fix(4677): preserve JSDoc for mapped type properties in hover

internal/fourslash/_scripts/failingTests.txt

@@ -375,7 +375,6 @@ TestQuickInfoJSDocFunctionThis
 TestQuickInfoJsDocGetterSetterNoCrash1
 TestQuickInfoJsdocTypedefMissingType
 TestQuickInfoJSExport
-TestQuickInfoMappedSpreadTypes
 TestQuickInfoMappedType
 TestQuickInfoMeaning
 TestQuickInfoModuleVariables
@@ -409,7 +408,6 @@ TestQuickInfoTypeOfThisInStatics
 TestQuickInfoTypeOnlyNamespaceAndClass
 TestQuickInfoUnionOfNamespaces
 TestQuickInfoUntypedModuleImport
-TestQuickinfoWrongComment
 TestRecursiveInternalModuleImport
 TestRegexDetection
 TestSelfReferencedExternalModule

internal/fourslash/tests/hoverMappedTypePropertyJSDoc_test.go

@@ -0,0 +1,37 @@
+package fourslash_test
+
+import (
+	"testing"
+
+	"github.com/microsoft/typescript-go/internal/fourslash"
+	"github.com/microsoft/typescript-go/internal/testutil"
+)
+
+func TestHoverMappedTypePropertyJSDoc(t *testing.T) {
+	t.Parallel()
+	defer testutil.RecoverAndFail(t, "Panic on fourslash test")
+	const content = `
+// @filename: a.ts
+export declare const A: Readonly<{
+  /**
+   * x prop
+   */
+  readonly X: 200;
+
+  /**
+   * y prop
+   */
+  readonly Y: 201;
+}>;
+
+A.X/*1*/;
+
+// @filename: b.ts
+import { A } from './a';
+
+A.X/*2*/;
+`
+	f, done := fourslash.NewFourslash(t, nil /*capabilities*/, content)
+	defer done()
+	f.VerifyBaselineHover(t)
+}

internal/ls/hover.go

@@ -639,7 +639,7 @@ func getQuickInfoAndDeclarationAtLocation(c *checker.Checker, symbol *ast.Symbol
 					writeTypeClassified(t, container, typeFormatFlags)
 				}
 			}
-			setDeclaration(symbol.ValueDeclaration)
+			setDeclaration(core.OrElse(symbol.ValueDeclaration, core.FirstOrNil(symbol.Declarations)))
 		}
 		if flags&ast.SymbolFlagsEnumMember != 0 {
 			writeNewLine()

testdata/baselines/reference/fourslash/quickInfo/hoverMappedTypePropertyJSDoc.baseline

@@ -0,0 +1,93 @@
+// === QuickInfo ===
+=== /a.ts ===
+// export declare const A: Readonly<{
+//   /**
+//    * x prop
+//    */
+//   readonly X: 200;
+// 
+//   /**
+//    * y prop
+//    */
+//   readonly Y: 201;
+// }>;
+// 
+// A.X;
+//   ^
+// | ----------------------------------------------------------------------
+// | ```typescript
+// | (property) X: 200
+// | ```
+// | x prop
+// | ----------------------------------------------------------------------
+// 
+=== /b.ts ===
+// import { A } from './a';
+// 
+// A.X;
+//   ^
+// | ----------------------------------------------------------------------
+// | ```typescript
+// | (property) X: 200
+// | ```
+// | x prop
+// | ----------------------------------------------------------------------
+// 
+
+
+[
+  {
+    "marker": {
+      "Position": 130,
+      "LSPosition": {
+        "line": 12,
+        "character": 3
+      },
+      "Name": "1",
+      "Data": {}
+    },
+    "item": {
+      "contents": {
+        "kind": "markdown",
+        "value": "```typescript\n(property) X: 200\n```\nx prop"
+      },
+      "range": {
+        "start": {
+          "line": 12,
+          "character": 2
+        },
+        "end": {
+          "line": 12,
+          "character": 3
+        }
+      }
+    }
+  },
+  {
+    "marker": {
+      "Position": 29,
+      "LSPosition": {
+        "line": 2,
+        "character": 3
+      },
+      "Name": "2",
+      "Data": {}
+    },
+    "item": {
+      "contents": {
+        "kind": "markdown",
+        "value": "```typescript\n(property) X: 200\n```\nx prop"
+      },
+      "range": {
+        "start": {
+          "line": 2,
+          "character": 2
+        },
+        "end": {
+          "line": 2,
+          "character": 3
+        }
+      }
+    }
+  }
+]

testdata/baselines/reference/fourslash/quickInfo/quickInfoOnUnionPropertiesWithIdenticalJSDocComments01.baseline

@@ -30,7 +30,7 @@
 // | ```typescript
 // | (property) language?: string | undefined
 // | ```
-// | 
+// | A language id, like `typescript`.
 // | ----------------------------------------------------------------------
 [
   {
@@ -46,7 +46,7 @@
     "item": {
       "contents": {
         "kind": "markdown",
-        "value": "```typescript\n(property) language?: string | undefined\n```\n"
+        "value": "```typescript\n(property) language?: string | undefined\n```\nA language id, like `typescript`."
       },
       "range": {
         "start": {