cmake: Use C99 and define GNU and POSIX flags directly at source files

Fixes #50

CompilerChecks.cmake

@@ -16,7 +16,7 @@ if (UNIX)
         endif()
     endif()
 
-    add_c_compiler_flag("-std=gnu99" SUPPORTED_COMPILER_FLAGS)
+    add_c_compiler_flag("-std=c99" SUPPORTED_COMPILER_FLAGS)
     add_c_compiler_flag("-Wpedantic" SUPPORTED_COMPILER_FLAGS)
     add_c_compiler_flag("-Wall" SUPPORTED_COMPILER_FLAGS)
     add_c_compiler_flag("-Wshadow" SUPPORTED_COMPILER_FLAGS)

example/mock/uptime/CMakeLists.txt

@@ -1,7 +1,11 @@
 add_library(proc_uptime proc_uptime.c)
 
 add_executable(uptime uptime.c)
-target_compile_options(uptime PRIVATE ${DEFAULT_C_COMPILE_FLAGS})
+target_compile_options(uptime
+                       PRIVATE
+                           ${DEFAULT_C_COMPILE_FLAGS}
+                           -D_GNU_SOURCE
+                           -D_XOPEN_SOURCE=600)
 target_link_libraries(uptime proc_uptime)
 set_property(TARGET
                  uptime
@@ -11,7 +15,7 @@ set_property(TARGET
 
 add_cmocka_test(test_uptime
                 SOURCES test_uptime.c
-                COMPILE_OPTIONS ${DEFAULT_C_COMPILE_FLAGS}
+                COMPILE_OPTIONS ${DEFAULT_C_COMPILE_FLAGS} -D_GNU_SOURCE -D_XOPEN_SOURCE=600
                 LINK_LIBRARIES cmocka::cmocka)
 set_property(TARGET
                  test_uptime

src/CMakeLists.txt

@@ -33,6 +33,12 @@ target_compile_options(cmocka
                        PRIVATE
                            ${DEFAULT_C_COMPILE_FLAGS}
                            -DHAVE_CONFIG_H)
+
+target_compile_definitions(cmocka
+                           PRIVATE
+                               _GNU_SOURCE
+                               _XOPEN_SOURCE=700)
+
 if (CMOCKA_PLATFORM_INCLUDE)
     target_compile_options(cmocka
                            PRIVATE
@@ -80,6 +86,12 @@ if (UNIT_TESTING)
                            PRIVATE
                                ${DEFAULT_C_COMPILE_FLAGS}
                                -DHAVE_CONFIG_H)
+
+    target_compile_definitions(cmocka-static
+                               PRIVATE
+                                   _GNU_SOURCE
+                                   _XOPEN_SOURCE=700)
+
     if (CMOCKA_PLATFORM_INCLUDE)
         target_compile_options(cmocka-static
                                PRIVATE

tests/CMakeLists.txt

@@ -58,7 +58,7 @@ endif()
 foreach(_CMOCKA_TEST ${CMOCKA_TESTS})
     add_cmocka_test(${_CMOCKA_TEST}
                     SOURCES ${_CMOCKA_TEST}.c
-                    COMPILE_OPTIONS ${DEFAULT_C_COMPILE_FLAGS}
+                    COMPILE_OPTIONS ${DEFAULT_C_COMPILE_FLAGS} -D_GNU_SOURCE -D_XOPEN_SOURCE=700
                     LINK_LIBRARIES cmocka::static
                     LINK_OPTIONS ${DEFAULT_LINK_FLAGS})
     target_include_directories(${_CMOCKA_TEST} PRIVATE ${cmocka_BINARY_DIR})