fix(43030): fix instantiated null/undefined type from JS initializer (#43933)

a-tarasyuk · web-flow · commit 463c79440fbf · 2021-05-11T15:57:16.000-07:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -20025,9 +20025,13 @@ namespace ts {
             return (type as TypeReference).cachedEquivalentBaseType = instantiatedBase;
         }
 
+        function isEmptyLiteralType(type: Type): boolean {
+            return strictNullChecks ? type === implicitNeverType : type === undefinedWideningType;
+        }
+
         function isEmptyArrayLiteralType(type: Type): boolean {
             const elementType = getElementTypeOfArrayType(type);
-            return strictNullChecks ? elementType === implicitNeverType : elementType === undefinedWideningType;
+            return !!elementType && isEmptyLiteralType(elementType);
         }
 
         function isTupleLikeType(type: Type): boolean {
@@ -32355,7 +32359,7 @@ namespace ts {
         function widenTypeInferredFromInitializer(declaration: HasExpressionInitializer, type: Type) {
             const widened = getCombinedNodeFlags(declaration) & NodeFlags.Const || isDeclarationReadonly(declaration) ? type : getWidenedLiteralType(type);
             if (isInJSFile(declaration)) {
-                if (widened.flags & TypeFlags.Nullable) {
+                if (isEmptyLiteralType(widened)) {
                     reportImplicitAny(declaration, anyType);
                     return anyType;
                 }
diff --git a/tests/baselines/reference/typeFromJSInitializer.errors.txt b/tests/baselines/reference/typeFromJSInitializer.errors.txt
@@ -1,12 +1,16 @@
 tests/cases/conformance/salsa/a.js(3,5): error TS7008: Member 'unknown' implicitly has an 'any' type.
 tests/cases/conformance/salsa/a.js(4,5): error TS7008: Member 'unknowable' implicitly has an 'any' type.
 tests/cases/conformance/salsa/a.js(5,5): error TS7008: Member 'empty' implicitly has an 'any[]' type.
-tests/cases/conformance/salsa/a.js(25,12): error TS7006: Parameter 'a' implicitly has an 'any' type.
 tests/cases/conformance/salsa/a.js(25,29): error TS7006: Parameter 'l' implicitly has an 'any[]' type.
+tests/cases/conformance/salsa/a.js(27,5): error TS2322: Type 'undefined' is not assignable to type 'null'.
+tests/cases/conformance/salsa/a.js(29,5): error TS2322: Type '1' is not assignable to type 'null'.
+tests/cases/conformance/salsa/a.js(30,5): error TS2322: Type 'true' is not assignable to type 'null'.
+tests/cases/conformance/salsa/a.js(31,5): error TS2322: Type '{}' is not assignable to type 'null'.
+tests/cases/conformance/salsa/a.js(32,5): error TS2322: Type '"ok"' is not assignable to type 'null'.
 tests/cases/conformance/salsa/a.js(37,5): error TS2322: Type '"error"' is not assignable to type 'number | undefined'.
 
 
-==== tests/cases/conformance/salsa/a.js (6 errors) ====
+==== tests/cases/conformance/salsa/a.js (10 errors) ====
     function A () {
         // should get any on this-assignments in constructor
         this.unknown = null
@@ -38,17 +42,25 @@ tests/cases/conformance/salsa/a.js(37,5): error TS2322: Type '"error"' is not as
     
     // should get any on parameter initialisers
     function f(a = null, b = n, l = []) {
-               ~~~~~~~~
-!!! error TS7006: Parameter 'a' implicitly has an 'any' type.
                                 ~~~~~~
 !!! error TS7006: Parameter 'l' implicitly has an 'any[]' type.
-        // a should be any
+        // a should be null in strict mode
         a = undefined
+        ~
+!!! error TS2322: Type 'undefined' is not assignable to type 'null'.
         a = null
         a = 1
+        ~
+!!! error TS2322: Type '1' is not assignable to type 'null'.
         a = true
+        ~
+!!! error TS2322: Type 'true' is not assignable to type 'null'.
         a = {}
+        ~
+!!! error TS2322: Type '{}' is not assignable to type 'null'.
         a = 'ok'
+        ~
+!!! error TS2322: Type '"ok"' is not assignable to type 'null'.
     
         // b should be number | undefined, not any
         b = 1
@@ -77,6 +89,6 @@ tests/cases/conformance/salsa/a.js(37,5): error TS2322: Type '"error"' is not as
     const isUndef = v => v === undefined;
     const e = [1, undefined];
     
-    // should be  undefined[]
+    // should be undefined[]
     const g = e.filter(isUndef);
     
diff --git a/tests/baselines/reference/typeFromJSInitializer.symbols b/tests/baselines/reference/typeFromJSInitializer.symbols
@@ -103,7 +103,7 @@ function f(a = null, b = n, l = []) {
 >n : Symbol(n, Decl(a.js, 21, 3))
 >l : Symbol(l, Decl(a.js, 24, 27))
 
-    // a should be any
+    // a should be null in strict mode
     a = undefined
 >a : Symbol(a, Decl(a.js, 24, 11))
 >undefined : Symbol(undefined)
@@ -186,7 +186,7 @@ const e = [1, undefined];
 >e : Symbol(e, Decl(a.js, 56, 5))
 >undefined : Symbol(undefined)
 
-// should be  undefined[]
+// should be undefined[]
 const g = e.filter(isUndef);
 >g : Symbol(g, Decl(a.js, 59, 5))
 >e.filter : Symbol(Array.filter, Decl(lib.es5.d.ts, --, --), Decl(lib.es5.d.ts, --, --))
diff --git a/tests/baselines/reference/typeFromJSInitializer.types b/tests/baselines/reference/typeFromJSInitializer.types
@@ -127,43 +127,43 @@ var n;
 
 // should get any on parameter initialisers
 function f(a = null, b = n, l = []) {
->f : (a?: any, b?: number | undefined, l?: any[]) => void
->a : any
+>f : (a?: null, b?: number | undefined, l?: any[]) => void
+>a : null
 >null : null
 >b : number | undefined
 >n : number | undefined
 >l : any[]
 >[] : never[]
 
-    // a should be any
+    // a should be null in strict mode
     a = undefined
 >a = undefined : undefined
->a : any
+>a : null
 >undefined : undefined
 
     a = null
 >a = null : null
->a : any
+>a : null
 >null : null
 
     a = 1
 >a = 1 : 1
->a : any
+>a : null
 >1 : 1
 
     a = true
 >a = true : true
->a : any
+>a : null
 >true : true
 
     a = {}
 >a = {} : {}
->a : any
+>a : null
 >{} : {}
 
     a = 'ok'
 >a = 'ok' : "ok"
->a : any
+>a : null
 >'ok' : "ok"
 
     // b should be number | undefined, not any
@@ -254,7 +254,7 @@ const e = [1, undefined];
 >1 : 1
 >undefined : undefined
 
-// should be  undefined[]
+// should be undefined[]
 const g = e.filter(isUndef);
 >g : undefined[]
 >e.filter(isUndef) : undefined[]
diff --git a/tests/baselines/reference/typeFromJSInitializer2.symbols b/tests/baselines/reference/typeFromJSInitializer2.symbols
@@ -0,0 +1,22 @@
+=== tests/cases/conformance/salsa/a.js ===
+/** @type {() => undefined} */
+function f1() {
+>f1 : Symbol(f1, Decl(a.js, 0, 0))
+
+    return undefined;
+>undefined : Symbol(undefined)
+}
+const a = f1()
+>a : Symbol(a, Decl(a.js, 4, 5))
+>f1 : Symbol(f1, Decl(a.js, 0, 0))
+
+/** @type {() => null} */
+function f2() {
+>f2 : Symbol(f2, Decl(a.js, 4, 14))
+
+    return null;
+}
+const b = f2()
+>b : Symbol(b, Decl(a.js, 10, 5))
+>f2 : Symbol(f2, Decl(a.js, 4, 14))
+
diff --git a/tests/baselines/reference/typeFromJSInitializer2.types b/tests/baselines/reference/typeFromJSInitializer2.types
@@ -0,0 +1,25 @@
+=== tests/cases/conformance/salsa/a.js ===
+/** @type {() => undefined} */
+function f1() {
+>f1 : () => undefined
+
+    return undefined;
+>undefined : undefined
+}
+const a = f1()
+>a : undefined
+>f1() : undefined
+>f1 : () => undefined
+
+/** @type {() => null} */
+function f2() {
+>f2 : () => null
+
+    return null;
+>null : null
+}
+const b = f2()
+>b : null
+>f2() : null
+>f2 : () => null
+
diff --git a/tests/baselines/reference/typeFromJSInitializer3.symbols b/tests/baselines/reference/typeFromJSInitializer3.symbols
@@ -0,0 +1,22 @@
+=== tests/cases/conformance/salsa/a.js ===
+/** @type {() => undefined} */
+function f1() {
+>f1 : Symbol(f1, Decl(a.js, 0, 0))
+
+    return undefined;
+>undefined : Symbol(undefined)
+}
+const a = f1()
+>a : Symbol(a, Decl(a.js, 4, 5))
+>f1 : Symbol(f1, Decl(a.js, 0, 0))
+
+/** @type {() => null} */
+function f2() {
+>f2 : Symbol(f2, Decl(a.js, 4, 14))
+
+    return null;
+}
+const b = f2()
+>b : Symbol(b, Decl(a.js, 10, 5))
+>f2 : Symbol(f2, Decl(a.js, 4, 14))
+
diff --git a/tests/baselines/reference/typeFromJSInitializer3.types b/tests/baselines/reference/typeFromJSInitializer3.types
@@ -0,0 +1,25 @@
+=== tests/cases/conformance/salsa/a.js ===
+/** @type {() => undefined} */
+function f1() {
+>f1 : () => undefined
+
+    return undefined;
+>undefined : undefined
+}
+const a = f1()
+>a : undefined
+>f1() : undefined
+>f1 : () => undefined
+
+/** @type {() => null} */
+function f2() {
+>f2 : () => null
+
+    return null;
+>null : null
+}
+const b = f2()
+>b : null
+>f2() : null
+>f2 : () => null
+
diff --git a/tests/baselines/reference/typeFromJSInitializer4.errors.txt b/tests/baselines/reference/typeFromJSInitializer4.errors.txt
@@ -0,0 +1,35 @@
+tests/cases/conformance/salsa/a.js(5,12): error TS7006: Parameter 'a' implicitly has an 'any' type.
+tests/cases/conformance/salsa/a.js(5,29): error TS7006: Parameter 'l' implicitly has an 'any[]' type.
+tests/cases/conformance/salsa/a.js(17,5): error TS2322: Type 'string' is not assignable to type 'number'.
+
+
+==== tests/cases/conformance/salsa/a.js (3 errors) ====
+    /** @type {number | undefined} */
+    var n;
+    
+    // should get any on parameter initialisers
+    function f(a = null, b = n, l = []) {
+               ~~~~~~~~
+!!! error TS7006: Parameter 'a' implicitly has an 'any' type.
+                                ~~~~~~
+!!! error TS7006: Parameter 'l' implicitly has an 'any[]' type.
+        // a should be any
+        a = undefined
+        a = null
+        a = 1
+        a = true
+        a = {}
+        a = 'ok'
+    
+        // b should be number | undefined, not any
+        b = 1
+        b = undefined
+        b = 'error'
+        ~
+!!! error TS2322: Type 'string' is not assignable to type 'number'.
+    
+        // l should be any[]
+        l.push(1)
+        l.push('ok')
+    }
+    
diff --git a/tests/baselines/reference/typeFromJSInitializer4.symbols b/tests/baselines/reference/typeFromJSInitializer4.symbols
@@ -0,0 +1,56 @@
+=== tests/cases/conformance/salsa/a.js ===
+/** @type {number | undefined} */
+var n;
+>n : Symbol(n, Decl(a.js, 1, 3))
+
+// should get any on parameter initialisers
+function f(a = null, b = n, l = []) {
+>f : Symbol(f, Decl(a.js, 1, 6))
+>a : Symbol(a, Decl(a.js, 4, 11))
+>b : Symbol(b, Decl(a.js, 4, 20))
+>n : Symbol(n, Decl(a.js, 1, 3))
+>l : Symbol(l, Decl(a.js, 4, 27))
+
+    // a should be any
+    a = undefined
+>a : Symbol(a, Decl(a.js, 4, 11))
+>undefined : Symbol(undefined)
+
+    a = null
+>a : Symbol(a, Decl(a.js, 4, 11))
+
+    a = 1
+>a : Symbol(a, Decl(a.js, 4, 11))
+
+    a = true
+>a : Symbol(a, Decl(a.js, 4, 11))
+
+    a = {}
+>a : Symbol(a, Decl(a.js, 4, 11))
+
+    a = 'ok'
+>a : Symbol(a, Decl(a.js, 4, 11))
+
+    // b should be number | undefined, not any
+    b = 1
+>b : Symbol(b, Decl(a.js, 4, 20))
+
+    b = undefined
+>b : Symbol(b, Decl(a.js, 4, 20))
+>undefined : Symbol(undefined)
+
+    b = 'error'
+>b : Symbol(b, Decl(a.js, 4, 20))
+
+    // l should be any[]
+    l.push(1)
+>l.push : Symbol(Array.push, Decl(lib.es5.d.ts, --, --))
+>l : Symbol(l, Decl(a.js, 4, 27))
+>push : Symbol(Array.push, Decl(lib.es5.d.ts, --, --))
+
+    l.push('ok')
+>l.push : Symbol(Array.push, Decl(lib.es5.d.ts, --, --))
+>l : Symbol(l, Decl(a.js, 4, 27))
+>push : Symbol(Array.push, Decl(lib.es5.d.ts, --, --))
+}
+
diff --git a/tests/baselines/reference/typeFromJSInitializer4.types b/tests/baselines/reference/typeFromJSInitializer4.types
diff --git a/tests/cases/conformance/salsa/typeFromJSInitializer.ts b/tests/cases/conformance/salsa/typeFromJSInitializer.ts
diff --git a/tests/cases/conformance/salsa/typeFromJSInitializer2.ts b/tests/cases/conformance/salsa/typeFromJSInitializer2.ts
diff --git a/tests/cases/conformance/salsa/typeFromJSInitializer3.ts b/tests/cases/conformance/salsa/typeFromJSInitializer3.ts
diff --git a/tests/cases/conformance/salsa/typeFromJSInitializer4.ts b/tests/cases/conformance/salsa/typeFromJSInitializer4.ts
