https://gcc.gnu.org/g:a54d4dafe55697e8b1fb9ee340ab0932280be7da
commit r15-10852-ga54d4dafe55697e8b1fb9ee340ab0932280be7da Author: Nathaniel Shead <[email protected]> Date: Sat Feb 21 22:32:25 2026 +1100 libcpp: Fix ICE with directives-only and cpp_maybe_module_directive [PR124153] When doing directives-only processing (-E -fdirectives-only, or -M) we crash if we hit an unexpected CPP_PRAGMA_EOL because we 'know' we're in a module directive but the in_deferred_pragma flag is no longer set. Fixed by undoing the "finished a module directive" behaviour within cpp_maybe_module_directive if we're bailing due to an ill-formed peeked token. PR c++/124153 libcpp/ChangeLog: * lex.cc (cpp_maybe_module_directive): Set in_deferred_pragma and eol when we see an unexpected CPP_PRAGMA_EOL. gcc/testsuite/ChangeLog: * g++.dg/modules/cpp-22.C: New test. Signed-off-by: Nathaniel Shead <[email protected]> Reviewed-by: Jason Merrill <[email protected]> (cherry picked from commit deba30681df43bab1a62e0cddd280e382b7c3381) Diff: --- gcc/testsuite/g++.dg/modules/cpp-22.C | 6 ++++++ libcpp/lex.cc | 11 ++++++++++- 2 files changed, 16 insertions(+), 1 deletion(-) diff --git a/gcc/testsuite/g++.dg/modules/cpp-22.C b/gcc/testsuite/g++.dg/modules/cpp-22.C new file mode 100644 index 000000000000..9c80ab0657bb --- /dev/null +++ b/gcc/testsuite/g++.dg/modules/cpp-22.C @@ -0,0 +1,6 @@ +// PR c++/124153 +// { dg-additional-options "-fmodules -fdirectives-only -E" } + +// directives-only mode currently does not do error checking. +export module hello // { dg-error "expected ';'" "" { xfail *-*-* } } +import world; diff --git a/libcpp/lex.cc b/libcpp/lex.cc index 37c301dcd20e..a3ba74de3e30 100644 --- a/libcpp/lex.cc +++ b/libcpp/lex.cc @@ -3670,6 +3670,15 @@ cpp_maybe_module_directive (cpp_reader *pfile, cpp_token *result) peek->flags |= NO_DOT_COLON; break; } + else if (peek->type == CPP_PRAGMA_EOL) + { + /* This is a broken module-directive; undo the clearing + of in_deferred_pragma from _cpp_lex_direct so callers + don't crash, and make sure we process the EOL again. */ + pfile->state.in_deferred_pragma = true; + eol = true; + break; + } else break; } @@ -3699,7 +3708,7 @@ cpp_maybe_module_directive (cpp_reader *pfile, cpp_token *result) { /* Put the peeked tokens back. */ _cpp_backup_tokens_direct (pfile, backup); - /* But if the last one was an EOL in the not_module case, forget it. */ + /* But if the last one was an EOL, forget it. */ if (eol) pfile->lookaheads--; }
