| Message ID | 20220711211719.GA61164@ldh-imac.local |
|---|---|
| State | New |
| Headers | show |
| Series | preprocessor: Set input_location to the most recently seen token | expand |
On Mon, 11 Jul 2022, Lewis Hyatt via Gcc-patches wrote: > Hello- > > As discussed here: > https://gcc.gnu.org/pipermail/gcc-patches/2022-July/598136.html > > Here is another short patch that improves "#pragma GCC diagnostic" handling. > Longer term, it will be desirable to make the handling of this pragma > independent of the global input_location. But in the meantime, some glitches > like this one can be readily addressed by making input_location point to > something better. In this case, input_location during preprocessing (-E or > -save-temps) is made to point to the most recently seen token rather than the > beginning of the file. To the best of my knowledge, nothing else besides > "#pragma GCC diagnostic" handling can observe input_location during > token streaming, so this is expected not to have any other > repercussions. Bootstrap + regtest does look clean on x86-64 Linux. > > By the way, the new testcase fails when compiled with C++, but it's not > because of pragma handling, it's rather because the C++ frontend changes the > location on the warning to the wrong place. Once done_lexing has been set to > true, it changes the location of all warnings to input_location, however > that's not correct when the location is the cached location of a macro > definition; the original location is preferable. I will file a separate PR > about that, and have xfailed that testcase for now, since I am not quite there > with grokking the reason it behaves this way, and anyway it's not related to > this 1-line fix for gcc -E. > > Please let me know how it looks? Thanks! OK.
diff --git a/gcc/c-family/c-ppoutput.cc b/gcc/c-family/c-ppoutput.cc index cd38c969ea0..98081ccfbb0 100644 --- a/gcc/c-family/c-ppoutput.cc +++ b/gcc/c-family/c-ppoutput.cc @@ -210,6 +210,10 @@ void token_streamer::stream (cpp_reader *pfile, const cpp_token *token, location_t loc) { + /* Keep input_location up to date, since it is needed for processing early + pragmas such as #pragma GCC diagnostic. */ + input_location = loc; + if (token->type == CPP_PADDING) { avoid_paste = true; diff --git a/gcc/testsuite/c-c++-common/pragma-diag-14.c b/gcc/testsuite/c-c++-common/pragma-diag-14.c new file mode 100644 index 00000000000..618e7e1ef27 --- /dev/null +++ b/gcc/testsuite/c-c++-common/pragma-diag-14.c @@ -0,0 +1,9 @@ +/* { dg-do preprocess } */ +/* { dg-additional-options "-Wunused-macros" } */ + +/* In the past, the pragma has erroneously disabled the warning because the + location was not tracked properly with -E or -save-temps; check that it works + now. */ + +#define X /* { dg-warning "-:-Wunused-macros" } */ +#pragma GCC diagnostic ignored "-Wunused-macros" diff --git a/gcc/testsuite/c-c++-common/pragma-diag-15.c b/gcc/testsuite/c-c++-common/pragma-diag-15.c new file mode 100644 index 00000000000..d8076b4f93a --- /dev/null +++ b/gcc/testsuite/c-c++-common/pragma-diag-15.c @@ -0,0 +1,13 @@ +/* { dg-do compile } */ +/* { dg-additional-options "-Wunused-macros" } */ + +/* In the past, the pragma has erroneously disabled the warning because the + location was not tracked properly with -E or -save-temps; check that it works + now. + + This test currently fails for C++ but it's not because of the pragma, it's + because the location of the macro definition is incorrectly set. This is a + separate issue, will resolve it in a later patch. */ + +#define X /* { dg-warning "-:-Wunused-macros" {} { xfail c++ } } */ +#pragma GCC diagnostic ignored "-Wunused-macros"