVC 15.0 and newer, compile with C11 standard
-if (MSVC AND MSVC_VERSION GREATER_EQUAL 1910)
-  set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} /std:c11")
+# set a required C standard so we can load stdbool.h
+if(MSVC)
+  set(CMAKE_C_STANDARD 11)
+else()
+  set(CMAKE_C_STANDARD 99)
 endif()
+set(CMAKE_C_STANDARD_REQUIRED YES)
 
 if(CMAKE_BUILD_TYPE STREQUAL "Ubsan")
   set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fsanitize=undefined")