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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
116 lines
2.9 KiB
Plaintext
116 lines
2.9 KiB
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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package Core library "prelude/operators/bitwise";
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import library "prelude/types/int_literal";
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// TODO: Per the design, the associated type `Result` in each of these
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// interfaces should have a default value of `Self`:
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//
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// default let Result: type = Self;
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// TODO: Per the design, for each *With interface there should also be a
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// non-With named constraint, such as:
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//
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// constraint BitAnd {
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// extend require impls BitAndWith(Self) where .Result = Self;
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// }
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// Bit complement: `^a`.
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interface BitComplement {
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let Result: type;
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fn Op(self) -> Result;
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}
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// Bitwise AND: `a & b`.
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interface BitAndWith(Other: type) {
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let Result: type;
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fn Op(self, other: Other) -> Result;
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}
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// Bitwise AND with assignment: `a &= b`.
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interface BitAndAssignWith(Other: type) {
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fn Op(ref self, other: Other);
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}
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// Bitwise OR: `a | b`.
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interface BitOrWith(Other: type) {
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let Result: type;
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fn Op(self, other: Other) -> Result;
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}
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// Bitwise OR with assignment: `a |= b`.
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interface BitOrAssignWith(Other: type) {
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fn Op(ref self, other: Other);
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}
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// Bitwise XOR: `a ^ b`.
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interface BitXorWith(Other: type) {
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let Result: type;
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fn Op(self, other: Other) -> Result;
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}
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// Bitwise XOR with assignment: `a ^= b`.
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interface BitXorAssignWith(Other: type) {
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fn Op(ref self, other: Other);
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}
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// Left shift: `a << b`.
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interface LeftShiftWith(Other: type) {
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let Result: type;
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fn Op(self, other: Other) -> Result;
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}
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// Left shift with assignment: `a <<= b`.
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interface LeftShiftAssignWith(Other: type) {
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fn Op(ref self, other: Other);
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}
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// Right shift: `a >> b`.
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interface RightShiftWith(Other: type) {
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let Result: type;
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fn Op(self, other: Other) -> Result;
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}
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// Right shift with assignment: `a >>= b`.
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interface RightShiftAssignWith(Other: type) {
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fn Op(ref self, other: Other);
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}
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// Operations for IntLiteral. These need to be here because IntLiteral has no
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// associated library of its own.
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impl IntLiteral as BitAndWith(Self) where .Result = Self {
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fn Op(self, other: Self) -> Self = "int.and";
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}
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impl IntLiteral as BitComplement where .Result = Self {
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fn Op(self) -> Self = "int.complement";
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}
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impl IntLiteral as BitOrWith(Self) where .Result = Self {
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fn Op(self, other: Self) -> Self = "int.or";
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}
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impl IntLiteral as BitXorWith(Self) where .Result = Self {
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fn Op(self, other: Self) -> Self = "int.xor";
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}
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impl IntLiteral as LeftShiftWith(Self) where .Result = Self {
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fn Op(self, other: Self) -> Self = "int.left_shift";
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}
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impl IntLiteral as RightShiftWith(Self) where .Result = Self {
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fn Op(self, other: Self) -> Self = "int.right_shift";
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}
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// Operations for `type`. These need to be here because `type` has no
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// associated library of its own.
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// Facet type combination.
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impl type as BitAndWith(Self) where .Result = Self {
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fn Op(self, other: Self) -> Self = "type.and";
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}
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