https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90995
--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-8 branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:feb0b5e3339e3b3f710c4f82d5997c1cd6af67ae commit r8-10469-gfeb0b5e3339e3b3f710c4f82d5997c1cd6af67ae Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Mar 17 21:21:16 2020 +0100 c++: Fix parsing of invalid enum specifiers [PR90995] The testcase shows some accepts-invalid (the ones without alignas) and ice-on-invalid-code (the ones with alignas) cases. If the enum doesn't have an underlying type and is not a definition, the caller retries to parse it as elaborated type specifier. E.g. for enum struct S s it will then pedwarn that elaborated type specifier shouldn't have the struct/class keywords. The problem is if the enum specifier is not followed by { when it has underlying type. In that case we have already called cp_parser_parse_definitely to end the tentative parsing started at the beginning of cp_parser_enum_specifier. But the cp_parser_error (parser, "expected %<;%> or %<{%>"); doesn't emit any error because the whole function is called from yet another tentative parse and the caller starts parsing the elaborated type specifier where the cp_parser_enum_specifier stopped (i.e. after the underlying type token(s)). The ultimate caller than commits the tentative parsing (and even if it wouldn't, it wouldn't know what kind of error to report). I think after seeing enum {,struct,class} : type not being followed by { or ;, there is no reason not to report it right away, as it can't be valid C++, which is what the patch does. Not sure if we shouldn't also return error_mark_node instead of NULL_TREE, so that the caller doesn't try to parse it as elaborated type specifier (the patch doesn't do that right now). Furthermore, while reading the code, I've noticed that parser->colon_corrects_to_scope_p is saved and set to false at the start of the function, but not restored back in some cases. Don't have a testcase where this would be a problem, but it just seems wrong. Either we can in the two spots replace return NULL_TREE; with { type = NULL_TREE; goto out; } or we could perhaps abuse warning_sentinel or create a special class with dtor to clean the flag up. And lastly, I've fixed some formatting issues in the function while reading it. 2020-03-17 Jakub Jelinek <ja...@redhat.com> PR c++/90995 * parser.c (cp_parser_enum_specifier): Use temp_override for parser->colon_corrects_to_scope_p, replace goto out with return. If scoped enum or enum with underlying type is not followed by { or ;, call cp_parser_commit_to_tentative_parse before calling cp_parser_error and make sure to return error_mark_node instead of NULL_TREE. Formatting fixes. * g++.dg/cpp0x/enum40.C: New test. (cherry picked from commit 980a7a0be5a114e285c49ab05ac70881e4f27fc3)
