Add `Name.renderForSource` util

compiler/tests/org/jetbrains/kotlin/renderer/RenderingUtilsTest.kt

diff --git a/compiler/tests/org/jetbrains/kotlin/renderer/RenderingUtilsTest.kt b/compiler/tests/org/jetbrains/kotlin/renderer/RenderingUtilsTest.kt
index c63ae3b..3d1ed41 100644
--- a/compiler/tests/org/jetbrains/kotlin/renderer/RenderingUtilsTest.kt
+++ b/compiler/tests/org/jetbrains/kotlin/renderer/RenderingUtilsTest.kt
@@ -9,6 +9,7 @@
 import org.jetbrains.kotlin.name.SpecialNames.NO_NAME_PROVIDED
 import org.jetbrains.kotlin.name.SpecialNames.UNDERSCORE_FOR_UNUSED_VAR
 import org.jetbrains.kotlin.name.render
+import org.jetbrains.kotlin.name.renderForSource
 import org.junit.jupiter.api.Test
 import kotlin.test.assertEquals
 
@@ -34,4 +35,26 @@
         assertEquals("`return`", keywordIdentifier.render(stipSpecialMarkers = true))
         assertEquals("`return`", keywordIdentifier.render(stipSpecialMarkers = false))
     }
+
+    @Test
+    fun testRenderForSource() {
+        assertEquals("_", UNDERSCORE_FOR_UNUSED_VAR.renderForSource())
+        assertEquals("_", UNDERSCORE_FOR_UNUSED_VAR.renderForSource(stripSpecialMarker = true))
+
+        val normalIdentifier = Name.identifier("normal")
+        assertEquals("normal", normalIdentifier.render(stipSpecialMarkers = true))
+        assertEquals("normal", normalIdentifier.render(stipSpecialMarkers = false))
+
+        val escapedIdentifier = Name.identifier("`escaped`")
+        assertEquals("``escaped``", escapedIdentifier.render(stipSpecialMarkers = true))
+        assertEquals("``escaped``", escapedIdentifier.render(stipSpecialMarkers = false))
+
+        assertEquals("no name provided", NO_NAME_PROVIDED.render(stipSpecialMarkers = true))
+        assertEquals("`<no name provided>`", NO_NAME_PROVIDED.render(stipSpecialMarkers = false))
+
+        // Check a keyword
+        val keywordIdentifier = Name.identifier("return")
+        assertEquals("`return`", keywordIdentifier.render(stipSpecialMarkers = true))
+        assertEquals("`return`", keywordIdentifier.render(stipSpecialMarkers = false))
+    }
 }

core/names/src/org/jetbrains/kotlin/name/nameRenderingUtils.kt

diff --git a/core/names/src/org/jetbrains/kotlin/name/nameRenderingUtils.kt b/core/names/src/org/jetbrains/kotlin/name/nameRenderingUtils.kt
index 5242f9a..87500ba 100644
--- a/core/names/src/org/jetbrains/kotlin/name/nameRenderingUtils.kt
+++ b/core/names/src/org/jetbrains/kotlin/name/nameRenderingUtils.kt
@@ -14,6 +14,12 @@
     return if ((!stipSpecialMarkers || !isSpecial) && shouldBeEscaped(string)) '`' + string + '`' else string
 }
 
+fun Name.renderForSource(stripSpecialMarker: Boolean = false): String {
+    if (this == SpecialNames.UNDERSCORE_FOR_UNUSED_VAR) return "_"
+
+    return render(stripSpecialMarker)
+}
+
 private fun shouldBeEscaped(string: String): Boolean {
     return string in KeywordStringsGenerated.KEYWORDS ||
             string.any { !Character.isLetterOrDigit(it) && it != '_' } ||
@@ -38,4 +44,4 @@
             append(element.render())
         }
     }
-}
\ No newline at end of file
+}