Escape in BLangNodeBuilder

compiler/ballerina-lang/src/main/java/org/wso2/ballerinalang/compiler/parser/BLangNodeBuilder.java

@@ -6049,10 +6049,10 @@ private BLangIdentifier createIdentifier(Location pos, String value, String orig
         }
 
         if (value.startsWith(IDENTIFIER_LITERAL_PREFIX)) {
-            bLIdentifer.setValue(Utils.unescapeUnicodeCodepoints(value.substring(1)));
+            bLIdentifer.setValue(Utils.unescapeBallerina(value.substring(1)));
             bLIdentifer.setLiteral(true);
         } else {
-            bLIdentifer.setValue(Utils.unescapeUnicodeCodepoints(value));
+            bLIdentifer.setValue(Utils.unescapeBallerina(value));
             bLIdentifer.setLiteral(false);
         }
         bLIdentifer.setOriginalValue(originalValue);

misc/identifier-util/src/main/java/io/ballerina/identifier/Utils.java

@@ -88,7 +88,8 @@ private static String encodeIdentifier(String identifier) {
      * @return a new unescaped {@code String}, {@code null} if null string input
      */
     public static String unescapeJava(String str) {
-        return StringEscapeUtils.unescapeJava(str);
+        String result = str.replaceAll("\\\\(\\d)", "$1");
+        return StringEscapeUtils.unescapeJava(result);
     }
 
     private static Identifier encodeGeneratedName(String identifier) {

tests/jballerina-unit-test/src/test/java/org/ballerinalang/test/identifiers/IdentifierTest.java

@@ -74,6 +74,15 @@ public void testInvalidImportOnMultipleFiles() {
         assertEquals(result.getErrorCount(), index);
     }
 
+    @Test(description = "Test identifiers containing escape character")
+    public void testEscapedIdentifier() {
+        CompileResult result = BCompileUtil.compile("test-src/identifiers/identifier_with_escape_char.bal");
+        int index = 0;
+        validateError(result, index++, "redeclared symbol 'a3'", 19, 9);
+        validateError(result, index++, "redeclared symbol 'student-performance'", 21, 9);
+        assertEquals(result.getErrorCount(), index);
+    }
+
     @Test(dataProvider = "functionsWithSelfAsIdentifier")
     public void testSelfAsIdentifier(String function) {
         CompileResult result = BCompileUtil.compile("test-src/identifiers/self_as_identifier.bal");

tests/jballerina-unit-test/src/test/resources/test-src/identifiers/identifier_with_escape_char.bal

@@ -0,0 +1,22 @@
+// Copyright (c) 2023, WSO2 LLC. (https://www.wso2.com) All Rights Reserved.
+//
+// WSO2 LLC. licenses this file to you under the Apache License,
+// Version 2.0 (the "License"); you may not use this file except
+// in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+public function foo() {
+    int a\3 = 0;
+    int a3 = 2;
+    int student\-performance = 3;
+    int student\u{002D}performance = 2;
+}