Exposing canonical filename logic

Search Terms

canonical filename

Suggestion

I'd like to re-use the get-canonical-filename logic:
https://github.com/microsoft/TypeScript/blob/d68295e74e4897f588e73edf72089eb238904f02/src/compiler/core.ts#L1906-L1909

Use Cases

I want to use ts.resolveModuleName and the accompanying ts.createModuleResolutionCache to resolve ImportDeclarations (as per this comment's suggestion).
createModuleResolutionCache requires a parameter getCanonicalFileName. I think it makes the most sense to use the same logic as the compiler itself here, which is the function I linked above.

I could just copy-and-paste this function, but that feels wrong and might lead to discrepancies in the future if toFileNameLowerCase (which is not exposed either) is ever updated.

Examples

const cache = ts.createModuleResolutionCache(currentDirectory, ts.createGetCanonicalFileName(true/false));
const resolved = ts.resolveModuleName(name, file, compilerOptions, host, cache);

Checklist

My suggestion meets these guidelines:

• This wouldn't be a breaking change in existing TypeScript/JavaScript code
• This wouldn't change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn't a runtime feature (e.g. library functionality, non-ECMAScript syntax with JavaScript output, etc.)
• This feature would agree with the rest of TypeScript's Design Goals.

Start with the canonical filename logic at src/compiler/core.ts lines 1906-1909 and inspect the createModuleResolutionCache entry point. Compare it with toFileNameLowerCase, also linked in the issue, and determine the public helper shape needed by the example. Done means consumers can reuse the compiler's canonical filename behavior for module resolution without copying the logic.