Avoid using PossibleMatch in HashMap

The hashCode collides just based on the name, thus is not working for
cases where classes have same names. So let's use another key instead.

Author: mickaelistria

org.eclipse.jdt.core.javac/src/org/eclipse/jdt/internal/core/search/matching/DOMJavaSearchDelegate.java

@@ -24,6 +24,7 @@
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.IdentityHashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -117,23 +118,23 @@
 import org.eclipse.jdt.internal.core.util.Util;
 
 public class DOMJavaSearchDelegate implements IJavaSearchDelegate {
-	private Map<PossibleMatch, NodeSetWrapper> matchToWrapper = new HashMap<>();
 	public DOMJavaSearchDelegate() {
-
+		// must be kept as it's used by an extension point
 	}
 
 	@Override
 	public void locateMatches(MatchLocator locator, IJavaProject javaProject, PossibleMatch[] possibleMatches, int start,
 			int length) throws CoreException {
 		locator.initialize((JavaProject)javaProject, length);
+
+		Map<MatchingNodeSet, NodeSetWrapper> wrappedSets = new IdentityHashMap<>(); // PossibleMatch hashCode collides too easily
 		for( int i = 0; i < possibleMatches.length; i++ ) {
-			matchToWrapper.put(possibleMatches[i], wrapNodeSet(possibleMatches[i].nodeSet));
+			wrappedSets.put(possibleMatches[i].nodeSet, wrapNodeSet(possibleMatches[i].nodeSet));
 		}
 
-
-		Map<String, String> map = javaProject.getOptions(true);
-		map.put(CompilerOptions.OPTION_TaskTags, org.eclipse.jdt.internal.compiler.util.Util.EMPTY_STRING);
-		locator.options = new CompilerOptions(map);
+		Map<String, String> options = javaProject.getOptions(true);
+		options.put(CompilerOptions.OPTION_TaskTags, org.eclipse.jdt.internal.compiler.util.Util.EMPTY_STRING);
+		locator.options = new CompilerOptions(options);
 
 		// Original implementation used Map throughout, however,
 		// PossibleMatch was determined to be a bad / non-unique key where the
@@ -192,15 +193,10 @@ public void acceptAST(org.eclipse.jdt.core.ICompilationUnit source,
 				if (pm != null) {
 					for (int i = 0; i < possibleMatches.length; i++) {
 						if (possibleMatches[i] == pm) {
-//							String s = CharOperation.toString(pm.compoundName);
-//							if( "g1.t.s.ref.R1".equals(s)) {
-//							if( "g3.t.ref.R4".equals(s)) {
-//								int z = 5; z++; if( z == 3 ) {}
-//							}
 							domUnits[i] = ast;
 							nonNullDomIndexes.add(i);
 							locator.currentPossibleMatch = pm;
-							NodeSetWrapper wrapper = matchToWrapper.get(possibleMatches[i]);
+							NodeSetWrapper wrapper = wrappedSets.get(possibleMatches[i].nodeSet);
 							ast.accept(new PatternLocatorVisitor(locator, wrapper));
 							return;
 						}
@@ -214,7 +210,7 @@ public void acceptAST(org.eclipse.jdt.core.ICompilationUnit source,
 		for (int x : nonNullDomIndexes) {
 			PossibleMatch possibleMatch = possibleMatches[x];
 			locator.currentPossibleMatch = possibleMatch;
-			NodeSetWrapper wrapper = this.matchToWrapper.get(possibleMatch);
+			NodeSetWrapper wrapper = wrappedSets.get(possibleMatch.nodeSet);
 			for (org.eclipse.jdt.core.dom.ASTNode node : wrapper.trustedASTNodeLevels.keySet()) {
 				int level = wrapper.trustedASTNodeLevels.get(node);
 				SearchMatch match = toMatch(locator, node, level, possibleMatch);