[Bug objc++/49070] [8/9/10/11 regression] ObjC++ compiler fails to compile ObjC method invocations without keyword arguments

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49070

--- Comment #7 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Iain D Sandoe
<iains@gcc.gnu.org>:

https://gcc.gnu.org/g:e3cac00975a1de879dc8356285a8908c25026ec4

commit r10-9536-ge3cac00975a1de879dc8356285a8908c25026ec4
Author: Iain Sandoe <iain@sandoe.co.uk>
Date:   Fri Feb 26 10:21:02 2021 +0000

    Objective-C++ : Fix handling of unnamed message parms [PR49070].

    When we are parsing an Objective-C++ message, a colon is a valid
    terminator for a assignment-expression.  That is:

    [receiver meth:x:x:x:x];

    Is a valid, if somewhat unreadable, construction; corresponding
    to a method declaration like:

    - (id) meth:(id)arg0 :(id)arg1 :(id)arg2 :(id)arg3;

    Where three of the message params have no selector name.

    If fact, although it might be unintentional, Objective-C/C++ can
    accept message selectors with all the parms unnamed (this applies
    to the clang implementation too, which is taken as the reference
    for the language).

    For regular C++, the pattern x:x is not valid in that position an
    an error is emitted with a fixit for the expected scope token.

    If we simply made that error conditional on !c_dialect_objc()
    that would regress Objective-C++ diagnostics for cases outside a
    message selector, so we add a state flag for this.

    gcc/cp/ChangeLog:

            PR objc++/49070
            * parser.c (cp_debug_parser): Add Objective-C++ message
            state flag.
            (cp_parser_nested_name_specifier_opt): Allow colon to
            terminate an assignment-expression when parsing Objective-
            C++ messages.
            (cp_parser_objc_message_expression): Set and clear message
            parsing state on entry and exit.
            * parser.h (struct cp_parser): Add a context flag for
            Objective-C++ message state.

    gcc/testsuite/ChangeLog:

            PR objc++/49070
            * obj-c++.dg/pr49070.mm: New test.
            * objc.dg/unnamed-parms.m: New test.

    (cherry picked from commit 0cc218d42c241ed286cc5af9fb7d2e45386f7a24)