Ignore override of function in rule function-naming

A function override should not be reported as the interface of class that defines the function might be out of scope of the project in which case the function name can not be changed. Note that the function will still be reported at the interface or class itself whenever that interface or class is defined inside the scope of the project.

Closes #2271

CHANGELOG.md

@@ -14,6 +14,7 @@ This project adheres to [Semantic Versioning](https://semver.org/).
 * Fix indent of multiline object declaration inside class `indent` [#2257](https://github.com/pinterest/ktlint/issue/2257)
 * Ignore anonymous function in rule `function-naming` [#2260](https://github.com/pinterest/ktlint/issue/2260)
 * Do not force blank line before function in right hand side of assignment `blank-line-before-declaration` [#2260](https://github.com/pinterest/ktlint/issue/2260)
+* Ignore override of function in rule `function-naming` [#2271](https://github.com/pinterest/ktlint/issue/2271)
 
 ### Changed
 

ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionNamingRule.kt

@@ -4,11 +4,14 @@ import com.pinterest.ktlint.rule.engine.core.api.ElementType.FUN
 import com.pinterest.ktlint.rule.engine.core.api.ElementType.FUN_KEYWORD
 import com.pinterest.ktlint.rule.engine.core.api.ElementType.IDENTIFIER
 import com.pinterest.ktlint.rule.engine.core.api.ElementType.IMPORT_DIRECTIVE
+import com.pinterest.ktlint.rule.engine.core.api.ElementType.MODIFIER_LIST
+import com.pinterest.ktlint.rule.engine.core.api.ElementType.OVERRIDE_KEYWORD
 import com.pinterest.ktlint.rule.engine.core.api.ElementType.VALUE_PARAMETER_LIST
 import com.pinterest.ktlint.rule.engine.core.api.RuleId
 import com.pinterest.ktlint.rule.engine.core.api.SinceKtlint
 import com.pinterest.ktlint.rule.engine.core.api.SinceKtlint.Status.EXPERIMENTAL
 import com.pinterest.ktlint.rule.engine.core.api.SinceKtlint.Status.STABLE
+import com.pinterest.ktlint.rule.engine.core.api.children
 import com.pinterest.ktlint.rule.engine.core.api.nextCodeSibling
 import com.pinterest.ktlint.ruleset.standard.StandardRule
 import com.pinterest.ktlint.ruleset.standard.rules.internal.regExIgnoringDiacriticsAndStrokesOnLetters
@@ -47,7 +50,8 @@ public class FunctionNamingRule : StandardRule("function-naming") {
                 node.isFactoryMethod() ||
                     node.isTestMethod() ||
                     node.hasValidFunctionName() ||
-                    node.isAnonymousFunction()
+                    node.isAnonymousFunction() ||
+                    node.isOverrideFunction()
             }?.let {
                 val identifierOffset =
                     node
@@ -86,6 +90,17 @@ public class FunctionNamingRule : StandardRule("function-naming") {
                 ?.nextCodeSibling()
                 ?.elementType
 
+    /*
+     * A function override should not be reported as the interface of class that defines the function might be out of scope of the project
+     * in which case the function name can not be changed. Note that the function will still be reported at the interface or class itself
+     * whenever that interface or class is defined inside the scope of the project.
+     */
+    private fun ASTNode.isOverrideFunction() =
+        findChildByType(MODIFIER_LIST)
+            ?.children()
+            .orEmpty()
+            .any { it.elementType == OVERRIDE_KEYWORD }
+
     private companion object {
         val VALID_FUNCTION_NAME_REGEXP = "[a-z][A-Za-z\\d]*".regExIgnoringDiacriticsAndStrokesOnLetters()
         val VALID_TEST_FUNCTION_NAME_REGEXP = "(`.*`)|([a-z][A-Za-z\\d_]*)".regExIgnoringDiacriticsAndStrokesOnLetters()

ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionNamingRuleTest.kt

@@ -182,4 +182,18 @@ class FunctionNamingRuleTest {
             """.trimIndent()
         functionNamingRuleAssertThat(code).hasNoLintViolations()
     }
+
+    @Test
+    fun `Issue 2271 - Given an override fun then do not report a violation of the rule as it might not be possible to change the signature of the rule when defined outside scope of project`() {
+        val code =
+            """
+            // Assume that Bar is defined outside the scope of the project. As of that the function signature can not be changed to comply
+            // to the function-naming rule. In case that Bar is defined inside the scope of the project, the violation will still be
+            // reported in the Bar class/interface itself.
+            class Foo : Bar {
+                override fun Something()
+            }
+            """.trimIndent()
+        functionNamingRuleAssertThat(code).hasNoLintViolations()
+    }
 }