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https://github.com/carbon-language/carbon-lang.git
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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
99 lines
5.6 KiB
Plaintext
99 lines
5.6 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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//
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// AUTOUPDATE
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// TIP: To test this file alone, run:
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// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/parse/testdata/generics/interface/associated_constants.carbon
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// TIP: To dump output, run:
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// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/generics/interface/associated_constants.carbon
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// --- associated_constants.carbon
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library "[[@TEST_NAME]]";
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interface I {
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let T: type;
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final let I: i32;
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default let D: bool;
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}
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// --- initializer.carbon
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library "[[@TEST_NAME]]";
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interface I {
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let T: type = (i32, i32);
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final let I: i32 = 42;
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default let D: bool = false;
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}
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// CHECK:STDOUT: - filename: associated_constants.carbon
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// CHECK:STDOUT: parse_tree: [
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// CHECK:STDOUT: {kind: 'FileStart', text: ''},
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// CHECK:STDOUT: {kind: 'LibraryIntroducer', text: 'library'},
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// CHECK:STDOUT: {kind: 'LibraryName', text: '"associated_constants"'},
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// CHECK:STDOUT: {kind: 'LibraryDecl', text: ';', subtree_size: 3},
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// CHECK:STDOUT: {kind: 'InterfaceIntroducer', text: 'interface'},
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// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'I'},
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// CHECK:STDOUT: {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 3},
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// CHECK:STDOUT: {kind: 'AssociatedConstantIntroducer', text: 'let'},
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// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'T'},
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// CHECK:STDOUT: {kind: 'TypeTypeLiteral', text: 'type'},
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// CHECK:STDOUT: {kind: 'AssociatedConstantNameAndType', text: ':', subtree_size: 3},
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// CHECK:STDOUT: {kind: 'AssociatedConstantDecl', text: ';', subtree_size: 5},
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// CHECK:STDOUT: {kind: 'AssociatedConstantIntroducer', text: 'let'},
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// CHECK:STDOUT: {kind: 'FinalModifier', text: 'final'},
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// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'I'},
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// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
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// CHECK:STDOUT: {kind: 'AssociatedConstantNameAndType', text: ':', subtree_size: 3},
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// CHECK:STDOUT: {kind: 'AssociatedConstantDecl', text: ';', subtree_size: 6},
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// CHECK:STDOUT: {kind: 'AssociatedConstantIntroducer', text: 'let'},
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// CHECK:STDOUT: {kind: 'DefaultModifier', text: 'default'},
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// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'D'},
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// CHECK:STDOUT: {kind: 'BoolTypeLiteral', text: 'bool'},
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// CHECK:STDOUT: {kind: 'AssociatedConstantNameAndType', text: ':', subtree_size: 3},
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// CHECK:STDOUT: {kind: 'AssociatedConstantDecl', text: ';', subtree_size: 6},
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// CHECK:STDOUT: {kind: 'InterfaceDefinition', text: '}', subtree_size: 21},
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// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
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// CHECK:STDOUT: ]
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// CHECK:STDOUT: - filename: initializer.carbon
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// CHECK:STDOUT: parse_tree: [
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// CHECK:STDOUT: {kind: 'FileStart', text: ''},
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// CHECK:STDOUT: {kind: 'LibraryIntroducer', text: 'library'},
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// CHECK:STDOUT: {kind: 'LibraryName', text: '"initializer"'},
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// CHECK:STDOUT: {kind: 'LibraryDecl', text: ';', subtree_size: 3},
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// CHECK:STDOUT: {kind: 'InterfaceIntroducer', text: 'interface'},
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// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'I'},
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// CHECK:STDOUT: {kind: 'InterfaceDefinitionStart', text: '{', subtree_size: 3},
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// CHECK:STDOUT: {kind: 'AssociatedConstantIntroducer', text: 'let'},
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// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'T'},
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// CHECK:STDOUT: {kind: 'TypeTypeLiteral', text: 'type'},
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// CHECK:STDOUT: {kind: 'AssociatedConstantNameAndType', text: ':', subtree_size: 3},
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// CHECK:STDOUT: {kind: 'AssociatedConstantInitializer', text: '='},
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// CHECK:STDOUT: {kind: 'TupleLiteralStart', text: '('},
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// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
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// CHECK:STDOUT: {kind: 'TupleLiteralComma', text: ','},
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// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
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// CHECK:STDOUT: {kind: 'TupleLiteral', text: ')', subtree_size: 5},
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// CHECK:STDOUT: {kind: 'AssociatedConstantDecl', text: ';', subtree_size: 11},
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// CHECK:STDOUT: {kind: 'AssociatedConstantIntroducer', text: 'let'},
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// CHECK:STDOUT: {kind: 'FinalModifier', text: 'final'},
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// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'I'},
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// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
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// CHECK:STDOUT: {kind: 'AssociatedConstantNameAndType', text: ':', subtree_size: 3},
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// CHECK:STDOUT: {kind: 'AssociatedConstantInitializer', text: '='},
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// CHECK:STDOUT: {kind: 'IntLiteral', text: '42'},
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// CHECK:STDOUT: {kind: 'AssociatedConstantDecl', text: ';', subtree_size: 8},
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// CHECK:STDOUT: {kind: 'AssociatedConstantIntroducer', text: 'let'},
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// CHECK:STDOUT: {kind: 'DefaultModifier', text: 'default'},
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// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'D'},
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// CHECK:STDOUT: {kind: 'BoolTypeLiteral', text: 'bool'},
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// CHECK:STDOUT: {kind: 'AssociatedConstantNameAndType', text: ':', subtree_size: 3},
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// CHECK:STDOUT: {kind: 'AssociatedConstantInitializer', text: '='},
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// CHECK:STDOUT: {kind: 'BoolLiteralFalse', text: 'false'},
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// CHECK:STDOUT: {kind: 'AssociatedConstantDecl', text: ';', subtree_size: 8},
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// CHECK:STDOUT: {kind: 'InterfaceDefinition', text: '}', subtree_size: 31},
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// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
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// CHECK:STDOUT: ]
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