Issue implicit any in JS files on widened inferred types from initializers in binding patterns (#1064)

Author: Andarist

internal/checker/checker.go

@@ -16092,6 +16092,21 @@ func (c *Checker) padTupleType(t *Type, pattern *ast.Node) *Type {
 }
 
 func (c *Checker) widenTypeInferredFromInitializer(declaration *ast.Node, t *Type) *Type {
+	widened := c.getWidenedLiteralTypeForInitializer(declaration, t)
+	if ast.IsInJSFile(declaration) {
+		if c.isEmptyLiteralType(widened) {
+			c.reportImplicitAny(declaration, c.anyType, WideningKindNormal)
+			return c.anyType
+		}
+		if c.isEmptyArrayLiteralType(widened) {
+			c.reportImplicitAny(declaration, c.anyArrayType, WideningKindNormal)
+			return c.anyArrayType
+		}
+	}
+	return widened
+}
+
+func (c *Checker) getWidenedLiteralTypeForInitializer(declaration *ast.Node, t *Type) *Type {
 	if c.getCombinedNodeFlagsCached(declaration)&ast.NodeFlagsConstant != 0 || isDeclarationReadonly(declaration) {
 		return t
 	}
@@ -17212,7 +17227,7 @@ func (c *Checker) getTypeFromBindingElement(element *ast.Node, includePatternInT
 		if ast.IsBindingPattern(element.Name()) {
 			contextualType = c.getTypeFromBindingPattern(element.Name(), true /*includePatternInType*/, false /*reportErrors*/)
 		}
-		return c.addOptionality(c.widenTypeInferredFromInitializer(element, c.checkDeclarationInitializer(element, CheckModeNormal, contextualType)))
+		return c.addOptionality(c.getWidenedLiteralTypeForInitializer(element, c.checkDeclarationInitializer(element, CheckModeNormal, contextualType)))
 	}
 	if ast.IsBindingPattern(element.Name()) {
 		return c.getTypeFromBindingPattern(element.Name(), includePatternInType, reportErrors)

testdata/baselines/reference/submodule/conformance/destructuringParameterDeclaration9(strict=true).errors.txt

@@ -0,0 +1,49 @@
+index.js(15,9): error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+
+
+==== index.js (1 errors) ====
+    /**
+     * @param {Object} [config]
+     * @param {Partial<Record<'json' | 'jsonc' | 'json5', string[]>>} [config.additionalFiles]
+     */
+    export function prepareConfig({
+        additionalFiles: {
+            json = []
+        } = {}
+    } = {}) {
+        json // string[]
+    }
+    
+    export function prepareConfigWithoutAnnotation({
+        additionalFiles: {
+            json = []
+            ~~~~
+!!! error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+        } = {}
+    } = {}) {
+        json
+    }
+    
+    /** @type {(param: {
+      additionalFiles?: Partial<Record<"json" | "jsonc" | "json5", string[]>>;
+    }) => void} */
+    export const prepareConfigWithContextualSignature = ({
+        additionalFiles: {
+            json = []
+        } = {}
+    } = {})=>  {
+        json // string[]
+    }
+    
+    // Additional repros from https://github.com/microsoft/TypeScript/issues/59936
+    
+    /**
+     * @param {{ a?: { json?: string[] }}} [config]
+     */
+    function f1({ a: { json = [] } = {} } = {}) { return json }
+    
+    /**
+     * @param {[[string[]?]?]} [x]
+     */
+    function f2([[json = []] = []] = []) { return json }
+    

testdata/baselines/reference/submodule/conformance/destructuringParameterDeclaration9(strict=true).types

@@ -32,7 +32,7 @@ export function prepareConfigWithoutAnnotation({
 >additionalFiles : any
 
         json = []
->json : never[]
+>json : any[]
 >[] : never[]
 
     } = {}
@@ -42,7 +42,7 @@ export function prepareConfigWithoutAnnotation({
 >{} : {}
 
     json
->json : never[]
+>json : any[]
 }
 
 /** @type {(param: {

testdata/baselines/reference/submodule/conformance/typeFromJSInitializer.errors.txt

@@ -1,15 +1,14 @@
 a.js(7,9): error TS7009: 'new' expression, whose target lacks a construct signature, implicitly has an 'any' type.
+a.js(25,29): error TS7006: Parameter 'l' implicitly has an 'any[]' type.
 a.js(27,5): error TS2322: Type 'undefined' is not assignable to type 'null'.
 a.js(29,5): error TS2322: Type '1' is not assignable to type 'null'.
 a.js(30,5): error TS2322: Type 'true' is not assignable to type 'null'.
 a.js(31,5): error TS2322: Type '{}' is not assignable to type 'null'.
 a.js(32,5): error TS2322: Type '"ok"' is not assignable to type 'null'.
 a.js(37,5): error TS2322: Type 'string' is not assignable to type 'number'.
-a.js(40,12): error TS2345: Argument of type '1' is not assignable to parameter of type 'never'.
-a.js(41,12): error TS2345: Argument of type '"ok"' is not assignable to parameter of type 'never'.
 
 
-==== a.js (9 errors) ====
+==== a.js (8 errors) ====
     function A () {
         // should get any on this-assignments in constructor
         this.unknown = null
@@ -37,6 +36,8 @@ a.js(41,12): error TS2345: Argument of type '"ok"' is not assignable to paramete
 
     // should get any on parameter initialisers
     function f(a = null, b = n, l = []) {
+                                ~~~~~~
+!!! error TS7006: Parameter 'l' implicitly has an 'any[]' type.
         // a should be null in strict mode
         a = undefined
         ~
@@ -64,11 +65,7 @@ a.js(41,12): error TS2345: Argument of type '"ok"' is not assignable to paramete
 
         // l should be any[]
         l.push(1)
-               ~
-!!! error TS2345: Argument of type '1' is not assignable to parameter of type 'never'.
         l.push('ok')
-               ~~~~
-!!! error TS2345: Argument of type '"ok"' is not assignable to parameter of type 'never'.
     }
 
     // should get any on variable initialisers

testdata/baselines/reference/submodule/conformance/typeFromJSInitializer.types

@@ -128,11 +128,11 @@ var n;
 
 // should get any on parameter initialisers
 function f(a = null, b = n, l = []) {
->f : (a?: null, b?: number | undefined, l?: never[]) => void
+>f : (a?: null, b?: number | undefined, l?: any[]) => void
 >a : null
 >b : number | undefined
 >n : number | undefined
->l : never[]
+>l : any[]
 >[] : never[]
 
     // a should be null in strict mode
@@ -184,16 +184,16 @@ function f(a = null, b = n, l = []) {
     // l should be any[]
     l.push(1)
 >l.push(1) : number
->l.push : (...items: never[]) => number
->l : never[]
->push : (...items: never[]) => number
+>l.push : (...items: any[]) => number
+>l : any[]
+>push : (...items: any[]) => number
 >1 : 1
 
     l.push('ok')
 >l.push('ok') : number
->l.push : (...items: never[]) => number
->l : never[]
->push : (...items: never[]) => number
+>l.push : (...items: any[]) => number
+>l : any[]
+>push : (...items: any[]) => number
 >'ok' : "ok"
 }
 

testdata/baselines/reference/submoduleAccepted/conformance/destructuringParameterDeclaration9(strict=true).errors.txt.diff

@@ -9,24 +9,7 @@
 
      additionalFiles: {
  >additionalFiles : any
-@@= skipped -26, +26 lines =@@
- >additionalFiles : any
-
-         json = []
-->json : any[]
-+>json : never[]
- >[] : never[]
-
-     } = {}
-@@= skipped -10, +10 lines =@@
- >{} : {}
-
-     json
-->json : any[]
-+>json : never[]
- }
-
- /** @type {(param: {
+@@= skipped -43, +43 lines =@@
    additionalFiles?: Partial<Record<"json" | "jsonc" | "json5", string[]>>;
  }) => void} */
  export const prepareConfigWithContextualSignature = ({
@@ -37,7 +20,7 @@
 
      additionalFiles: {
  >additionalFiles : any
-@@= skipped -33, +33 lines =@@
+@@= skipped -26, +26 lines =@@
   * @param {{ a?: { json?: string[] }}} [config]
   */
  function f1({ a: { json = [] } = {} } = {}) { return json }

testdata/baselines/reference/submoduleAccepted/conformance/destructuringParameterDeclaration9(strict=true).types.diff

@@ -4,22 +4,16 @@
 -a.js(3,5): error TS7008: Member 'unknown' implicitly has an 'any' type.
 -a.js(4,5): error TS7008: Member 'unknowable' implicitly has an 'any' type.
 -a.js(5,5): error TS7008: Member 'empty' implicitly has an 'any[]' type.
--a.js(25,29): error TS7006: Parameter 'l' implicitly has an 'any[]' type.
 +a.js(7,9): error TS7009: 'new' expression, whose target lacks a construct signature, implicitly has an 'any' type.
+ a.js(25,29): error TS7006: Parameter 'l' implicitly has an 'any[]' type.
  a.js(27,5): error TS2322: Type 'undefined' is not assignable to type 'null'.
  a.js(29,5): error TS2322: Type '1' is not assignable to type 'null'.
- a.js(30,5): error TS2322: Type 'true' is not assignable to type 'null'.
- a.js(31,5): error TS2322: Type '{}' is not assignable to type 'null'.
- a.js(32,5): error TS2322: Type '"ok"' is not assignable to type 'null'.
+@@= skipped -9, +7 lines =@@
  a.js(37,5): error TS2322: Type 'string' is not assignable to type 'number'.
--
--
+
+
 -==== a.js (10 errors) ====
-+a.js(40,12): error TS2345: Argument of type '1' is not assignable to parameter of type 'never'.
-+a.js(41,12): error TS2345: Argument of type '"ok"' is not assignable to parameter of type 'never'.
-+
-+
-+==== a.js (9 errors) ====
++==== a.js (8 errors) ====
      function A () {
          // should get any on this-assignments in constructor
          this.unknown = null
@@ -37,25 +31,4 @@
 +!!! error TS7009: 'new' expression, whose target lacks a construct signature, implicitly has an 'any' type.
      a.unknown = 1
      a.unknown = true
-     a.unknown = {}
-@@= skipped -41, +36 lines =@@
-     
-     // should get any on parameter initialisers
-     function f(a = null, b = n, l = []) {
--                                ~~~~~~
--!!! error TS7006: Parameter 'l' implicitly has an 'any[]' type.
-         // a should be null in strict mode
-         a = undefined
-         ~
-@@= skipped -29, +27 lines =@@
-     
-         // l should be any[]
-         l.push(1)
-+               ~
-+!!! error TS2345: Argument of type '1' is not assignable to parameter of type 'never'.
-         l.push('ok')
-+               ~~~~
-+!!! error TS2345: Argument of type '"ok"' is not assignable to parameter of type 'never'.
-     }
-     
-     // should get any on variable initialisers
+     a.unknown = {}

testdata/baselines/reference/submoduleAccepted/conformance/typeFromJSInitializer.errors.txt.diff

@@ -163,40 +163,4 @@
 +>push : any
  >'hi' : "hi"
 
- /** @type {number | undefined} */
-@@= skipped -126, +126 lines =@@
-
- // should get any on parameter initialisers
- function f(a = null, b = n, l = []) {
-->f : (a?: null, b?: number | undefined, l?: any[]) => void
-+>f : (a?: null, b?: number | undefined, l?: never[]) => void
- >a : null
- >b : number | undefined
- >n : number | undefined
-->l : any[]
-+>l : never[]
- >[] : never[]
-
-     // a should be null in strict mode
-@@= skipped -56, +56 lines =@@
-     // l should be any[]
-     l.push(1)
- >l.push(1) : number
-->l.push : (...items: any[]) => number
-->l : any[]
-->push : (...items: any[]) => number
-+>l.push : (...items: never[]) => number
-+>l : never[]
-+>push : (...items: never[]) => number
- >1 : 1
-
-     l.push('ok')
- >l.push('ok') : number
-->l.push : (...items: any[]) => number
-->l : any[]
-->push : (...items: any[]) => number
-+>l.push : (...items: never[]) => number
-+>l : never[]
-+>push : (...items: never[]) => number
- >'ok' : "ok"
- }
+ /** @type {number | undefined} */