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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
47 lines
866 B
Plaintext
47 lines
866 B
Plaintext
// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
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// Exceptions. See /LICENSE for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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// More single line comments
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package Carbon api;
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interface HasValueParam(T: type, V: T) {
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fn Go(self) -> T;
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}
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impl () as HasValueParam(i32, 5) {
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fn Go(self) -> i32 { return 42; }
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}
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class Point {
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fn Origin() -> Self {
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return {.x = 0, .y = 0};
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}
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var x: i32;
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var y: i32;
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}
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fn Procedure() -> i32 {
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returned var zoop: i32 = 0;
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while (DoSomeJob() {
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zoop += 1;
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}
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return var;
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}
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fn Main() -> i32 {
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let str = "Hello world";
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let hex = 0xABCDEF1234567890;
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let bin = 0b0000111001010010;
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let dec = 123456789012345678;
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let big: Carbon.Int(1024) = 1234;
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let aaa: auto = "Carbon";
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let view: StringView = "Carbon";
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return Procedure();
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}
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