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carbon-lang/toolchain/parse/testdata/package_expr/fail_in_name.carbon
T
Richard Smith 49024c8d83 Improve diagnostics and error recovery for invalid identifiers. (#7249)
If a keyword or a sized type literal (eg, `f2`) is used in a context
where we are confident that we are expecting an identifier -- either
before a `:` in a binding pattern or after a `.` in a member access or
designator -- then recover as if a raw identifier was used.

This appears to be a particular stumbling block for coding agents, so
seems worth paying special attention to.

Add a mechanism to the tokenized buffer to track additional tokens
synthesized for error recovery so that we can keep the lexed token
sequence immutable and still satisfy the invariants throughout the rest
of the toolchain for recovery tokens. Thanks to chandlerc for suggesting
this approach!
2026-05-22 23:53:19 +00:00

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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/package_expr/fail_in_name.carbon
// TIP: To dump output, run:
// TIP: bazel run //toolchain/testing:file_test -- --dump_output --file_tests=toolchain/parse/testdata/package_expr/fail_in_name.carbon
// CHECK:STDERR: fail_in_name.carbon:[[@LINE+4]]:14: error: unexpected expression before : in binding pattern [ExpectedBindingName]
// CHECK:STDERR: var package.n: i32;
// CHECK:STDERR: ^
// CHECK:STDERR:
var package.n: i32;
// `val` is a keyword, but during error recovery we treat it as an identifier.
// CHECK:STDERR: fail_in_name.carbon:[[@LINE+8]]:13: error: expected identifier after `.`; prefix reserved word with `r#` to form a valid identifier [ExpectedIdentifierAfterPeriodOrArrow]
// CHECK:STDERR: var package.val: i32;
// CHECK:STDERR: ^~~
// CHECK:STDERR:
// CHECK:STDERR: fail_in_name.carbon:[[@LINE+4]]:16: error: unexpected expression before : in binding pattern [ExpectedBindingName]
// CHECK:STDERR: var package.val: i32;
// CHECK:STDERR: ^
// CHECK:STDERR:
var package.val: i32;
// CHECK:STDERR: fail_in_name.carbon:[[@LINE+4]]:11: error: `namespace` introducer should be followed by a name [ExpectedDeclName]
// CHECK:STDERR: namespace package.NS;
// CHECK:STDERR: ^~~~~~~
// CHECK:STDERR:
namespace package.NS;
// CHECK:STDERR: fail_in_name.carbon:[[@LINE+4]]:7: error: `class` introducer should be followed by a name [ExpectedDeclName]
// CHECK:STDERR: class package.C {
// CHECK:STDERR: ^~~~~~~
// CHECK:STDERR:
class package.C {
}
// CHECK:STDOUT: - filename: fail_in_name.carbon
// CHECK:STDOUT: parse_tree: [
// CHECK:STDOUT: {kind: 'FileStart', text: ''},
// CHECK:STDOUT: {kind: 'VariableIntroducer', text: 'var'},
// CHECK:STDOUT: {kind: 'PackageExpr', text: 'package'},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'n'},
// CHECK:STDOUT: {kind: 'MemberAccessExpr', text: '.', subtree_size: 3},
// CHECK:STDOUT: {kind: 'VariablePattern', text: 'var', has_error: yes, subtree_size: 4},
// CHECK:STDOUT: {kind: 'VariableDecl', text: ';', subtree_size: 6},
// CHECK:STDOUT: {kind: 'VariableIntroducer', text: 'var'},
// CHECK:STDOUT: {kind: 'PackageExpr', text: 'package'},
// CHECK:STDOUT: {kind: 'IdentifierNameNotBeforeSignature', text: 'val'},
// CHECK:STDOUT: {kind: 'MemberAccessExpr', text: '.', subtree_size: 3},
// CHECK:STDOUT: {kind: 'VariablePattern', text: 'var', has_error: yes, subtree_size: 4},
// CHECK:STDOUT: {kind: 'VariableDecl', text: ';', subtree_size: 6},
// CHECK:STDOUT: {kind: 'NamespaceStart', text: 'namespace'},
// CHECK:STDOUT: {kind: 'InvalidParse', text: 'package', has_error: yes},
// CHECK:STDOUT: {kind: 'Namespace', text: ';', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'ClassIntroducer', text: 'class'},
// CHECK:STDOUT: {kind: 'InvalidParse', text: 'package', has_error: yes},
// CHECK:STDOUT: {kind: 'ClassDecl', text: '}', has_error: yes, subtree_size: 3},
// CHECK:STDOUT: {kind: 'FileEnd', text: ''},
// CHECK:STDOUT: ]