Avoid circular reference in this-property assignments

sandersn · sandersn · commit b518ea0d4a03 · 2020-04-07T13:02:26.000-07:00
To do this, don't check this-property assigments that have the this-property of the lhs appearing somewhere on the rhs: ```js class C { m() { this.x = 12 this.x = this.x + this.y } } ``` I tried suppressing the circularity error, but because we cache the first type discovered for a property, this still results in an implicit any for `x` in the previous example. It just doesn't have an error. Fixes #35099
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -7596,6 +7596,9 @@ namespace ts {
                 }
                 return anyType;
             }
+            if (containsThisProperty(expression.left, expression.right)) {
+                return anyType;
+            }
             const type = resolvedSymbol ? getTypeOfSymbol(resolvedSymbol) : getWidenedLiteralType(checkExpressionCached(expression.right));
             if (type.flags & TypeFlags.Object &&
                 kind === AssignmentDeclarationKind.ModuleExports &&
@@ -7634,6 +7637,14 @@ namespace ts {
             return type;
         }
 
+        function containsThisProperty(thisProperty: Expression, expression: Expression) {
+            return isPropertyAccessExpression(thisProperty)
+                && thisProperty.expression.kind === SyntaxKind.ThisKeyword
+                && forEachChildRecursively(
+                    expression,
+                    n => isPropertyAccessExpression(n) && n.expression.kind === SyntaxKind.ThisKeyword && n.name.escapedText === thisProperty.name.escapedText);
+        }
+
         function isDeclarationInConstructor(expression: Expression) {
             const thisContainer = getThisContainer(expression, /*includeArrowFunctions*/ false);
             // Properties defined in a constructor (or base constructor, or javascript constructor function) don't get undefined added.
diff --git a/tests/baselines/reference/thisPropertyAssignmentCircular.js b/tests/baselines/reference/thisPropertyAssignmentCircular.js
@@ -0,0 +1,22 @@
+//// [thisPropertyAssignmentCircular.js]
+export class Foo {
+    constructor() {
+        this.foo = "Hello";
+    }
+    slicey() {
+        this.foo = this.foo.slice();
+    }
+    m() {
+        this.foo
+    }
+}
+
+
+
+
+//// [thisPropertyAssignmentCircular.d.ts]
+export class Foo {
+    foo: string;
+    slicey(): void;
+    m(): void;
+}
diff --git a/tests/baselines/reference/thisPropertyAssignmentCircular.symbols b/tests/baselines/reference/thisPropertyAssignmentCircular.symbols
@@ -0,0 +1,33 @@
+=== tests/cases/conformance/salsa/thisPropertyAssignmentCircular.js ===
+export class Foo {
+>Foo : Symbol(Foo, Decl(thisPropertyAssignmentCircular.js, 0, 0))
+
+    constructor() {
+        this.foo = "Hello";
+>this.foo : Symbol(Foo.foo, Decl(thisPropertyAssignmentCircular.js, 1, 19), Decl(thisPropertyAssignmentCircular.js, 4, 14))
+>this : Symbol(Foo, Decl(thisPropertyAssignmentCircular.js, 0, 0))
+>foo : Symbol(Foo.foo, Decl(thisPropertyAssignmentCircular.js, 1, 19), Decl(thisPropertyAssignmentCircular.js, 4, 14))
+    }
+    slicey() {
+>slicey : Symbol(Foo.slicey, Decl(thisPropertyAssignmentCircular.js, 3, 5))
+
+        this.foo = this.foo.slice();
+>this.foo : Symbol(Foo.foo, Decl(thisPropertyAssignmentCircular.js, 1, 19), Decl(thisPropertyAssignmentCircular.js, 4, 14))
+>this : Symbol(Foo, Decl(thisPropertyAssignmentCircular.js, 0, 0))
+>foo : Symbol(Foo.foo, Decl(thisPropertyAssignmentCircular.js, 1, 19), Decl(thisPropertyAssignmentCircular.js, 4, 14))
+>this.foo.slice : Symbol(String.slice, Decl(lib.es5.d.ts, --, --))
+>this.foo : Symbol(Foo.foo, Decl(thisPropertyAssignmentCircular.js, 1, 19), Decl(thisPropertyAssignmentCircular.js, 4, 14))
+>this : Symbol(Foo, Decl(thisPropertyAssignmentCircular.js, 0, 0))
+>foo : Symbol(Foo.foo, Decl(thisPropertyAssignmentCircular.js, 1, 19), Decl(thisPropertyAssignmentCircular.js, 4, 14))
+>slice : Symbol(String.slice, Decl(lib.es5.d.ts, --, --))
+    }
+    m() {
+>m : Symbol(Foo.m, Decl(thisPropertyAssignmentCircular.js, 6, 5))
+
+        this.foo
+>this.foo : Symbol(Foo.foo, Decl(thisPropertyAssignmentCircular.js, 1, 19), Decl(thisPropertyAssignmentCircular.js, 4, 14))
+>this : Symbol(Foo, Decl(thisPropertyAssignmentCircular.js, 0, 0))
+>foo : Symbol(Foo.foo, Decl(thisPropertyAssignmentCircular.js, 1, 19), Decl(thisPropertyAssignmentCircular.js, 4, 14))
+    }
+}
+
diff --git a/tests/baselines/reference/thisPropertyAssignmentCircular.types b/tests/baselines/reference/thisPropertyAssignmentCircular.types
@@ -0,0 +1,37 @@
+=== tests/cases/conformance/salsa/thisPropertyAssignmentCircular.js ===
+export class Foo {
+>Foo : Foo
+
+    constructor() {
+        this.foo = "Hello";
+>this.foo = "Hello" : "Hello"
+>this.foo : string
+>this : this
+>foo : string
+>"Hello" : "Hello"
+    }
+    slicey() {
+>slicey : () => void
+
+        this.foo = this.foo.slice();
+>this.foo = this.foo.slice() : string
+>this.foo : string
+>this : this
+>foo : string
+>this.foo.slice() : string
+>this.foo.slice : (start?: number, end?: number) => string
+>this.foo : string
+>this : this
+>foo : string
+>slice : (start?: number, end?: number) => string
+    }
+    m() {
+>m : () => void
+
+        this.foo
+>this.foo : string
+>this : this
+>foo : string
+    }
+}
+
diff --git a/tests/cases/conformance/salsa/thisPropertyAssignmentCircular.ts b/tests/cases/conformance/salsa/thisPropertyAssignmentCircular.ts
@@ -0,0 +1,16 @@
+// @allowJs: true
+// @checkJs: true
+// @declaration: true
+// @emitDeclarationOnly: true
+// @filename: thisPropertyAssignmentCircular.js
+export class Foo {
+    constructor() {
+        this.foo = "Hello";
+    }
+    slicey() {
+        this.foo = this.foo.slice();
+    }
+    m() {
+        this.foo
+    }
+}
