fixUnusedIdentifier: Support deleting @template tag (microsoft#25597)

* fixUnusedIdentifier: Support deleting @template tag

* Just return createTextRangeFromNode instead of adjusting range

Author: Andy

src/services/textChanges.ts

@@ -1053,18 +1053,29 @@ namespace ts.textChanges {
                     break;
 
                 case SyntaxKind.TypeParameter: {
-                    const typeParameters = getEffectiveTypeParameterDeclarations(<DeclarationWithTypeParameters>node.parent);
-                    if (typeParameters.length === 1) {
-                        const { pos, end } = cast(typeParameters, isNodeArray);
-                        const previousToken = getTokenAtPosition(sourceFile, pos - 1);
-                        const nextToken = getTokenAtPosition(sourceFile, end);
-                        Debug.assert(previousToken.kind === SyntaxKind.LessThanToken);
-                        Debug.assert(nextToken.kind === SyntaxKind.GreaterThanToken);
-
-                        changes.deleteNodeRange(sourceFile, previousToken, nextToken);
-                    }
-                    else {
-                        deleteNodeInList(changes, deletedNodesInLists, sourceFile, node);
+                    const typeParam = node as TypeParameterDeclaration;
+                    switch (typeParam.parent.kind) {
+                        case SyntaxKind.JSDocTemplateTag:
+                            changes.deleteRange(sourceFile, getRangeToDeleteJsDocTag(typeParam.parent, sourceFile));
+                            break;
+                        case SyntaxKind.InferType:
+                            // TODO: GH#25594
+                            break;
+                        default: {
+                            const typeParameters = getEffectiveTypeParameterDeclarations(typeParam.parent);
+                            if (typeParameters.length === 1) {
+                                const { pos, end } = cast(typeParameters, isNodeArray);
+                                const previousToken = getTokenAtPosition(sourceFile, pos - 1);
+                                const nextToken = getTokenAtPosition(sourceFile, end);
+                                Debug.assert(previousToken.kind === SyntaxKind.LessThanToken);
+                                Debug.assert(nextToken.kind === SyntaxKind.GreaterThanToken);
+
+                                changes.deleteNodeRange(sourceFile, previousToken, nextToken);
+                            }
+                            else {
+                                deleteNodeInList(changes, deletedNodesInLists, sourceFile, node);
+                            }
+                        }
                     }
                     break;
                 }
@@ -1166,6 +1177,12 @@ namespace ts.textChanges {
                     Debug.assertNever(gp);
             }
         }
+
+        function getRangeToDeleteJsDocTag(node: JSDocTag, sourceFile: SourceFile): TextRange {
+            const { parent } = node;
+            const toDelete = parent.kind === SyntaxKind.JSDocComment && parent.comment === undefined && parent.tags!.length === 1 ? parent : node;
+            return createTextRangeFromNode(toDelete, sourceFile);
+        }
     }
 
     /** Warning: This deletes comments too. See `copyComments` in `convertFunctionToEs6Class`. */

src/services/utilities.ts

@@ -1160,6 +1160,10 @@ namespace ts {
         return createTextSpanFromBounds(node.getStart(sourceFile), node.getEnd());
     }
 
+    export function createTextRangeFromNode(node: Node, sourceFile: SourceFile): TextRange {
+        return createTextRange(node.getStart(sourceFile), node.end);
+    }
+
     export function createTextSpanFromRange(range: TextRange): TextSpan {
         return createTextSpanFromBounds(range.pos, range.end);
     }

tests/cases/fourslash/codeFixUnusedIdentifier_all_delete_js.ts

@@ -0,0 +1,63 @@
+/// <reference path='fourslash.ts' />
+
+// @allowJs: true
+
+// @Filename: /a.js
+/////** @template T Parameter doc comment */
+////function f() {}
+////
+/////**
+//// * Doc
+//// * @template T Comment
+//// */
+////function g() {}
+////
+/////**
+//// * Doc
+//// * @template T Comment
+//// * @template U Comment
+//// */
+////function h() {}
+////
+/////** @template T Comment @return {void} */
+////function i() {}
+////
+/////**
+////Doc
+////@template T comment
+////@template U comment
+////@param {number} x
+////*/
+////function j(x) { return x; }
+
+verify.codeFixAll({
+    fixId: "unusedIdentifier_delete",
+    fixAllDescription: "Delete all unused declarations",
+    newFileContent:
+`
+function f() {}
+
+/**
+ * Doc
+ * Comment
+ */
+function g() {}
+
+/**
+ * Doc
+ * Comment
+ * Comment
+ */
+function h() {}
+
+/** Comment @return {void} */
+function i() {}
+
+/**
+Doc
+comment
+comment
+@param {number} x
+*/
+function j(x) { return x; }`,
+});