[Bug c++/94553] Revise [basic.scope.declarative]/4.2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94553 Marek Polacek changed: What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED --- Comment #8 from Marek Polacek --- Fixed.
[Bug c++/94553] Revise [basic.scope.declarative]/4.2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94553 --- Comment #7 from CVS Commits --- The master branch has been updated by Marek Polacek : https://gcc.gnu.org/g:54980635c537f3130481da2d8b1109c775db8bb0 commit r11-1714-g54980635c537f3130481da2d8b1109c775db8bb0 Author: Marek Polacek Date: Fri Jun 26 12:40:59 2020 -0400 c++: Check uniqueness of concepts/variable templates [PR94553] This patch wraps up PR94553. Variable template names have no C compatibility implications so they should be unique in their declarative region. It occurred to me that this applies to concepts as well. This is not specified in [basic.scope.declarative]/4.2 but that seems like a bug in the standard. I couldn't use variable_template_p because that uses PRIMARY_TEMPLATE_P which uses DECL_PRIMARY_TEMPLATE and that might not have been set up yet (push_template_decl hasn't yet been called). PRIMARY_TEMPLATE_P is important to distinguish between a variable template and a variable in a function template. But I think we don't have to worry about that in duplicate_decls: a template declaration cannot appear at block scope, and additional checks in duplicate_decls suggest that it won't ever see a TEMPLATE_DECL for a variable in a function template. So checking that the DECL_TEMPLATE_RESULT is a VAR_DECL seems to be fine. I could have added a default argument to variable_template_p too to avoid checking PRIMARY_TEMPLATE_P but it didn't seem worth the effort. gcc/cp/ChangeLog: PR c++/94553 * decl.c (duplicate_decls): Make sure a concept or a variable template is unique in its declarative region. gcc/testsuite/ChangeLog: PR c++/94553 * g++.dg/cpp1y/pr68578.C: Adjust dg-error. * g++.dg/cpp1y/var-templ66.C: New test. * g++.dg/cpp2a/concepts-redecl1.C: New test.
[Bug c++/94553] Revise [basic.scope.declarative]/4.2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94553
--- Comment #6 from Marek Polacek ---
I think it would make sense to detect this too:
struct E { };
template concept E = false;
template concept F = false;
struct F { };
[Bug c++/94553] Revise [basic.scope.declarative]/4.2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94553 --- Comment #5 from Marek Polacek --- The structured binding part is now fixed, but the variable template part isn't yet, so not closing.
[Bug c++/94553] Revise [basic.scope.declarative]/4.2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94553 --- Comment #4 from CVS Commits --- The master branch has been updated by Marek Polacek : https://gcc.gnu.org/g:2a8565fa1182ed326721a50c700f9f5275355d40 commit r11-529-g2a8565fa1182ed326721a50c700f9f5275355d40 Author: Marek Polacek 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, _specs, SD_INITIALIZED, 13969NULL_TREE, NULL_TREE, _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.
[Bug c++/94553] Revise [basic.scope.declarative]/4.2
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94553 Marek Polacek changed: What|Removed |Added Status|UNCONFIRMED |ASSIGNED Ever confirmed|0 |1 Assignee|unassigned at gcc dot gnu.org |mpolacek at gcc dot gnu.org Last reconfirmed||2020-05-13 --- Comment #3 from Marek Polacek --- A patch for DR 2289 posted: https://gcc.gnu.org/pipermail/gcc-patches/2020-May/545692.html
