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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
56 lines
2.7 KiB
Plaintext
56 lines
2.7 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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// INCLUDE-FILE: toolchain/testing/testdata/min_prelude/none.carbon
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// TODO: Add ranges and switch to "--dump-sem-ir-ranges=only".
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// EXTRA-ARGS: --dump-sem-ir-ranges=if-present
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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/check/testdata/function/generic/forward_decl.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/check/testdata/function/generic/forward_decl.carbon
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fn F(generic T: type);
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// CHECK:STDOUT: --- forward_decl.carbon
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// CHECK:STDOUT:
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// CHECK:STDOUT: constants {
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// CHECK:STDOUT: %type: type = facet_type <type> [concrete]
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// CHECK:STDOUT: %.Self.frozen: %type = symbolic_binding .Self [symbolic_self]
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// CHECK:STDOUT: %pattern_type: type = pattern_type type [concrete]
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// CHECK:STDOUT: %T.patt: %pattern_type = symbolic_binding_pattern T, 0 [symbolic]
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// CHECK:STDOUT: %T: type = symbolic_binding T, 0 [symbolic]
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// CHECK:STDOUT: %F.type: type = fn_type @F [concrete]
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// CHECK:STDOUT: %F: %F.type = struct_value () [concrete]
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: file {
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// CHECK:STDOUT: package: <namespace> = namespace [concrete] {
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// CHECK:STDOUT: .F = %F.decl
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// CHECK:STDOUT: }
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// CHECK:STDOUT: %F.decl: %F.type = fn_decl @F [concrete = constants.%F] {
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// CHECK:STDOUT: %T.patt.loc15_15.1: %pattern_type = symbolic_binding_pattern T, 0 [symbolic = %T.patt.loc15_15.2 (constants.%T.patt)]
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// CHECK:STDOUT: } {
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// CHECK:STDOUT: %.loc15_17.1: type = splice_block %.loc15_17.2 [concrete = type] {
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// CHECK:STDOUT: %.Self.frozen: %type = symbolic_binding .Self [symbolic_self = constants.%.Self.frozen]
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// CHECK:STDOUT: %.loc15_17.2: type = type_literal type [concrete = type]
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// CHECK:STDOUT: }
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// CHECK:STDOUT: %T.loc15_15.2: type = symbolic_binding T, 0 [symbolic = %T.loc15_15.1 (constants.%T)]
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// CHECK:STDOUT: }
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: generic fn @F(%T.loc15_15.2: type) {
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// CHECK:STDOUT: %T.patt.loc15_15.2: %pattern_type = symbolic_binding_pattern T, 0 [symbolic = %T.patt.loc15_15.2 (constants.%T.patt)]
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// CHECK:STDOUT: %T.loc15_15.1: type = symbolic_binding T, 0 [symbolic = %T.loc15_15.1 (constants.%T)]
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// CHECK:STDOUT:
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// CHECK:STDOUT: fn();
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: specific @F(constants.%T) {
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// CHECK:STDOUT: %T.patt.loc15_15.2 => constants.%T.patt
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// CHECK:STDOUT: %T.loc15_15.1 => constants.%T
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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