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[69.118.112.187]) by smtp.gmail.com with ESMTPSA id k5-20020a05621414e500b0065b0e724f83sm1043426qvw.6.2023.10.27.16.22.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 27 Oct 2023 16:22:22 -0700 (PDT) From: Patrick Palka X-Google-Original-From: Patrick Palka Date: Fri, 27 Oct 2023 19:22:21 -0400 (EDT) To: Jason Merrill cc: Patrick Palka , gcc-patches@gcc.gnu.org Subject: Re: [PATCH v3 3/3] c++: note other candidates when diagnosing deletedness In-Reply-To: <35674d69-7c49-4b2d-99fb-977cf34e7e9a@redhat.com> Message-ID: <4ed7c5e7-6707-a679-aa83-d72736e0806a@idea> References: <20231027195532.2566822-1-ppalka@redhat.com> <20231027195532.2566822-3-ppalka@redhat.com> <35674d69-7c49-4b2d-99fb-977cf34e7e9a@redhat.com> MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: multipart/mixed; boundary="8323329-1915168053-1698448942=:986507" X-Spam-Status: No, score=-13.8 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H4,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1915168053-1698448942=:986507 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT On Fri, 27 Oct 2023, Jason Merrill wrote: > On 10/27/23 15:55, Patrick Palka wrote: > > With the previous two patches in place, we can now extend our > > deletedness diagnostic to note the other considered candidates, e.g.: > > > > deleted16.C: In function 'int main()': > > deleted16.C:10:4: error: use of deleted function 'void f(int)' > > 10 | f(0); > > | ~^~~ > > deleted16.C:5:6: note: declared here > > 5 | void f(int) = delete; > > | ^ > > deleted16.C:5:6: note: candidate: 'void f(int)' (deleted) > > deleted16.C:6:6: note: candidate: 'void f(...)' > > 6 | void f(...); > > | ^ > > deleted16.C:7:6: note: candidate: 'void f(int, int)' > > 7 | void f(int, int); > > | ^ > > deleted16.C:7:6: note: candidate expects 2 arguments, 1 provided > > > > These notes are controlled by a new command line flag -fnote-all-cands, > > which also controls whether we note ignored candidates more generally. > > > > gcc/ChangeLog: > > > > * doc/invoke.texi (C++ Dialect Options): Document -fnote-all-cands. > > > > gcc/c-family/ChangeLog: > > > > * c.opt: Add -fnote-all-cands. > > > > gcc/cp/ChangeLog: > > > > * call.cc (print_z_candidates): Only print ignored candidates > > when -fnote-all-cands is set. > > (build_over_call): When diagnosing deletedness, call > > print_z_candidates if -fnote-all-cands is set. > > My suggestion was also to suggest using the flag in cases where it would make > a difference, e.g. > > note: some candidates omitted, use '-fnote-all-cands' to display them Ah thanks, fixed. That'll help a lot with discoverability of the flag. > > Maybe "-fdiagnostics-all-candidates"? Nice, that's a better name indeed :) How does the following look? Full bootstrap/regtest in progress. Here's the output of e.g. deleted16a.C. I think I'd prefer to not print the source line when emitting the suggestion, but I don't know how to do that properly (aside from e.g. emitting the note at UNKNOWN_LOCATION). In file included from gcc/testsuite/g++.dg/cpp0x/deleted16a.C:4: gcc/testsuite/g++.dg/cpp0x/deleted16.C: In function ‘int main()’: gcc/testsuite/g++.dg/cpp0x/deleted16.C:21:4: error: use of deleted function ‘void f(int)’ 21 | f(0); // { dg-error "deleted" } | ~^~~ gcc/testsuite/g++.dg/cpp0x/deleted16.C:6:6: note: declared here 6 | void f(int) = delete; // { dg-message "declared here" } | ^ gcc/testsuite/g++.dg/cpp0x/deleted16.C:21:4: note: use ‘-fdiagnostics-all-candidates’ to display considered candidates 21 | f(0); // { dg-error "deleted" } | ~^~~ gcc/testsuite/g++.dg/cpp0x/deleted16.C:22:4: error: use of deleted function ‘void g(int)’ 22 | g(0); // { dg-error "deleted" } | ~^~~ gcc/testsuite/g++.dg/cpp0x/deleted16.C:12:6: note: declared here 12 | void g(int) = delete; // { dg-message "declared here" } | ^ gcc/testsuite/g++.dg/cpp0x/deleted16.C:22:4: note: use ‘-fdiagnostics-all-candidates’ to display considered candidates 22 | g(0); // { dg-error "deleted" } | ~^~~ gcc/testsuite/g++.dg/cpp0x/deleted16.C:23:4: error: use of deleted function ‘void h(T, T) [with T = int]’ 23 | h(1, 1); // { dg-error "deleted" } | ~^~~~~~ gcc/testsuite/g++.dg/cpp0x/deleted16.C:17:24: note: declared here 17 | template void h(T, T) = delete; // { dg-message "declared here|candidate" } | ^ gcc/testsuite/g++.dg/cpp0x/deleted16.C:23:4: note: use ‘-fdiagnostics-all-candidates’ to display considered candidates 23 | h(1, 1); // { dg-error "deleted" } | ~^~~~~~ -- >8 -- Subject: [PATCH 3/3] c++: note other candidates when diagnosing deletedness With the previous two patches in place, we can now extend our deletedness diagnostic to note the other considered candidates, e.g.: deleted16.C: In function 'int main()': deleted16.C:10:4: error: use of deleted function 'void f(int)' 10 | f(0); | ~^~~ deleted16.C:5:6: note: declared here 5 | void f(int) = delete; | ^ deleted16.C:5:6: note: candidate: 'void f(int)' (deleted) deleted16.C:6:6: note: candidate: 'void f(...)' 6 | void f(...); | ^ deleted16.C:7:6: note: candidate: 'void f(int, int)' 7 | void f(int, int); | ^ deleted16.C:7:6: note: candidate expects 2 arguments, 1 provided These notes are controlled by a new command line flag -fdiagnostics-all-candidates which also controls whether we note ignored candidates more generally. gcc/ChangeLog: * doc/invoke.texi (C++ Dialect Options): Document -fdiagnostics-all-candidates. gcc/c-family/ChangeLog: * c.opt: Add -fdiagnostics-all-candidates. gcc/cp/ChangeLog: * call.cc (print_z_candidates): Only print ignored candidates when -fdiagnostics-all-candidates is set, otherwise suggest the flag. (build_over_call): When diagnosing deletedness, note other candidates only if -fdiagnostics-all-candidates is set, otherwise suggest the flag. gcc/testsuite/ChangeLog: * g++.dg/overload/error6.C: Pass -fdiagnostics-all-candidates. * g++.dg/cpp0x/deleted16.C: New test. * g++.dg/cpp0x/deleted16a.C: New test. * g++.dg/overload/error6a.C: New test. --- gcc/c-family/c.opt | 4 ++++ gcc/cp/call.cc | 19 ++++++++++++++++++- gcc/doc/invoke.texi | 5 +++++ gcc/testsuite/g++.dg/cpp0x/deleted16.C | 25 +++++++++++++++++++++++++ gcc/testsuite/g++.dg/cpp0x/deleted16a.C | 12 ++++++++++++ gcc/testsuite/g++.dg/overload/error6.C | 1 + gcc/testsuite/g++.dg/overload/error6a.C | 6 ++++++ 7 files changed, 71 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/g++.dg/cpp0x/deleted16.C create mode 100644 gcc/testsuite/g++.dg/cpp0x/deleted16a.C create mode 100644 gcc/testsuite/g++.dg/overload/error6a.C diff --git a/gcc/c-family/c.opt b/gcc/c-family/c.opt index 44b9c862c14..c12c86bb8ed 100644 --- a/gcc/c-family/c.opt +++ b/gcc/c-family/c.opt @@ -1781,6 +1781,10 @@ fdiagnostics-show-template-tree C++ ObjC++ Var(flag_diagnostics_show_template_tree) Init(0) Print hierarchical comparisons when template types are mismatched. +fdiagnostics-all-candidates +C++ ObjC++ Var(flag_diagnostics_all_candidates) +Note all candidates during overload resolution failure. + fdirectives-only C ObjC C++ ObjC++ Preprocess directives only. diff --git a/gcc/cp/call.cc b/gcc/cp/call.cc index 81cc029dddb..e9c099eedb8 100644 --- a/gcc/cp/call.cc +++ b/gcc/cp/call.cc @@ -4090,6 +4090,12 @@ print_z_candidates (location_t loc, struct z_candidate *candidates, { if (only_viable_p.is_true () && candidates->viable != 1) break; + if (ignored_candidate_p (candidates) && !flag_diagnostics_all_candidates) + { + inform (loc, "some candidates omitted; " + "use %<-fdiagnostics-all-candidates%> to display them"); + break; + } print_z_candidate (loc, N_("candidate:"), candidates); } } @@ -9933,7 +9939,18 @@ build_over_call (struct z_candidate *cand, int flags, tsubst_flags_t complain) if (DECL_DELETED_FN (fn)) { if (complain & tf_error) - mark_used (fn); + { + mark_used (fn); + if (cand->next) + { + if (flag_diagnostics_all_candidates) + print_z_candidates (input_location, cand, /*only_viable_p=*/false); + else + inform (input_location, + "use %<-fdiagnostics-all-candidates%> to display " + "considered candidates"); + } + } return error_mark_node; } diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 5a9284d635c..7e9f68d31b3 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -3311,6 +3311,11 @@ called. If the handler returns, execution continues normally. @item -fcoroutines Enable support for the C++ coroutines extension (experimental). +@opindex fdiagnostics-all-candidates +@item -fdiagnostics-all-candidates +Permit the C++ front end to note all candidates during overload resolution +failure, including when a deleted function is selected. + @opindex fno-elide-constructors @opindex felide-constructors @item -fno-elide-constructors diff --git a/gcc/testsuite/g++.dg/cpp0x/deleted16.C b/gcc/testsuite/g++.dg/cpp0x/deleted16.C new file mode 100644 index 00000000000..d4347942c42 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/deleted16.C @@ -0,0 +1,25 @@ +// Verify -fdiagnostics-all-candidates makes us note other candidates +// when a deleted function is selected by overload resolution. +// { dg-do compile { target c++11 } } +// { dg-additional-options "-fdiagnostics-all-candidates" } + +void f(int) = delete; // { dg-message "declared here" } +void f(...); // { dg-message "candidate" } +void f(int, int); // { dg-message "candidate" } + +// An example where the perfect candidate optimization causes us +// to ignore function templates. +void g(int) = delete; // { dg-message "declared here" } +template void g(T); // { dg-message "candidate" } + +// An example where we have a strictly viable candidate and +// an incompletely considered bad candidate. +template void h(T, T) = delete; // { dg-message "declared here|candidate" } +void h(int*, int) = delete; // { dg-message "candidate" } + +int main() { + f(0); // { dg-error "deleted" } + g(0); // { dg-error "deleted" } + h(1, 1); // { dg-error "deleted" } + // { dg-error "invalid conversion" "" { target *-*-* } .-1 } when noting 2nd cand +} diff --git a/gcc/testsuite/g++.dg/cpp0x/deleted16a.C b/gcc/testsuite/g++.dg/cpp0x/deleted16a.C new file mode 100644 index 00000000000..e62306fa3d1 --- /dev/null +++ b/gcc/testsuite/g++.dg/cpp0x/deleted16a.C @@ -0,0 +1,12 @@ +// Verify we suggest -fdiagnostics-all-candidates when diagnosing +// overload resolution selecting a deleted function. +// { dg-do compile { target c++11 } } +#include "deleted16.C" + +// { dg-error "deleted" "" { target *-*-* } 21 } +// { dg-error "deleted" "" { target *-*-* } 22 } +// { dg-error "deleted" "" { target *-*-* } 23 } + +// { dg-message "use '-fdiagnostics-all-candidates'" "" { target *-*-* } 21 } +// { dg-message "use '-fdiagnostics-all-candidates'" "" { target *-*-* } 22 } +// { dg-message "use '-fdiagnostics-all-candidates'" "" { target *-*-* } 23 } diff --git a/gcc/testsuite/g++.dg/overload/error6.C b/gcc/testsuite/g++.dg/overload/error6.C index 86a12eaa8de..3186a297bfc 100644 --- a/gcc/testsuite/g++.dg/overload/error6.C +++ b/gcc/testsuite/g++.dg/overload/error6.C @@ -1,5 +1,6 @@ // Verify we note even non-template candidates when diagnosing // overload resolution failure for a template-id. +// { dg-additional-options "-fdiagnostics-all-candidates" } template void f(T); // { dg-message "candidate" } void f(int); // { dg-message {candidate: 'void f\(int\)' \(ignored\)} } diff --git a/gcc/testsuite/g++.dg/overload/error6a.C b/gcc/testsuite/g++.dg/overload/error6a.C new file mode 100644 index 00000000000..e86ab5158ab --- /dev/null +++ b/gcc/testsuite/g++.dg/overload/error6a.C @@ -0,0 +1,6 @@ +// Verify we suggest -fdiagnostics-all-candidates when there are +// omitted candidates. +#include "error6.C" + +// { dg-error "no match" "" { target *-*-* } 9 } +// { dg-message "use '-fdiagnostics-all-candidates'" "" { target *-*-* } 9 } -- 2.42.0.482.g2e8e77cbac --8323329-1915168053-1698448942=:986507--