Explicitly typed special assignments are context sensitive

src/compiler/checker.ts

@@ -15782,22 +15782,22 @@ namespace ts {
         }
 
         // In an assignment expression, the right operand is contextually typed by the type of the left operand.
-        // Don't do this for special property assignments to avoid circularity.
+        // Don't do this for special property assignments unless there is a type tag on the assignment, to avoid circularity from checking the right operand.
         function isContextSensitiveAssignment(binaryExpression: BinaryExpression): boolean {
             const kind = getSpecialPropertyAssignmentKind(binaryExpression);
             switch (kind) {
                 case SpecialPropertyAssignmentKind.None:
                     return true;
                 case SpecialPropertyAssignmentKind.Property:
-                    // 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`.
-                    return !binaryExpression.left.symbol;
                 case SpecialPropertyAssignmentKind.ExportsProperty:
-                case SpecialPropertyAssignmentKind.ModuleExports:
+                case SpecialPropertyAssignmentKind.Prototype:
                 case SpecialPropertyAssignmentKind.PrototypeProperty:
+                    // 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`.
+                    return !binaryExpression.left.symbol || binaryExpression.left.symbol.valueDeclaration && !!getJSDocTypeTag(binaryExpression.left.symbol.valueDeclaration);
                 case SpecialPropertyAssignmentKind.ThisProperty:
-                case SpecialPropertyAssignmentKind.Prototype:
-                    return false;
+                case SpecialPropertyAssignmentKind.ModuleExports:
+                    return !binaryExpression.symbol || binaryExpression.symbol.valueDeclaration && !!getJSDocTypeTag(binaryExpression.symbol.valueDeclaration);
                 default:
                     return Debug.assertNever(kind);
             }

tests/baselines/reference/conflictingCommonJSES2015Exports.types

@@ -7,11 +7,11 @@ export function abc(a, b, c) { return 5; }
 >5 : 5
 
 module.exports = { abc };
->module.exports = { abc } : { [x: string]: any; abc: (a: any, b: any, c: any) => number; }
+>module.exports = { abc } : { abc: (a: any, b: any, c: any) => number; }
 >module.exports : any
 >module : any
 >exports : any
->{ abc } : { [x: string]: any; abc: (a: any, b: any, c: any) => number; }
+>{ abc } : { abc: (a: any, b: any, c: any) => number; }
 >abc : (a: any, b: any, c: any) => number
 
 === tests/cases/conformance/salsa/use.js ===

tests/baselines/reference/contextualTypedSpecialAssignment.errors.txt

@@ -0,0 +1,92 @@
+tests/cases/conformance/salsa/mod.js(5,7): error TS7006: Parameter 'n' implicitly has an 'any' type.
+tests/cases/conformance/salsa/test.js(52,7): error TS7006: Parameter 'n' implicitly has an 'any' type.
+tests/cases/conformance/salsa/test.js(70,7): error TS7006: Parameter 'n' implicitly has an 'any' type.
+
+
+==== tests/cases/conformance/salsa/test.js (2 errors) ====
+    /** @typedef {{
+        status: 'done'
+        m(n: number): void
+    }} DoneStatus */
+
+    // property assignment
+    var ns = {}
+    /** @type {DoneStatus} */
+    ns.x = {
+        status: 'done',
+        m(n) { }
+    }
+
+    ns.x = {
+        status: 'done',
+        m(n) { }
+    }
+    ns.x
+
+
+    // this-property assignment
+    class Thing {
+        constructor() {
+            /** @type {DoneStatus} */
+            this.s = {
+                status: 'done',
+                m(n) { }
+            }
+        }
+
+        fail() {
+            this.s = {
+                status: 'done',
+                m(n) { }
+            }
+        }
+    }
+
+    // exports-property assignment
+
+    /** @type {DoneStatus} */
+    exports.x = {
+        status: "done",
+        m(n) { }
+    }
+    exports.x
+
+    /** @type {DoneStatus} contextual typing is allowed, but module.exports.y: any.
+    Guess it doesn't check the type tag? */
+    module.exports.y = {
+        status: "done",
+        m(n) { }
+          ~
+!!! error TS7006: Parameter 'n' implicitly has an 'any' type.
+    }
+    module.exports.y
+
+    // prototype-property assignment
+    /** @type {DoneStatus} */
+    Thing.prototype.x = {
+        status: 'done',
+        m(n) { }
+    }
+    Thing.prototype.x
+
+    // prototype assignment
+    function F() {
+    }
+    /** @type {DoneStatus} */
+    F.prototype = {
+        status: "done",
+        m(n) { }
+          ~
+!!! error TS7006: Parameter 'n' implicitly has an 'any' type.
+    }
+
+==== tests/cases/conformance/salsa/mod.js (1 errors) ====
+    // module.exports assignment
+    /** @type {{ status: 'done' }} */
+    module.exports = {
+        status: "done",
+        m(n) { }
+          ~
+!!! error TS7006: Parameter 'n' implicitly has an 'any' type.
+    }
+

tests/baselines/reference/contextualTypedSpecialAssignment.symbols

@@ -0,0 +1,173 @@
+=== tests/cases/conformance/salsa/test.js ===
+/** @typedef {{
+    status: 'done'
+    m(n: number): void
+}} DoneStatus */
+
+// property assignment
+var ns = {}
+>ns : Symbol(ns, Decl(test.js, 6, 3))
+
+/** @type {DoneStatus} */
+ns.x = {
+>ns.x : Symbol(ns.x, Decl(test.js, 6, 11), Decl(test.js, 11, 1))
+>ns : Symbol(ns, Decl(test.js, 6, 3))
+>x : Symbol(ns.x, Decl(test.js, 6, 11), Decl(test.js, 11, 1))
+
+    status: 'done',
+>status : Symbol(status, Decl(test.js, 8, 8))
+
+    m(n) { }
+>m : Symbol(m, Decl(test.js, 9, 19))
+>n : Symbol(n, Decl(test.js, 10, 6))
+}
+
+ns.x = {
+>ns.x : Symbol(ns.x, Decl(test.js, 6, 11), Decl(test.js, 11, 1))
+>ns : Symbol(ns, Decl(test.js, 6, 3))
+>x : Symbol(ns.x, Decl(test.js, 6, 11), Decl(test.js, 11, 1))
+
+    status: 'done',
+>status : Symbol(status, Decl(test.js, 13, 8))
+
+    m(n) { }
+>m : Symbol(m, Decl(test.js, 14, 19))
+>n : Symbol(n, Decl(test.js, 15, 6))
+}
+ns.x
+>ns.x : Symbol(ns.x, Decl(test.js, 6, 11), Decl(test.js, 11, 1))
+>ns : Symbol(ns, Decl(test.js, 6, 3))
+>x : Symbol(ns.x, Decl(test.js, 6, 11), Decl(test.js, 11, 1))
+
+
+// this-property assignment
+class Thing {
+>Thing : Symbol(Thing, Decl(test.js, 17, 4))
+
+    constructor() {
+        /** @type {DoneStatus} */
+        this.s = {
+>this.s : Symbol(Thing.s, Decl(test.js, 22, 19), Decl(test.js, 30, 12))
+>this : Symbol(Thing, Decl(test.js, 17, 4))
+>s : Symbol(Thing.s, Decl(test.js, 22, 19), Decl(test.js, 30, 12))
+
+            status: 'done',
+>status : Symbol(status, Decl(test.js, 24, 18))
+
+            m(n) { }
+>m : Symbol(m, Decl(test.js, 25, 27))
+>n : Symbol(n, Decl(test.js, 26, 14))
+        }
+    }
+
+    fail() {
+>fail : Symbol(Thing.fail, Decl(test.js, 28, 5))
+
+        this.s = {
+>this.s : Symbol(Thing.s, Decl(test.js, 22, 19), Decl(test.js, 30, 12))
+>this : Symbol(Thing, Decl(test.js, 17, 4))
+>s : Symbol(Thing.s, Decl(test.js, 22, 19), Decl(test.js, 30, 12))
+
+            status: 'done',
+>status : Symbol(status, Decl(test.js, 31, 18))
+
+            m(n) { }
+>m : Symbol(m, Decl(test.js, 32, 27))
+>n : Symbol(n, Decl(test.js, 33, 14))
+        }
+    }
+}
+
+// exports-property assignment
+
+/** @type {DoneStatus} */
+exports.x = {
+>exports.x : Symbol(x, Decl(test.js, 36, 1))
+>exports : Symbol(x, Decl(test.js, 36, 1))
+>x : Symbol(x, Decl(test.js, 36, 1))
+
+    status: "done",
+>status : Symbol(status, Decl(test.js, 41, 13))
+
+    m(n) { }
+>m : Symbol(m, Decl(test.js, 42, 19))
+>n : Symbol(n, Decl(test.js, 43, 6))
+}
+exports.x
+>exports.x : Symbol(x, Decl(test.js, 36, 1))
+>exports : Symbol("tests/cases/conformance/salsa/test", Decl(test.js, 0, 0))
+>x : Symbol(x, Decl(test.js, 36, 1))
+
+/** @type {DoneStatus} contextual typing is allowed, but module.exports.y: any.
+Guess it doesn't check the type tag? */
+module.exports.y = {
+>module.exports : Symbol(y, Decl(test.js, 45, 9))
+>module : Symbol(module)
+>y : Symbol(y, Decl(test.js, 45, 9))
+
+    status: "done",
+>status : Symbol(status, Decl(test.js, 49, 20))
+
+    m(n) { }
+>m : Symbol(m, Decl(test.js, 50, 19))
+>n : Symbol(n, Decl(test.js, 51, 6))
+}
+module.exports.y
+>module : Symbol(module)
+
+// prototype-property assignment
+/** @type {DoneStatus} */
+Thing.prototype.x = {
+>Thing.prototype.x : Symbol(Thing.x, Decl(test.js, 53, 16))
+>Thing.prototype : Symbol(Thing.x, Decl(test.js, 53, 16))
+>Thing : Symbol(Thing, Decl(test.js, 17, 4))
+>prototype : Symbol(Thing.prototype)
+>x : Symbol(Thing.x, Decl(test.js, 53, 16))
+
+    status: 'done',
+>status : Symbol(status, Decl(test.js, 57, 21))
+
+    m(n) { }
+>m : Symbol(m, Decl(test.js, 58, 19))
+>n : Symbol(n, Decl(test.js, 59, 6))
+}
+Thing.prototype.x
+>Thing.prototype.x : Symbol(Thing.x, Decl(test.js, 53, 16))
+>Thing.prototype : Symbol(Thing.prototype)
+>Thing : Symbol(Thing, Decl(test.js, 17, 4))
+>prototype : Symbol(Thing.prototype)
+>x : Symbol(Thing.x, Decl(test.js, 53, 16))
+
+// prototype assignment
+function F() {
+>F : Symbol(F, Decl(test.js, 61, 17), Decl(test.js, 65, 1))
+}
+/** @type {DoneStatus} */
+F.prototype = {
+>F.prototype : Symbol(F.prototype, Decl(test.js, 65, 1))
+>F : Symbol(F, Decl(test.js, 61, 17), Decl(test.js, 65, 1))
+>prototype : Symbol(F.prototype, Decl(test.js, 65, 1))
+
+    status: "done",
+>status : Symbol(status, Decl(test.js, 67, 15))
+
+    m(n) { }
+>m : Symbol(m, Decl(test.js, 68, 19))
+>n : Symbol(n, Decl(test.js, 69, 6))
+}
+
+=== tests/cases/conformance/salsa/mod.js ===
+// module.exports assignment
+/** @type {{ status: 'done' }} */
+module.exports = {
+>module : Symbol(export=, Decl(mod.js, 0, 0))
+>exports : Symbol(export=, Decl(mod.js, 0, 0))
+
+    status: "done",
+>status : Symbol(status, Decl(mod.js, 2, 18))
+
+    m(n) { }
+>m : Symbol(m, Decl(mod.js, 3, 19))
+>n : Symbol(n, Decl(mod.js, 4, 6))
+}
+