EA-28828 - IOOBE: CharArray.charAt

Corrected pasting at the document start

java/java-tests/testSrc/com/intellij/codeInsight/editorActions/BlockIndentOnPasteTest.groovy

@@ -156,6 +156,23 @@ class Test {
      }
     }
 }\
+'''
+    doTest(before, toPaste, expected)
+  }
+
+  void testPasteAtDocumentStartColumn() {
+    def before = '<caret>'
+
+    def toPaste =
+    '''\
+          class Test {
+          }\
+'''
+
+
+    def expected = '''\
+class Test {
+}\
 '''
     doTest(before, toPaste, expected)
   }

platform/lang-impl/src/com/intellij/codeInsight/editorActions/PasteHandler.java

@@ -383,7 +383,7 @@ public class PasteHandler extends EditorActionHandler {
     final int i = CharArrayUtil.shiftBackward(chars, startOffset - 1, " \t");
     
     // Handle situation when pasted block doesn't start new line.
-    if (chars.charAt(i) != '\n') {
+    if (i > 0 && chars.charAt(i) != '\n') {
       int firstNonWsOffset = CharArrayUtil.shiftForward(chars, firstLineStart, " \t");
       if (firstNonWsOffset > firstLineStart) {
         CharSequence toInsert = chars.subSequence(firstLineStart, firstNonWsOffset);