options: restore special behavior of CFLAGS vs. c_args

For compatibility with Autotools, CFLAGS is added to the linker command
line if the compiler acts as a linker driver.  However, this behavior
was lost in commit d37d649b0 ("Make all Meson level options overridable
per subproject.", 2025-02-13).

The issue is that (for example) c_link_args is stored in env.options, and
from that point on it is treated as a machine-file option.  This includes
not being able to override it in compilers.get_global_options:

- initialize_from_top_level_project_call places it in pending_options

- add_lang_args passes the right value to add_compiler_option

- add_compiler_option calls add_system_option_internal

- add_system_option_internal fishes the value out of pending_options
  and ignores what get_global_options provided.

Instead, store the putative values of the compiler options coming from
the environment in a separate dictionary, that is only accessed by
get_global_options. This way it never appears in pending_options, and
also there is no internal *_env_args variable anymore.

Fixes: #14533
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 12 insertions, 5 deletions

diff --git a/mesonbuild/compilers/compilers.py b/mesonbuild/compilers/compilers.py
index ad252a136..d0934fc73 100644
--- a/mesonbuild/compilers/compilers.py
+++ b/mesonbuild/compilers/compilers.py
@@ -1424,12 +1424,19 @@ def get_global_options(lang: str,
     description = f'Extra arguments passed to the {lang}'
     argkey = OptionKey(f'{lang}_args', machine=for_machine)
     largkey = OptionKey(f'{lang}_link_args', machine=for_machine)
-    envkey = OptionKey(f'{lang}_env_args', machine=for_machine)
 
-    comp_key = argkey if argkey in env.options else envkey
+    comp_args_from_envvar = False
+    comp_options = env.coredata.optstore.get_pending_value(argkey)
+    if comp_options is None:
+        comp_args_from_envvar = True
+        comp_options = env.env_opts.get(argkey, [])
+
+    link_args_from_envvar = False
+    link_options = env.coredata.optstore.get_pending_value(largkey)
+    if link_options is None:
+        link_args_from_envvar = True
+        link_options = env.env_opts.get(largkey, [])
 
-    comp_options = env.options.get(comp_key, [])
-    link_options = env.options.get(largkey, [])
     assert isinstance(comp_options, (str, list)), 'for mypy'
     assert isinstance(link_options, (str, list)), 'for mypy'
 
@@ -1443,7 +1450,7 @@ def get_global_options(lang: str,
         description + ' linker',
         link_options, split_args=True, allow_dups=True)
 
-    if comp.INVOKES_LINKER and comp_key == envkey:
+    if comp.INVOKES_LINKER and comp_args_from_envvar and link_args_from_envvar:
         # If the compiler acts as a linker driver, and we're using the
         # environment variable flags for both the compiler and linker
         # arguments, then put the compiler flags in the linker flags as well.