Files
carbon-lang/toolchain/parse/testdata/generics/impl/fail_impl.carbon
T
Chandler Carruth 8be274cf60 Replace :! binding syntax with phase keywords and contextual defaults (#7479)
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
2026-07-11 01:22:44 +00:00

186 lines
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// Part of the Carbon Language project, under the Apache License v2.0 with LLVM
// Exceptions. See /LICENSE for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
// AUTOUPDATE
// TIP: To test this file alone, run:
// TIP: bazel test //toolchain/testing:file_test --test_arg=--file_tests=toolchain/parse/testdata/generics/impl/fail_impl.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/generics/impl/fail_impl.carbon
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:10: error: expected `as` in `impl` declaration [ImplExpectedAs]
// CHECK:STDERR: impl foo bar;
// CHECK:STDERR: ^~~
// CHECK:STDERR:
impl foo bar;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:12: error: expected expression [ExpectedExpr]
// CHECK:STDERR: impl i32 as;
// CHECK:STDERR: ^
// CHECK:STDERR:
impl i32 as;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:18: error: `impl` declarations must either end with a `;` or have a `{ ... }` block for a definition [ExpectedDeclSemiOrDefinition]
// CHECK:STDERR: impl bool as bar unexpected;
// CHECK:STDERR: ^~~~~~~~~~
// CHECK:STDERR:
impl bool as bar unexpected;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:6: error: expected expression [ExpectedExpr]
// CHECK:STDERR: impl return as A;
// CHECK:STDERR: ^~~~~~
// CHECK:STDERR:
impl return as A;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:6: error: expected expression [ExpectedExpr]
// CHECK:STDERR: impl return B;
// CHECK:STDERR: ^~~~~~
// CHECK:STDERR:
impl return B;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+8]]:13: error: expected `[` after `forall` in `impl` declaration [ImplExpectedAfterForall]
// CHECK:STDERR: impl forall f32;
// CHECK:STDERR: ^~~
// CHECK:STDERR:
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:16: error: expected `as` in `impl` declaration [ImplExpectedAs]
// CHECK:STDERR: impl forall f32;
// CHECK:STDERR: ^
// CHECK:STDERR:
impl forall f32;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:19: error: expected `as` in `impl` declaration [ImplExpectedAs]
// CHECK:STDERR: impl forall [] u32;
// CHECK:STDERR: ^
// CHECK:STDERR:
impl forall [] u32;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:25: error: expected `as` in `impl` declaration [ImplExpectedAs]
// CHECK:STDERR: impl forall [invalid] i8;
// CHECK:STDERR: ^
// CHECK:STDERR:
impl forall [invalid] i8;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:13: error: expected `[` after `forall` in `impl` declaration [ImplExpectedAfterForall]
// CHECK:STDERR: impl forall f16 as Quux;
// CHECK:STDERR: ^~~
// CHECK:STDERR:
impl forall f16 as Quux;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:26: error: expected `as` in `impl` declaration [ImplExpectedAs]
// CHECK:STDERR: impl forall [T: type] str;
// CHECK:STDERR: ^
// CHECK:STDERR:
impl forall [T: type] str;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:25: error: expected `as` in `impl` declaration [ImplExpectedAs]
// CHECK:STDERR: impl forall [T: type] T missing_as;
// CHECK:STDERR: ^~~~~~~~~~
// CHECK:STDERR:
impl forall [T: type] T missing_as;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:38: error: `impl` declarations must either end with a `;` or have a `{ ... }` block for a definition [ExpectedDeclSemiOrDefinition]
// CHECK:STDERR: impl forall [T: type] T as Interface extra;
// CHECK:STDERR: ^~~~~
// CHECK:STDERR:
impl forall [T: type] T as Interface extra;
// CHECK:STDERR: fail_impl.carbon:[[@LINE+4]]:5: error: expected expression [ExpectedExpr]
// CHECK:STDERR: impl;
// CHECK:STDERR: ^
// CHECK:STDERR:
impl;
impl
// CHECK:STDERR: fail_impl.carbon:[[@LINE+90]]:21: error: expected expression [ExpectedExpr]
// CHECK:STDERR: // CHECK:STDOUT: ]
// CHECK:STDERR: ^
// CHECK:STDERR:
// CHECK:STDOUT: - filename: fail_impl.carbon
// CHECK:STDOUT: parse_tree: [
// CHECK:STDOUT: {kind: 'FileStart', text: ''},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'IdentifierNameExpr', text: 'foo'},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i32'},
// CHECK:STDOUT: {kind: 'ImplTypeAs', text: 'as', subtree_size: 2},
// CHECK:STDOUT: {kind: 'InvalidParse', text: ';', has_error: yes},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 5},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'BoolTypeLiteral', text: 'bool'},
// CHECK:STDOUT: {kind: 'ImplTypeAs', text: 'as', subtree_size: 2},
// CHECK:STDOUT: {kind: 'IdentifierNameExpr', text: 'bar'},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 5},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'InvalidParse', text: 'return', has_error: yes},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'InvalidParse', text: 'return', has_error: yes},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'Forall', text: 'forall'},
// CHECK:STDOUT: {kind: 'InvalidParse', text: 'f32', has_error: yes},
// CHECK:STDOUT: {kind: 'FloatTypeLiteral', text: 'f32'},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 5},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'Forall', text: 'forall'},
// CHECK:STDOUT: {kind: 'ImplicitParamListStart', text: '['},
// CHECK:STDOUT: {kind: 'ImplicitParamList', text: ']', subtree_size: 2},
// CHECK:STDOUT: {kind: 'UnsignedIntTypeLiteral', text: 'u32'},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 6},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'Forall', text: 'forall'},
// CHECK:STDOUT: {kind: 'ImplicitParamListStart', text: '['},
// CHECK:STDOUT: {kind: 'IdentifierNameExpr', text: 'invalid'},
// CHECK:STDOUT: {kind: 'ImplicitParamList', text: ']', subtree_size: 3},
// CHECK:STDOUT: {kind: 'IntTypeLiteral', text: 'i8'},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 7},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'Forall', text: 'forall'},
// CHECK:STDOUT: {kind: 'InvalidParse', text: 'f16', has_error: yes},
// CHECK:STDOUT: {kind: 'FloatTypeLiteral', text: 'f16'},
// CHECK:STDOUT: {kind: 'ImplTypeAs', text: 'as', subtree_size: 2},
// CHECK:STDOUT: {kind: 'IdentifierNameExpr', text: 'Quux'},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 7},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'Forall', text: 'forall'},
// CHECK:STDOUT: {kind: 'ImplicitParamListStart', text: '['},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'T'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':', subtree_size: 2},
// CHECK:STDOUT: {kind: 'TypeTypeLiteral', text: 'type'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':', subtree_size: 4},
// CHECK:STDOUT: {kind: 'ImplicitParamList', text: ']', subtree_size: 6},
// CHECK:STDOUT: {kind: 'StringTypeLiteral', text: 'str'},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 10},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'Forall', text: 'forall'},
// CHECK:STDOUT: {kind: 'ImplicitParamListStart', text: '['},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'T'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':', subtree_size: 2},
// CHECK:STDOUT: {kind: 'TypeTypeLiteral', text: 'type'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':', subtree_size: 4},
// CHECK:STDOUT: {kind: 'ImplicitParamList', text: ']', subtree_size: 6},
// CHECK:STDOUT: {kind: 'IdentifierNameExpr', text: 'T'},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 10},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'Forall', text: 'forall'},
// CHECK:STDOUT: {kind: 'ImplicitParamListStart', text: '['},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'T'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPatternStart', text: ':', subtree_size: 2},
// CHECK:STDOUT: {kind: 'TypeTypeLiteral', text: 'type'},
// CHECK:STDOUT: {kind: 'CompileTimeBindingPattern', text: ':', subtree_size: 4},
// CHECK:STDOUT: {kind: 'ImplicitParamList', text: ']', subtree_size: 6},
// CHECK:STDOUT: {kind: 'IdentifierNameExpr', text: 'T'},
// CHECK:STDOUT: {kind: 'ImplTypeAs', text: 'as', subtree_size: 2},
// CHECK:STDOUT: {kind: 'IdentifierNameExpr', text: 'Interface'},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 12},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'InvalidParse', text: ';', has_error: yes},
// CHECK:STDOUT: {kind: 'ImplDecl', text: ';', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'ImplIntroducer', text: 'impl'},
// CHECK:STDOUT: {kind: 'InvalidParse', text: '', has_error: yes},
// CHECK:STDOUT: {kind: 'ImplDecl', text: 'impl', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
// CHECK:STDOUT: ]