Error on modules-as-namespaces

[Copilot]

• Parser: Emit parse error on identifier names when module keyword is used for namespace declarations
• Parser: Dotted names get errors on each component (e.g., module A.B {} → errors on A and B)
• Parser: AST uses KindNamespaceKeyword for error recovery
• Checker: Remove now-unreachable suggestion diagnostic code
• Checker: Remove unused getNonModifierTokenRangeOfNode utility
• Printer tests: Remove module a{} and module a.b{} tests (now produce parse errors)
• Baselines: Match TypeScript exactly (diff files deleted)
• All tests pass

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[jakebailey]

@copilot the intent is that module is illegal and produces a parse error

[Copilot]

@copilot the intent is that module is illegal and produces a parse error

Updated in e50c1d7. The parser now emits a parse error (TS1540) on each identifier name when module is used for namespace declarations, including on each component of dotted names (e.g., module A.B {} errors on both A and B). The AST still uses KindNamespaceKeyword for error recovery. Baselines now match TypeScript exactly — both diff files were deleted.

[jakebailey]

I guess this is fine, though I think I was hoping to hard remove it and not even have this diagnostic, as though module foo { were entirely illegal.

[Copilot]

Pull request overview

Removes support for module-keyword namespace declarations by turning them into parser errors, aligning behavior and baselines with upstream TypeScript.

Changes:

• Parser now errors on module X {} (and per-component on dotted names) and uses KindNamespaceKeyword for recovery.
• Checker cleanup: removes now-unreachable suggestion diagnostics and a related utility.
• Updates/removes printer tests and baseline diff artifacts to match TypeScript outputs.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
internal/parser/parser.go	Emits parse errors for module-keyword namespace declarations; normalizes AST keyword to namespace for recovery.
internal/checker/checker.go	Removes unreachable suggestion diagnostic for module-keyword namespace declarations.
internal/checker/utilities.go	Removes unused helper previously used for the suggestion diagnostic span.
internal/printer/printer_test.go	Drops printer cases that now fail to parse (module a{}, module a.b{}).
testdata/baselines/reference/submodule/compiler/moduleKeywordDeprecated.errors.txt.diff	Deletes baseline diff artifact.
testdata/baselines/reference/submodule/compiler/moduleKeywordDeprecated.errors.txt	Adds/updates baseline error output in the non-diff format.
testdata/baselines/reference/submodule/compiler/escapedIdentifiers.errors.txt.diff	Deletes baseline diff artifact.
testdata/baselines/reference/submodule/compiler/escapedIdentifiers.errors.txt	Updates baseline to include the newly parser-emitted TS1540 error.

[DanielRosenwasser]

I guess this is fine, though I think I was hoping to hard remove it and not even have this diagnostic

It's better to just gracefully parse it for as long as we can and issue a parse error.