https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94553
--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
To fix CWG 2289, we need this:
--- a/gcc/cp/decl.c
+++ b/gcc/cp/decl.c
@@ -1705,6 +1705,9 @@ duplicate_decls (tree newdecl, tree olddecl, bool
newdecl_is_friend)
inform (olddecl_loc, "previous declaration %q#D", olddecl);
return error_mark_node;
}
+ else if ((VAR_P (olddecl) && DECL_DECOMPOSITION_P (olddecl))
+ || (VAR_P (newdecl) && DECL_DECOMPOSITION_P (newdecl)))
+ /* A structured binding must be unique in its declarative region. */;
else if (DECL_IMPLICIT_TYPEDEF_P (olddecl)
|| DECL_IMPLICIT_TYPEDEF_P (newdecl))
/* One is an implicit typedef, that's ok. */
but that's not enough to detect the 'A' case:
cp_parser_decomposition_declaration
uses
13968 tree decl2 = start_decl (declarator, &decl_specs, SD_INITIALIZED,
13969 NULL_TREE, NULL_TREE, &elt_pushed_scope);
to create the 'A' VAR_DECL but in this start_decl's grokdeclarator we don't do
fit_decomposition_lang_decl because the declarator kind is not cdk_decomp, so
then when start_decl calls maybe_push_decl, the decl 'A' isn't
DECL_DECOMPOSITION_P and we don't detect this case. So we need a way to signal
to start_decl that it should fit_decomposition_lang_decl.
