Use comments from host variable declaration when exporting a signature in js declarations (microsoft#37594)

Author: weswigham

src/compiler/checker.ts

@@ -6132,7 +6132,8 @@ namespace ts {
                         // Each overload becomes a separate function declaration, in order
                         const decl = signatureToSignatureDeclarationHelper(sig, SyntaxKind.FunctionDeclaration, context, includePrivateSymbol, bundled) as FunctionDeclaration;
                         decl.name = createIdentifier(localName);
-                        addResult(setTextRange(decl, sig.declaration), modifierFlags);
+                        // for expressions assigned to `var`s, use the `var` as the text range
+                        addResult(setTextRange(decl, sig.declaration && isVariableDeclaration(sig.declaration.parent) && sig.declaration.parent.parent || sig.declaration), modifierFlags);
                     }
                     // Module symbol emit will take care of module-y members, provided it has exports
                     if (!(symbol.flags & (SymbolFlags.ValueModule | SymbolFlags.NamespaceModule) && !!symbol.exports && !!symbol.exports.size)) {

tests/baselines/reference/jsDeclarationsDocCommentsOnConsts.js

@@ -0,0 +1,42 @@
+//// [index1.js]
+/**
+ * const doc comment
+ */
+const x = (a) => {
+    return '';
+};
+
+/**
+ * function doc comment
+ */
+function b() {
+    return 0;
+}
+
+module.exports = {x, b}
+
+//// [index1.js]
+/**
+ * const doc comment
+ */
+var x = function (a) {
+    return '';
+};
+/**
+ * function doc comment
+ */
+function b() {
+    return 0;
+}
+module.exports = { x: x, b: b };
+
+
+//// [index1.d.ts]
+/**
+ * const doc comment
+ */
+export function x(a: any): string;
+/**
+ * function doc comment
+ */
+export function b(): number;

tests/baselines/reference/jsDeclarationsDocCommentsOnConsts.symbols

@@ -0,0 +1,27 @@
+=== tests/cases/conformance/jsdoc/declarations/index1.js ===
+/**
+ * const doc comment
+ */
+const x = (a) => {
+>x : Symbol(x, Decl(index1.js, 3, 5))
+>a : Symbol(a, Decl(index1.js, 3, 11))
+
+    return '';
+};
+
+/**
+ * function doc comment
+ */
+function b() {
+>b : Symbol(b, Decl(index1.js, 5, 2))
+
+    return 0;
+}
+
+module.exports = {x, b}
+>module.exports : Symbol("tests/cases/conformance/jsdoc/declarations/index1", Decl(index1.js, 0, 0))
+>module : Symbol(export=, Decl(index1.js, 12, 1))
+>exports : Symbol(export=, Decl(index1.js, 12, 1))
+>x : Symbol(x, Decl(index1.js, 14, 18))
+>b : Symbol(b, Decl(index1.js, 14, 20))
+

tests/baselines/reference/jsDeclarationsDocCommentsOnConsts.types

@@ -0,0 +1,33 @@
+=== tests/cases/conformance/jsdoc/declarations/index1.js ===
+/**
+ * const doc comment
+ */
+const x = (a) => {
+>x : (a: any) => string
+>(a) => {    return '';} : (a: any) => string
+>a : any
+
+    return '';
+>'' : ""
+
+};
+
+/**
+ * function doc comment
+ */
+function b() {
+>b : () => number
+
+    return 0;
+>0 : 0
+}
+
+module.exports = {x, b}
+>module.exports = {x, b} : { x: (a: any) => string; b: () => number; }
+>module.exports : { x: (a: any) => string; b: () => number; }
+>module : { "\"tests/cases/conformance/jsdoc/declarations/index1\"": { x: (a: any) => string; b: () => number; }; }
+>exports : { x: (a: any) => string; b: () => number; }
+>{x, b} : { x: (a: any) => string; b: () => number; }
+>x : (a: any) => string
+>b : () => number
+

tests/cases/conformance/jsdoc/declarations/jsDeclarationsDocCommentsOnConsts.ts

@@ -0,0 +1,21 @@
+// @allowJs: true
+// @checkJs: true
+// @target: es5
+// @outDir: ./out
+// @declaration: true
+// @filename: index1.js
+/**
+ * const doc comment
+ */
+const x = (a) => {
+    return '';
+};
+
+/**
+ * function doc comment
+ */
+function b() {
+    return 0;
+}
+
+module.exports = {x, b}