CMake: updates compiler definitions

src/CMakeLists.txt

@@ -2,6 +2,26 @@ add_executable(zbbs-client-tui)
 
 set_property(TARGET zbbs-client-tui PROPERTY C_STANDARD 23)
 
+if(
+  (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC") OR
+  (CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC")
+)
+  if (ZBBS_DEBUG)
+    target_compile_options(zbbs-client-tui PRIVATE /W3)
+    message("Include debug info (Microsoft)")
+  endif()
+elseif(
+  (CMAKE_CXX_COMPILER_ID STREQUAL "GNU") OR
+  (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
+)
+  add_compile_definitions(_GNU_SOURCE) 
+  # target_compile_definitions(zbbs-client-tui PRIVATE _GNU_SOURCE) -> doesn't work
+  if (ZBBS_DEBUG)
+    target_compile_options(zbbs-client-tui PRIVATE -Wall -ggdb -pedantic)
+    message("Include debug info (GNU/Clang)")
+  endif()
+endif()
+
 file(GLOB M_HEADERS "*.h")
 file(GLOB M_SOURCES "*.c")
 
@@ -28,24 +48,4 @@ target_link_libraries(zbbs-client-tui
         widget
         modals
         ${CURSES_LIBRARIES}
-)
-
-if (ZBBS_DEBUG)
-if(
-  (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC") OR
-  (CMAKE_CXX_COMPILER_FRONTEND_VARIANT STREQUAL "MSVC")
-)
-
-  target_compile_options(zbbs-client-tui PRIVATE /W3)
-  message("Include debug info (Microsoft)")
-
-elseif(
-  (CMAKE_CXX_COMPILER_ID STREQUAL "GNU") OR
-  (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
-)
-
-  target_compile_options(zbbs-client-tui PRIVATE -Wall -ggdb -pedantic)
-  message("Include debug info (GNU/Clang)")
-
-endif()
-endif()
+)