[C++ Patch/RFC] PR 80145

[Jason Merrill via gcc-patches]

OK.

On Thu, Mar 23, 2017 at 3:07 PM, Paolo Carlini <paolo.carlini@oracle.com> wrote:
> Hi,
>
> this ICE on invalid code isn't a regression, thus a patch probably doesn't
> qualify for Stage 4, but IMHO I made good progress on it and I'm sending
> what I have now anyway... The ICE happens during error recovery after a
> sensible diagnostic for the first declaration in:
>
> auto* foo() { return 0; }
> auto* foo();
>
> After the error, finish_function does:
>
> apply_deduced_return_type (fndecl, void_type_node);
> fntype = TREE_TYPE (fndecl);
>
> which then is inconsistent with the auto* return type of the second
> declaration and leads to an ICE in merge_types (which duplicate_decls
> thought was safe to call because types_match is true (evidently: decls_match
> uses fndecl_declared_return_type)). Thus, in terms of error recovery, I
> think that in cases like the one at issue it makes sense not to replace
> auto* after the error and leave the return type untouched: certainly the
> below passes testing and avoids ICEing on the testcase at issue and a
> variant of it.
>
> Thanks,
> Paolo.
>
> //////////////////
>