https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94553
--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Marek Polacek <mpola...@gcc.gnu.org>: https://gcc.gnu.org/g:2a8565fa1182ed326721a50c700f9f5275355d40 commit r11-529-g2a8565fa1182ed326721a50c700f9f5275355d40 Author: Marek Polacek <pola...@redhat.com> Date: Tue May 19 23:53:28 2020 -0400 c++: Implement DR 2289, Uniqueness of structured binding names [PR94553] DR 2289 clarified that since structured bindings have no C compatibility implications, they should be unique in their declarative region, see [basic.scope.declarative]/4.2. The duplicate_decls hunk is the gist of the patch, but that alone would not be 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 I needed a way to signal to start_decl that it should fit_decomposition_lang_decl. In this patch, I'm adding SD_DECOMPOSITION flag to say that the variable is initialized and it should also be marked as DECL_DECOMPOSITION_P. DR 2289 PR c++/94553 * cp-tree.h (SD_DECOMPOSITION): New flag. * decl.c (duplicate_decls): Make sure a structured binding is unique in its declarative region. (start_decl): If INITIALIZED is SD_DECOMPOSITION, call fit_decomposition_lang_decl. (grokdeclarator): Compare INITIALIZED directly to SD_* flags. * parser.c (cp_parser_decomposition_declaration): Pass SD_DECOMPOSITION to start_decl. * g++.dg/cpp1z/decomp52.C: New test.
