From d44b7bb154a80c1db285f165057b8f3362d1a683 Mon Sep 17 00:00:00 2001
From: yosuke ota <otameshiyo23@gmail.com>
Date: Tue, 29 Jun 2021 13:39:48 +0900
Subject: [PATCH 1/2] Add no-not-function-handler rule

---
 README.md                                     |   1 +
 docs/rules/README.md                          |   1 +
 docs/rules/no-not-function-handler.md         |  61 +++++++++++
 docs/rules/no-object-in-text-mustaches.md     |   6 +
 src/configs/recommended.ts                    |   1 +
 src/rules/indent-helpers/es.ts                |   7 +-
 src/rules/indent-helpers/svelte.ts            |   5 +-
 src/rules/indent-helpers/ts.ts                |   5 +-
 src/rules/no-not-function-handler.ts          | 103 ++++++++++++++++++
 src/types.ts                                  |   7 +-
 src/utils/ast-utils.ts                        |  40 ++++++-
 src/utils/rules.ts                            |   2 +
 .../invalid/array01-errors.json               |   7 ++
 .../invalid/array01-input.svelte              |   5 +
 .../invalid/class01-errors.json               |   7 ++
 .../invalid/class01-input.svelte              |   4 +
 .../invalid/object01-errors.json              |   7 ++
 .../invalid/object01-input.svelte             |   5 +
 .../invalid/string01-errors.json              |  12 ++
 .../invalid/string01-input.svelte             |   7 ++
 .../invalid/value01-errors.json               |  17 +++
 .../invalid/value01-input.svelte              |   9 ++
 .../valid/function01-input.svelte             |   7 ++
 .../valid/null01-input.svelte                 |   6 +
 tests/src/rules/no-not-function-handler.ts    |  16 +++
 typings/eslint-utils/index.d.ts               |   7 ++
 26 files changed, 338 insertions(+), 17 deletions(-)
 create mode 100644 docs/rules/no-not-function-handler.md
 create mode 100644 src/rules/no-not-function-handler.ts
 create mode 100644 tests/fixtures/rules/no-not-function-handler/invalid/array01-errors.json
 create mode 100644 tests/fixtures/rules/no-not-function-handler/invalid/array01-input.svelte
 create mode 100644 tests/fixtures/rules/no-not-function-handler/invalid/class01-errors.json
 create mode 100644 tests/fixtures/rules/no-not-function-handler/invalid/class01-input.svelte
 create mode 100644 tests/fixtures/rules/no-not-function-handler/invalid/object01-errors.json
 create mode 100644 tests/fixtures/rules/no-not-function-handler/invalid/object01-input.svelte
 create mode 100644 tests/fixtures/rules/no-not-function-handler/invalid/string01-errors.json
 create mode 100644 tests/fixtures/rules/no-not-function-handler/invalid/string01-input.svelte
 create mode 100644 tests/fixtures/rules/no-not-function-handler/invalid/value01-errors.json
 create mode 100644 tests/fixtures/rules/no-not-function-handler/invalid/value01-input.svelte
 create mode 100644 tests/fixtures/rules/no-not-function-handler/valid/function01-input.svelte
 create mode 100644 tests/fixtures/rules/no-not-function-handler/valid/null01-input.svelte
 create mode 100644 tests/src/rules/no-not-function-handler.ts

diff --git a/README.md b/README.md
index fb31df855..c511f7f07 100644
--- a/README.md
+++ b/README.md
@@ -246,6 +246,7 @@ These rules relate to possible syntax or logic errors in Svelte code:
 | Rule ID | Description |    |
 |:--------|:------------|:---|
 | [@ota-meshi/svelte/no-dupe-else-if-blocks](https://ota-meshi.github.io/eslint-plugin-svelte/rules/no-dupe-else-if-blocks.html) | disallow duplicate conditions in `{#if}` / `{:else if}` chains | :star: |
+| [@ota-meshi/svelte/no-not-function-handler](https://ota-meshi.github.io/eslint-plugin-svelte/rules/no-not-function-handler.html) | disallow use of not function in event handler | :star: |
 | [@ota-meshi/svelte/no-object-in-text-mustaches](https://ota-meshi.github.io/eslint-plugin-svelte/rules/no-object-in-text-mustaches.html) | disallow objects in text mustache interpolation | :star: |
 
 ## Security Vulnerability
diff --git a/docs/rules/README.md b/docs/rules/README.md
index d3baf4bdc..6a2d2cb02 100644
--- a/docs/rules/README.md
+++ b/docs/rules/README.md
@@ -16,6 +16,7 @@ These rules relate to possible syntax or logic errors in Svelte code:
 | Rule ID | Description |    |
 |:--------|:------------|:---|
 | [@ota-meshi/svelte/no-dupe-else-if-blocks](./no-dupe-else-if-blocks.md) | disallow duplicate conditions in `{#if}` / `{:else if}` chains | :star: |
+| [@ota-meshi/svelte/no-not-function-handler](./no-not-function-handler.md) | disallow use of not function in event handler | :star: |
 | [@ota-meshi/svelte/no-object-in-text-mustaches](./no-object-in-text-mustaches.md) | disallow objects in text mustache interpolation | :star: |
 
 ## Security Vulnerability
diff --git a/docs/rules/no-not-function-handler.md b/docs/rules/no-not-function-handler.md
new file mode 100644
index 000000000..99b977e3c
--- /dev/null
+++ b/docs/rules/no-not-function-handler.md
@@ -0,0 +1,61 @@
+---
+pageClass: "rule-details"
+sidebarDepth: 0
+title: "@ota-meshi/svelte/no-not-function-handler"
+description: "disallow use of not function in event handler"
+---
+
+# @ota-meshi/svelte/no-not-function-handler
+
+> disallow use of not function in event handler
+
+- :exclamation: <badge text="This rule has not been released yet." vertical="middle" type="error"> **_This rule has not been released yet._** </badge>
+- :gear: This rule is included in `"plugin:@ota-meshi/svelte/recommended"`.
+
+## :book: Rule Details
+
+This rule reports where you used not function value in event handlers.  
+If you use a non-function value for the event handler, it event handler will not be called. It's almost always a mistake. You may have written a lot of unnecessary curly braces.
+
+<eslint-code-block>
+
+<!--eslint-skip-->
+
+```svelte
+<script>
+  /* eslint @ota-meshi/svelte/no-not-function-handler: "error" */
+  function foo() {
+    /*  */
+  }
+  const bar = 42
+</script>
+
+<!-- ✓ GOOD -->
+<button on:click={foo} />
+<button
+  on:click={() => {
+    /*  */
+  }}
+/>
+
+<!-- ✗ BAD -->
+<button on:click={{ foo }} />
+<button on:click={bar} />
+```
+
+</eslint-code-block>
+
+## :wrench: Options
+
+Nothing.
+
+## :couple: Related Rules
+
+- [@ota-meshi/svelte/no-object-in-text-mustaches]
+
+[@ota-meshi/svelte/no-object-in-text-mustaches]: ./no-object-in-text-mustaches.md
+
+## :mag: Implementation
+
+- [Rule source](https://github.com/ota-meshi/eslint-plugin-svelte/blob/main/src/rules/no-not-function-handler.ts)
+- [Test source](https://github.com/ota-meshi/eslint-plugin-svelte/blob/main/tests/src/rules/no-not-function-handler.ts)
diff --git a/docs/rules/no-object-in-text-mustaches.md b/docs/rules/no-object-in-text-mustaches.md
index 8cd8f0c6a..1a5dde235 100644
--- a/docs/rules/no-object-in-text-mustaches.md
+++ b/docs/rules/no-object-in-text-mustaches.md
@@ -42,6 +42,12 @@ When you use an object for text interpolation, it is drawn as `[object Object]`.
 
 Nothing.
 
+## :couple: Related Rules
+
+- [@ota-meshi/svelte/no-invalid-handler]
+
+[@ota-meshi/svelte/no-invalid-handler]: ./no-invalid-handler.md
+
 ## :mag: Implementation
 
 - [Rule source](https://github.com/ota-meshi/eslint-plugin-svelte/blob/main/src/rules/no-object-in-text-mustaches.ts)
diff --git a/src/configs/recommended.ts b/src/configs/recommended.ts
index 870a83f21..f466ee787 100644
--- a/src/configs/recommended.ts
+++ b/src/configs/recommended.ts
@@ -11,6 +11,7 @@ export = {
     "@ota-meshi/svelte/no-at-html-tags": "error",
     "@ota-meshi/svelte/no-dupe-else-if-blocks": "error",
     "@ota-meshi/svelte/no-inner-declarations": "error",
+    "@ota-meshi/svelte/no-not-function-handler": "error",
     "@ota-meshi/svelte/no-object-in-text-mustaches": "error",
     "@ota-meshi/svelte/system": "error",
   },
diff --git a/src/rules/indent-helpers/es.ts b/src/rules/indent-helpers/es.ts
index 4f2dcf99f..d8dd87f04 100644
--- a/src/rules/indent-helpers/es.ts
+++ b/src/rules/indent-helpers/es.ts
@@ -21,12 +21,11 @@ type NodeWithParent =
   | (Exclude<ESTree.Node, ESTree.Program> & { parent: ASTNode })
   | AST.SvelteProgram
   | AST.SvelteReactiveStatement
-type NodeListenerMap<T extends NodeWithParent = NodeWithParent> = {
-  [key in NodeWithParent["type"]]: T extends { type: key } ? T : never
-}
 
 type NodeListener = {
-  [T in keyof NodeListenerMap]: (node: NodeListenerMap[T]) => void
+  [key in NodeWithParent["type"]]: (
+    node: NodeWithParent & { type: key },
+  ) => void
 }
 
 /**
diff --git a/src/rules/indent-helpers/svelte.ts b/src/rules/indent-helpers/svelte.ts
index cdfcdac99..3d7afcd8f 100644
--- a/src/rules/indent-helpers/svelte.ts
+++ b/src/rules/indent-helpers/svelte.ts
@@ -8,12 +8,9 @@ type NodeWithoutES = Exclude<
   AST.SvelteNode,
   AST.SvelteProgram | AST.SvelteReactiveStatement
 >
-type NodeListenerMap<T extends NodeWithoutES = NodeWithoutES> = {
-  [key in NodeWithoutES["type"]]: T extends { type: key } ? T : never
-}
 
 type NodeListener = {
-  [T in keyof NodeListenerMap]: (node: NodeListenerMap[T]) => void
+  [key in NodeWithoutES["type"]]: (node: NodeWithoutES & { type: key }) => void
 }
 const PREFORMATTED_ELEMENT_NAMES = ["pre", "textarea"]
 
diff --git a/src/rules/indent-helpers/ts.ts b/src/rules/indent-helpers/ts.ts
index 7939b2703..fcd494bab 100644
--- a/src/rules/indent-helpers/ts.ts
+++ b/src/rules/indent-helpers/ts.ts
@@ -32,11 +32,8 @@ type NodeWithoutES = Exclude<
   | TSESTree.JSXSpreadChild
   | TSESTree.JSXText
 >
-type NodeListenerMap<T extends NodeWithoutES = NodeWithoutES> = {
-  [key in NodeWithoutES["type"]]: T extends { type: key } ? T : never
-}
 type NodeListener = {
-  [T in keyof NodeListenerMap]: (node: NodeListenerMap[T]) => void
+  [key in NodeWithoutES["type"]]: (node: NodeWithoutES & { type: key }) => void
 }
 
 /**
diff --git a/src/rules/no-not-function-handler.ts b/src/rules/no-not-function-handler.ts
new file mode 100644
index 000000000..94936588c
--- /dev/null
+++ b/src/rules/no-not-function-handler.ts
@@ -0,0 +1,103 @@
+import type { AST } from "svelte-eslint-parser"
+import type * as ESTree from "estree"
+import { createRule } from "../utils"
+import { findVariable } from "../utils/ast-utils"
+
+const PHRASES = {
+  ObjectExpression: "object",
+  ArrayExpression: "array",
+  ClassExpression: "class",
+  Literal(node: ESTree.Literal): string | null {
+    if ("regex" in node) {
+      return "regex value"
+    }
+    if ("bigint" in node) {
+      return "bigint value"
+    }
+    if (node.value == null) {
+      return null
+    }
+    return `${typeof node.value} value`
+  },
+  TemplateLiteral: "string value",
+}
+export default createRule("no-not-function-handler", {
+  meta: {
+    docs: {
+      description: "disallow use of not function in event handler",
+      category: "Possible Errors",
+      recommended: true,
+    },
+    schema: [],
+    messages: {
+      unexpected: "Unexpected {{phrase}} in event handler.",
+    },
+    type: "problem", // "problem", or "layout",
+  },
+  create(context) {
+    /** Find data expression */
+    function findRootExpression(
+      node: ESTree.Expression,
+      already = new Set<ESTree.Identifier>(),
+    ): ESTree.Expression {
+      if (node.type !== "Identifier" || already.has(node)) {
+        return node
+      }
+      already.add(node)
+      const variable = findVariable(context, node)
+      if (!variable || variable.defs.length !== 1) {
+        return node
+      }
+      const def = variable.defs[0]
+      if (def.type === "Variable") {
+        if (def.parent.kind === "const" && def.node.init) {
+          const init = def.node.init
+          return findRootExpression(init, already)
+        }
+      }
+      return node
+    }
+
+    /** Verify for `on:` directive value */
+    function verify(node: AST.SvelteEventHandlerDirective["expression"]) {
+      if (!node) {
+        return
+      }
+      const expression = findRootExpression(node)
+
+      if (
+        expression.type !== "ObjectExpression" &&
+        expression.type !== "ArrayExpression" &&
+        expression.type !== "ClassExpression" &&
+        expression.type !== "Literal" &&
+        expression.type !== "TemplateLiteral"
+      ) {
+        return
+      }
+      const phraseValue = PHRASES[expression.type]
+      const phrase =
+        typeof phraseValue === "function"
+          ? phraseValue(expression as never)
+          : phraseValue
+      if (phrase == null) {
+        return
+      }
+      context.report({
+        node,
+        messageId: "unexpected",
+        data: {
+          phrase,
+        },
+      })
+    }
+
+    return {
+      SvelteDirective(node) {
+        if (node.kind !== "EventHandler") {
+          return
+        }
+        verify(node.expression)
+      },
+    }
+  },
+})
diff --git a/src/types.ts b/src/types.ts
index 33d1a83c6..75fd389bc 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -16,12 +16,11 @@ export type ASTNode =
 type ASTNodeWithParent =
   | (Exclude<ASTNode, ESTree.Program> & { parent: ASTNode })
   | AST.SvelteProgram
-type ASTNodeListenerMap<T extends ASTNodeWithParent = ASTNodeWithParent> = {
-  [key in ASTNodeWithParent["type"]]: T extends { type: key } ? T : never
-}
 
 export type ASTNodeListener = {
-  [T in keyof ASTNodeListenerMap]?: (node: ASTNodeListenerMap[T]) => void
+  [key in ASTNodeWithParent["type"]]?: (
+    node: ASTNodeWithParent & { type: key },
+  ) => void
 }
 export interface RuleListener extends ASTNodeListener {
   onCodePathStart?(codePath: Rule.CodePath, node: never): void
diff --git a/src/utils/ast-utils.ts b/src/utils/ast-utils.ts
index 1cfa94873..770995e23 100644
--- a/src/utils/ast-utils.ts
+++ b/src/utils/ast-utils.ts
@@ -1,6 +1,8 @@
-import type { ASTNode, SourceCode } from "../types"
+import type { ASTNode, RuleContext, SourceCode } from "../types"
 import type * as ESTree from "estree"
 import type { AST as SvAST } from "svelte-eslint-parser"
+import * as eslintUtils from "eslint-utils"
+import type { Scope } from "eslint"
 
 /**
  * Checks whether or not the tokens of two given nodes are same.
@@ -191,3 +193,39 @@ export function getStaticAttributeValue(
   }
   return str
 }
+
+/**
+ * Find the variable of a given name.
+ */
+export function findVariable(
+  context: RuleContext,
+  node: ESTree.Identifier,
+): Scope.Variable | null {
+  return eslintUtils.findVariable(getScope(context, node), node)
+}
+
+/**
+ * Gets the scope for the current node
+ */
+export function getScope(
+  context: RuleContext,
+  currentNode: ESTree.Node,
+): Scope.Scope {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any -- ignore
+  const scopeManager = (context.getSourceCode() as any).scopeManager
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any -- ignore
+  let node: any = currentNode
+  for (; node; node = node.parent || null) {
+    const scope = scopeManager.acquire(node, false)
+
+    if (scope) {
+      if (scope.type === "function-expression-name") {
+        return scope.childScopes[0]
+      }
+      return scope
+    }
+  }
+
+  return scopeManager.scopes[0]
+}
diff --git a/src/utils/rules.ts b/src/utils/rules.ts
index 4ec015b87..a9fa6e79b 100644
--- a/src/utils/rules.ts
+++ b/src/utils/rules.ts
@@ -8,6 +8,7 @@ import noAtDebugTags from "../rules/no-at-debug-tags"
 import noAtHtmlTags from "../rules/no-at-html-tags"
 import noDupeElseIfBlocks from "../rules/no-dupe-else-if-blocks"
 import noInnerDeclarations from "../rules/no-inner-declarations"
+import noNotFunctionHandler from "../rules/no-not-function-handler"
 import noObjectInTextMustaches from "../rules/no-object-in-text-mustaches"
 import noTargetBlank from "../rules/no-target-blank"
 import noUselessMustaches from "../rules/no-useless-mustaches"
@@ -26,6 +27,7 @@ export const rules = [
   noAtHtmlTags,
   noDupeElseIfBlocks,
   noInnerDeclarations,
+  noNotFunctionHandler,
   noObjectInTextMustaches,
   noTargetBlank,
   noUselessMustaches,
diff --git a/tests/fixtures/rules/no-not-function-handler/invalid/array01-errors.json b/tests/fixtures/rules/no-not-function-handler/invalid/array01-errors.json
new file mode 100644
index 000000000..a2406b698
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/invalid/array01-errors.json
@@ -0,0 +1,7 @@
+[
+  {
+    "message": "Unexpected array in event handler.",
+    "line": 5,
+    "column": 19
+  }
+]
diff --git a/tests/fixtures/rules/no-not-function-handler/invalid/array01-input.svelte b/tests/fixtures/rules/no-not-function-handler/invalid/array01-input.svelte
new file mode 100644
index 000000000..d6374bf1c
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/invalid/array01-input.svelte
@@ -0,0 +1,5 @@
+<script>
+  const a = "hello!"
+</script>
+
+<button on:click={[a]} />
diff --git a/tests/fixtures/rules/no-not-function-handler/invalid/class01-errors.json b/tests/fixtures/rules/no-not-function-handler/invalid/class01-errors.json
new file mode 100644
index 000000000..d2d13e902
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/invalid/class01-errors.json
@@ -0,0 +1,7 @@
+[
+  {
+    "message": "Unexpected class in event handler.",
+    "line": 4,
+    "column": 19
+  }
+]
diff --git a/tests/fixtures/rules/no-not-function-handler/invalid/class01-input.svelte b/tests/fixtures/rules/no-not-function-handler/invalid/class01-input.svelte
new file mode 100644
index 000000000..edb41ed1e
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/invalid/class01-input.svelte
@@ -0,0 +1,4 @@
+<script>
+</script>
+
+<button on:click={class B {}} />
diff --git a/tests/fixtures/rules/no-not-function-handler/invalid/object01-errors.json b/tests/fixtures/rules/no-not-function-handler/invalid/object01-errors.json
new file mode 100644
index 000000000..4dae8a793
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/invalid/object01-errors.json
@@ -0,0 +1,7 @@
+[
+  {
+    "message": "Unexpected object in event handler.",
+    "line": 5,
+    "column": 19
+  }
+]
diff --git a/tests/fixtures/rules/no-not-function-handler/invalid/object01-input.svelte b/tests/fixtures/rules/no-not-function-handler/invalid/object01-input.svelte
new file mode 100644
index 000000000..09ef9b95f
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/invalid/object01-input.svelte
@@ -0,0 +1,5 @@
+<script>
+  function fn() {}
+</script>
+
+<button on:click={{ fn }} />
diff --git a/tests/fixtures/rules/no-not-function-handler/invalid/string01-errors.json b/tests/fixtures/rules/no-not-function-handler/invalid/string01-errors.json
new file mode 100644
index 000000000..66595af9c
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/invalid/string01-errors.json
@@ -0,0 +1,12 @@
+[
+  {
+    "message": "Unexpected string value in event handler.",
+    "line": 6,
+    "column": 19
+  },
+  {
+    "message": "Unexpected string value in event handler.",
+    "line": 7,
+    "column": 19
+  }
+]
diff --git a/tests/fixtures/rules/no-not-function-handler/invalid/string01-input.svelte b/tests/fixtures/rules/no-not-function-handler/invalid/string01-input.svelte
new file mode 100644
index 000000000..563cedfaa
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/invalid/string01-input.svelte
@@ -0,0 +1,7 @@
+<script>
+  const a = "hello!"
+  const b = `${a} world`
+</script>
+
+<button on:click={a} />
+<button on:click={b} />
diff --git a/tests/fixtures/rules/no-not-function-handler/invalid/value01-errors.json b/tests/fixtures/rules/no-not-function-handler/invalid/value01-errors.json
new file mode 100644
index 000000000..f783fb68f
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/invalid/value01-errors.json
@@ -0,0 +1,17 @@
+[
+  {
+    "message": "Unexpected number value in event handler.",
+    "line": 7,
+    "column": 19
+  },
+  {
+    "message": "Unexpected bigint value in event handler.",
+    "line": 8,
+    "column": 19
+  },
+  {
+    "message": "Unexpected regex value in event handler.",
+    "line": 9,
+    "column": 19
+  }
+]
diff --git a/tests/fixtures/rules/no-not-function-handler/invalid/value01-input.svelte b/tests/fixtures/rules/no-not-function-handler/invalid/value01-input.svelte
new file mode 100644
index 000000000..fdbf9c556
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/invalid/value01-input.svelte
@@ -0,0 +1,9 @@
+<script>
+  const a = 42
+  const b = 42n
+  const c = /reg/
+</script>
+
+<button on:click={a} />
+<button on:click={b} />
+<button on:click={c} />
diff --git a/tests/fixtures/rules/no-not-function-handler/valid/function01-input.svelte b/tests/fixtures/rules/no-not-function-handler/valid/function01-input.svelte
new file mode 100644
index 000000000..046c7b144
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/valid/function01-input.svelte
@@ -0,0 +1,7 @@
+<script>
+  let a = "hello!"
+  function fn() {}
+</script>
+
+<button on:click={() => a} />
+<button on:click={fn} />
diff --git a/tests/fixtures/rules/no-not-function-handler/valid/null01-input.svelte b/tests/fixtures/rules/no-not-function-handler/valid/null01-input.svelte
new file mode 100644
index 000000000..6732bc586
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/valid/null01-input.svelte
@@ -0,0 +1,6 @@
+<script>
+  let a = null
+</script>
+
+<button on:click={null} />
+<button on:click={a} />
diff --git a/tests/src/rules/no-not-function-handler.ts b/tests/src/rules/no-not-function-handler.ts
new file mode 100644
index 000000000..3de1bfa86
--- /dev/null
+++ b/tests/src/rules/no-not-function-handler.ts
@@ -0,0 +1,16 @@
+import { RuleTester } from "eslint"
+import rule from "../../../src/rules/no-not-function-handler"
+import { loadTestCases } from "../../utils/utils"
+
+const tester = new RuleTester({
+  parserOptions: {
+    ecmaVersion: 2020,
+    sourceType: "module",
+  },
+})
+
+tester.run(
+  "no-not-function-handler",
+  rule as any,
+  loadTestCases("no-not-function-handler"),
+)
diff --git a/typings/eslint-utils/index.d.ts b/typings/eslint-utils/index.d.ts
index 63c2a768b..5a4112cdc 100644
--- a/typings/eslint-utils/index.d.ts
+++ b/typings/eslint-utils/index.d.ts
@@ -1,4 +1,6 @@
 import type { AST } from "svelte-eslint-parser"
+import type { Scope } from "eslint"
+import type * as ESTree from "estree"
 type Token = { type: string; value: string }
 export function isArrowToken(token: Token): boolean
 export function isCommaToken(token: Token): boolean
@@ -22,3 +24,8 @@ export function isNotClosingBracketToken(token: Token): boolean
 export function isNotOpeningBraceToken(token: Token): boolean
 export function isNotClosingBraceToken(token: Token): boolean
 export function isNotCommentToken(token: Token): boolean
+
+export function findVariable(
+  initialScope: Scope.Scope,
+  nameOrNode: ESTree.Identifier | string,
+): Scope.Variable

From 570136510417a6cb0ee1f5906054b57c82623a7d Mon Sep 17 00:00:00 2001
From: yosuke ota <otameshiyo23@gmail.com>
Date: Tue, 29 Jun 2021 13:43:08 +0900
Subject: [PATCH 2/2] add test

---
 .../rules/no-not-function-handler/valid/bind01-input.svelte   | 4 ++++
 1 file changed, 4 insertions(+)
 create mode 100644 tests/fixtures/rules/no-not-function-handler/valid/bind01-input.svelte

diff --git a/tests/fixtures/rules/no-not-function-handler/valid/bind01-input.svelte b/tests/fixtures/rules/no-not-function-handler/valid/bind01-input.svelte
new file mode 100644
index 000000000..e6c2db22d
--- /dev/null
+++ b/tests/fixtures/rules/no-not-function-handler/valid/bind01-input.svelte
@@ -0,0 +1,4 @@
+<script>
+</script>
+
+<input bind:value={""} />