mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-09-24 20:20:10 +01:00
Adrien Leravat
d02366f881
Prevent copies when initializing value expression from reference expression. This is based on https://github.com/carbon-language/carbon-lang/pull/2006, which introduces expression categories, and how it is possible to convert to/from those different categories. Continuation of https://github.com/carbon-language/carbon-lang/pull/2907 ## Functional changes * Initializing a value expression from a reference expression takes its value without a copy * Reading from the value expression causes an error if the value changed from the time it was initialized * In this situation, prevents a copy both for variable definitions, and call parameter bindings ## Main implementation changes * Add new `ExpressionCategoryAction`, which evaluates an expression and returns an `ExpressionValue` containing its category and address (if any), in addition to the resulting `Value*` * `ExpressionAction`s now invokes `ExpressionCategoryAction` and unwraps the returned `ExpressionValue` * `RuntimeScope::BindAndPin` method, and corresponding when attempting to read a `value_node`. ## Next work * Avoid unnecessary copies from value expression to value expression, after ensuring that even value expression temporaries are registered for destruction (https://github.com/Pixep/carbon-lang/pull/9)
25 lines
552 B
Plaintext
25 lines
552 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
|
|
|
|
package ExplorerTest api;
|
|
|
|
class C {
|
|
var i: i32;
|
|
}
|
|
|
|
fn Foo(c: C) {
|
|
Print("{0}", c.i);
|
|
}
|
|
|
|
fn Main() -> i32 {
|
|
var c: C = { .i = 1 };
|
|
let pinned_c: C = c;
|
|
c.i = 2;
|
|
// CHECK:STDERR: RUNTIME ERROR: fail_pinned_value_subobject_changed.carbon:[[@LINE+1]]: Reference has changed since this value was bound.
|
|
Foo(pinned_c);
|
|
return 0;
|
|
}
|