🤖 Pick PR #54208 (Properly handle typeof this.xxx i...) into release-5.1 (#54413)

Co-authored-by: Anders Hejlsberg <[email protected]>

Author: TypeScript Bot

Diff for: src/compiler/checker.ts

@@ -18813,25 +18813,16 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
                 case SyntaxKind.TypeQuery:
                     const entityName = (node as TypeQueryNode).exprName;
                     const firstIdentifier = getFirstIdentifier(entityName);
-                    const firstIdentifierSymbol = getResolvedSymbol(firstIdentifier);
-                    const tpDeclaration = tp.symbol.declarations![0]; // There is exactly one declaration, otherwise `containsReference` is not called
-                    let tpScope: Node;
-                    if (tpDeclaration.kind === SyntaxKind.TypeParameter) { // Type parameter is a regular type parameter, e.g. foo<T>
-                        tpScope = tpDeclaration.parent;
-                    }
-                    else if (tp.isThisType) {
-                         // Type parameter is the this type, and its declaration is the class declaration.
-                        tpScope = tpDeclaration;
-                    }
-                    else {
-                        // Type parameter's declaration was unrecognized.
-                        // This could happen if the type parameter comes from e.g. a JSDoc annotation, so we default to returning true.
-                        return true;
-                    }
-
-                    if (firstIdentifierSymbol.declarations) {
-                        return some(firstIdentifierSymbol.declarations, idDecl => isNodeDescendantOf(idDecl, tpScope)) ||
-                            some((node as TypeQueryNode).typeArguments, containsReference);
+                    if (!isThisIdentifier(firstIdentifier)) { // Don't attempt to analyze typeof this.xxx
+                        const firstIdentifierSymbol = getResolvedSymbol(firstIdentifier);
+                        const tpDeclaration = tp.symbol.declarations![0]; // There is exactly one declaration, otherwise `containsReference` is not called
+                        const tpScope = tpDeclaration.kind === SyntaxKind.TypeParameter ? tpDeclaration.parent : // Type parameter is a regular type parameter, e.g. foo<T>
+                            tp.isThisType ? tpDeclaration : // Type parameter is the this type, and its declaration is the class declaration.
+                            undefined; // Type parameter's declaration was unrecognized, e.g. comes from JSDoc annotation.
+                        if (firstIdentifierSymbol.declarations && tpScope) {
+                            return some(firstIdentifierSymbol.declarations, idDecl => isNodeDescendantOf(idDecl, tpScope)) ||
+                                some((node as TypeQueryNode).typeArguments, containsReference);
+                        }
                     }
                     return true;
                 case SyntaxKind.MethodDeclaration:

Diff for: tests/baselines/reference/typeofThisInMethodSignature.symbols

@@ -0,0 +1,23 @@
+=== tests/cases/compiler/typeofThisInMethodSignature.ts ===
+// Repro from #54167
+
+export class A {
+>A : Symbol(A, Decl(typeofThisInMethodSignature.ts, 0, 0))
+
+	x = 1
+>x : Symbol(A.x, Decl(typeofThisInMethodSignature.ts, 2, 16))
+
+	a(x: typeof this.x): void {}
+>a : Symbol(A.a, Decl(typeofThisInMethodSignature.ts, 3, 6))
+>x : Symbol(x, Decl(typeofThisInMethodSignature.ts, 4, 3))
+>this.x : Symbol(A.x, Decl(typeofThisInMethodSignature.ts, 2, 16))
+>this : Symbol(A, Decl(typeofThisInMethodSignature.ts, 0, 0))
+>x : Symbol(A.x, Decl(typeofThisInMethodSignature.ts, 2, 16))
+}
+
+const a = new A().a(1);
+>a : Symbol(a, Decl(typeofThisInMethodSignature.ts, 7, 5))
+>new A().a : Symbol(A.a, Decl(typeofThisInMethodSignature.ts, 3, 6))
+>A : Symbol(A, Decl(typeofThisInMethodSignature.ts, 0, 0))
+>a : Symbol(A.a, Decl(typeofThisInMethodSignature.ts, 3, 6))
+

Diff for: tests/baselines/reference/typeofThisInMethodSignature.types

@@ -0,0 +1,27 @@
+=== tests/cases/compiler/typeofThisInMethodSignature.ts ===
+// Repro from #54167
+
+export class A {
+>A : A
+
+	x = 1
+>x : number
+>1 : 1
+
+	a(x: typeof this.x): void {}
+>a : (x: typeof this.x) => void
+>x : number
+>this.x : number
+>this : this
+>x : number
+}
+
+const a = new A().a(1);
+>a : void
+>new A().a(1) : void
+>new A().a : (x: number) => void
+>new A() : A
+>A : typeof A
+>a : (x: number) => void
+>1 : 1
+

Diff for: tests/cases/compiler/typeofThisInMethodSignature.ts

@@ -0,0 +1,11 @@
+// @strict: true
+// @noEmit: true
+
+// Repro from #54167
+
+export class A {
+	x = 1
+	a(x: typeof this.x): void {}
+}
+
+const a = new A().a(1);