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carbon-lang/toolchain/check/testdata/impl/generic_method_constraint.carbon
Bartłomiej Rosa 505c4ae308 Fix crash building impl witness thunks for constrained generic methods (#7956)
When building an impl witness thunk for a generic associated function,
trailing self-specific arguments could still mention outer interface
parameters (or `Self`) in their types. That left a SymbolicBinding that
did not belong to the thunk's generic, and evaluation aborted instead of
succeeding.

Substitute the outer specific arguments into those trailing arguments
with `SubstConstant` before adjusting bind indices.

Fixes #7919.
2026-10-19 21:10:56 +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/none.carbon
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/check/testdata/impl/generic_method_constraint.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/impl/generic_method_constraint.carbon
// Regression tests for https://github.com/carbon-language/carbon-lang/issues/7919:
// building an impl witness thunk must not crash when an associated function's
// generic parameter constraint depends on an enclosing interface parameter.
// --- dependent_on_interface_param.carbon
library "[[@TEST_NAME]]";
interface A(T: type) {
fn F(self);
}
interface B(T: type) {
fn G[U: A(T)](u: U);
}
class C {}
impl C as B(()) {
fn G[U: A(())](unused u: U) {}
}
// --- dependent_on_self.carbon
library "[[@TEST_NAME]]";
interface A(T: type) {
fn F(self);
}
interface B(T: type) {
fn G[U: A(Self)](u: U);
}
class C {}
impl C as B(()) {
fn G[U: A(C)](unused u: U) {}
}
// --- independent_constraint_still_ok.carbon
library "[[@TEST_NAME]]";
interface A {
fn F(self);
}
interface B(T: type) {
fn G[U: A](u: U, t: T);
}
class C {}
impl C as B(()) {
fn G[U: A](unused u: U, unused t: ()) {}
}