### Eclipse Workspace Patch 1.0
#P org.eclipse.jdt.core.tests.compiler
Index: src/org/eclipse/jdt/core/tests/compiler/regression/BatchCompilerTest.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/BatchCompilerTest.java,v
retrieving revision 1.176
diff -u -r1.176 BatchCompilerTest.java
--- src/org/eclipse/jdt/core/tests/compiler/regression/BatchCompilerTest.java	3 Oct 2008 08:39:27 -0000	1.176
+++ src/org/eclipse/jdt/core/tests/compiler/regression/BatchCompilerTest.java	10 Oct 2008 16:32:07 -0000
@@ -1654,6 +1654,7 @@
         "      finalBound           type parameter with final bound\n" +
         "      finally            + finally block not completing normally\n" +
         "      forbidden          + use of types matching a forbidden access rule\n" +
+        "      hashCode               missing hashCode() method when overriding equals()\n" + 
         "      hiding               macro for fieldHiding, localHiding, typeHiding and\n" +
         "                           maskedCatchBlock\n" +
         "      incomplete-switch    same as enumSwitch\n" +
@@ -1799,6 +1800,7 @@
 			"		<option key=\"org.eclipse.jdt.core.compiler.problem.localVariableHiding\" value=\"ignore\"/>\n" +
 			"		<option key=\"org.eclipse.jdt.core.compiler.problem.methodWithConstructorName\" value=\"warning\"/>\n" +
 			"		<option key=\"org.eclipse.jdt.core.compiler.problem.missingDeprecatedAnnotation\" value=\"ignore\"/>\n" +
+			"		<option key=\"org.eclipse.jdt.core.compiler.problem.missingHashCodeMethod\" value=\"ignore\"/>\n" +
 			"		<option key=\"org.eclipse.jdt.core.compiler.problem.missingJavadocComments\" value=\"ignore\"/>\n" +
 			"		<option key=\"org.eclipse.jdt.core.compiler.problem.missingJavadocCommentsOverriding\" value=\"disabled\"/>\n" +
 			"		<option key=\"org.eclipse.jdt.core.compiler.problem.missingJavadocCommentsVisibility\" value=\"public\"/>\n" +
Index: src/org/eclipse/jdt/core/tests/compiler/regression/MethodVerifyTest.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/MethodVerifyTest.java,v
retrieving revision 1.161
diff -u -r1.161 MethodVerifyTest.java
--- src/org/eclipse/jdt/core/tests/compiler/regression/MethodVerifyTest.java	9 Oct 2008 14:10:09 -0000	1.161
+++ src/org/eclipse/jdt/core/tests/compiler/regression/MethodVerifyTest.java	10 Oct 2008 16:32:09 -0000
@@ -8929,4 +8929,47 @@
 		"----------\n"
 	);
 }
+
+//https://bugs.eclipse.org/bugs/show_bug.cgi?id=38751
+public void test175() {
+	Map options = getCompilerOptions();
+	options.put(CompilerOptions.OPTION_ReportMissingHashCodeMethod, CompilerOptions.WARNING);
+	this.runNegativeTest(
+		new String[] {
+			"A.java",
+			"class A {\n" +
+			"	@Override public boolean equals(Object o) { return true; }\n" +
+			"}"
+		},
+		"----------\n" + 
+		"1. WARNING in A.java (at line 1)\n" + 
+		"	class A {\n" + 
+		"	      ^\n" + 
+		"The type A should also implement hashcode() since it overrides Object.equals()\n" + 
+		"----------\n",
+	null,
+	false,
+	options);
+}
+
+//https://bugs.eclipse.org/bugs/show_bug.cgi?id=38751
+public void test176() {
+	Map options = getCompilerOptions();
+	options.put(CompilerOptions.OPTION_ReportMissingHashCodeMethod, CompilerOptions.WARNING);
+	this.runNegativeTest(
+		new String[] {
+			"A.java",
+			"class A {\n" +
+			"	@Override public boolean equals(Object o) { return true; }\n" +
+			"	@Override public int hashCode() { return 1; }\n" +
+			"}\n" +
+			"class B extends A {\n" +
+			"	@Override public boolean equals(Object o) { return false; }\n" +
+			"}"
+		},
+		"",
+	null,
+	false,
+	options);
+}
 }
Index: src/org/eclipse/jdt/core/tests/compiler/regression/CompilerInvocationTests.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core.tests.compiler/src/org/eclipse/jdt/core/tests/compiler/regression/CompilerInvocationTests.java,v
retrieving revision 1.20
diff -u -r1.20 CompilerInvocationTests.java
--- src/org/eclipse/jdt/core/tests/compiler/regression/CompilerInvocationTests.java	5 Sep 2008 10:24:40 -0000	1.20
+++ src/org/eclipse/jdt/core/tests/compiler/regression/CompilerInvocationTests.java	10 Oct 2008 16:32:08 -0000
@@ -852,6 +852,7 @@
 		expectedProblemAttributes.put("ExternalProblemNotFixable", new ProblemAttributes(CategorizedProblem.CAT_INTERNAL));
 		expectedProblemAttributes.put("ExternalProblemFixable", new ProblemAttributes(CategorizedProblem.CAT_INTERNAL));
 		expectedProblemAttributes.put("MissingSynchronizedModifierInInheritedMethod", new ProblemAttributes(CategorizedProblem.CAT_POTENTIAL_PROGRAMMING_PROBLEM));
+		expectedProblemAttributes.put("ShouldImplementHashcode", new ProblemAttributes(CategorizedProblem.CAT_POTENTIAL_PROGRAMMING_PROBLEM));
 		StringBuffer failures = new StringBuffer();
 		Field[] fields = (iProblemClass = IProblem.class).getFields();
 		boolean watchInternalCategory = false, printHeader = true;
@@ -2002,6 +2003,7 @@
 		expectedProblemAttributes.put("ExternalProblemFixable", SKIP);
 		expectedProblemAttributes.put("ComparingIdentical", new ProblemAttributes(JavaCore.COMPILER_PB_COMPARING_IDENTICAL));
 		expectedProblemAttributes.put("MissingSynchronizedModifierInInheritedMethod", new ProblemAttributes(JavaCore.COMPILER_PB_MISSING_SYNCHRONIZED_ON_INHERITED_METHOD));
+		expectedProblemAttributes.put("ShouldImplementHashcode", new ProblemAttributes(JavaCore.COMPILER_PB_MISSING_HASHCODE_METHOD));
 		Map constantNamesIndex = new HashMap();
 		Field[] fields = JavaCore.class.getFields();
 		for (int i = 0, length = fields.length; i < length; i++) {
#P org.eclipse.jdt.core
Index: compiler/org/eclipse/jdt/core/compiler/IProblem.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/compiler/org/eclipse/jdt/core/compiler/IProblem.java,v
retrieving revision 1.205
diff -u -r1.205 IProblem.java
--- compiler/org/eclipse/jdt/core/compiler/IProblem.java	3 Oct 2008 16:20:02 -0000	1.205
+++ compiler/org/eclipse/jdt/core/compiler/IProblem.java	10 Oct 2008 16:32:11 -0000
@@ -627,6 +627,8 @@
 	int ObjectMustBeClass = Internal + 330;
 	/** @since 3.4 */
 	int RedundantSuperinterface = TypeRelated + 331;
+	/** @since 3.5 */
+	int ShouldImplementHashcode = TypeRelated + 332;
 
 	/** @deprecated - problem is no longer generated, use {@link #UndefinedType} instead */
 	int SuperclassNotFound =  TypeRelated + 329 + ProblemReasons.NotFound; // TypeRelated + 330
Index: batch/org/eclipse/jdt/internal/compiler/batch/messages.properties
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/batch/org/eclipse/jdt/internal/compiler/batch/messages.properties,v
retrieving revision 1.770
diff -u -r1.770 messages.properties
--- batch/org/eclipse/jdt/internal/compiler/batch/messages.properties	9 Oct 2008 08:13:06 -0000	1.770
+++ batch/org/eclipse/jdt/internal/compiler/batch/messages.properties	10 Oct 2008 16:32:11 -0000
@@ -251,6 +251,7 @@
 \      finalBound           type parameter with final bound\n\
 \      finally            + finally block not completing normally\n\
 \      forbidden          + use of types matching a forbidden access rule\n\
+\      hashCode               missing hashCode() method when overriding equals()\n\
 \      hiding               macro for fieldHiding, localHiding, typeHiding and\n\
 \                           maskedCatchBlock\n\
 \      incomplete-switch    same as enumSwitch\n\
Index: batch/org/eclipse/jdt/internal/compiler/batch/Main.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/batch/org/eclipse/jdt/internal/compiler/batch/Main.java,v
retrieving revision 1.334
diff -u -r1.334 Main.java
--- batch/org/eclipse/jdt/internal/compiler/batch/Main.java	9 Oct 2008 11:56:49 -0000	1.334
+++ batch/org/eclipse/jdt/internal/compiler/batch/Main.java	10 Oct 2008 16:32:11 -0000
@@ -3205,6 +3205,11 @@
 					CompilerOptions.OPTION_ReportTypeParameterHiding,
 					isEnabling ? CompilerOptions.WARNING : CompilerOptions.IGNORE);
 				return;
+			} else if (token.equals("hashCode")) { //$NON-NLS-1$
+				this.options.put(
+					CompilerOptions.OPTION_ReportMissingHashCodeMethod,
+					isEnabling ? CompilerOptions.WARNING : CompilerOptions.IGNORE);
+				return;
 			}
 			break;
 		case 'i' :
Index: compiler/org/eclipse/jdt/internal/compiler/problem/messages.properties
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/problem/messages.properties,v
retrieving revision 1.241
diff -u -r1.241 messages.properties
--- compiler/org/eclipse/jdt/internal/compiler/problem/messages.properties	3 Oct 2008 16:20:02 -0000	1.241
+++ compiler/org/eclipse/jdt/internal/compiler/problem/messages.properties	10 Oct 2008 16:32:13 -0000
@@ -256,6 +256,7 @@
 329 = The type java.lang.Object cannot have a superclass or superinterfaces
 330 = The type java.lang.Object must be a class
 331 = Redundant superinterface {0} for the type {1}, already defined by {2}
+332 = The type {0} should also implement hashcode() since it overrides Object.equals()
 
 ###[obsolete] 330 = {0} cannot be resolved or is not a valid superclass
 ###[obsolete] 331 = Superclass {0} is not visible
Index: compiler/org/eclipse/jdt/internal/compiler/problem/ProblemReporter.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/problem/ProblemReporter.java,v
retrieving revision 1.379
diff -u -r1.379 ProblemReporter.java
--- compiler/org/eclipse/jdt/internal/compiler/problem/ProblemReporter.java	3 Oct 2008 16:20:02 -0000	1.379
+++ compiler/org/eclipse/jdt/internal/compiler/problem/ProblemReporter.java	10 Oct 2008 16:32:13 -0000
@@ -323,6 +323,9 @@
 			
 		case IProblem.MissingSynchronizedModifierInInheritedMethod:
 			return CompilerOptions.MissingSynchronizedModifierInInheritedMethod;
+
+		case IProblem.ShouldImplementHashcode:
+			return CompilerOptions.ShouldImplementHashcode;
 	}
 	return 0;
 }
@@ -370,7 +373,8 @@
 			case CompilerOptions.FallthroughCase :
 			case CompilerOptions.OverridingMethodWithoutSuperInvocation :
 			case CompilerOptions.ComparingIdentical :
-			case CompilerOptions.MissingSynchronizedModifierInInheritedMethod :				
+			case CompilerOptions.MissingSynchronizedModifierInInheritedMethod :
+			case CompilerOptions.ShouldImplementHashcode :
 				return CategorizedProblem.CAT_POTENTIAL_PROGRAMMING_PROBLEM;
 			
 			case CompilerOptions.OverriddenPackageDefaultMethod :
@@ -7265,4 +7269,13 @@
 		typeRef.sourceStart,
 		typeRef.sourceEnd);
 }
+
+public void shouldImplementHashcode(SourceTypeBinding type) {	
+	this.handle(
+		IProblem.ShouldImplementHashcode,
+		new String[] {new String(type.sourceName())},
+		new String[] {new String(type.sourceName())},
+		type.sourceStart(),
+		type.sourceEnd());
+}
 }
Index: model/org/eclipse/jdt/core/JavaCore.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/model/org/eclipse/jdt/core/JavaCore.java,v
retrieving revision 1.628
diff -u -r1.628 JavaCore.java
--- model/org/eclipse/jdt/core/JavaCore.java	9 Oct 2008 08:13:08 -0000	1.628
+++ model/org/eclipse/jdt/core/JavaCore.java	10 Oct 2008 16:32:14 -0000
@@ -986,6 +986,19 @@
 	 */
 	public static final String COMPILER_PB_MISSING_DEPRECATED_ANNOTATION = PLUGIN_ID + ".compiler.problem.missingDeprecatedAnnotation"; //$NON-NLS-1$
 	/**
+	 * Compiler option ID: Reporting Missing HashCode Method.
+	 * <p>When enabled, the compiler will issue an error or a warning if a type
+	 * overrides Object.equals(Object) but does not override hashCode().
+	 * <dl>
+	 * <dt>Option id:</dt><dd><code>"org.eclipse.jdt.core.compiler.problem.missingHashCodeMethod"</code></dd>
+	 * <dt>Possible values:</dt><dd><code>{ "error", "warning", "ignore" }</code></dd>
+	 * <dt>Default:</dt><dd><code>"ignore"</code></dd>
+	 * </dl>
+	 * @since 3.5
+	 * @category CompilerOptionID
+	 */
+	public static final String COMPILER_PB_MISSING_HASHCODE_METHOD = PLUGIN_ID + ".compiler.problem.missingHashCodeMethod"; //$NON-NLS-1$
+	/**
 	 * Compiler option ID: Reporting Incomplete Enum Switch.
 	 * <p>When enabled, the compiler will issue an error or a warning whenever
 	 *    an enum constant has no corresponding case label in an enum switch
Index: .settings/org.eclipse.jdt.core.prefs
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/.settings/org.eclipse.jdt.core.prefs,v
retrieving revision 1.18
diff -u -r1.18 org.eclipse.jdt.core.prefs
--- .settings/org.eclipse.jdt.core.prefs	6 Oct 2008 15:29:00 -0000	1.18
+++ .settings/org.eclipse.jdt.core.prefs	10 Oct 2008 16:32:11 -0000
@@ -44,6 +44,7 @@
 org.eclipse.jdt.core.compiler.problem.localVariableHiding=warning
 org.eclipse.jdt.core.compiler.problem.methodWithConstructorName=warning
 org.eclipse.jdt.core.compiler.problem.missingDeprecatedAnnotation=ignore
+org.eclipse.jdt.core.compiler.problem.missingHashCodeMethod=warning
 org.eclipse.jdt.core.compiler.problem.missingJavadocComments=ignore
 org.eclipse.jdt.core.compiler.problem.missingJavadocCommentsOverriding=enabled
 org.eclipse.jdt.core.compiler.problem.missingJavadocCommentsVisibility=public
Index: compiler/org/eclipse/jdt/internal/compiler/impl/CompilerOptions.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/impl/CompilerOptions.java,v
retrieving revision 1.208
diff -u -r1.208 CompilerOptions.java
--- compiler/org/eclipse/jdt/internal/compiler/impl/CompilerOptions.java	12 Sep 2008 13:28:53 -0000	1.208
+++ compiler/org/eclipse/jdt/internal/compiler/impl/CompilerOptions.java	10 Oct 2008 16:32:12 -0000
@@ -122,6 +122,7 @@
 	public static final String OPTION_ReportRedundantSuperinterface =  "org.eclipse.jdt.core.compiler.problem.redundantSuperinterface"; //$NON-NLS-1$
 	public static final String OPTION_ReportComparingIdentical =  "org.eclipse.jdt.core.compiler.problem.comparingIdentical"; //$NON-NLS-1$
 	public static final String OPTION_ReportMissingSynchronizedOnInheritedMethod =  "org.eclipse.jdt.core.compiler.problem.missingSynchronizedOnInheritedMethod"; //$NON-NLS-1$
+	public static final String OPTION_ReportMissingHashCodeMethod =  "org.eclipse.jdt.core.compiler.problem.missingHashCodeMethod"; //$NON-NLS-1$
 
 	// Backward compatibility
 	public static final String OPTION_ReportInvalidAnnotation = "org.eclipse.jdt.core.compiler.problem.invalidAnnotation"; //$NON-NLS-1$
@@ -224,8 +225,7 @@
 	public static final int MissingSynchronizedModifierInInheritedMethod= IrritantSet.GROUP1 | ASTNode.Bit29;
 
 	// group 2
-	// NEXT IRRITANT GOES HERE (group1 is complete already)
-	//	public static final int FirstInGroup2 = IrritantSet.GROUP2 | ASTNode.Bit1;
+	public static final int ShouldImplementHashcode= IrritantSet.GROUP2 | ASTNode.Bit1;
 	
 	// Map: String optionKey --> Long irritant>
 	private static Map OptionToIrritants;
@@ -476,6 +476,8 @@
 				return OPTION_ReportComparingIdentical;
 			case MissingSynchronizedModifierInInheritedMethod :
 				return OPTION_ReportMissingSynchronizedOnInheritedMethod;
+			case ShouldImplementHashcode :
+				return OPTION_ReportMissingHashCodeMethod;
 		}
 		return null;
 	}
@@ -890,6 +892,7 @@
 		optionsMap.put(OPTION_ReportRedundantSuperinterface, getSeverityString(RedundantSuperinterface));
 		optionsMap.put(OPTION_ReportComparingIdentical, getSeverityString(ComparingIdentical));
 		optionsMap.put(OPTION_ReportMissingSynchronizedOnInheritedMethod, getSeverityString(MissingSynchronizedModifierInInheritedMethod));
+		optionsMap.put(OPTION_ReportMissingHashCodeMethod, getSeverityString(ShouldImplementHashcode));
 		return optionsMap;
 	}
 
@@ -1260,6 +1263,7 @@
 		if ((optionValue = optionsMap.get(OPTION_ReportRedundantSuperinterface)) != null) updateSeverity(RedundantSuperinterface, optionValue);
 		if ((optionValue = optionsMap.get(OPTION_ReportComparingIdentical)) != null) updateSeverity(ComparingIdentical, optionValue);
 		if ((optionValue = optionsMap.get(OPTION_ReportMissingSynchronizedOnInheritedMethod)) != null) updateSeverity(MissingSynchronizedModifierInInheritedMethod, optionValue);
+		if ((optionValue = optionsMap.get(OPTION_ReportMissingHashCodeMethod)) != null) updateSeverity(ShouldImplementHashcode, optionValue);
 
 		// Javadoc options
 		if ((optionValue = optionsMap.get(OPTION_DocCommentSupport)) != null) {
@@ -1456,6 +1460,7 @@
 		buf.append("\n\t- redundant superinterface: ").append(getSeverityString(RedundantSuperinterface)); //$NON-NLS-1$
 		buf.append("\n\t- comparing identical expr: ").append(getSeverityString(ComparingIdentical)); //$NON-NLS-1$
 		buf.append("\n\t- missing synchronized on inherited method: ").append(getSeverityString(MissingSynchronizedModifierInInheritedMethod)); //$NON-NLS-1$
+		buf.append("\n\t- should implement hashCode() method: ").append(getSeverityString(ShouldImplementHashcode)); //$NON-NLS-1$
 		return buf.toString();
 	}
 	
Index: compiler/org/eclipse/jdt/internal/compiler/lookup/MethodVerifier.java
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.core/compiler/org/eclipse/jdt/internal/compiler/lookup/MethodVerifier.java,v
retrieving revision 1.97
diff -u -r1.97 MethodVerifier.java
--- compiler/org/eclipse/jdt/internal/compiler/lookup/MethodVerifier.java	26 Aug 2008 11:52:54 -0000	1.97
+++ compiler/org/eclipse/jdt/internal/compiler/lookup/MethodVerifier.java	10 Oct 2008 16:32:12 -0000
@@ -24,6 +24,8 @@
 	HashtableOfObject currentMethods;
 	LookupEnvironment environment;
 	private boolean allowCompatibleReturnTypes;
+	char[] equals = "equals".toCharArray(); //$NON-NLS-1$
+	char[] hashCode = "hashCode".toCharArray(); //$NON-NLS-1$
 /*
 Binding creation is responsible for reporting all problems with types:
 	- all modifier problems (duplicates & multiple visibility modifiers + incompatible combinations - abstract/final)
@@ -247,6 +249,18 @@
 	// no op before 1.5
 }
 
+void checkForMissingHashCodeMethod() {
+	MethodBinding[] choices = this.type.getMethods(this.equals);
+	boolean overridesEquals = false;
+	for (int i = choices.length; !overridesEquals && --i >= 0;)
+		overridesEquals = choices[i].parameters.length == 1 && choices[i].parameters[0].id == TypeIds.T_JavaLangObject;
+	if (overridesEquals) {
+		MethodBinding hashCodeMethod = this.type.getExactMethod(this.hashCode, Binding.NO_PARAMETERS, null);
+		if (hashCodeMethod != null && hashCodeMethod.declaringClass.id == TypeIds.T_JavaLangObject)
+			this.problemReporter().shouldImplementHashcode(this.type);
+	}
+}
+
 void checkForRedundantSuperinterfaces(ReferenceBinding superclass, ReferenceBinding[] superInterfaces) {
 	if (superInterfaces == Binding.NO_SUPERINTERFACES) return;
 
@@ -861,6 +875,8 @@
 	computeMethods();
 	computeInheritedMethods();
 	checkMethods();
+	if (this.type.isClass())
+		checkForMissingHashCodeMethod();
 }
 
 public String toString() {
#P org.eclipse.jdt.doc.isv
Index: guide/jdt_api_options.htm
===================================================================
RCS file: /cvsroot/eclipse/org.eclipse.jdt.doc.isv/guide/jdt_api_options.htm,v
retrieving revision 1.67
diff -u -r1.67 jdt_api_options.htm
--- guide/jdt_api_options.htm	3 Jun 2008 19:41:57 -0000	1.67
+++ guide/jdt_api_options.htm	10 Oct 2008 16:32:17 -0000
@@ -468,6 +468,20 @@
 </tr>
 
 <tr>
+<td colspan=2><b>Reporting Missing HashCode Method</b> (<b><a href="../reference/api/org/eclipse/jdt/core/JavaCore.html#COMPILER_PB_MISSING_HASHCODE_METHOD">COMPILER_PB_MISSING_HASHCODE_METHOD</a></b>)</td>
+</tr>
+<tr valign="top">
+<td rowspan=3>When enabled, the compiler will issue an error or a warning if a type overrides Object.equals(Object) but does not override hashCode().</td>
+<td><b><a href="../reference/api/org/eclipse/jdt/core/JavaCore.html#ERROR"><i>ERROR</i></a></b></td>
+</tr>
+<tr valign="top">
+<td><b><a href="../reference/api/org/eclipse/jdt/core/JavaCore.html#WARNING">WARNING</a></b></td>
+</tr>
+<tr valign="top">
+<td><b><a href="../reference/api/org/eclipse/jdt/core/JavaCore.html#IGNORE">IGNORE</a></b></td>
+</tr>
+
+<tr>
 <td colspan=2><b>Reporting Hidden Catch Block</b> (<b><a href="../reference/api/org/eclipse/jdt/core/JavaCore.html#COMPILER_PB_HIDDEN_CATCH_BLOCK">COMPILER_PB_HIDDEN_CATCH_BLOCK</a></b>)</td>
 </tr>
 <tr valign="top">