feat(compiler): improve error message when type alias is used as valu…

[hk2166]

feat(compiler): improve error message when type alias is used as value

• Add specific diagnostic for when a type-only symbol is used as a value
• Replace generic "Cannot find name" error with more helpful message
• Add new diagnostic TS2888: "Cannot find name '{0}'. '{1}' only refers to a type, but is being used as a value here."
• Enhance getCannotFindNameDiagnosticForName to check for type symbols
• Add comprehensive test cases for type aliases, interfaces, and generic types

Fixes issue where users got confusing "Cannot find name" errors when
accidentally using type aliases as values, now provides clear guidance
that the identifier refers to a type.

Closes #7900

[Copilot]

Pull Request Overview

This PR improves error messages when type-only symbols (such as type aliases, interfaces, or type parameters) are accidentally used as values. Instead of showing a generic "Cannot find name" error, it now provides a more helpful error message that explicitly states the identifier refers to a type but is being used as a value.

Key Changes

• Added new diagnostic message TS2888 with format: "Cannot find name '{0}'. '{1}' only refers to a type, but is being used as a value here."
• Modified getCannotFindNameDiagnosticForName in checker.ts to detect type-only symbols
• Added comprehensive test cases covering type aliases, interfaces, and generic types

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
src/compiler/diagnosticMessages.json	Added new error diagnostic TS2888 for type-used-as-value scenarios
src/compiler/checker.ts	Enhanced name resolution error detection to identify type-only symbols
tests/cases/compiler/typeAliasUsedAsValue.ts	Comprehensive test coverage for various type-as-value error cases

[Copilot]

The error code 2888 is significantly out of sequence. It's placed between codes 2552 and 2553 in the file, but 2888 is over 300 codes higher. This breaks the sequential ordering convention used throughout the file. The code should likely be 2553 or the next available sequential code in the 2500s range to maintain consistency with the surrounding diagnostic codes.

[Copilot]

The diagnostic message requires two parameters ('{0}' for the identifier name and '{1}' for the type symbol name), but the current implementation doesn't provide a way to pass the second parameter. When this diagnostic is used in onFailedToResolveSymbol (line 3282 in checker.ts), it will call error(errorLocation, nameNotFoundMessage, diagnosticName(nameArg)) which only provides one argument. You need to either: (1) change the diagnostic message to only use one parameter like the existing "'{0}' only refers to a type, but is being used as a value here." (code 2693), or (2) modify the error reporting mechanism to pass both the identifier name and the type symbol name as separate arguments. The existing diagnostic 2693 might already serve this purpose.

[hk2166]

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[hk2166]

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