Issue implicit any in JS files on widened inferred types from initializers in binding patterns

internal/checker/checker.go

@@ -15884,6 +15884,21 @@ 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
 	}
@@ -17004,7 +17019,7 @@ 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 +1,58 @@
+index.js(7,9): error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+index.js(15,9): error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+index.js(37,20): error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+index.js(42,15): error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+
+
+==== index.js (4 errors) ====
+    /**
+     * @param {Object} [config]
+     * @param {Partial<Record<'json' | 'jsonc' | 'json5', string[]>>} [config.additionalFiles]
+     */
+    export function prepareConfig({
+        additionalFiles: {
+            json = []
+            ~~~~
+!!! error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+        } = {}
+    } = {}) {
+        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 }
+                       ~~~~
+!!! error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+
+    /**
+     * @param {[[string[]?]?]} [x]
+     */
+    function f2([[json = []] = []] = []) { return json }
+                  ~~~~
+!!! error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+

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

@@ -12,7 +12,7 @@ export function prepareConfig({
 >additionalFiles : any
 
         json = []
->json : never[]
+>json : any[]
 >[] : never[]
 
     } = {}
@@ -22,7 +22,7 @@ export function prepareConfig({
 >{} : {}
 
     json // string[]
->json : never[]
+>json : any[]
 }
 
 export function prepareConfigWithoutAnnotation({
@@ -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: {
@@ -75,22 +75,22 @@ export const prepareConfigWithContextualSignature = ({
  * @param {{ a?: { json?: string[] }}} [config]
  */
 function f1({ a: { json = [] } = {} } = {}) { return json }
->f1 : ({ a: { json } }?: { a?: { json?: never[] | undefined; } | undefined; }) => never[]
+>f1 : ({ a: { json } }?: { a?: { json?: never[] | undefined; } | undefined; }) => any[]
 >a : any
->json : never[]
+>json : any[]
 >[] : never[]
 >{} : {}
 >{} : {}
->json : never[]
+>json : any[]
 
 /**
  * @param {[[string[]?]?]} [x]
  */
 function f2([[json = []] = []] = []) { return json }
->f2 : ([[json]]?: [([(never[] | undefined)?] | undefined)?]) => never[]
->json : never[]
+>f2 : ([[json]]?: [([(never[] | undefined)?] | undefined)?]) => any[]
+>json : any[]
 >[] : never[]
 >[] : []
 >[] : []
->json : never[]
+>json : any[]
 

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

@@ -1,53 +1,39 @@
 --- old.destructuringParameterDeclaration9(strict=true).errors.txt
 +++ new.destructuringParameterDeclaration9(strict=true).errors.txt
 @@= skipped -0, +0 lines =@@
--index.js(15,9): error TS7031: Binding element 'json' implicitly has an 'any[]' type.
++index.js(7,9): error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+ 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 }
--    
-+<no content>
++index.js(37,20): error TS7031: Binding element 'json' implicitly has an 'any[]' type.
++index.js(42,15): error TS7031: Binding element 'json' implicitly has an 'any[]' type.
++
++
++==== index.js (4 errors) ====
+     /**
+      * @param {Object} [config]
+      * @param {Partial<Record<'json' | 'jsonc' | 'json5', string[]>>} [config.additionalFiles]
+@@= skipped -8, +11 lines =@@
+     export function prepareConfig({
+         additionalFiles: {
+             json = []
++            ~~~~
++!!! error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+         } = {}
+     } = {}) {
+         json // string[]
+@@= skipped -32, +34 lines =@@
+      * @param {{ a?: { json?: string[] }}} [config]
+      */
+     function f1({ a: { json = [] } = {} } = {}) { return json }
++                       ~~~~
++!!! error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+
+     /**
+      * @param {[[string[]?]?]} [x]
+      */
+     function f2([[json = []] = []] = []) { return json }
++                  ~~~~
++!!! error TS7031: Binding element 'json' implicitly has an 'any[]' type.
+

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

@@ -12,7 +12,7 @@
 
          json = []
 ->json : string[]
-+>json : never[]
++>json : any[]
  >[] : never[]
 
      } = {}
@@ -21,28 +21,11 @@
 
      json // string[]
 ->json : string[]
-+>json : never[]
++>json : any[]
  }
 
  export function prepareConfigWithoutAnnotation({
-@@= skipped -10, +10 lines =@@
- >additionalFiles : any
-
-         json = []
-->json : any[]
-+>json : never[]
- >[] : never[]
-
-     } = {}
-@@= skipped -10, +10 lines =@@
- >{} : {}
-
-     json
-->json : any[]
-+>json : never[]
- }
-
- /** @type {(param: {
+@@= skipped -27, +27 lines =@@
    additionalFiles?: Partial<Record<"json" | "jsonc" | "json5", string[]>>;
  }) => void} */
  export const prepareConfigWithContextualSignature = ({
@@ -53,31 +36,31 @@
 
      additionalFiles: {
  >additionalFiles : any
-@@= skipped -33, +33 lines =@@
+@@= skipped -26, +26 lines =@@
   * @param {{ a?: { json?: string[] }}} [config]
   */
  function f1({ a: { json = [] } = {} } = {}) { return json }
 ->f1 : ({ a: { json } }?: { a?: { json?: string[]; }; }) => string[]
-+>f1 : ({ a: { json } }?: { a?: { json?: never[] | undefined; } | undefined; }) => never[]
++>f1 : ({ a: { json } }?: { a?: { json?: never[] | undefined; } | undefined; }) => any[]
  >a : any
 ->json : string[]
-+>json : never[]
++>json : any[]
  >[] : never[]
  >{} : {}
  >{} : {}
 ->json : string[]
-+>json : never[]
++>json : any[]
 
  /**
   * @param {[[string[]?]?]} [x]
   */
  function f2([[json = []] = []] = []) { return json }
 ->f2 : ([[json]]?: [[string[]?]?]) => string[]
 ->json : string[]
-+>f2 : ([[json]]?: [([(never[] | undefined)?] | undefined)?]) => never[]
-+>json : never[]
++>f2 : ([[json]]?: [([(never[] | undefined)?] | undefined)?]) => any[]
++>json : any[]
  >[] : never[]
  >[] : []
  >[] : []
 ->json : string[]
-+>json : never[]
++>json : any[]