Bug 383502 - Injected-class-names of different instances of the same

template found in different base classes

Change-Id: I4eed0443e95ca388a771f158ba16ec27298f7afb
Signed-off-by: Nathan Ridge <zeratul976@hotmail.com>

core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2CPPTests.java

@@ -7825,6 +7825,23 @@ public class AST2CPPTests extends AST2TestBase {
 		parseAndCheckBindings();
 	}
 	
+	//	template<class>
+	//	struct ContainerOf {
+	//		int numParts;
+	//	};
+	//
+	//	struct HumanPart;
+	//	struct RobotPart;
+	//
+	//	struct BionicMan : ContainerOf<HumanPart>, ContainerOf<RobotPart> {
+	//		int numRoboParts() {
+	//			return ContainerOf<RobotPart>::numParts;
+	//		}
+	//	};
+	public void testInheritanceFromMultipleInstancesOfSameTemplate_383502() throws Exception {
+		parseAndCheckBindings();
+	}
+
 	//	int v1;
 	//	static int v2;
 	//	extern int v3;

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/BaseClassLookup.java

@@ -28,10 +28,13 @@ import org.eclipse.cdt.core.dom.ast.IProblemBinding;
 import org.eclipse.cdt.core.dom.ast.IScope;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPASTNameSpecifier;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPASTQualifiedName;
+import org.eclipse.cdt.core.dom.ast.cpp.ICPPASTTemplateId;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPBase;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPClassScope;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPClassType;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPMember;
+import org.eclipse.cdt.core.dom.ast.cpp.ICPPTemplateDefinition;
+import org.eclipse.cdt.core.dom.ast.cpp.ICPPTemplateInstance;
 import org.eclipse.cdt.core.parser.util.ArrayUtil;
 import org.eclipse.cdt.core.parser.util.CharArrayObjectMap;
 import org.eclipse.cdt.internal.core.dom.parser.ProblemBinding;
@@ -384,16 +387,62 @@ class BaseClassLookup {
 		}
 		if (numBindingsToAdd < fBindings.length)
 			fBindings[numBindingsToAdd] = null;
+		boolean possibleAmbiguity = false;
 		if (result.length > 0 && numBindingsToAdd > 0 && data.problem == null) {
-			// Matches are found in more than one base class - this is an indication of ambiguity.
+			// Matches are found in more than one base class - this is usually 
-			data.problem= new ProblemBinding(data.getLookupName(),
+			// an indication of ambiguity (but see below).
-					IProblemBinding.SEMANTIC_AMBIGUOUS_LOOKUP, result);
+			possibleAmbiguity = true;
 		}
 		result= ArrayUtil.addAll(result, fBindings);
+		if (possibleAmbiguity) {
+			// [temp.local] p4:
+			//   A lookup that finds an injected-class-name can result in an
+			//   ambiguity in certain cases (for example, if it is found in
+			//   more than one base class). If all of the injected-class-names
+			//   that are found refer to specializations of the same class
+			//   template, and if the name is used as a template-name, the
+			//   reference refers to the class template itself and not a
+			//   specialization thereof, and is not ambiguous.
+			result = collapseInjectedClassNames(data, result);
+			if (result.length > 1) {
+				data.problem= new ProblemBinding(data.getLookupName(),
+						IProblemBinding.SEMANTIC_AMBIGUOUS_LOOKUP, result);
+			}
+		}
 		for (int i= 0; i < fChildren.size(); i++) {
 			BaseClassLookup child = fChildren.get(i);
 			result= child.collectResult(data, fVirtual.get(i), result);
 		}
 		return result;
 	}
+	
+	// If all bindings in 'result' are instances of the same class template,
+	// collapse them to the class template itself. Only applies if the lookup
+	// is for a name used as a template-name.
+	private IBinding[] collapseInjectedClassNames(LookupData data, IBinding[] result) {
+		IASTName lookupName = data.getLookupName();
+		if (lookupName == null || lookupName.getPropertyInParent() != ICPPASTTemplateId.TEMPLATE_NAME) {
+			// Name not used as a template-name.
+			return result;
+		}
+		ICPPTemplateDefinition template = null;
+		for (IBinding binding : result) {
+			if (binding instanceof ICPPClassType && binding instanceof ICPPTemplateInstance) {
+				ICPPTemplateDefinition specialized = 
+						(ICPPTemplateDefinition) ((ICPPTemplateInstance) binding).getSpecializedBinding();
+				if (template == null) {
+					template = specialized;
+					continue;
+				}
+				if (template == specialized) {
+					continue;
+				}
+			}
+			return result;
+		}
+		if (template != null) {
+			return new IBinding[] { template };
+		}
+		return result;
+	}
 }