2 files changed, 36 insertions, 3 deletions
diff --git a/src/reflect/scala/reflect/internal/util/SourceFile.scala b/src/reflect/scala/reflect/internal/util/SourceFile.scala
index 9866b043bb..add072aa71 100644
--- a/src/reflect/scala/reflect/internal/util/SourceFile.scala
+++ b/src/reflect/scala/reflect/internal/util/SourceFile.scala
@@ -40,8 +40,8 @@ abstract class SourceFile {
   def lineToString(index: Int): String = {
     val start = lineToOffset(index)
     var end = start
-    while (!isEndOfLine(end)) end += 1
-    content.slice(start, end) mkString ""
+    while (!isEndOfLine(end) && end <= length) end += 1
+    new String(content, start, end - start)
   }
 
   @tailrec
@@ -136,7 +136,7 @@ class BatchSourceFile(val file : AbstractFile, val content0: Array[Char]) extend
 
   private def charAtIsEOL(idx: Int)(p: Char => Boolean) = {
     // don't identify the CR in CR LF as a line break, since LF will do.
-    def notCRLF0 = content(idx) != CR || idx + 1 >= length || content(idx + 1) != LF
+    def notCRLF0 = content(idx) != CR || !content.isDefinedAt(idx + 1) || content(idx + 1) != LF
 
     idx < length && notCRLF0 && p(content(idx))
   }
diff --git a/test/junit/scala/reflect/internal/util/SourceFileTest.scala b/test/junit/scala/reflect/internal/util/SourceFileTest.scala
new file mode 100644
index 0000000000..bbd5685ef7
--- /dev/null
+++ b/test/junit/scala/reflect/internal/util/SourceFileTest.scala
@@ -0,0 +1,33 @@
+package scala.reflect.internal.util
+
+import org.junit.Assert._
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.junit.runners.JUnit4
+
+@RunWith(classOf[JUnit4])
+class SourceFileTest {
+  def lineContentOf(code: String, offset: Int) =
+    Position.offset(new BatchSourceFile("", code), offset).lineContent
+
+  @Test
+  def si8205_overflow(): Unit = {
+    val file = new BatchSourceFile("", "code no newline")
+    // the bug in lineToString counted until MaxValue, and the AIOOBE came from here
+    assertFalse(file.isEndOfLine(Int.MaxValue))
+  }
+
+  @Test
+  def si8205_lineToString(): Unit = {
+    assertEquals("", lineContentOf("", 0))
+    assertEquals("abc", lineContentOf("abc", 0))
+    assertEquals("abc", lineContentOf("abc", 3))
+    assertEquals("code no newline", lineContentOf("code no newline", 1))
+    assertEquals("", lineContentOf("\n", 0))
+    assertEquals("abc", lineContentOf("abc\ndef", 0))
+    assertEquals("abc", lineContentOf("abc\ndef", 3))
+    assertEquals("def", lineContentOf("abc\ndef", 4))
+    assertEquals("def", lineContentOf("abc\ndef", 6))
+    assertEquals("def", lineContentOf("abc\ndef\n", 7))
+  }
+}