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 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" } -- 2.35.1.677.gabf474a5dd