fix: don't remove arrow from lambdas that are when/if leaf nodes (#2758)
Co-authored-by: Paul Dingemans <paul-dingemans@users.noreply.github.com>
diff --git a/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionLiteralRule.kt b/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionLiteralRule.kt
index e183e28..165da85 100644
--- a/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionLiteralRule.kt
+++ b/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionLiteralRule.kt
@@ -4,13 +4,16 @@
import com.pinterest.ktlint.rule.engine.core.api.AutocorrectDecision
import com.pinterest.ktlint.rule.engine.core.api.ElementType.ARROW
import com.pinterest.ktlint.rule.engine.core.api.ElementType.BLOCK
+import com.pinterest.ktlint.rule.engine.core.api.ElementType.ELSE
import com.pinterest.ktlint.rule.engine.core.api.ElementType.FUNCTION_LITERAL
import com.pinterest.ktlint.rule.engine.core.api.ElementType.LAMBDA_ARGUMENT
import com.pinterest.ktlint.rule.engine.core.api.ElementType.LAMBDA_EXPRESSION
import com.pinterest.ktlint.rule.engine.core.api.ElementType.LBRACE
import com.pinterest.ktlint.rule.engine.core.api.ElementType.RBRACE
+import com.pinterest.ktlint.rule.engine.core.api.ElementType.THEN
import com.pinterest.ktlint.rule.engine.core.api.ElementType.VALUE_PARAMETER
import com.pinterest.ktlint.rule.engine.core.api.ElementType.VALUE_PARAMETER_LIST
+import com.pinterest.ktlint.rule.engine.core.api.ElementType.WHEN_ENTRY
import com.pinterest.ktlint.rule.engine.core.api.IndentConfig
import com.pinterest.ktlint.rule.engine.core.api.Rule.VisitorModifier.RunAfterRule.Mode.REGARDLESS_WHETHER_RUN_AFTER_RULE_IS_LOADED_OR_DISABLED
import com.pinterest.ktlint.rule.engine.core.api.RuleId
@@ -366,7 +369,9 @@
require(arrow.elementType == ARROW)
arrow
.prevSibling { it.elementType == VALUE_PARAMETER_LIST }
- ?.takeIf { it.findChildByType(VALUE_PARAMETER) == null && arrow.isFollowedByNonEmptyBlock() }
+ ?.takeIf { it.hasEmptyParameterList() }
+ ?.takeUnless { arrow.isLambdaExpressionNotWrappedInBlock() }
+ ?.takeIf { arrow.isFollowedByNonEmptyBlock() }
?.let {
emit(arrow.startOffset, "Arrow is redundant when parameter list is empty", true)
.ifAutocorrectAllowed {
@@ -379,6 +384,29 @@
}
}
+ private fun ASTNode.hasEmptyParameterList(): Boolean {
+ require(elementType == VALUE_PARAMETER_LIST)
+ return findChildByType(VALUE_PARAMETER) == null
+ }
+
+ private fun ASTNode.isLambdaExpressionNotWrappedInBlock(): Boolean {
+ require(elementType == ARROW)
+ return parent(LAMBDA_EXPRESSION)
+ ?.treeParent
+ ?.elementType
+ ?.let { parentElementType ->
+ // Allow:
+ // val foo = when {
+ // 1 == 2 -> { -> "hi" }
+ // else -> { -> "ho" }
+ // }
+ // or
+ // val foo = if (cond) { -> "hi" } else { -> "ho" } parent ->
+ parentElementType == WHEN_ENTRY || parentElementType == THEN || parentElementType == ELSE
+ }
+ ?: false
+ }
+
private fun ASTNode.isFollowedByNonEmptyBlock(): Boolean {
require(elementType == ARROW)
return nextSibling { it.elementType == BLOCK }?.firstChildNode != null
diff --git a/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionLiteralRuleTest.kt b/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionLiteralRuleTest.kt
index 26a809d..58c3ff8 100644
--- a/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionLiteralRuleTest.kt
+++ b/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/rules/FunctionLiteralRuleTest.kt
@@ -506,4 +506,76 @@
""".trimIndent()
functionLiteralRuleAssertThat(code).hasNoLintViolations()
}
+
+ @Test
+ fun `Issue 2758 - Given function literal with an arrow without parameters arrow literal as leaf of when then do not remove the arrow`() {
+ val code =
+ """
+ val foo =
+ when {
+ false -> { -> "bar" }
+ else -> { -> "baz" }
+ }
+ """.trimIndent()
+ functionLiteralRuleAssertThat(code).hasNoLintViolations()
+ }
+
+ @Test
+ fun `Issue 2758 - Given function literal with an arrow without parameters arrow literal not as leaf of when then do remove the arrow`() {
+ val code =
+ """
+ val foo =
+ when {
+ false -> { { -> "bar" } }
+ else -> { { -> "baz" } }
+ }
+ """.trimIndent()
+ val formattedCode =
+ """
+ val foo =
+ when {
+ false -> { { "bar" } }
+ else -> { { "baz" } }
+ }
+ """.trimIndent()
+ functionLiteralRuleAssertThat(code)
+ .hasLintViolations(
+ LintViolation(3, 22, "Arrow is redundant when parameter list is empty"),
+ LintViolation(4, 21, "Arrow is redundant when parameter list is empty"),
+ ).isFormattedAs(formattedCode)
+ }
+
+ @Test
+ fun `Issue 2758 - Given function literal with an arrow without parameters arrow literal as leaf of if then do not remove the arrow`() {
+ val code =
+ """
+ val foo = if (cond) { -> "bar" } else { -> "baz" }
+ """.trimIndent()
+ functionLiteralRuleAssertThat(code).hasNoLintViolations()
+ }
+
+ @Test
+ fun `Issue 2758 - Given function literal with an arrow without parameters arrow literal not as leaf of if then do remove the arrow`() {
+ val code =
+ """
+ val foo = if (cond) {
+ { -> "bar" }
+ } else {
+ { -> "baz" }
+ }
+ """.trimIndent()
+ val formattedCode =
+ """
+ val foo = if (cond) {
+ { "bar" }
+ } else {
+ { "baz" }
+ }
+ """.trimIndent()
+ functionLiteralRuleAssertThat(code)
+ .hasLintViolations(
+ LintViolation(2, 7, "Arrow is redundant when parameter list is empty"),
+ LintViolation(4, 7, "Arrow is redundant when parameter list is empty"),
+ ).isFormattedAs(formattedCode)
+ }
}
