Allow references to uninitialized ambient properties (#36112)

Previously these were incorrectly treated just like normal properties:

```ts
class Parent {
    a: any;
    constructor(arg: any) {
        this.a = arg;
    }
}
class Child extends Parent {
    declare a: number;
    constructor(arg: number) {
        super(arg);
        console.log(this.a);  // Property 'a' is used before being assigned. (2565)
    }
}
```

Fixes #35327

src/compiler/checker.ts

@@ -23298,7 +23298,7 @@ namespace ts {
                 const declaration = prop && prop.valueDeclaration;
                 if (declaration && isInstancePropertyWithoutInitializer(declaration)) {
                     const flowContainer = getControlFlowContainer(node);
-                    if (flowContainer.kind === SyntaxKind.Constructor && flowContainer.parent === declaration.parent) {
+                    if (flowContainer.kind === SyntaxKind.Constructor && flowContainer.parent === declaration.parent && !(declaration.flags & NodeFlags.Ambient)) {
                         assumeUninitialized = true;
                     }
                 }

tests/baselines/reference/derivedUninitializedPropertyDeclaration.errors.txt

@@ -85,4 +85,19 @@ tests/cases/conformance/classes/propertyMemberDeclarations/derivedUninitializedP
         q!: 1 | 2 | 3 // ok, extends a property from an interface
         r!: 4 | 5 // error, from class
     }
+    
+    // #35327
+    class L {
+        a: any;
+        constructor(arg: any) {
+            this.a = arg;
+        }
+    }
+    class M extends L {
+        declare a: number;
+        constructor(arg: number) {
+            super(arg);
+            console.log(this.a);  // should be OK, M.a is ambient
+        }
+    }
     

tests/baselines/reference/derivedUninitializedPropertyDeclaration.js

@@ -65,6 +65,21 @@ class K extends J {
     q!: 1 | 2 | 3 // ok, extends a property from an interface
     r!: 4 | 5 // error, from class
 }
+
+// #35327
+class L {
+    a: any;
+    constructor(arg: any) {
+        this.a = arg;
+    }
+}
+class M extends L {
+    declare a: number;
+    constructor(arg: number) {
+        super(arg);
+        console.log(this.a);  // should be OK, M.a is ambient
+    }
+}
 
 
 //// [derivedUninitializedPropertyDeclaration.js]
@@ -178,3 +193,19 @@ var K = /** @class */ (function (_super) {
     }
     return K;
 }(J));
+// #35327
+var L = /** @class */ (function () {
+    function L(arg) {
+        this.a = arg;
+    }
+    return L;
+}());
+var M = /** @class */ (function (_super) {
+    __extends(M, _super);
+    function M(arg) {
+        var _this = _super.call(this, arg) || this;
+        console.log(_this.a); // should be OK, M.a is ambient
+        return _this;
+    }
+    return M;
+}(L));

tests/baselines/reference/derivedUninitializedPropertyDeclaration.symbols

@@ -147,3 +147,44 @@ class K extends J {
 >r : Symbol(K.r, Decl(derivedUninitializedPropertyDeclaration.ts, 63, 17))
 }
 
+// #35327
+class L {
+>L : Symbol(L, Decl(derivedUninitializedPropertyDeclaration.ts, 65, 1))
+
+    a: any;
+>a : Symbol(L.a, Decl(derivedUninitializedPropertyDeclaration.ts, 68, 9))
+
+    constructor(arg: any) {
+>arg : Symbol(arg, Decl(derivedUninitializedPropertyDeclaration.ts, 70, 16))
+
+        this.a = arg;
+>this.a : Symbol(L.a, Decl(derivedUninitializedPropertyDeclaration.ts, 68, 9))
+>this : Symbol(L, Decl(derivedUninitializedPropertyDeclaration.ts, 65, 1))
+>a : Symbol(L.a, Decl(derivedUninitializedPropertyDeclaration.ts, 68, 9))
+>arg : Symbol(arg, Decl(derivedUninitializedPropertyDeclaration.ts, 70, 16))
+    }
+}
+class M extends L {
+>M : Symbol(M, Decl(derivedUninitializedPropertyDeclaration.ts, 73, 1))
+>L : Symbol(L, Decl(derivedUninitializedPropertyDeclaration.ts, 65, 1))
+
+    declare a: number;
+>a : Symbol(M.a, Decl(derivedUninitializedPropertyDeclaration.ts, 74, 19))
+
+    constructor(arg: number) {
+>arg : Symbol(arg, Decl(derivedUninitializedPropertyDeclaration.ts, 76, 16))
+
+        super(arg);
+>super : Symbol(L, Decl(derivedUninitializedPropertyDeclaration.ts, 65, 1))
+>arg : Symbol(arg, Decl(derivedUninitializedPropertyDeclaration.ts, 76, 16))
+
+        console.log(this.a);  // should be OK, M.a is ambient
+>console.log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>console : Symbol(console, Decl(lib.dom.d.ts, --, --))
+>log : Symbol(Console.log, Decl(lib.dom.d.ts, --, --))
+>this.a : Symbol(M.a, Decl(derivedUninitializedPropertyDeclaration.ts, 74, 19))
+>this : Symbol(M, Decl(derivedUninitializedPropertyDeclaration.ts, 73, 1))
+>a : Symbol(M.a, Decl(derivedUninitializedPropertyDeclaration.ts, 74, 19))
+    }
+}
+

tests/baselines/reference/derivedUninitializedPropertyDeclaration.types

@@ -150,3 +150,47 @@ class K extends J {
 >r : 5 | 4
 }
 
+// #35327
+class L {
+>L : L
+
+    a: any;
+>a : any
+
+    constructor(arg: any) {
+>arg : any
+
+        this.a = arg;
+>this.a = arg : any
+>this.a : any
+>this : this
+>a : any
+>arg : any
+    }
+}
+class M extends L {
+>M : M
+>L : L
+
+    declare a: number;
+>a : number
+
+    constructor(arg: number) {
+>arg : number
+
+        super(arg);
+>super(arg) : void
+>super : typeof L
+>arg : number
+
+        console.log(this.a);  // should be OK, M.a is ambient
+>console.log(this.a) : void
+>console.log : (message?: any, ...optionalParams: any[]) => void
+>console : Console
+>log : (message?: any, ...optionalParams: any[]) => void
+>this.a : number
+>this : this
+>a : number
+    }
+}
+

tests/cases/conformance/classes/propertyMemberDeclarations/derivedUninitializedPropertyDeclaration.ts

@@ -65,3 +65,18 @@ class K extends J {
     q!: 1 | 2 | 3 // ok, extends a property from an interface
     r!: 4 | 5 // error, from class
 }
+
+// #35327
+class L {
+    a: any;
+    constructor(arg: any) {
+        this.a = arg;
+    }
+}
+class M extends L {
+    declare a: number;
+    constructor(arg: number) {
+        super(arg);
+        console.log(this.a);  // should be OK, M.a is ambient
+    }
+}