Cannot read properties of undefined (reading 'length')

[nevedaren]

Bug Report

🔎 Search Terms

Cannot read properties of undefined, tsc crash

🕗 Version & Regression Information

First noticed on 5.0.0-dev.20221118 nightly build, persists on 5.0.0-dev.20221122

⏯ Playground Link

https://www.typescriptlang.org/play?module=1&ts=5.0.0-dev.20221122#code/KYDwDg9gTgLgBDAnmYcBiEIB4AqcC8cAzjFAJYB2A5gHwFwDeAvgNwBQbA9J3AAIBmZADbAKAQwC2wAFxxBIgEwA6GEQ5kJkWIwwQmcqBAlwA5Es6UwAVxgn2bflYoBjGGQgU4AIzFRcNAApgESkKGFldAEpGNjg4KGAYKyhPAEZ2Jg4fKADUuDEidEwsCisJL2AoGkiWIA

💻 Code

// main.ts
import {Foo} from './x';

function bar<T>(element: Foo) {
  return 1;
}

bar(1 as Foo<number>);

// x.ts
export type Foo<T = string> = {};

🙁 Actual behavior

A crash:

/usr/local/lib/node_modules/typescript/lib/tsc.js:98593
      throw e;
      ^

TypeError: Cannot read properties of undefined (reading 'length')
    at inferFromTypeArguments (/usr/local/lib/node_modules/typescript/lib/tsc.js:55506:54)
    at inferFromTypes (/usr/local/lib/node_modules/typescript/lib/tsc.js:55314:11)
    at inferTypes (/usr/local/lib/node_modules/typescript/lib/tsc.js:55300:5)
    at inferTypeArguments (/usr/local/lib/node_modules/typescript/lib/tsc.js:61051:11)
    at chooseOverload (/usr/local/lib/node_modules/typescript/lib/tsc.js:61672:33)
    at resolveCall (/usr/local/lib/node_modules/typescript/lib/tsc.js:61539:16)
    at resolveCallExpression (/usr/local/lib/node_modules/typescript/lib/tsc.js:61870:12)
    at resolveSignature (/usr/local/lib/node_modules/typescript/lib/tsc.js:62215:16)
    at getResolvedSignature (/usr/local/lib/node_modules/typescript/lib/tsc.js:62235:20)
    at checkCallExpression (/usr/local/lib/node_modules/typescript/lib/tsc.js:62340:23)

🙂 Expected behavior

Success or compilation errors.

[nicolas377]

Running git bisect with this repro shows the error popped up at a3092c7 (#51152).

[Andarist]

This particular error goes away with this patch (unfortunately, it breaks other things though):

diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 92a989a2bc..394fa24674 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -14901,7 +14901,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                     const resolved = resolveAlias(aliasSymbol);
                     if (resolved && resolved.flags & SymbolFlags.TypeAlias) {
                         newAliasSymbol = resolved;
-                        aliasTypeArguments = typeArgumentsFromTypeReferenceNode(node);
+                        aliasTypeArguments = getTypeArgumentsForAliasSymbol(newAliasSymbol);
                     }
                 }
             }

I'm not entirely sure if this patch produces a correct result for this test case as I'm not entirely sure what to expect out of the .types and .symbols snapshots here. It compiles and doesn't produce any errors though.