c++: ICE with failed __is_constructible constraint [PR100474]

  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?

	PR c++/100474

gcc/cp/ChangeLog:

	* constraint.cc (diagnose_trait_expr): Rename to ...
	(maybe_diagnose_trait_expr): ... this.  Return a boolean
	indicating whether we handled the trait.
	(diagnose_atomic_constraint) <case TRAIT_EXPR>: Fall through to
	the default case if maybe_diagnose_trait_expr returns false.

gcc/testsuite/ChangeLog:

	* g++.dg/cpp2a/concepts-traits3.C: New test.
---
 gcc/cp/constraint.cc                          | 16 +++++++++-------
 gcc/testsuite/g++.dg/cpp2a/concepts-traits3.C | 10 ++++++++++
 2 files changed, 19 insertions(+), 7 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/cpp2a/concepts-traits3.C
  

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.

> 	PR c++/100474
> 
> gcc/cp/ChangeLog:
> 
> 	* constraint.cc (diagnose_trait_expr): Rename to ...
> 	(maybe_diagnose_trait_expr): ... this.  Return a boolean
> 	indicating whether we handled the trait.
> 	(diagnose_atomic_constraint) <case TRAIT_EXPR>: Fall through to
> 	the default case if maybe_diagnose_trait_expr returns false.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/cpp2a/concepts-traits3.C: New test.
> ---
>   gcc/cp/constraint.cc                          | 16 +++++++++-------
>   gcc/testsuite/g++.dg/cpp2a/concepts-traits3.C | 10 ++++++++++
>   2 files changed, 19 insertions(+), 7 deletions(-)
>   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..27b1b9bb659 100644
> --- a/gcc/cp/constraint.cc
> +++ b/gcc/cp/constraint.cc
> @@ -3567,10 +3567,10 @@ get_constraint_error_location (tree t)
>     return input_location;
>   }
>   
> -/* Emit a diagnostic for a failed trait.  */
> +/* Maybe emit a friendlier diagnostic for the failed trait.  */
>   
> -static void
> -diagnose_trait_expr (tree expr, tree args)
> +static bool
> +maybe_diagnose_trait_expr (tree expr, tree args)
>   {
>     location_t loc = cp_expr_location (expr);
>   
> @@ -3655,8 +3655,9 @@ diagnose_trait_expr (tree expr, tree args)
>         inform (loc, "  %qT is not a union", t1);
>         break;
>       default:
> -      gcc_unreachable ();
> +      return false;
>       }
> +  return true;
>   }
>   
>   /* Diagnose a substitution failure in the atomic constraint T using ARGS.  */
> @@ -3685,9 +3686,6 @@ diagnose_atomic_constraint (tree t, tree args, tree result, sat_info info)
>     STRIP_ANY_LOCATION_WRAPPER (expr);
>     switch (TREE_CODE (expr))
>       {
> -    case TRAIT_EXPR:
> -      diagnose_trait_expr (expr, args);
> -      break;
>       case REQUIRES_EXPR:
>         gcc_checking_assert (info.diagnose_unsatisfaction_p ());
>         /* Clear in_decl before replaying the substitution to avoid emitting
> @@ -3696,6 +3694,10 @@ diagnose_atomic_constraint (tree t, tree args, tree result, sat_info info)
>         info.in_decl = NULL_TREE;
>         tsubst_requires_expr (expr, args, info);
>         break;
> +    case TRAIT_EXPR:
> +      if (maybe_diagnose_trait_expr (expr, args))
> +	break;
> +      /* Fall through.  */
>       default:
>         if (!same_type_p (TREE_TYPE (result), boolean_type_node))
>   	error_at (loc, "constraint %qE has type %qT, not %<bool%>",
> 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..33152242988
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/cpp2a/concepts-traits3.C
> @@ -0,0 +1,10 @@
> +// PR c++/100474
> +// { dg-do compile { target c++20 } }
> +
> +template<class T, class... Args>
> +concept C = __is_constructible(T, Args...); // { dg-message "evaluated to 'false'" }
> +struct S {
> +  S() = delete;
> +};
> +
> +static_assert(C<S>); // { dg-error "assert" }
  

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" }
  

On 3/30/22 08:56, Patrick Palka wrote:
> 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?

Let's leave a comment about why there's no 'default'.  OK with that change.

> -- >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" }