From 06f2b809ef7e29717662f9be006ec80cd3d07c91 Mon Sep 17 00:00:00 2001
From: RebeccaStevens <rebecca.stevens@outlook.co.nz>
Date: Sun, 20 Oct 2024 14:42:03 +0000
Subject: [PATCH] fix(functional-parameters): default options not being applied
 to option overrides (#888)

---
 docs/rules/functional-parameters.md | 23 +++++++++++++----
 src/configs/recommended.ts          |  1 +
 src/rules/functional-parameters.ts  | 40 +++++++++++++++++++++++------
 3 files changed, 51 insertions(+), 13 deletions(-)

diff --git a/docs/rules/functional-parameters.md b/docs/rules/functional-parameters.md
index f993f007e..2c055a4de 100644
--- a/docs/rules/functional-parameters.md
+++ b/docs/rules/functional-parameters.md
@@ -132,11 +132,24 @@ const defaults = {
 
 ```ts
 const recommendedOptions = {
-  enforceParameterCount: {
-    ignoreLambdaExpression: true,
-    ignoreIIFE: true,
-    ignoreGettersAndSetters: true,
-  },
+  enforceParameterCount: false,
+  overrides: [
+    {
+      specifiers: [
+        {
+          from: "file",
+        },
+      ],
+      options: {
+        enforceParameterCount: {
+          count: "atLeastOne",
+          ignoreLambdaExpression: true,
+          ignoreIIFE: true,
+          ignoreGettersAndSetters: true,
+        },
+      },
+    },
+  ],
 };
 ```
 
diff --git a/src/configs/recommended.ts b/src/configs/recommended.ts
index 4bdad7761..bf4c078e3 100644
--- a/src/configs/recommended.ts
+++ b/src/configs/recommended.ts
@@ -41,6 +41,7 @@ const overrides = {
           ],
           options: {
             enforceParameterCount: {
+              count: "atLeastOne",
               ignoreLambdaExpression: true,
               ignoreIIFE: true,
               ignoreGettersAndSetters: true,
diff --git a/src/rules/functional-parameters.ts b/src/rules/functional-parameters.ts
index 4d65a75b0..073f5cb3e 100644
--- a/src/rules/functional-parameters.ts
+++ b/src/rules/functional-parameters.ts
@@ -127,7 +127,7 @@ const schema: JSONSchema4[] = [
 /**
  * The default options for the rule.
  */
-const defaultOptions: RawOptions = [
+const defaultOptions = [
   {
     allowRestParameter: false,
     allowArgumentsKeyword: false,
@@ -138,7 +138,7 @@ const defaultOptions: RawOptions = [
       ignoreGettersAndSetters: true,
     },
   },
-];
+] satisfies RawOptions;
 
 /**
  * The possible error messages.
@@ -234,6 +234,31 @@ function getParamCountViolations(
   return [];
 }
 
+/**
+ * Add the default options to the given options.
+ */
+function getOptionsWithDefaults(
+  options: Readonly<Options> | null,
+): Options | null {
+  if (options === null) {
+    return null;
+  }
+
+  const topLevel = {
+    ...defaultOptions[0],
+    ...options,
+  };
+  return typeof topLevel.enforceParameterCount === "object"
+    ? {
+        ...topLevel,
+        enforceParameterCount: {
+          ...defaultOptions[0].enforceParameterCount,
+          ...topLevel.enforceParameterCount,
+        },
+      }
+    : topLevel;
+}
+
 /**
  * Check if the given function node has a reset parameter this rule.
  */
@@ -243,10 +268,8 @@ function checkFunction(
   rawOptions: Readonly<RawOptions>,
 ): RuleResult<keyof typeof errorMessages, RawOptions> {
   const options = upgradeRawOverridableOptions(rawOptions[0]);
-  const optionsToUse = getCoreOptions<CoreOptions, Options>(
-    node,
-    context,
-    options,
+  const optionsToUse = getOptionsWithDefaults(
+    getCoreOptions<CoreOptions, Options>(node, context, options),
   );
 
   if (optionsToUse === null) {
@@ -291,10 +314,11 @@ function checkIdentifier(
 
   const functionNode = getEnclosingFunction(node);
   const options = upgradeRawOverridableOptions(rawOptions[0]);
-  const optionsToUse =
+  const optionsToUse = getOptionsWithDefaults(
     functionNode === null
       ? options
-      : getCoreOptions<CoreOptions, Options>(functionNode, context, options);
+      : getCoreOptions<CoreOptions, Options>(functionNode, context, options),
+  );
 
   if (optionsToUse === null) {
     return {