Cherry-pick PR microsoft#38276 into release-3.9

Component commits:
b664c3d Fix jsdoc variadic type nodes not being remapped to equivalent TS in output

Author: weswigham

src/compiler/checker.ts

@@ -5566,6 +5566,9 @@ namespace ts {
                     if (isJSDocNonNullableType(node)) {
                         return visitNode(node.type, visitExistingNodeTreeSymbols);
                     }
+                    if (isJSDocVariadicType(node)) {
+                        return createArrayTypeNode(visitNode((node as JSDocVariadicType).type, visitExistingNodeTreeSymbols));
+                    }
                     if (isTypeReferenceNode(node) && isIdentifier(node.typeName) && node.typeName.escapedText === "") {
                         return setOriginalNode(createKeywordTypeNode(SyntaxKind.AnyKeyword), node);
                     }
@@ -5592,8 +5595,8 @@ namespace ts {
                                 mapDefined(node.parameters, (p, i) => p.name && isIdentifier(p.name) && p.name.escapedText === "new" ? (newTypeNode = p.type, undefined) : createParameter(
                                     /*decorators*/ undefined,
                                     /*modifiers*/ undefined,
-                                    p.dotDotDotToken,
-                                    p.name || p.dotDotDotToken ? `args` : `arg${i}`,
+                                    getEffectiveDotDotDotForParameter(p),
+                                    p.name || getEffectiveDotDotDotForParameter(p) ? `args` : `arg${i}`,
                                     p.questionToken,
                                     visitNode(p.type, visitExistingNodeTreeSymbols),
                                     /*initializer*/ undefined
@@ -5607,8 +5610,8 @@ namespace ts {
                                 map(node.parameters, (p, i) => createParameter(
                                     /*decorators*/ undefined,
                                     /*modifiers*/ undefined,
-                                    p.dotDotDotToken,
-                                    p.name || p.dotDotDotToken ? `args` : `arg${i}`,
+                                    getEffectiveDotDotDotForParameter(p),
+                                    p.name || getEffectiveDotDotDotForParameter(p) ? `args` : `arg${i}`,
                                     p.questionToken,
                                     visitNode(p.type, visitExistingNodeTreeSymbols),
                                     /*initializer*/ undefined
@@ -5652,6 +5655,10 @@ namespace ts {
 
                     return visitEachChild(node, visitExistingNodeTreeSymbols, nullTransformationContext);
 
+                    function getEffectiveDotDotDotForParameter(p: ParameterDeclaration) {
+                        return p.dotDotDotToken || (p.type && isJSDocVariadicType(p.type) ? createToken(SyntaxKind.DotDotDotToken) : undefined);
+                    }
+
                     function rewriteModuleSpecifier(parent: ImportTypeNode, lit: StringLiteral) {
                         if (bundled) {
                             if (context.tracker && context.tracker.moduleResolverHost) {

tests/baselines/reference/jsFileCompilationRestParamJsDocFunction.types

@@ -10,7 +10,7 @@
  * @returns {*} Returns the result of `func`.
  */
 function apply(func, thisArg, ...args) {
->apply : (func: Function, thisArg: any, ...args: ...*) => any
+>apply : (func: Function, thisArg: any, ...args: any[]) => any
 >func : Function
 >thisArg : any
 >args : any[]

tests/baselines/reference/jsdocParseDotDotDotInJSDocFunction.types

@@ -2,7 +2,7 @@
 // from bcryptjs
 /** @param {function(...[*])} callback */
 function g(callback) {
->g : (callback: (arg0: ...[*]) => ) => void
+>g : (callback: (...args: [any][]) => ) => void
 >callback : (...arg0: [any][]) => any
 
     callback([1], [2], [3])

tests/baselines/reference/jsdocParseStarEquals.types

@@ -2,7 +2,7 @@
 /** @param {...*=} args
     @return {*=} */
 function f(...args) {
->f : (...args: ...*=) => any | undefined
+>f : (...args: (any | undefined)[]) => any | undefined
 >args : any[]
 
     return null

tests/baselines/reference/jsdocPrefixPostfixParsing.types

@@ -15,7 +15,7 @@
  * @param {...number?[]!} k - (number[] | null)[]
  */
 function f(x, y, z, a, b, c, e, f, g, h, i, j, k) {
->f : (x: number[], y: number[], z: (number[]), a: (number | null)[], b: number[] | null, c: (number[]) | null, e: ...?number, f: ...?number, g: ...?!number, h: ...!?number, i: ...number[], j: ...?!number[], k: ...!?number[]) => void
+>f : (x: number[], y: number[], z: (number[]), a: (number | null)[], b: number[] | null, c: (number[]) | null, e: (number | null)[], f: (number | null)[], g: (number | null)[], h: (number | null)[], i: number[][], j: (number[] | null)[], k: (number | null)[][]) => void
 >x : number[]
 >y : number[]
 >z : number[]

tests/baselines/reference/jsdocRestParameter_es6.types

@@ -1,7 +1,7 @@
 === /a.js ===
 /** @param {...number} a */
 function f(...a) {
->f : (...a: ...number) => void
+>f : (...a: number[]) => void
 >a : number[]
 
     a; // number[]