On Tue, 29 Mar 2022, Jason Merrill wrote:
> On 3/29/22 15:22, Patrick Palka wrote:
> > Here we're crashing when diagnosing a failed __is_constructible constraint
> > because diagnose_atomic_constraint don't know how to diagnose a trait
> > that diagnose_trait_expr doesn't specifically handle. This patch fixes
> > this by falling through to the default case in this situation.
> >
> > Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> > trunk and perhaps 11?
>
> Hmm, it seems reasonable, but I think it would be better to actually handle
> all the traits. Removing the default, I get
>
> > constraint.cc:3585:10: warning: enumeration value ‘CPTK_BASES’ not handled
> > in switch [-Wswitch]
> > constraint.cc:3585:10: warning: enumeration value ‘CPTK_DIRECT_BASES’ not
> > handled in switch [-Wswitch]
> > constraint.cc:3585:10: warning: enumeration value ‘CPTK_UNDERLYING_TYPE’ not
> > handled in switch [-Wswitch]
>
> These we don't need to handle.
>
> > constraint.cc:3585:10: warning: enumeration value
> > ‘CPTK_HAS_UNIQUE_OBJ_REPRESENTATIONS’ not handled in switch \
> > constraint.cc:3585:10: warning: enumeration value ‘CPTK_IS_AGGREGATE’ not
> > handled in switch [-Wswitch]
> > constraint.cc:3585:10: warning: enumeration value
> > ‘CPTK_IS_TRIVIALLY_ASSIGNABLE’ not handled in switch [-Wswit\
> > constraint.cc:3585:10: warning: enumeration value
> > ‘CPTK_IS_TRIVIALLY_CONSTRUCTIBLE’ not handled in switch [-Ws\
> > constraint.cc:3585:10: warning: enumeration value
> > ‘CPTK_IS_TRIVIALLY_COPYABLE’ not handled in switch [-Wswitch\
> > constraint.cc:3585:10: warning: enumeration value ‘CPTK_IS_ASSIGNABLE’ not
> > handled in switch [-Wswitch]
> > constraint.cc:3585:10: warning: enumeration value ‘CPTK_IS_CONSTRUCTIBLE’
> > not handled in switch [-Wswitch]
> > constraint.cc:3585:10: warning: enumeration value
> > ‘CPTK_IS_NOTHROW_ASSIGNABLE’ not handled in switch [-Wswitch\
> > constraint.cc:3585:10: warning: enumeration value
> > ‘CPTK_IS_NOTHROW_CONSTRUCTIBLE’ not handled in switch [-Wswi\
>
> These we should.
>
> I think we should leave off the default so that when we add more traits we get
> a warning that we need to handle them here.
Sounds good, like so?
-- >8 --
Subject: [PATCH] c++: ICE with failed __is_constructible constraint [PR100474]
Here we're crashing when diagnosing a failed __is_constructible constraint
because diagnose_trait_expr doesn't recognize this trait (along with a
bunch of other traits). Fix this by adding handling for all remaining
traits and removing the default case so that when we add a new trait we
get a warning that diagnose_trait_expr needs to handle it.
Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk and perhaps 11?
PR c++/100474
gcc/cp/ChangeLog:
* constraint.cc (diagnose_trait_expr): Handle all remaining
traits appropriately. Remove default case.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/concepts-traits3.C: New test.
---
gcc/cp/constraint.cc | 41 +++++++++++-
gcc/testsuite/g++.dg/cpp2a/concepts-traits3.C | 66 +++++++++++++++++++
2 files changed, 106 insertions(+), 1 deletion(-)
create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-traits3.C
diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index c5a991b9e71..b970ac9772d 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -3654,7 +3654,46 @@ diagnose_trait_expr (tree expr, tree args)
case CPTK_IS_UNION:
inform (loc, " %qT is not a union", t1);
break;
- default:
+ case CPTK_IS_AGGREGATE:
+ inform (loc, " %qT is not an aggregate", t1);
+ break;
+ case CPTK_IS_TRIVIALLY_COPYABLE:
+ inform (loc, " %qT is not trivially copyable", t1);
+ break;
+ case CPTK_IS_ASSIGNABLE:
+ inform (loc, " %qT is not assignable from %qT", t1, t2);
+ break;
+ case CPTK_IS_TRIVIALLY_ASSIGNABLE:
+ inform (loc, " %qT is not trivially assignable from %qT", t1, t2);
+ break;
+ case CPTK_IS_NOTHROW_ASSIGNABLE:
+ inform (loc, " %qT is not %<nothrow%> assignable from %qT", t1, t2);
+ break;
+ case CPTK_IS_CONSTRUCTIBLE:
+ if (!t2)
+ inform (loc, " %qT is not default constructible", t1);
+ else
+ inform (loc, " %qT is not constructible from %qE", t1, t2);
+ break;
+ case CPTK_IS_TRIVIALLY_CONSTRUCTIBLE:
+ if (!t2)
+ inform (loc, " %qT is not trivially default constructible", t1);
+ else
+ inform (loc, " %qT is not trivially constructible from %qE", t1, t2);
+ break;
+ case CPTK_IS_NOTHROW_CONSTRUCTIBLE:
+ if (!t2)
+ inform (loc, " %qT is not %<nothrow%> default constructible", t1);
+ else
+ inform (loc, " %qT is not %<nothrow%> constructible from %qE", t1, t2);
+ break;
+ case CPTK_HAS_UNIQUE_OBJ_REPRESENTATIONS:
+ inform (loc, " %qT does not have unique object representations", t1);
+ break;
+ case CPTK_BASES:
+ case CPTK_DIRECT_BASES:
+ case CPTK_UNDERLYING_TYPE:
+ /* We shouldn't see these non-expression traits. */
gcc_unreachable ();
}
}
diff --git a/gcc/testsuite/g++.dg/cpp2a/concepts-traits3.C
b/gcc/testsuite/g++.dg/cpp2a/concepts-traits3.C
new file mode 100644
index 00000000000..f20608b6918
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/concepts-traits3.C
@@ -0,0 +1,66 @@
+// PR c++/100474
+// { dg-do compile { target c++20 } }
+
+struct S { S() = delete; S(const S&); };
+
+template<class T>
+concept Aggregate = __is_aggregate(T);
+// { dg-message "'S' is not an aggregate" "" { target *-*-* } .-1 }
+
+template<class T>
+concept TriviallyCopyable = __is_trivially_copyable(T);
+// { dg-message "'S' is not trivially copyable" "" { target *-*-* } .-1 }
+
+template<class T, class U>
+concept Assignable = __is_assignable(T, U);
+// { dg-message "'S' is not assignable from 'int'" "" { target *-*-* } .-1 }
+
+template<class T, class U>
+concept TriviallyAssignable = __is_trivially_assignable(T, U);
+// { dg-message "'S' is not trivially assignable from 'int'" "" { target *-*-*
} .-1 }
+
+template<class T, class U>
+concept NothrowAssignable = __is_nothrow_assignable(T, U);
+// { dg-message "'S' is not 'nothrow' assignable from 'int'" "" { target *-*-*
} .-1 }
+
+template<class T, class... Args>
+concept Constructible = __is_constructible(T, Args...);
+// { dg-message "'S' is not default constructible" "" { target *-*-* } .-1 }
+// { dg-message "'S' is not constructible from 'int'" "" { target *-*-* } .-2
}
+// { dg-message "'S' is not constructible from 'int, char'" "" { target *-*-*
} .-3 }
+
+template<class T, class... Args>
+concept TriviallyConstructible = __is_trivially_constructible(T, Args...);
+// { dg-message "'S' is not trivially default constructible" "" { target *-*-*
} .-1 }
+// { dg-message "'S' is not trivially constructible from 'int'" "" { target
*-*-* } .-2 }
+// { dg-message "'S' is not trivially constructible from 'int, char'" "" {
target *-*-* } .-3 }
+
+template<class T, class... Args>
+concept NothrowConstructible = __is_nothrow_constructible(T, Args...);
+// { dg-message "'S' is not 'nothrow' default constructible" "" { target *-*-*
} .-1 }
+// { dg-message "'S' is not 'nothrow' constructible from 'int'" "" { target
*-*-* } .-2 }
+// { dg-message "'S' is not 'nothrow' constructible from 'int, char'" "" {
target *-*-* } .-3 }
+
+template<class T>
+concept UniqueObjReps = __has_unique_object_representations(T);
+// { dg-message "'S' does not have unique object representations" "" { target
*-*-* } .-1 }
+
+static_assert(Aggregate<S>); // { dg-error "assert" }
+static_assert(TriviallyCopyable<S>); // { dg-error "assert" }
+static_assert(Assignable<S, int>); // { dg-error "assert" }
+static_assert(TriviallyAssignable<S, int>); // { dg-error "assert" }
+static_assert(NothrowAssignable<S, int>); // { dg-error "assert" }
+
+static_assert(Constructible<S>); // { dg-error "assert" }
+static_assert(Constructible<S, int>); // { dg-error "assert" }
+static_assert(Constructible<S, int, char>); // { dg-error "assert" }
+
+static_assert(TriviallyConstructible<S>); // { dg-error "assert" }
+static_assert(TriviallyConstructible<S, int>); // { dg-error "assert" }
+static_assert(TriviallyConstructible<S, int, char>); // { dg-error "assert" }
+
+static_assert(NothrowConstructible<S>); // { dg-error "assert" }
+static_assert(NothrowConstructible<S, int>); // { dg-error "assert" }
+static_assert(NothrowConstructible<S, int, char>); // { dg-error "assert" }
+
+static_assert(UniqueObjReps<S>); // { dg-error "assert" }
--
2.35.1.693.g805e0a6808
