From 1d52f00562f22fe7c82db5311c5b41b36d804841 Mon Sep 17 00:00:00 2001
From: Paul Dingemans <pdingemans@bol.com>
Date: Sun, 31 Oct 2021 12:36:13 +0100
Subject: [PATCH] Fix KDOC indentation for tab indentation style

Closes #850
---
 .../ruleset/standard/IndentationRule.kt       | 29 ++++++++++--
 .../ruleset/standard/IndentationRuleTest.kt   | 47 +++++++++++++++++++
 2 files changed, 73 insertions(+), 3 deletions(-)

diff --git a/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/IndentationRule.kt b/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/IndentationRule.kt
index 4f62f7952a..b50dbf294d 100644
--- a/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/IndentationRule.kt
+++ b/ktlint-ruleset-standard/src/main/kotlin/com/pinterest/ktlint/ruleset/standard/IndentationRule.kt
@@ -27,6 +27,8 @@ import com.pinterest.ktlint.core.ast.ElementType.FUN
 import com.pinterest.ktlint.core.ast.ElementType.FUNCTION_LITERAL
 import com.pinterest.ktlint.core.ast.ElementType.GT
 import com.pinterest.ktlint.core.ast.ElementType.KDOC
+import com.pinterest.ktlint.core.ast.ElementType.KDOC_END
+import com.pinterest.ktlint.core.ast.ElementType.KDOC_LEADING_ASTERISK
 import com.pinterest.ktlint.core.ast.ElementType.KDOC_START
 import com.pinterest.ktlint.core.ast.ElementType.LAMBDA_EXPRESSION
 import com.pinterest.ktlint.core.ast.ElementType.LBRACE
@@ -44,7 +46,6 @@ import com.pinterest.ktlint.core.ast.ElementType.RBRACE
 import com.pinterest.ktlint.core.ast.ElementType.RBRACKET
 import com.pinterest.ktlint.core.ast.ElementType.REGULAR_STRING_PART
 import com.pinterest.ktlint.core.ast.ElementType.RPAR
-import com.pinterest.ktlint.core.ast.ElementType.SAFE_ACCESS
 import com.pinterest.ktlint.core.ast.ElementType.SAFE_ACCESS_EXPRESSION
 import com.pinterest.ktlint.core.ast.ElementType.SHORT_STRING_TEMPLATE_ENTRY
 import com.pinterest.ktlint.core.ast.ElementType.STRING_TEMPLATE
@@ -989,7 +990,14 @@ class IndentationRule : Rule("indent"), Rule.Modifier.RestrictToRootLast {
                     }
                 }
                 IndentStyle.TAB -> {
-                    if (' ' in nodeIndent) {
+                    val isKdocIndent = node.isKDocIndent()
+                    val indentWithoutKdocIndent =
+                        if (isKdocIndent) {
+                            nodeIndent.removeSuffix(" ")
+                        } else {
+                            nodeIndent
+                        }
+                    if (' ' in indentWithoutKdocIndent) {
                         emit(
                             node.startOffset + text.length - nodeIndent.length,
                             "Unexpected space character(s)",
@@ -998,7 +1006,13 @@ class IndentationRule : Rule("indent"), Rule.Modifier.RestrictToRootLast {
                         // First normalize the indent to spaces using the tab width.
                         val asSpaces = nodeIndent.replace("\t", " ".repeat(editorConfig.tabWidth))
                         // Then divide that space-based indent into tabs.
-                        "\t".repeat(asSpaces.length / editorConfig.tabWidth)
+                        "\t".repeat(asSpaces.length / editorConfig.tabWidth) +
+                            // Re-add the kdoc indent when it was present before
+                            if (isKdocIndent) {
+                                " "
+                            } else {
+                                ""
+                            }
                     } else {
                         nodeIndent
                     }
@@ -1117,6 +1131,15 @@ class IndentationRule : Rule("indent"), Rule.Modifier.RestrictToRootLast {
     }
 }
 
+private fun ASTNode.isKDocIndent() =
+    if (text.lastOrNull() == ' ') {
+        // The indentation of a KDoc comment contains a space as the last character regardless of the indentation style
+        // (tabs or spaces) except for the starting line of the KDoc comment
+        nextLeaf()?.elementType == KDOC_LEADING_ASTERISK || nextLeaf()?.elementType == KDOC_END
+    } else {
+        false
+    }
+
 private fun ASTNode.isIndentBeforeClosingQuote() =
     elementType == CLOSING_QUOTE || (text.isBlank() && nextCodeSibling()?.elementType == CLOSING_QUOTE)
 
diff --git a/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/IndentationRuleTest.kt b/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/IndentationRuleTest.kt
index 499472818a..d42d1036ca 100644
--- a/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/IndentationRuleTest.kt
+++ b/ktlint-ruleset-standard/src/test/kotlin/com/pinterest/ktlint/ruleset/standard/IndentationRuleTest.kt
@@ -1296,6 +1296,53 @@ internal class IndentationRuleTest {
         assertThat(IndentationRule().format(code)).isEqualTo(code)
     }
 
+    @Test
+    fun `format kdoc`() {
+        @Suppress("RemoveCurlyBracesFromTemplate")
+        val code =
+            """
+            /**
+             * some function1
+             */
+            fun someFunction1() {
+                return Unit
+            }
+
+            class SomeClass {
+                /**
+                 * some function2
+                 */
+                fun someFunction2() {
+                    return Unit
+                }
+            }
+            """.trimIndent()
+        @Suppress("RemoveCurlyBracesFromTemplate")
+        val codeTabs =
+            """
+            /**
+             * some function1
+             */
+            fun someFunction1() {
+            ${TAB}return Unit
+            }
+
+            class SomeClass {
+            ${TAB}/**
+            ${TAB} * some function2
+            ${TAB} */
+            ${TAB}fun someFunction2() {
+            ${TAB}${TAB}return Unit
+            ${TAB}}
+            }
+            """.trimIndent()
+        assertThat(IndentationRule().lint(code)).isEmpty()
+        assertThat(IndentationRule().format(code)).isEqualTo(code)
+
+        assertThat(IndentationRule().lint(codeTabs, INDENT_STYLE_TABS)).isEmpty()
+        assertThat(IndentationRule().format(codeTabs, INDENT_STYLE_TABS)).isEqualTo(codeTabs)
+    }
+
     private companion object {
         const val MULTILINE_STRING_QUOTE = "${'"'}${'"'}${'"'}"
         const val TAB = "${'\t'}"