https://gcc.gnu.org/bugzilla/show_bug.cgi?id=53920
--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Lewis Hyatt <lhy...@gcc.gnu.org>: https://gcc.gnu.org/g:e46f4d7430c5210465791603735ab219ef263c51 commit r13-1544-ge46f4d7430c5210465791603735ab219ef263c51 Author: Lewis Hyatt <lhy...@gmail.com> Date: Tue Jul 5 17:15:28 2022 -0400 diagnostics: Honor #pragma GCC diagnostic in the preprocessor [PR53431] As discussed on PR c++/53431, currently, "#pragma GCC diagnostic" does not always take effect for diagnostics generated by libcpp. The reason is that libcpp itself does not interpret this pragma and only sends it on to the frontend, hence the pragma is only honored if the frontend arranges for it. The C frontend does process the pragma immediately (more or less) after seeing the token, so things work fine there. The PR points out that it doesn't work for C++, because the C++ frontend doesn't handle anything until it has read all the tokens from libcpp. The underlying problem is not C++-specific, though, and for instance, gcc -E has the same issue. This commit fixes the PR by adding the concept of an early pragma handler that can be registered by frontends, which gives them a chance to process diagnostic pragmas from libcpp before it is too late for them to take effect. The C++ and preprocess-only frontends are modified to use early pragmas and correct the behavior. gcc/c-family/ChangeLog: PR preprocessor/53920 PR c++/53431 * c-common.cc (c_option_is_from_cpp_diagnostics): New function. * c-common.h (c_option_is_from_cpp_diagnostics): Declare. (c_pp_stream_token): Declare. * c-ppoutput.cc (init_pp_output): Refactor logic about skipping pragmas to... (should_output_pragmas): ...here. New function. (token_streamer::stream): Support handling early pragmas. (do_line_change): Likewise. (c_pp_stream_token): New function. * c-pragma.cc (struct pragma_diagnostic_data): New helper class. (pragma_diagnostic_lex_normal): New function. Moved logic for interpreting GCC diagnostic pragmas here. (pragma_diagnostic_lex_pp): New function for parsing diagnostic pragmas directly from libcpp. (handle_pragma_diagnostic): Refactor into helper function... (handle_pragma_diagnostic_impl): ...here. New function. (handle_pragma_diagnostic_early): New function. (handle_pragma_diagnostic_early_pp): New function. (struct pragma_ns_name): Renamed to... (struct pragma_pp_data): ...this. Add new "early_handler" member. (c_register_pragma_1): Support early pragmas in the preprocessor. (c_register_pragma_with_early_handler): New function. (c_register_pragma): Support the new early handlers in struct internal_pragma_handler. (c_register_pragma_with_data): Likewise. (c_register_pragma_with_expansion): Likewise. (c_register_pragma_with_expansion_and_data): Likewise. (c_invoke_early_pragma_handler): New function. (c_pp_invoke_early_pragma_handler): New function. (init_pragma): Add early pragma support for diagnostic pragmas. * c-pragma.h (struct internal_pragma_handler): Add new early handler members. (c_register_pragma_with_early_handler): Declare. (c_invoke_early_pragma_handler): Declare. (c_pp_invoke_early_pragma_handler): Declare. gcc/cp/ChangeLog: PR c++/53431 * parser.cc (cp_parser_pragma_kind): Move earlier in the file. (cp_lexer_handle_early_pragma): New function. (cp_lexer_new_main): Support parsing and handling early pragmas. (c_parse_file): Adapt to changes in cp_lexer_new_main. gcc/testsuite/ChangeLog: PR preprocessor/53920 PR c++/53431 * c-c++-common/pragma-diag-11.c: New test. * c-c++-common/pragma-diag-12.c: New test. * c-c++-common/pragma-diag-13.c: New test.
