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<class T> 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<class T> void g(T); // { dg-message "candidate" }
+
+// An example where we have a strictly viable candidate and
+// an incompletely considered bad candidate.
+template<class T> 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<class T> 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
