Crash in checkNestedBlockScopedBinding with export as namespace (?)

[mprobst]

TypeScript Version: 3.2.0-dev.201xxxxx

Search Terms:

• checkNestedBlockScopedBinding
• TypeError: Cannot read property 'kind' of undefined

Code

I've yet been unable to isolate a reasonably self-contained example. This involves third party typings for THREE in a specific version that are re-exported via a declare global and export as namespace, and apparently in a specific version.

What appears to happen though is that checkNestedBlockScopedBinding tries to check if the valueDeclaration is in a catch clause:

            if (languageVersion >= ScriptTarget.ES2015 ||
                (symbol.flags & (SymbolFlags.BlockScopedVariable | SymbolFlags.Class)) === 0 ||
                symbol.valueDeclaration.parent.kind === SyntaxKind.CatchClause) {
                return;
            }

However valueDeclaration can be a SourceFile in this case, which means .parent is undefined, and thus the .kind check throws.

Expected behavior:

No crash.

Actual behavior:

Crashes with a stack trace of:

Compilation failed TypeError: Cannot read property 'kind' of undefined
    at checkNestedBlockScopedBinding (lib/typescript.js:45938:48)
    at checkIdentifier (lib/typescript.js:45844:13)
    at checkExpressionWorker (lib/typescript.js:51828:28)
    at checkExpression (lib/typescript.js:51800:42)
    at checkNonNullExpression (lib/typescript.js:48151:37)
    at checkPropertyAccessExpressionOrQualifiedName (lib/typescript.js:48184:28)
    at checkPropertyAccessExpression (lib/typescript.js:48177:20)
    at checkExpressionWorker (lib/typescript.js:51857:28)
    at checkExpression (lib/typescript.js:51800:42)
    at checkNonNullExpression (lib/typescript.js:48151:37)
    at resolveNewExpression (lib/typescript.js:49546:34)
    at resolveSignature (lib/typescript.js:49817:28)
    at getResolvedSignature (lib/typescript.js:49847:26)
    at checkCallExpression (lib/typescript.js:49939:29)
    at checkExpressionWorker (lib/typescript.js:51866:28)
    at checkExpression (lib/typescript.js:51800:42)
    at checkExpressionCached (lib/typescript.js:51646:38)
    at getTypeOfExpression (lib/typescript.js:51767:28)
    at checkDeclarationInitializer (lib/typescript.js:51657:24)
    at getTypeForVariableLikeDeclaration (lib/typescript.js:35286:28)
    at getWidenedTypeForVariableLikeDeclaration (lib/typescript.js:35570:56)
    at getTypeOfVariableOrParameterOrPropertyWorker (lib/typescript.js:35684:24)
    at getTypeOfVariableOrParameterOrProperty (lib/typescript.js:35606:48)
    at getTypeOfSymbol (lib/typescript.js:35895:24)
    at checkVariableLikeDeclaration (lib/typescript.js:54098:41)
    at checkVariableDeclaration (lib/typescript.js:54171:20)
    at checkSourceElement (lib/typescript.js:56192:28)
    at Object.forEach (lib/typescript.js:210:30)
    at checkVariableStatement (lib/typescript.js:54181:16)
    at checkSourceElement (lib/typescript.js:56161:28)
    at Object.forEach (lib/typescript.js:210:30)
    at checkSourceFileWorker (lib/typescript.js:56360:20)
    at checkSourceFile (lib/typescript.js:56332:13)
    at getDiagnosticsWorker (lib/typescript.js:56407:17)
    at Object.getDiagnostics (lib/typescript.js:56393:24)
    at lib/typescript.js:87124:85
    at runWithCancellationToken (lib/typescript.js:87090:24)
    at getSemanticDiagnosticsForFileNoCache (lib/typescript.js:87113:20)
    at getAndCacheDiagnostics (lib/typescript.js:87361:26)
    at getSemanticDiagnosticsForFile (lib/typescript.js:87110:20)
    at getDiagnosticsHelper (lib/typescript.js:87052:24)
    at Object.getSemanticDiagnostics (lib/typescript.js:87065:20)

[mprobst]

Repro:

// three.d.ts
export namespace THREE {
  export class Vector2 {}
}

// global.d.ts
import * as _three from './three';

export as namespace THREE;

declare global {
  export const THREE: typeof _three;
}

// test.ts
const m = new THREE.Vector2();

[sandersn]

This kind of merged symbol causes crashes in two places, actually, because it's marked BlockScoped, which makes us assume that it must be something that is inside a SourceFile. However, block-scoped checks don't make sense for this kind of symbol, so I'll exclude them by looking at the kind of the valueDeclaration, as @mprobst suggests above.