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carbon-lang/toolchain/check/testdata/facet/validate_impl_constraints.carbon
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Jon Ross-Perkins 9704dc670e Change the Destroy blanket impls to be more specific (#6098)
The main direction of this change is the edits to `destroy.carbon`
(matching in both prelude and min_prelude).

Previously there was a no-op blanket impl for `Destroy`, which hid all
missing implementations of `Destroy`. This does a few things:

- Sets up builtin aggregate destruction for struct and tuple types as
before, but also adds C++ class types and array types to the same
handling. (all as a TODO for actual implementation)
- Also maybe-unformed destruction, for now at least. (there's a chance I
may try a different approach on this, but the impl lookup wasn't working
as I'd hope in order to write it in code)
- Adds handlers for simple things that are easy to do in code: `type`,
`bool`, pointers. (because these are no-op destruction)
- Redirect `const T` destruction to `T` destruction.

This leaves as future issues:

- `partial T` destruction. (this can't be done similar to `const`
because it only works for non-`final` class types; I think `class`
definitions should just generate what's needed)
- Destruction of other prelude-provided types. (will probably come up as
we implement class destruction, that the adapted builtin type doesn't
implement `Destroy` -- but may end up special-casing that in a way that
moots it)

This moves the `&` operator from `facet_types.carbon` to
`convert.carbon` because more things need to handle type and now that
we're getting separate copy and destroy interfaces. It should be
low-cost (an interface and builtin) so hopefully this is the right
balance for complexity and re-use.

A few tests are also edited in order to focus them more on what they
intend to test, and avoid a `Destroy` dependency.
2025-09-18 22:10:50 +00:00

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// 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
//
// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/convert.carbon
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/facet/validate_impl_constraints.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/facet/validate_impl_constraints.carbon
// --- self_impls_modifies_assoc_constant.carbon
library "[[@TEST_NAME]]";
interface I { let X:! type; }
fn F(T:! I where .X = ()) {}
fn G(T:! I where .Self impls (I where .X = ())) {
F(T);
}
// --- fail_self_impls_modifies_assoc_constant_type_differs.carbon
library "[[@TEST_NAME]]";
interface I { let X:! type; }
fn F(T:! I where .X = ()) {}
fn G(T:! I where .Self impls (I where .X = {})) {
// CHECK:STDERR: fail_self_impls_modifies_assoc_constant_type_differs.carbon:[[@LINE+7]]:3: error: cannot convert type `T` that implements `I where .(I.X) = {}` into type implementing `I where .(I.X) = ()` [ConversionFailureFacetToFacet]
// CHECK:STDERR: F(T);
// CHECK:STDERR: ^~~~
// CHECK:STDERR: fail_self_impls_modifies_assoc_constant_type_differs.carbon:[[@LINE-6]]:6: note: initializing generic parameter `T` declared here [InitializingGenericParam]
// CHECK:STDERR: fn F(T:! I where .X = ()) {}
// CHECK:STDERR: ^
// CHECK:STDERR:
F(T);
}
// --- fail_todo_where_impls_tests_associated_constant_of_generic_type.carbon
library "[[@TEST_NAME]]";
class C(U:! type) {}
// C(U) impls M if U impls L.
interface L {}
interface M { let M0:! type; }
impl forall [U:! L] C(U) as M where .M0 = {} {}
// U requires that C(.Self) impls M.
// - C(.Self) impls M can be rewritten as C(U) impls M.
// - C(U) impls M if U impls L => Requires U impls L.
fn F(U:! type where C(.Self) impls (M where .M0 = {})) {}
fn G(T:! L) {
// CHECK:STDERR: fail_todo_where_impls_tests_associated_constant_of_generic_type.carbon:[[@LINE+7]]:3: error: cannot convert type `T` that implements `L` into type implementing `type where...` [ConversionFailureFacetToFacet]
// CHECK:STDERR: F(T);
// CHECK:STDERR: ^~~~
// CHECK:STDERR: fail_todo_where_impls_tests_associated_constant_of_generic_type.carbon:[[@LINE-6]]:6: note: initializing generic parameter `U` declared here [InitializingGenericParam]
// CHECK:STDERR: fn F(U:! type where C(.Self) impls (M where .M0 = {})) {}
// CHECK:STDERR: ^
// CHECK:STDERR:
F(T);
}
// --- fail_where_impls_tests_associated_constant_of_generic_type_type_differs.carbon
library "[[@TEST_NAME]]";
class C(U:! type) {}
// C(U) impls M if U impls L.
interface L {}
interface M { let M0:! type; }
impl forall [U:! L] C(U) as M where .M0 = () {}
// U requires that C(.Self) impls M.
// - C(.Self) impls M can be rewritten as C(U) impls M.
// - C(U) impls M if U impls L => Requires U impls L.
fn F(U:! type where C(.Self) impls (M where .M0 = {})) {}
fn G(T:! L) {
// CHECK:STDERR: fail_where_impls_tests_associated_constant_of_generic_type_type_differs.carbon:[[@LINE+7]]:3: error: cannot convert type `T` that implements `L` into type implementing `type where...` [ConversionFailureFacetToFacet]
// CHECK:STDERR: F(T);
// CHECK:STDERR: ^~~~
// CHECK:STDERR: fail_where_impls_tests_associated_constant_of_generic_type_type_differs.carbon:[[@LINE-6]]:6: note: initializing generic parameter `U` declared here [InitializingGenericParam]
// CHECK:STDERR: fn F(U:! type where C(.Self) impls (M where .M0 = {})) {}
// CHECK:STDERR: ^
// CHECK:STDERR:
F(T);
}
// --- self_in_interface_generic_param_unconstrained.carbon
library "[[@TEST_NAME]]";
interface Z {}
interface I(T:! type) {}
fn F(T:! I(.Self) where .Self impls Z) {}
fn G(T:! Z & I(.Self)) {
F(T);
}
// --- fail_todo_self_in_interface_generic_param_constrained.carbon
library "[[@TEST_NAME]]";
interface Z {}
interface I(T:! Z) {}
// Implied constraint: .Self impls Z, which is satisfied and checked at the end
// of the fn signature.
// CHECK:STDERR: fail_todo_self_in_interface_generic_param_constrained.carbon:[[@LINE+7]]:10: error: cannot convert type `.Self` that implements `type` into type implementing `Z` [ConversionFailureFacetToFacet]
// CHECK:STDERR: fn F(T:! I(.Self) where .Self impls Z) {}
// CHECK:STDERR: ^~~~~~~~
// CHECK:STDERR: fail_todo_self_in_interface_generic_param_constrained.carbon:[[@LINE-7]]:13: note: initializing generic parameter `T` declared here [InitializingGenericParam]
// CHECK:STDERR: interface I(T:! Z) {}
// CHECK:STDERR: ^
// CHECK:STDERR:
fn F(T:! I(.Self) where .Self impls Z) {}
// CHECK:STDERR: fail_todo_self_in_interface_generic_param_constrained.carbon:[[@LINE+7]]:14: error: cannot convert type `.Self` that implements `type` into type implementing `Z` [ConversionFailureFacetToFacet]
// CHECK:STDERR: fn G(T:! Z & I(.Self)) {
// CHECK:STDERR: ^~~~~~~~
// CHECK:STDERR: fail_todo_self_in_interface_generic_param_constrained.carbon:[[@LINE-16]]:13: note: initializing generic parameter `T` declared here [InitializingGenericParam]
// CHECK:STDERR: interface I(T:! Z) {}
// CHECK:STDERR: ^
// CHECK:STDERR:
fn G(T:! Z & I(.Self)) {
F(T);
}