IG: don't report (more) invisible characters as unnecessary escapes (IDEA-169813)

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/internationalization/UnnecessaryUnicodeEscapeInspection.java

@@ -37,7 +37,10 @@ import org.jetbrains.annotations.Nullable;
 
 import java.nio.ByteBuffer;
 import java.nio.CharBuffer;
-import java.nio.charset.*;
+import java.nio.charset.Charset;
+import java.nio.charset.CharsetEncoder;
+import java.nio.charset.CoderResult;
+import java.nio.charset.CodingErrorAction;
 
 /**
  * @author Bas Leijdekkers
@@ -146,7 +149,17 @@ public class UnnecessaryUnicodeEscapeInspection extends BaseInspection {
             StringUtil.isHexDigit(text.charAt(nextChar + 3))) {
           final int escapeEnd = nextChar + 4;
           final char d = (char)Integer.parseInt(text.substring(nextChar, escapeEnd), 16);
-          if (Character.isISOControl(d)) {
+          final int type = Character.getType(d);
+          if (type == Character.CONTROL ||
+              type == Character.FORMAT ||
+              type == Character.PRIVATE_USE ||
+              type == Character.SURROGATE ||
+              type == Character.UNASSIGNED ||
+              type == Character.LINE_SEPARATOR ||
+              type == Character.PARAGRAPH_SEPARATOR) {
+            continue;
+          }
+          if (type == Character.SPACE_SEPARATOR && d != ' ') {
             continue;
           }
           byteBuffer.clear();

plugins/InspectionGadgets/test/com/siyeh/igtest/internationalization/unnecessary_unicode_escape/UnnecessaryUnicodeEscape.java

@@ -5,6 +5,9 @@ class UnnecessaryUnicodeEscape {
   // control char & not representable char: \u0010 \u00e4
 
   char[] surrogates = new char[]{'\ud800','\udc00'};
+
+  String t = "<warning descr="Unicode escape sequence '\u0020' can be replaced with ' '">\u0020</warning>";
+  String u = "\u200B\u200E\u00A0\u200F";
 }
 @SuppressWarnings("UnnecessaryUnicodeEscape")
 class Suppress {