Avoid circularity error caused by requesting contextual type for late bound expando members

Author: Andarist

src/compiler/checker.ts

@@ -31536,13 +31536,23 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 if (isPossiblyAliasedThisProperty(binaryExpression, kind)) {
                     return getContextualTypeForThisPropertyAssignment(binaryExpression);
                 }
+                let nodeSymbol;
+                if (canHaveSymbol(binaryExpression.left)) {
+                    nodeSymbol = binaryExpression.left.symbol;
+                    if (!nodeSymbol) {
+                        const resolvedSymbol = getNodeLinks(binaryExpression.left).resolvedSymbol;
+                        if (resolvedSymbol && getIsLateCheckFlag(resolvedSymbol)) {
+                            nodeSymbol = resolvedSymbol;
+                        }
+                    }
+                }
                 // If `binaryExpression.left` was assigned a symbol, then this is a new declaration; otherwise it is an assignment to an existing declaration.
                 // See `bindStaticPropertyAssignment` in `binder.ts`.
-                else if (!canHaveSymbol(binaryExpression.left) || !binaryExpression.left.symbol) {
+                if (!nodeSymbol) {
                     return getTypeOfExpression(binaryExpression.left);
                 }
                 else {
-                    const decl = binaryExpression.left.symbol.valueDeclaration;
+                    const decl = nodeSymbol.valueDeclaration;
                     if (!decl) {
                         return undefined;
                     }
@@ -31565,6 +31575,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                             return undefined;
                         }
                     }
+                    Debug.assert(canHaveSymbol(binaryExpression.left));
                     return isInJSFile(decl) || decl === binaryExpression.left ? undefined : getTypeOfExpression(binaryExpression.left);
                 }
             case AssignmentDeclarationKind.ExportsProperty:

tests/baselines/reference/uniqueSymbolExpando1.symbols

@@ -0,0 +1,22 @@
+//// [tests/cases/compiler/uniqueSymbolExpando1.ts] ////
+
+=== uniqueSymbolExpando1.ts ===
+// https://github.com/microsoft/TypeScript/issues/61214
+
+const TestSymbol: unique symbol = Symbol();
+>TestSymbol : Symbol(TestSymbol, Decl(uniqueSymbolExpando1.ts, 2, 5))
+>Symbol : Symbol(Symbol, Decl(lib.es5.d.ts, --, --), Decl(lib.es2015.symbol.d.ts, --, --), Decl(lib.es2015.symbol.wellknown.d.ts, --, --), Decl(lib.es2019.symbol.d.ts, --, --))
+
+const c = () => {
+>c : Symbol(c, Decl(uniqueSymbolExpando1.ts, 4, 5), Decl(uniqueSymbolExpando1.ts, 6, 2), Decl(uniqueSymbolExpando1.ts, 7, 26))
+
+  return "Hello, world!";
+};
+c["testProp"] = ["Hello"];
+>c : Symbol(c, Decl(uniqueSymbolExpando1.ts, 4, 5), Decl(uniqueSymbolExpando1.ts, 6, 2), Decl(uniqueSymbolExpando1.ts, 7, 26))
+>"testProp" : Symbol(c["testProp"], Decl(uniqueSymbolExpando1.ts, 6, 2))
+
+c[TestSymbol] = ["Hello"];
+>c : Symbol(c, Decl(uniqueSymbolExpando1.ts, 4, 5), Decl(uniqueSymbolExpando1.ts, 6, 2), Decl(uniqueSymbolExpando1.ts, 7, 26))
+>TestSymbol : Symbol(TestSymbol, Decl(uniqueSymbolExpando1.ts, 2, 5))
+

tests/baselines/reference/uniqueSymbolExpando1.types

@@ -0,0 +1,52 @@
+//// [tests/cases/compiler/uniqueSymbolExpando1.ts] ////
+
+=== uniqueSymbolExpando1.ts ===
+// https://github.com/microsoft/TypeScript/issues/61214
+
+const TestSymbol: unique symbol = Symbol();
+>TestSymbol : unique symbol
+>           : ^^^^^^^^^^^^^
+>Symbol() : unique symbol
+>         : ^^^^^^^^^^^^^
+>Symbol : SymbolConstructor
+>       : ^^^^^^^^^^^^^^^^^
+
+const c = () => {
+>c : { (): string; testProp: string[]; [TestSymbol]: string[]; }
+>  : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+>() => {  return "Hello, world!";} : { (): string; testProp: string[]; [TestSymbol]: string[]; }
+>                                  : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+  return "Hello, world!";
+>"Hello, world!" : "Hello, world!"
+>                : ^^^^^^^^^^^^^^^
+
+};
+c["testProp"] = ["Hello"];
+>c["testProp"] = ["Hello"] : string[]
+>                          : ^^^^^^^^
+>c["testProp"] : string[]
+>              : ^^^^^^^^
+>c : { (): string; testProp: string[]; [TestSymbol]: string[]; }
+>  : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+>"testProp" : "testProp"
+>           : ^^^^^^^^^^
+>["Hello"] : string[]
+>          : ^^^^^^^^
+>"Hello" : "Hello"
+>        : ^^^^^^^
+
+c[TestSymbol] = ["Hello"];
+>c[TestSymbol] = ["Hello"] : string[]
+>                          : ^^^^^^^^
+>c[TestSymbol] : string[]
+>              : ^^^^^^^^
+>c : { (): string; testProp: string[]; [TestSymbol]: string[]; }
+>  : ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+>TestSymbol : unique symbol
+>           : ^^^^^^^^^^^^^
+>["Hello"] : string[]
+>          : ^^^^^^^^
+>"Hello" : "Hello"
+>        : ^^^^^^^
+

tests/baselines/reference/wellKnownSymbolExpando.types

@@ -8,7 +8,8 @@ function f() {}
 f[Symbol.iterator] = function() {}
 >f[Symbol.iterator] = function() {} : () => void
 >                                   : ^^^^^^^^^^
->f[Symbol.iterator] : any
+>f[Symbol.iterator] : () => void
+>                   : ^^^^^^^^^^
 >f : typeof f
 >  : ^^^^^^^^
 >Symbol.iterator : unique symbol

tests/cases/compiler/uniqueSymbolExpando1.ts

@@ -0,0 +1,13 @@
+// @strict: true
+// @target: esnext
+// @noEmit: true
+
+// https://github.com/microsoft/TypeScript/issues/61214
+
+const TestSymbol: unique symbol = Symbol();
+
+const c = () => {
+  return "Hello, world!";
+};
+c["testProp"] = ["Hello"];
+c[TestSymbol] = ["Hello"];

tests/cases/compiler/wellKnownSymbolExpando.ts

@@ -1,3 +1,4 @@
+// @strict: true
 // @noEmit: true
 // @target: esnext