feat(eslint-plugin): sync getFunctionHeadLoc implementation with upstream

packages/eslint-plugin/src/util/getFunctionHeadLoc.ts

@@ -1,71 +1,203 @@
+// adapted from https://github.com/eslint/eslint/blob/5bdaae205c3a0089ea338b382df59e21d5b06436/lib/rules/utils/ast-utils.js#L1668-L1787
+
 import type { TSESLint, TSESTree } from '@typescript-eslint/utils';
-import { AST_NODE_TYPES, AST_TOKEN_TYPES } from '@typescript-eslint/utils';
+import { AST_NODE_TYPES, ESLintUtils } from '@typescript-eslint/utils';
+
+import { isArrowToken, isOpeningParenToken } from './astUtils';
 
 type FunctionNode =
   | TSESTree.ArrowFunctionExpression
   | TSESTree.FunctionDeclaration
   | TSESTree.FunctionExpression;
 
 /**
- * Creates a report location for the given function.
- * The location only encompasses the "start" of the function, and not the body
- *
- * eg.
- *
- * ```
- * function foo(args) {}
- * ^^^^^^^^^^^^^^^^^^
- *
- * get y(args) {}
- * ^^^^^^^^^^^
- *
- * const x = (args) => {}
- *           ^^^^^^^^^
- * ```
+ * Gets the `(` token of the given function node.
+ * @param node The function node to get.
+ * @param sourceCode The source code object to get tokens.
+ * @returns `(` token.
  */
-export function getFunctionHeadLoc(
+function getOpeningParenOfParams(
   node: FunctionNode,
   sourceCode: TSESLint.SourceCode,
-): TSESTree.SourceLocation {
-  function getLocStart(): TSESTree.Position {
-    if (node.parent.type === AST_NODE_TYPES.MethodDefinition) {
-      // return the start location for class method
-
-      if (node.parent.decorators && node.parent.decorators.length > 0) {
-        // exclude decorators
-        return sourceCode.getTokenAfter(
-          node.parent.decorators[node.parent.decorators.length - 1],
-        )!.loc.start;
-      }
+): TSESTree.Token {
+  // If the node is an arrow function and doesn't have parens, this returns the identifier of the first param.
+  if (
+    node.type === AST_NODE_TYPES.ArrowFunctionExpression &&
+    node.params.length === 1
+  ) {
+    const argToken = ESLintUtils.nullThrows(
+      sourceCode.getFirstToken(node.params[0]),
+      ESLintUtils.NullThrowsReasons.MissingToken('parameter', 'arrow function'),
+    );
+    const maybeParenToken = sourceCode.getTokenBefore(argToken);
 
-      return node.parent.loc.start;
-    }
+    return maybeParenToken && isOpeningParenToken(maybeParenToken)
+      ? maybeParenToken
+      : argToken;
+  }
 
-    if (node.parent.type === AST_NODE_TYPES.Property && node.parent.method) {
-      // return the start location for object method shorthand
-      return node.parent.loc.start;
-    }
+  // Otherwise, returns paren.
+  return node.id != null
+    ? ESLintUtils.nullThrows(
+        sourceCode.getTokenAfter(node.id, isOpeningParenToken),
+        ESLintUtils.NullThrowsReasons.MissingToken('id', 'function'),
+      )
+    : ESLintUtils.nullThrows(
+        sourceCode.getFirstToken(node, isOpeningParenToken),
+        ESLintUtils.NullThrowsReasons.MissingToken(
+          'opening parenthesis',
+          'function',
+        ),
+      );
+}
 
-    // return the start location for a regular function
-    return node.loc.start;
-  }
+/**
+ * Gets the location of the given function node for reporting.
+ *
+ * - `function foo() {}`
+ *    ^^^^^^^^^^^^
+ * - `(function foo() {})`
+ *     ^^^^^^^^^^^^
+ * - `(function() {})`
+ *     ^^^^^^^^
+ * - `function* foo() {}`
+ *    ^^^^^^^^^^^^^
+ * - `(function* foo() {})`
+ *     ^^^^^^^^^^^^^
+ * - `(function*() {})`
+ *     ^^^^^^^^^
+ * - `() => {}`
+ *       ^^
+ * - `async () => {}`
+ *             ^^
+ * - `({ foo: function foo() {} })`
+ *       ^^^^^^^^^^^^^^^^^
+ * - `({ foo: function() {} })`
+ *       ^^^^^^^^^^^^^
+ * - `({ ['foo']: function() {} })`
+ *       ^^^^^^^^^^^^^^^^^
+ * - `({ [foo]: function() {} })`
+ *       ^^^^^^^^^^^^^^^
+ * - `({ foo() {} })`
+ *       ^^^
+ * - `({ foo: function* foo() {} })`
+ *       ^^^^^^^^^^^^^^^^^^
+ * - `({ foo: function*() {} })`
+ *       ^^^^^^^^^^^^^^
+ * - `({ ['foo']: function*() {} })`
+ *       ^^^^^^^^^^^^^^^^^^
+ * - `({ [foo]: function*() {} })`
+ *       ^^^^^^^^^^^^^^^^
+ * - `({ *foo() {} })`
+ *       ^^^^
+ * - `({ foo: async function foo() {} })`
+ *       ^^^^^^^^^^^^^^^^^^^^^^^
+ * - `({ foo: async function() {} })`
+ *       ^^^^^^^^^^^^^^^^^^^
+ * - `({ ['foo']: async function() {} })`
+ *       ^^^^^^^^^^^^^^^^^^^^^^^
+ * - `({ [foo]: async function() {} })`
+ *       ^^^^^^^^^^^^^^^^^^^^^
+ * - `({ async foo() {} })`
+ *       ^^^^^^^^^
+ * - `({ get foo() {} })`
+ *       ^^^^^^^
+ * - `({ set foo(a) {} })`
+ *       ^^^^^^^
+ * - `class A { constructor() {} }`
+ *              ^^^^^^^^^^^
+ * - `class A { foo() {} }`
+ *              ^^^
+ * - `class A { *foo() {} }`
+ *              ^^^^
+ * - `class A { async foo() {} }`
+ *              ^^^^^^^^^
+ * - `class A { ['foo']() {} }`
+ *              ^^^^^^^
+ * - `class A { *['foo']() {} }`
+ *              ^^^^^^^^
+ * - `class A { async ['foo']() {} }`
+ *              ^^^^^^^^^^^^^
+ * - `class A { [foo]() {} }`
+ *              ^^^^^
+ * - `class A { *[foo]() {} }`
+ *              ^^^^^^
+ * - `class A { async [foo]() {} }`
+ *              ^^^^^^^^^^^
+ * - `class A { get foo() {} }`
+ *              ^^^^^^^
+ * - `class A { set foo(a) {} }`
+ *              ^^^^^^^
+ * - `class A { static foo() {} }`
+ *              ^^^^^^^^^^
+ * - `class A { static *foo() {} }`
+ *              ^^^^^^^^^^^
+ * - `class A { static async foo() {} }`
+ *              ^^^^^^^^^^^^^^^^
+ * - `class A { static get foo() {} }`
+ *              ^^^^^^^^^^^^^^
+ * - `class A { static set foo(a) {} }`
+ *              ^^^^^^^^^^^^^^
+ * - `class A { foo = function() {} }`
+ *              ^^^^^^^^^^^^^^
+ * - `class A { static foo = function() {} }`
+ *              ^^^^^^^^^^^^^^^^^^^^^
+ * - `class A { foo = (a, b) => {} }`
+ *              ^^^^^^
+ * @param node The function node to get.
+ * @param sourceCode The source code object to get tokens.
+ * @returns The location of the function node for reporting.
+ */
+export function getFunctionHeadLoc(
+  node: FunctionNode,
+  sourceCode: TSESLint.SourceCode,
+): TSESTree.SourceLocation {
+  const parent = node.parent;
+  let start = null;
+  let end = null;
 
-  function getLocEnd(): TSESTree.Position {
-    if (node.type === AST_NODE_TYPES.ArrowFunctionExpression) {
-      // find the end location for arrow function expression
-      return sourceCode.getTokenBefore(
-        node.body,
-        token =>
-          token.type === AST_TOKEN_TYPES.Punctuator && token.value === '=>',
-      )!.loc.end;
+  if (
+    parent.type === AST_NODE_TYPES.MethodDefinition ||
+    parent.type === AST_NODE_TYPES.PropertyDefinition
+  ) {
+    // the decorator's range is included within the member
+    // however it's usually irrelevant to the member itself - so we don't want
+    // to highlight it ever.
+    if (parent.decorators.length > 0) {
+      const lastDecorator = parent.decorators[parent.decorators.length - 1];
+      const firstTokenAfterDecorator = ESLintUtils.nullThrows(
+        sourceCode.getTokenAfter(lastDecorator),
+        ESLintUtils.NullThrowsReasons.MissingToken(
+          'modifier or member name',
+          'class member',
+        ),
+      );
+      start = firstTokenAfterDecorator.loc.start;
+    } else {
+      start = parent.loc.start;
     }
+    end = getOpeningParenOfParams(node, sourceCode).loc.start;
+  } else if (parent.type === AST_NODE_TYPES.Property) {
+    start = parent.loc.start;
+    end = getOpeningParenOfParams(node, sourceCode).loc.start;
+  } else if (node.type === AST_NODE_TYPES.ArrowFunctionExpression) {
+    const arrowToken = ESLintUtils.nullThrows(
+      sourceCode.getTokenBefore(node.body, isArrowToken),
+      ESLintUtils.NullThrowsReasons.MissingToken(
+        'arrow token',
+        'arrow function',
+      ),
+    );
 
-    // return the end location for a regular function
-    return sourceCode.getTokenBefore(node.body)!.loc.end;
+    start = arrowToken.loc.start;
+    end = arrowToken.loc.end;
+  } else {
+    start = node.loc.start;
+    end = getOpeningParenOfParams(node, sourceCode).loc.start;
   }
 
   return {
-    start: getLocStart(),
-    end: getLocEnd(),
+    start: Object.assign({}, start),
+    end: Object.assign({}, end),
   };
 }