mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-27 22:02:33 +01:00
Richard Smith
374bf9f853
Per recent discussion, in `... where .A = B`, require that `B` is implicitly convertible to the type of `A` immediately, rather than treating that as part of the criteria that a type must satisfy to satisfy the resulting constraint. Extend the implementation of implicit conversion so that conversion of a type to a constraint checks that the type satisfies the constraint. As part of implementing this, stop duplicating rewrite constraints as equality constraints. Instead, when checking that a constraint is satisfied, check both its equality constraints and its rewrite constraints. This fixes an infinite recursion that would otherwise be caused by this change, and is also a necessary prerequisite for applying rewrite constraints to equality constraints, where we would otherwise collapse the implied equality constraints to a tautological `V == V` constraint. In passing, make ErrorBuilder support building the error message more incrementally and use that to improve diagnostics for mismatched values with equality constraints.
28 lines
750 B
Plaintext
28 lines
750 B
Plaintext
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
|
|
// Exceptions. See /LICENSE for license information.
|
|
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
|
|
//
|
|
// AUTOUPDATE
|
|
// RUN: %{not} %{explorer-run}
|
|
// RUN: %{not} %{explorer-run-trace}
|
|
|
|
package ExplorerTest api;
|
|
|
|
interface Iface {
|
|
let N:! i32;
|
|
}
|
|
|
|
fn F(T:! Iface where .N == 5) {}
|
|
|
|
class Good {}
|
|
class Bad {}
|
|
external impl Good as Iface where .N = 5 {}
|
|
external impl Bad as Iface where .N = 4 {}
|
|
|
|
fn Main() -> i32 {
|
|
F(Good);
|
|
// CHECK:STDERR: COMPILATION ERROR: {{.*}}/explorer/testdata/assoc_const/fail_different_value.carbon:[[@LINE+1]]: constraint requires that (T).(Iface.N) (with value 4) == 5, which is not known to be true
|
|
F(Bad);
|
|
return 0;
|
|
}
|