IDEA-111362 Generate constructor removes "m" from variable name

java/java-impl/src/com/intellij/psi/impl/source/codeStyle/JavaCodeStyleManagerImpl.java

@@ -748,8 +748,11 @@ public class JavaCodeStyleManagerImpl extends JavaCodeStyleManager {
     String suffix = getSuffixByVariableKind(variableKind);
     boolean doDecapitalize = false;
 
-    if (name.startsWith(prefix) && name.length() > prefix.length()) {
-      name = name.substring(prefix.length());
+    int pLength = prefix.length();
+    if (pLength > 0 && name.startsWith(prefix) && name.length() > pLength &&
+        // check it's not just a long camel word that happens to begin with the specified prefix
+        (!Character.isJavaIdentifierPart(prefix.charAt(pLength - 1)) || Character.isUpperCase(name.charAt(pLength)))) {
+      name = name.substring(pLength);
       doDecapitalize = true;
     }
 

java/java-tests/testData/codeInsight/generateConstructor/afterFieldPrefixCoincidence.java

@@ -0,0 +1,8 @@
+class Parent {
+    Object menu;
+
+    Parent(Object menu) {
+        this.menu = menu;
+    }
+}
+

java/java-tests/testData/codeInsight/generateConstructor/beforeFieldPrefixCoincidence.java

@@ -0,0 +1,5 @@
+class Parent {
+    Object menu;
+<caret>
+}
+

java/java-tests/testSrc/com/intellij/codeInsight/GenerateConstructorTest.java

@@ -50,6 +50,11 @@ public class GenerateConstructorTest extends LightCodeInsightTestCase {
   public void testFinalFieldPreselection() throws Exception { doTest(true); }
   public void testSubstitution() throws Exception { doTest(true); }
 
+  public void testFieldPrefixCoincidence() throws Exception {
+    CodeStyleSettingsManager.getInstance(getProject()).getCurrentSettings().FIELD_NAME_PREFIX = "m";
+    doTest();
+  }
+
   private void doTest() throws Exception {
     doTest(false);
   }