On Tue, Oct 19, 2021 at 10:48:04AM -0400, Jason Merrill wrote:
> What if we use NULL_TREE for the error case instead of error_mark_node, i.e.
>
> - DECL_LOCAL_DECL_ALIAS (decl) = alias;
> + if (alias != error_mark_node)
> + DECL_LOCAL_DECL_ALIAS (decl) = alias;
>
> ? That ought to avoid the need to change other functions, since they
> already check for null.
True, but I'm worried about e.g. maybe_version_functions which does
if (DECL_LOCAL_DECL_P (olddecl))
{
olddecl = DECL_LOCAL_DECL_ALIAS (olddecl);
maybe_mark_function_versioned (olddecl);
}
(I think the above will crash of DECL_LOCAL_DECL_ALIAS is NULL) and
if (DECL_LOCAL_DECL_P (newdecl))
{
/* Unfortunately, we can get here before pushdecl naturally calls
push_local_extern_decl_alias, so we need to call it directly. */
if (!DECL_LOCAL_DECL_ALIAS (newdecl))
push_local_extern_decl_alias (newdecl);
newdecl = DECL_LOCAL_DECL_ALIAS (newdecl);
maybe_mark_function_versioned (newdecl);
}
which means that if there is an error from push_local_extern_decl_alias,
we'd report it twice rather than once (once from here, another time
from do_pushdecl).
I'm afraid maybe_version_functions needs fixing no matter what,
but the NULL vs. error_mark_node decision is probably dependent on whether
it is ok to error twice or not.
Jakub
