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carbon-lang/explorer/testdata/constraint/dot_self_is_other.carbon
T
Richard Smith 2fef76e58c Basic support for .Self within :! bindings and where expressions. (#1311)
`.Self` is modeled as a new kind of expression, `DotSelfExpression`. Name resolution associates each occurrence of a `DotSelfExpression` with a generic binding, much like for an `IdentifierExpression`.

Both `:!` bindings and `where` expressions bring `.Self` into scope. The tentative intent is that if there are multiple `.Self`s in scope and they refer to different bindings, the result of using a `.Self` expression is an ambiguity error, but that is not implemented in this patch. Instead, like for `IdentifierExpression`s, we find the innermost enclosing definition of `.Self`.

`.Foo` expressions are rewritten to `.Self.Foo`, but this isn't enough to make them do anything useful, because associated constants aren't supported in general yet.
2022-06-14 21:49:01 -07:00

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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
//
// RUN: %{explorer} %s 2>&1 | \
// RUN: %{FileCheck} --match-full-lines --allow-unused-prefixes=false %s
// RUN: %{explorer} --parser_debug --trace_file=- %s 2>&1 | \
// RUN: %{FileCheck} --match-full-lines --allow-unused-prefixes %s
// AUTOUPDATE: %{explorer} %s
// CHECK: result: 12
package ExplorerTest api;
interface A { fn F() -> i32; }
interface B { fn F() -> i32; }
impl i32 as A { fn F() -> i32 { return 1; } }
impl i32 as B { fn F() -> i32 { return 2; } }
fn GetA[T:! A](x: T) -> i32 { return x.F(); }
fn GetAB[T:! B where .Self is A](x: T) -> i32 {
// Note that there's no ambiguity in the use of the name F here.
// `x.F` is `x.(B.F)` because the constraint only treats `B`, not
// `A`, as a lookup context.
return 10 * GetA(x) + x.F();
}
fn Main() -> i32 {
var v: i32 = 0;
return GetAB(v);
}