From c9c9f859f3f9118e707ff3cef6a2a02e2d599890 Mon Sep 17 00:00:00 2001
From: xiaofa <xiaofalzx@gmail.com>
Date: Thu, 17 Jan 2019 05:51:57 +0800
Subject: [PATCH 1/2] fix quick fix infer parameter types from usage in js file

---
 src/services/textChanges.ts                    |  4 +++-
 .../fourslash/codeFixInferFromUsageArrowJS.ts  | 18 ++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts

diff --git a/src/services/textChanges.ts b/src/services/textChanges.ts
index 4689e18508c..7dab7205841 100644
--- a/src/services/textChanges.ts
+++ b/src/services/textChanges.ts
@@ -340,7 +340,9 @@ namespace ts.textChanges {
         }
 
         public insertJsdocCommentBefore(sourceFile: SourceFile, node: HasJSDoc, tag: JSDoc): void {
-            const fnStart = node.getStart(sourceFile);
+            const fnStart = node.kind === SyntaxKind.ArrowFunction
+                ? node.parent.parent.getStart(sourceFile)
+                : node.getStart(sourceFile);
             if (node.jsDoc) {
                 for (const jsdoc of node.jsDoc) {
                     this.deleteRange(sourceFile, {
diff --git a/tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts b/tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts
new file mode 100644
index 00000000000..e867ae99c75
--- /dev/null
+++ b/tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts
@@ -0,0 +1,18 @@
+/// <reference path='fourslash.ts' />
+// @allowJs: true
+// @checkJs: true
+// @noEmit: true
+// @noImplicitAny: true
+// @Filename: test.js
+
+////const foo = x => x.y + 1;
+
+verify.codeFix({
+  description: "Infer parameter types from usage",
+  index: 0,
+  newFileContent:
+`/**
+ * @param {{ y: number; }} x
+ */
+const foo = x => x.y + 1;`,
+});
\ No newline at end of file

From ddbac8f3fe87bb6044ceab2f68eacd81d7dd6977 Mon Sep 17 00:00:00 2001
From: xiaofa <xiaofalzx@gmail.com>
Date: Sat, 26 Jan 2019 23:59:32 +0800
Subject: [PATCH 2/2] get appropriate parent jsdoc node for arrow functions

---
 src/services/codefixes/inferFromUsage.ts        | 12 +++++++++++-
 src/services/textChanges.ts                     |  4 +---
 .../fourslash/codeFixInferFromUsageArrowJS.ts   | 17 +++++++++++++----
 3 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/src/services/codefixes/inferFromUsage.ts b/src/services/codefixes/inferFromUsage.ts
index 8e5b962116d..f47f618f79d 100644
--- a/src/services/codefixes/inferFromUsage.ts
+++ b/src/services/codefixes/inferFromUsage.ts
@@ -274,7 +274,17 @@ namespace ts.codefix {
             return !!merged;
         }));
         const tag = createJSDocComment(comments.join("\n"), createNodeArray([...(oldTags || emptyArray), ...unmergedNewTags]));
-        changes.insertJsdocCommentBefore(sourceFile, parent, tag);
+        const jsDocNode = parent.kind === SyntaxKind.ArrowFunction ? getJsDocNodeForArrowFunction(parent) : parent;
+        jsDocNode.jsDoc = parent.jsDoc;
+        jsDocNode.jsDocCache = parent.jsDocCache;
+        changes.insertJsdocCommentBefore(sourceFile, jsDocNode, tag);
+    }
+
+    function getJsDocNodeForArrowFunction(signature: ArrowFunction): HasJSDoc {
+        if (signature.parent.kind === SyntaxKind.PropertyDeclaration) {
+            return <HasJSDoc>signature.parent;
+        }
+        return <HasJSDoc>signature.parent.parent;
     }
 
     function tryMergeJsdocTags(oldTag: JSDocTag, newTag: JSDocTag): JSDocTag | undefined {
diff --git a/src/services/textChanges.ts b/src/services/textChanges.ts
index 7dab7205841..4689e18508c 100644
--- a/src/services/textChanges.ts
+++ b/src/services/textChanges.ts
@@ -340,9 +340,7 @@ namespace ts.textChanges {
         }
 
         public insertJsdocCommentBefore(sourceFile: SourceFile, node: HasJSDoc, tag: JSDoc): void {
-            const fnStart = node.kind === SyntaxKind.ArrowFunction
-                ? node.parent.parent.getStart(sourceFile)
-                : node.getStart(sourceFile);
+            const fnStart = node.getStart(sourceFile);
             if (node.jsDoc) {
                 for (const jsdoc of node.jsDoc) {
                     this.deleteRange(sourceFile, {
diff --git a/tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts b/tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts
index e867ae99c75..0a800fd7d63 100644
--- a/tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts
+++ b/tests/cases/fourslash/codeFixInferFromUsageArrowJS.ts
@@ -6,13 +6,22 @@
 // @Filename: test.js
 
 ////const foo = x => x.y + 1;
+////class C {
+////    m = x => x.y + 1;
+////}
 
-verify.codeFix({
-  description: "Infer parameter types from usage",
-  index: 0,
+verify.codeFixAll({
+  fixId: "inferFromUsage",
+  fixAllDescription: "Infer all types from usage",
   newFileContent:
 `/**
  * @param {{ y: number; }} x
  */
-const foo = x => x.y + 1;`,
+const foo = x => x.y + 1;
+class C {
+    /**
+     * @param {{ y: number; }} x
+     */
+    m = x => x.y + 1;
+}`,
 });
\ No newline at end of file