[api-extractor] Naming conflict between import and global type renames global

[rudolf]

If there's two type references, one a named import, the other a global variable, api-extractor renames the global variable instead of renaming the named import.

Example:

import {React} from 'react';
export interface UsingNamedImport {
  children: React.ReactNode;
}

export interface UsingGlobal {
  children: React_2.ReactNode
}

[octogonz]

The problem is with _collectGlobalNames() which is used by _makeUniqueNames():
https://github.com/microsoft/web-build-tools/blob/d061216478054c8e2011bc3f4a1954b165f48264/apps/api-extractor/src/collector/Collector.ts#L386-L397

The above code aims to detect all names that are defined in the global namespace, but at the time we were unsure how to implement it. (This is tracked by #1095.) The proposal was to use internal compiler APIs like this:

const typeChecker = (this.program as any).getDiagnosticsProducingTypeChecker();
const resolver = (typeChecker as any).getEmitResolver();
resolver.hasGlobalName('Promise'); // --> true

However, the comments say that this produced 1,650 results which is a fairly large set that is likely to have unnecessary matches: For example, if we implement it that way, it would fix @skaapgif's example above. But the imported React would still get renamed even if the React global variable is not used.

Thus perhaps _collectGlobalNames() should /only/ return the global names that are actually referenced somewhere in the Collector's API surface.

@rbuckton Do you happen to know if there's an API similar to resolver.hasGlobalName() that can check a symbol to see whether it is referring to a global variable?

[rbuckton]

There's no public API for this currently, but a workaround is possible using checker.getSymbolsInScope

[octogonz]

Fixed by PR #1767 which was published with API Extractor 7.7.12.

[octogonz]

BTW I've also improved --diagnostics switch to report when globals are encountered, which will show the path of which file is referencing the React global.