Align error underlines properly when tabs are involved

sqldelight-gradle-plugin/src/main/kotlin/app/cash/sqldelight/core/SqlDelightEnvironment.kt

@@ -229,13 +229,15 @@ class SqlDelightEnvironment(
     val maxDigits = (log10(context.lineEnd.toDouble()) + 1).toInt()
     for (line in context.lineStart..context.lineEnd) {
       if (!tokenizer.hasMoreTokens()) break
-      result.append(("%0${maxDigits}d    %s\n").format(line, tokenizer.nextToken()))
+      val lineValue = tokenizer.nextToken()
+      result.append(("%0${maxDigits}d    %s\n").format(line, lineValue))
       if (element.lineStart == element.lineEnd && element.lineStart == line) {
-        // If its an error on a single line highlight where on the line.
+        // If it's an error on a single line highlight where on the line.
         result.append(("%${maxDigits}s    ").format(""))
-        if (element.charPositionInLine > 0) {
-          result.append(("%${element.charPositionInLine}s").format(""))
-        }
+        // Print tabs when you see it, spaces for everything else.
+        lineValue.subSequence(0 until element.charPositionInLine)
+          .map { char -> if (char != '\t') " " else char }
+          .forEach(result::append)
         result.append(("%s\n").format("^".repeat(element.textLength)))
       }
     }

sqldelight-gradle-plugin/src/test/bad-underlines/build.gradle

@@ -0,0 +1,12 @@
+plugins {
+  alias(libs.plugins.kotlin.jvm)
+  alias(libs.plugins.sqldelight)
+}
+
+sqldelight {
+  databases {
+    Database {
+      packageName = "com.example"
+    }
+  }
+}

sqldelight-gradle-plugin/src/test/bad-underlines/settings.gradle

@@ -0,0 +1,7 @@
+pluginManagement {
+    includeBuild("../build-logic-tests")
+}
+
+plugins {
+    id("sqldelightTests")
+}

sqldelight-gradle-plugin/src/test/bad-underlines/src/main/sqldelight/Test1.sq

@@ -0,0 +1,3 @@
+CREATE TABLE test1(
+	value	BIGINT
+);

sqldelight-gradle-plugin/src/test/kotlin/app/cash/sqldelight/tests/FailureTest.kt

@@ -26,4 +26,23 @@ class FailureTest {
       """.trimMargin(),
     )
   }
+
+  @Test fun `errors with tabs in line underline properly`() {
+    val fixtureRoot = File("src/test/bad-underlines")
+
+    val output = GradleRunner.create()
+      .withCommonConfiguration(fixtureRoot)
+      .withArguments("clean", "generateMainDatabaseInterface", "--stacktrace")
+      .buildAndFail()
+
+    assertThat(output.output).contains(
+      """
+      |Test1.sq: (2, 7): <type name real> expected, got 'BIGINT'
+      |1    CREATE TABLE test1(
+      |2    	value	BIGINT
+      |     	     	^^^^^^
+      |3    )
+      """.trimMargin(),
+    )
+  }
 }