[Bug c++/90995] [8/9 Regression] ICE in grokdeclarator, at cp/decl.c:12024

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90995

--- Comment #9 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:980a7a0be5a114e285c49ab05ac70881e4f27fc3

commit r9-8462-g980a7a0be5a114e285c49ab05ac70881e4f27fc3
Author: Jakub Jelinek <jakub@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  <jakub@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.