Allow single letters for parameter names

src/Nexus/PHPStan/Rules/Functions/FunctionNamingRule.php

@@ -72,7 +72,7 @@ public function processNode(Node $node, Scope $scope): array
                 continue; // @codeCoverageIgnore
             }
 
-            if (preg_match('/^[a-z][a-zA-Z0-9]+$/', $param->var->name) !== 1) {
+            if (preg_match('/^[a-z][a-zA-Z0-9]*$/', $param->var->name) !== 1) {
                 $errors[] = RuleErrorBuilder::message(\sprintf(
                     'Parameter #%d $%s of function %s() should be in camelCase format.',
                     $index + 1,

src/Nexus/PHPStan/Rules/Methods/MethodNamingRule.php

@@ -94,7 +94,7 @@ public function processNode(Node $node, Scope $scope): array
                 continue; // @codeCoverageIgnore
             }
 
-            if (preg_match('/^[a-z][a-zA-Z0-9]+$/', $param->var->name) !== 1) {
+            if (preg_match('/^[a-z][a-zA-Z0-9]*$/', $param->var->name) !== 1) {
                 $errors[] = RuleErrorBuilder::message(\sprintf(
                     'Parameter #%d $%s of %s::%s() should be in camelCase with no underscores.',
                     $index + 1,

tests/PHPStan/Rules/Functions/FunctionNamingRuleTest.php

@@ -45,7 +45,7 @@ public function testRule(): void
             ],
             [
                 'Function deride() should be namespaced using the "Nexus\\" namespace.',
-                20,
+                25,
             ],
         ]);
     }

tests/PHPStan/Rules/Functions/data/function-naming.php

@@ -14,6 +14,11 @@ function foo(
     ): string {
         return $_bar;
     }
+
+    function baz(string $i): void
+    {
+        echo $i;
+    }
 }
 
 namespace {

tests/PHPStan/Rules/Methods/data/method-naming.php

@@ -20,4 +20,9 @@ public function _boo(): void {}
     public function base_band(): void {}
 
     abstract public function readline(int $max_lifetime): void;
+
+    protected function baziter(int $i): int
+    {
+        return $i;
+    }
 }