From b04c399e258e686dddad879bf7e27d9e28fd6fde Mon Sep 17 00:00:00 2001 From: Lewis Hyatt Date: Tue, 12 Jul 2022 09:47:47 -0400 Subject: [PATCH] c++: Fix location for -Wunused-macros [PR66290] In C++, since all tokens are lexed from libcpp up front, diagnostics generated by libcpp after lexing has completed do not get a valid location from libcpp (rather, libcpp thinks they all pertain to the end of the file.) This has long been addressed using the global variable "done_lexing", which the C++ frontend sets at the appropriate time; when done_lexing is true, then c_cpp_diagnostic(), which outputs libcpp's diagnostics, uses input_location instead of the wrong libcpp location. The C++ frontend arranges that input_location will point to the token it is currently processing, so this generally works fine. However, there is one exception currently, which is -Wunused-macros. This gets generated at the end of processing in cpp_finish (), since we need to wait until then to determine whether a macro was eventually used or not. But the locations it passes to c_cpp_diagnostic () were remembered from the original lexing and hence they should not be overridden with input_location, which is now the one incorrectly pointing to the end of the file. Fixed by setting done_lexing=false again just prior to calling cpp_finish (). I also renamed the variable from done_lexing to "override_libcpp_locations", since it's now not strictly about lexing anymore. There is no new testcase with this patch, since we already had an xfailed testcase which is now fixed. gcc/c-family/ChangeLog: PR c++/66290 * c-common.h: Rename global done_lexing to override_libcpp_locations. * c-common.cc (c_cpp_diagnostic): Likewise. * c-opts.cc (c_common_finish): Set override_libcpp_locations (formerly done_lexing) immediately prior to calling cpp_finish (). gcc/cp/ChangeLog: PR c++/66290 * parser.cc (cp_lexer_new_main): Rename global done_lexing to override_libcpp_locations. gcc/testsuite/ChangeLog: PR c++/66290 * c-c++-common/pragma-diag-15.c: Remove xfail for C++. --- gcc/c-family/c-common.cc | 10 ++++++---- gcc/c-family/c-common.h | 8 +++++--- gcc/c-family/c-opts.cc | 6 ++++++ gcc/cp/parser.cc | 2 +- gcc/testsuite/c-c++-common/pragma-diag-15.c | 2 +- 5 files changed, 19 insertions(+), 9 deletions(-) diff --git a/gcc/c-family/c-common.cc b/gcc/c-family/c-common.cc index 655c3aefee6..6e41ceb38e9 100644 --- a/gcc/c-family/c-common.cc +++ b/gcc/c-family/c-common.cc @@ -284,9 +284,11 @@ int c_inhibit_evaluation_warnings; be generated. */ bool in_late_binary_op; -/* Whether lexing has been completed, so subsequent preprocessor - errors should use the compiler's input_location. */ -bool done_lexing = false; +/* Depending on which phase of processing we are in, we may need + to prefer input_location to libcpp's locations. (Specifically, + after the C++ lexer is done lexing tokens, but prior to calling + cpp_finish (), we need to do so. */ +bool override_libcpp_locations; /* Information about how a function name is generated. */ struct fname_var_t @@ -6681,7 +6683,7 @@ c_cpp_diagnostic (cpp_reader *pfile ATTRIBUTE_UNUSED, default: gcc_unreachable (); } - if (done_lexing) + if (override_libcpp_locations) richloc->set_range (0, input_location, SHOW_RANGE_WITH_CARET); diagnostic_set_info_translated (&diagnostic, msg, ap, richloc, dlevel); diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h index f9064393b4e..c06769b6f0b 100644 --- a/gcc/c-family/c-common.h +++ b/gcc/c-family/c-common.h @@ -767,10 +767,12 @@ extern int max_tinst_depth; extern int c_inhibit_evaluation_warnings; -/* Whether lexing has been completed, so subsequent preprocessor - errors should use the compiler's input_location. */ +/* Depending on which phase of processing we are in, we may need + to prefer input_location to libcpp's locations. (Specifically, + after the C++ lexer is done lexing tokens, but prior to calling + cpp_finish (), we need to do so. */ -extern bool done_lexing; +extern bool override_libcpp_locations; /* C types are partitioned into three subsets: object, function, and incomplete types. */ diff --git a/gcc/c-family/c-opts.cc b/gcc/c-family/c-opts.cc index b9f01a65ed7..4e1463689de 100644 --- a/gcc/c-family/c-opts.cc +++ b/gcc/c-family/c-opts.cc @@ -1281,6 +1281,12 @@ c_common_finish (void) } } + /* When we call cpp_finish (), it may generate some diagnostics using + locations it remembered from the preprocessing phase, e.g. for + -Wunused-macros. So inform c_cpp_diagnostic () not to override those + locations with input_location, which would be incorrect now. */ + override_libcpp_locations = false; + /* For performance, avoid tearing down cpplib's internal structures with cpp_destroy (). */ cpp_finish (parse_in, deps_stream); diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc index 826595a3722..33926d23179 100644 --- a/gcc/cp/parser.cc +++ b/gcc/cp/parser.cc @@ -755,7 +755,7 @@ cp_lexer_new_main (void) /* Subsequent preprocessor diagnostics should use compiler diagnostic functions to get the compiler source location. */ - done_lexing = true; + override_libcpp_locations = true; maybe_check_all_macros (parse_in); diff --git a/gcc/testsuite/c-c++-common/pragma-diag-15.c b/gcc/testsuite/c-c++-common/pragma-diag-15.c index d8076b4f93a..8ffff88d5e3 100644 --- a/gcc/testsuite/c-c++-common/pragma-diag-15.c +++ b/gcc/testsuite/c-c++-common/pragma-diag-15.c @@ -9,5 +9,5 @@ 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++ } } */ +#define X /* { dg-warning "-:-Wunused-macros" } */ #pragma GCC diagnostic ignored "-Wunused-macros"