mirror of
https://github.com/carbon-language/carbon-lang.git
synced 2026-10-04 22:02:52 +01:00
Chandler Carruth
8be274cf60
Implement the toolchain side of proposal #7254, removing the `:!` binding syntax for generic and template parameters in favor of the keywords `generic`, `template`, and `runtime` plus contextual defaults for phase. For valid programs this is semantics-preserving: each binding resolves to the same phase, and produces the same SemIR, as it did under `:!`/`:`. The parser derives a binding's phase from its syntactic context plus any explicit phase keyword; new diagnostics and error recovery for misused keywords are described below. Implementation details for each component: - Lexer: remove the `:!` (`ColonExclaim`) token, move its virtual parse-node budget onto `:`, and add the `generic` and `runtime` keywords. - Parser: thread a `BindingContext` (`ExplicitParam`, `DeducedParam`, or `CompileTimeEntityParam`) from declaration introducers down through parameter lists to each binding pattern, using a one-token lookahead to distinguish a name-qualifier parameter list from a declaration's own final list. Parameters of a compile-time entity (`class`, `interface`, `constraint`, `choice`, `alias`, `export`, `namespace`) and deduced `[]` parameters default to checked generic; explicit function parameters and local bindings default to runtime. `HandleBindingPattern` resolves the phase from that context plus the keyword: a `generic` keyword needs no node of its own (the phase is carried by the binding's node kind), while a `runtime` keyword is preserved as a `RuntimeBindingName` node so `check` can name it in a diagnostic. A phase keyword that is merely redundant with the contextual default is diagnosed here, without invalidating the parse tree. - Check: a phase keyword that is invalid for its context (for example `runtime` on a checked-generic parameter) is diagnosed here, and recovers by building an error binding that still introduces the name so that later uses of it do not produce cascading errors. The removed `:!` syntax is now rejected as an ordinary parse error. The `form`/`:?`/`->?` ("extended types") portion of proposal #7254 is left for a separate change. Assisted-by: Claude Code
158 lines
4.5 KiB
Plaintext
158 lines
4.5 KiB
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
|
|
//
|
|
// 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/impl/lookup/unused_generic_binding.carbon
|
|
// TIP: To dump output, run:
|
|
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/check/testdata/impl/lookup/unused_generic_binding.carbon
|
|
|
|
// --- fail_no_binding_used.carbon
|
|
library "[[@TEST_NAME]]";
|
|
|
|
interface I {
|
|
let T: type;
|
|
}
|
|
|
|
impl forall [U: type] U as I where .T = () {}
|
|
|
|
class C {}
|
|
|
|
// This impl can never deduce its implicit generic parameter `V`, which
|
|
// should be diagnosed.
|
|
//
|
|
// CHECK:STDERR: fail_no_binding_used.carbon:[[@LINE+4]]:13: error: `impl` with unused generic binding [ImplUnusedBinding]
|
|
// CHECK:STDERR: impl forall [V: type] C as I where .T = {.unmatched: ()} {}
|
|
// CHECK:STDERR: ^~~~~~~~~
|
|
// CHECK:STDERR:
|
|
impl forall [V: type] C as I where .T = {.unmatched: ()} {}
|
|
|
|
fn F() {
|
|
// This shows that the first impl declaration was matched even though the
|
|
// second is more specific. But since it has an unused generic parameter, it
|
|
// will never match. If the second was matched, this line would not type
|
|
// check.
|
|
let unused x: C.(I.T) = ();
|
|
}
|
|
|
|
// --- fail_one_binding_unused.carbon
|
|
library "[[@TEST_NAME]]";
|
|
|
|
interface I {
|
|
let T: type;
|
|
}
|
|
|
|
impl forall [U: type] U as I where .T = () {}
|
|
|
|
class C {}
|
|
|
|
// This impl can never deduce its implicit generic parameter `W`, which
|
|
// should be diagnosed.
|
|
// https://discord.com/channels/655572317891461132/941071822756143115/1354563497731686550
|
|
//
|
|
// CHECK:STDERR: fail_one_binding_unused.carbon:[[@LINE+4]]:13: error: `impl` with unused generic binding [ImplUnusedBinding]
|
|
// CHECK:STDERR: impl forall [V: type, W: type] V as I where .T = {.unmatched: ()} {}
|
|
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~
|
|
// CHECK:STDERR:
|
|
impl forall [V: type, W: type] V as I where .T = {.unmatched: ()} {}
|
|
|
|
fn F() {
|
|
// This shows that the first impl declaration was matched even though the
|
|
// second is more specific. If the second was matched, it would not type
|
|
// check.
|
|
let unused x: C.(I.T) = ();
|
|
}
|
|
|
|
// --- fail_inherited_binding_unused.carbon
|
|
library "[[@TEST_NAME]]";
|
|
|
|
interface I {
|
|
let T: type;
|
|
}
|
|
|
|
impl forall [U: type] U as I where .T = () {}
|
|
|
|
class C(U: type) {
|
|
// This impl can never deduce its inherited generic binding `U`, which
|
|
// should be diagnosed.
|
|
//
|
|
// TODO: We should point the diagnostic at the binding `U` in C.
|
|
//
|
|
// CHECK:STDERR: fail_inherited_binding_unused.carbon:[[@LINE+4]]:3: error: `impl` with unused generic binding [ImplUnusedBinding]
|
|
// CHECK:STDERR: impl C(()) as I where .T = {.unmatched: ()} {}
|
|
// CHECK:STDERR: ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
|
|
// CHECK:STDERR:
|
|
impl C(()) as I where .T = {.unmatched: ()} {}
|
|
}
|
|
|
|
fn F() {
|
|
let unused x: C(()).(I.T) = ();
|
|
}
|
|
|
|
// --- fail_inherited_binding_in_forall_unused.carbon
|
|
library "[[@TEST_NAME]]";
|
|
|
|
interface I {
|
|
let T: type;
|
|
}
|
|
|
|
impl forall [U: type] U as I where .T = () {}
|
|
|
|
class C(U: type) {
|
|
// This impl can never deduce its inherited generic binding `U`, which
|
|
// should be diagnosed.
|
|
//
|
|
// TODO: We should point the diagnostic at the binding `U` in C.
|
|
//
|
|
// CHECK:STDERR: fail_inherited_binding_in_forall_unused.carbon:[[@LINE+4]]:15: error: `impl` with unused generic binding [ImplUnusedBinding]
|
|
// CHECK:STDERR: impl forall [V: type] C(V) as I where .T = {.unmatched: ()} {}
|
|
// CHECK:STDERR: ^~~~~~~~~
|
|
// CHECK:STDERR:
|
|
impl forall [V: type] C(V) as I where .T = {.unmatched: ()} {}
|
|
}
|
|
|
|
fn F() {
|
|
let unused x: C(()).(I.T) = ();
|
|
}
|
|
|
|
// --- inherited_binding_used.carbon
|
|
library "[[@TEST_NAME]]";
|
|
|
|
interface I {
|
|
let T: type;
|
|
}
|
|
|
|
impl forall [U: type] U as I where .T = {.unmatched: ()} {}
|
|
|
|
class C(U: type) {
|
|
// `U` can be deduced here, so no diagnostic issued.
|
|
impl C(U) as I where .T = () {}
|
|
}
|
|
|
|
fn F() {
|
|
// The `impl` inside C is matched here.
|
|
let unused x: C(()).(I.T) = ();
|
|
}
|
|
|
|
// --- inherited_binding_in_forall_used.carbon
|
|
library "[[@TEST_NAME]]";
|
|
|
|
interface I(W: type) {
|
|
let T: type;
|
|
}
|
|
|
|
impl forall [U: type] U as I(U) where .T = {.unmatched: ()} {}
|
|
|
|
class C(U: type) {
|
|
// `U` can be deduced here, so no diagnostic issued.
|
|
impl forall [V: type] C(U) as I(V) where .T = () {}
|
|
}
|
|
|
|
fn F() {
|
|
// The `impl` inside C is matched here.
|
|
let unused x: C(()).(I({}).T) = ();
|
|
}
|