Add new experimental rule string-template-indent for `ktlint_offici…

…al` code style

This rule forces multiline string templates which are post-fixed with `.trimIndent()` to be formatted consistently. The opening and closing `"""` are placed on separate lines and the indentation of the content of the template is aligned with the `"""`.

Closes #925

CHANGELOG.md

@@ -233,6 +233,7 @@ Previously the default value for `.editorconfig` property `max_line_length` was
 * Recognize Kotlin Script when linting and formatting code from `stdin` with KtLint CLI ([#1832](https://github.com/pinterest/ktlint/issues/1832))
 * Add new experimental rule `no-blank-line-in-list` for `ktlint_official` code style. This rule disallows blank lines to be used in super type lists, type argument lists, type constraint lists, type parameter lists, value argument lists, and value parameter lists. This rule can also be run for other code styles but then its needs to be explicitly enabled. ([#1224](https://github.com/pinterest/ktlint/issues/1224))
 * Add new experimental rule `multiline-expression-wrapping` for `ktlint_official` code style. This forces a multiline expression as value in an assignment to start on a separate line. This rule can also be run for other code styles but then its needs to be explicitly enabled. ([#1217](https://github.com/pinterest/ktlint/issues/1217))
+* Add new experimental rule `string-template-indent` for `ktlint_official` code style. This forces multiline string templates which are post-fixed with `.trimIndent()` to be formatted consistently. The opening and closing `"""` are placed on separate lines and the indentation of the content of the template is aligned with the `"""`. This rule can also be run for other code styles but then its needs to be explicitly enabled. ([#925](https://github.com/pinterest/ktlint/issues/925))
 
 ### Removed
 

docs/rules/experimental.md

@@ -366,6 +366,46 @@ Consistent spacing between function name and opening parenthesis.
 
 Rule id: `spacing-between-function-name-and-opening-parenthesis`
 
+### String template indent
+
+Enforce consistent string template indentation for multiline string templates which are post-fixed with `.trimIndent()`. The opening and closing `"""` are placed on separate lines and the indentation of the content of the template is aligned with the `"""`.
+
+=== "[:material-heart:](#) Ktlint (ktlint_official code style)"
+
+    ```kotlin
+    val foo =
+        """
+        line1
+        line2
+        """.trimIndent()
+    fun foo() {
+        // The opening """ can not be wrapped to next line as that would result in a compilation error
+        return """
+            line1
+            line2
+            """.trimIndent()
+    }
+    ```
+=== "[:material-heart:](#) Ktlint (non ktlint_official code style)"
+
+    ```kotlin
+    val foo = """
+              line1
+              line2
+              """.trimIndent()
+    fun foo() {
+        return """
+            line1
+            line2
+        """.trimIndent()
+    }
+    ```
+
+Rule id: `string-template-indent`
+
+!!! Note
+    This rule is only run when `ktlint_code_style` is set to `ktlint_official` or when the rule is enabled explicitly.
+
 ### Try catch finally spacing
 
 Enforce consistent spacing in `try { .. } catch { .. } finally { .. }`.

ktlint-cli/build.gradle.kts

@@ -56,7 +56,8 @@ val shadowJarExecutable by tasks.registering(DefaultTask::class) {
     doLast {
         val execFile = outputs.files.files.first()
         execFile.appendText(
-            """#!/bin/sh
+            """
+            #!/bin/sh
 
             # From this SO answer: https://stackoverflow.com/a/56243046
 

ktlint-rule-engine-core/src/test/kotlin/com/pinterest/ktlint/rule/engine/core/api/ASTNodeExtensionTest.kt

@@ -438,13 +438,13 @@ class ASTNodeExtensionTest {
     fun `Given some identifiers at different indentation levels`() {
         val code =
             """
-                class Foo1 {
-                    val foo2 = "foo2"
+            class Foo1 {
+                val foo2 = "foo2"
 
-                    fun foo3() {
-                        val foo4 = "foo4"
-                    }
+                fun foo3() {
+                    val foo4 = "foo4"
                 }
+            }
             """.trimIndent()
 
         val actual =

ktlint-rule-engine-core/src/test/kotlin/com/pinterest/ktlint/rule/engine/core/api/editorconfig/EditorConfigTest.kt

@@ -262,9 +262,9 @@ class EditorConfigTest {
                 writeRootEditorConfigFile(
                     //language=EditorConfig
                     """
-                [*.{kt,kts}]
-                $ktlintTestRuleExecutionProperty1 = disabled
-                $ktlintTestRuleExecutionProperty2 = disabled
+                    [*.{kt,kts}]
+                    $ktlintTestRuleExecutionProperty1 = disabled
+                    $ktlintTestRuleExecutionProperty2 = disabled
                     """.trimIndent(),
                 )
             }

ktlint-rule-engine/src/main/kotlin/com/pinterest/ktlint/rule/engine/internal/EditorConfigLoader.kt

@@ -105,13 +105,14 @@ internal class EditorConfigLoader(
     private fun MutableMap<String, Property>.prettyPrint(normalizedFilePath: Path?) =
         map { entry -> "${entry.key}: ${entry.value.sourceValue}" }
             .joinToString(
-                prefix = "Effective editorconfig properties${
-                    if (normalizedFilePath == null) {
-                        ""
-                    } else {
-                        " for file '$normalizedFilePath'"
-                    }
-                }:\n\t",
+                prefix =
+                    "Effective editorconfig properties${
+                        if (normalizedFilePath == null) {
+                            ""
+                        } else {
+                            " for file '$normalizedFilePath'"
+                        }
+                    }:\n\t",
                 separator = "\n\t",
             )
 

ktlint-rule-engine/src/test/kotlin/com/pinterest/ktlint/rule/engine/internal/EditorConfigLoaderTest.kt

@@ -249,8 +249,8 @@ internal class EditorConfigLoaderTest {
                 writeRootEditorConfigFile(
                     //language=EditorConfig
                     """
-                [*.{kt,kts}]
-                some_property = some_value
+                    [*.{kt,kts}]
+                    some_property = some_value
                     """.trimIndent(),
                 )
             }
@@ -297,8 +297,8 @@ internal class EditorConfigLoaderTest {
                 writeRootEditorConfigFile(
                     //language=EditorConfig
                     """
-                [*.{kt,kts}]
-                some_property = some_value
+                    [*.{kt,kts}]
+                    some_property = some_value
                     """.trimIndent(),
                 )
             }
@@ -334,8 +334,8 @@ internal class EditorConfigLoaderTest {
                 writeRootEditorConfigFile(
                     //language=EditorConfig
                     """
-                [*.{kt,kts}]
-                some_property_1 = some_value_1
+                    [*.{kt,kts}]
+                    some_property_1 = some_value_1
                     """.trimIndent(),
                 )
             }
@@ -355,8 +355,8 @@ internal class EditorConfigLoaderTest {
                 writeRootEditorConfigFile(
                     //language=EditorConfig
                     """
-                [*.{kt,kts}]
-                some_property = some_value
+                    [*.{kt,kts}]
+                    some_property = some_value
                     """.trimIndent(),
                 )
             }

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

@@ -68,6 +68,7 @@ import com.pinterest.ktlint.ruleset.standard.rules.SpacingAroundUnaryOperatorRul
 import com.pinterest.ktlint.ruleset.standard.rules.SpacingBetweenDeclarationsWithAnnotationsRule
 import com.pinterest.ktlint.ruleset.standard.rules.SpacingBetweenDeclarationsWithCommentsRule
 import com.pinterest.ktlint.ruleset.standard.rules.SpacingBetweenFunctionNameAndOpeningParenthesisRule
+import com.pinterest.ktlint.ruleset.standard.rules.StringTemplateIndentRule
 import com.pinterest.ktlint.ruleset.standard.rules.StringTemplateRule
 import com.pinterest.ktlint.ruleset.standard.rules.TrailingCommaOnCallSiteRule
 import com.pinterest.ktlint.ruleset.standard.rules.TrailingCommaOnDeclarationSiteRule
@@ -147,6 +148,7 @@ public class StandardRuleSetProvider :
             RuleProvider { SpacingBetweenDeclarationsWithCommentsRule() },
             RuleProvider { SpacingBetweenFunctionNameAndOpeningParenthesisRule() },
             RuleProvider { StringTemplateRule() },
+            RuleProvider { StringTemplateIndentRule() },
             RuleProvider { TrailingCommaOnCallSiteRule() },
             RuleProvider { TrailingCommaOnDeclarationSiteRule() },
             RuleProvider { TryCatchFinallySpacingRule() },