From f8cfaad7b4f026e6be4fa4b86ea1e1864c630eae Mon Sep 17 00:00:00 2001
From: "Kirill A. Korinsky" <kirill@korins.ky>
Date: Sun, 11 Oct 2020 02:42:42 +0200
Subject: [PATCH] Introduced support of JDK15+

`java.lang.CharSequence` has `isEmpty` method since JDK 15 that makes impossibly
to compile scala by JDK15.

Fix it on the way that allows to compiled with JDK15 and before JDK15.

Link to the issue: https://github.com/scala/bug/issues/12172
---
 src/library/scala/collection/mutable/StringBuilder.scala | 6 ++++++
 src/reflect/scala/reflect/api/Names.scala                | 9 +++++++++
 src/reflect/scala/reflect/internal/Names.scala           | 6 +++---
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/library/scala/collection/mutable/StringBuilder.scala b/src/library/scala/collection/mutable/StringBuilder.scala
index 99421c45e8ed..b73be48cd43a 100644
--- a/src/library/scala/collection/mutable/StringBuilder.scala
+++ b/src/library/scala/collection/mutable/StringBuilder.scala
@@ -468,6 +468,12 @@ final class StringBuilder(val underlying: java.lang.StringBuilder) extends Abstr
    *  @return             the last applicable index where target occurs, or -1 if not found.
    */
   def lastIndexOf(str: String, fromIndex: Int): Int = underlying.lastIndexOf(str, fromIndex)
+
+  /** Tests whether this builder is empty.
+   *
+   *  @return  `true` if this builder contains nothing, `false` otherwise.
+   */
+  override def isEmpty: Boolean = underlying.length() == 0
 }
 
 object StringBuilder {
diff --git a/src/reflect/scala/reflect/api/Names.scala b/src/reflect/scala/reflect/api/Names.scala
index 8cddc5d6f062..dece857e7394 100644
--- a/src/reflect/scala/reflect/api/Names.scala
+++ b/src/reflect/scala/reflect/api/Names.scala
@@ -121,6 +121,15 @@ trait Names {
     /** The encoded name, still represented as a name.
      */
     def encodedName: Name
+
+    /** The length of this name. */
+    def length: Int
+
+    /** Tests whether this name is empty. */
+    def isEmpty: Boolean
+
+    /** Tests whether this name is not empty. */
+    def nonEmpty: Boolean
   }
 
   /** Create a new term name.
diff --git a/src/reflect/scala/reflect/internal/Names.scala b/src/reflect/scala/reflect/internal/Names.scala
index b557c4013886..285e5ec0f1e2 100644
--- a/src/reflect/scala/reflect/internal/Names.scala
+++ b/src/reflect/scala/reflect/internal/Names.scala
@@ -207,9 +207,9 @@ trait Names extends api.Names {
     def next: Name with ThisNameType
 
     /** The length of this name. */
-    final def length: Int = len
-    final def isEmpty = length == 0
-    final def nonEmpty = !isEmpty
+    override final def length: Int = len
+    override final def isEmpty: Boolean = length == 0
+    override final def nonEmpty: Boolean = !isEmpty
 
     def nameKind: String
     def isTermName: Boolean