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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
87 lines
4.1 KiB
Plaintext
87 lines
4.1 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/impl/fail_impl_bad_assoc_const.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/impl/fail_impl_bad_assoc_const.carbon
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interface I { let T: type; }
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// CHECK:STDERR: fail_impl_bad_assoc_const.carbon:[[@LINE+7]]:1: error: associated constant T not given a value in impl of interface I [ImplAssociatedConstantNeedsValue]
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// CHECK:STDERR: impl () as I {}
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// CHECK:STDERR: ^~~~~~~~~~~~~~
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// CHECK:STDERR: fail_impl_bad_assoc_const.carbon:[[@LINE-5]]:19: note: associated constant declared here [AssociatedConstantHere]
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// CHECK:STDERR: interface I { let T: type; }
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// CHECK:STDERR: ^~~~~~~
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// CHECK:STDERR:
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impl () as I {}
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// CHECK:STDOUT: --- fail_impl_bad_assoc_const.carbon
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// CHECK:STDOUT:
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// CHECK:STDOUT: constants {
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// CHECK:STDOUT: %I.type: type = facet_type <@I> [concrete]
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// CHECK:STDOUT: %Self: %I.type = symbolic_binding Self, 0 [symbolic]
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// CHECK:STDOUT: %I.assoc_type: type = assoc_entity_type @I [concrete]
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// CHECK:STDOUT: %assoc0: %I.assoc_type = assoc_entity element0, @I.WithSelf.%T [concrete]
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// CHECK:STDOUT: %empty_tuple.type: type = tuple_type () [concrete]
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// CHECK:STDOUT: %empty_tuple: %empty_tuple.type = tuple_value () [concrete]
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// CHECK:STDOUT: %I.impl_witness: <witness> = impl_witness @empty_tuple.type.as.I.impl.%I.impl_witness_table [concrete]
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// CHECK:STDOUT: %I.facet: %I.type = facet_value %empty_tuple.type, (%I.impl_witness) [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: .I = %I.decl
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// CHECK:STDOUT: }
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// CHECK:STDOUT: %I.decl: type = interface_decl @I [concrete = constants.%I.type] {} {}
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// CHECK:STDOUT: impl_decl @empty_tuple.type.as.I.impl [concrete] {} {
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// CHECK:STDOUT: %.loc24_7.1: %empty_tuple.type = tuple_literal () [concrete = constants.%empty_tuple]
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// CHECK:STDOUT: %.loc24_7.2: type = converted %.loc24_7.1, constants.%empty_tuple.type [concrete = constants.%empty_tuple.type]
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// CHECK:STDOUT: %I.ref: type = name_ref I, file.%I.decl [concrete = constants.%I.type]
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// CHECK:STDOUT: }
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: interface @I {
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// CHECK:STDOUT: %Self: %I.type = symbolic_binding Self, 0 [symbolic = constants.%Self]
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// CHECK:STDOUT: %I.WithSelf.decl = interface_with_self_decl @I [concrete]
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// CHECK:STDOUT:
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// CHECK:STDOUT: !with Self:
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// CHECK:STDOUT: %T: type = assoc_const_decl @T [concrete] {
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// CHECK:STDOUT: %assoc0: %I.assoc_type = assoc_entity element0, @I.WithSelf.%T [concrete = constants.%assoc0]
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: !members:
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// CHECK:STDOUT: .Self = %Self
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// CHECK:STDOUT: .T = @T.%assoc0
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// CHECK:STDOUT: witness = (@I.WithSelf.%T)
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// CHECK:STDOUT:
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// CHECK:STDOUT: !requires:
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// CHECK:STDOUT:
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// CHECK:STDOUT: !observes:
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: impl @empty_tuple.type.as.I.impl: %.loc24_7.2 as %I.ref {
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// CHECK:STDOUT: %I.impl_witness_table = impl_witness_table (<error>), @empty_tuple.type.as.I.impl [concrete]
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// CHECK:STDOUT: %I.impl_witness: <witness> = impl_witness %I.impl_witness_table [concrete = constants.%I.impl_witness]
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// CHECK:STDOUT:
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// CHECK:STDOUT: !members:
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// CHECK:STDOUT: extend %I.ref
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// CHECK:STDOUT: witness = %I.impl_witness
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: specific @I.WithSelf(constants.%Self) {
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// CHECK:STDOUT: !definition:
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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// CHECK:STDOUT: specific @I.WithSelf(constants.%I.facet) {
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// CHECK:STDOUT: !definition:
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// CHECK:STDOUT: }
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// CHECK:STDOUT:
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