build: switch back to c_std=gnu99 pending ObjC fix

It's better to warn by default on MSVC (which we were already doing before
we bumped to 1.4.0) than to fail by default on macOS.

Fixes: 51e3e7d9ae ("build: Bump Meson dependency to 1.4.0")

.gitlab-ci.yml

@@ -590,7 +590,9 @@ vs2017-x64:
   script:
     # FIXME: These should use --wrap-mode=nodownload but the Windows CI machines
     # aren’t currently set up for that.
-    - .gitlab-ci/test-msvc.bat ${MESON_COMMON_OPTIONS}
+    # FIXME: Use --meson-fatal-warnings once we've enabled c_std=gnu99,c99
+    # for the runner's Meson version.
+    - .gitlab-ci/test-msvc.bat --buildtype debug
                                --wrap-mode=default
                                --python.platlibdir=C:\Python37\site-packages
                                --python.purelibdir=C:\Python37\site-packages
@@ -623,7 +625,9 @@ vs2017-x64-static:
   script:
     # FIXME: These should use --wrap-mode=nodownload but the Windows CI machines
     # aren’t currently set up for that.
-    - .gitlab-ci/test-msvc.bat ${MESON_COMMON_OPTIONS}
+    # FIXME: Use --meson-fatal-warnings once we've enabled c_std=gnu99,c99
+    # for the runner's Meson version.
+    - .gitlab-ci/test-msvc.bat --buildtype debug
                                --wrap-mode=default
                                --default-library=static
                                --python.platlibdir=C:\Python37\site-packages
@@ -721,12 +725,8 @@ macos-arm64:
     # isn't currently set up for that. See:
     #  - https://gitlab.gnome.org/GNOME/glib/merge_requests/388
     #  - https://gitlab.gnome.org/Infrastructure/Infrastructure/issues/225
-
-    # FIXME: Override c_std to not be a list, until
-    # https://github.com/mesonbuild/meson/issues/13639 is fixed.
     - meson setup ${MESON_COMMON_OPTIONS}
             --wrap-mode=default
-            -Dc_std=gnu99
             --werror
             _build
     - meson compile -C _build

.gitlab-ci/test-msvc.bat

@@ -11,7 +11,6 @@ for %%x in (%*) do (
 )
 set args=%args:~1%
 
-:: FIXME: make warnings fatal
 pip3 install --upgrade --user meson==1.4.2 || goto :error
 meson setup %args% _build || goto :error
 meson compile -C _build || goto :error

meson.build

@@ -5,7 +5,11 @@ project('glib', 'c',
   default_options : [
     'buildtype=debugoptimized',
     'warning_level=3',
-    'c_std=gnu99,c99'
+    # FIXME: After https://github.com/mesonbuild/meson/issues/13639 is
+    # fixed, change this to
+    # meson.version().version_compare('>=FIXED_MESON_VERSION') ? 'c_std=gnu99,c99' : 'c_std=gnu99'
+    # to avoid a warning on MSVC.
+    'c_std=gnu99'
   ]
 )