Bug 402617 - Code completion for members of a field of a deferred class

instance

Change-Id: Idfd8535e62fa35bbed3385c5489fae81e65b64d5
Signed-off-by: Nathan Ridge <zeratul976@hotmail.com>

core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/CPPUnknownTypeScope.java

@@ -30,6 +30,7 @@ import org.eclipse.cdt.core.dom.ast.cpp.ICPPASTTemplateId;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPASTUsingDeclaration;
 import org.eclipse.cdt.core.index.IIndexFileSet;
 import org.eclipse.cdt.core.parser.util.CharArrayObjectMap;
+import org.eclipse.cdt.internal.core.dom.parser.cpp.semantics.CPPSemantics;
 
 /**
  * Models the scope represented by an unknown type (e.g.: typeof(template type parameter)).
@@ -147,14 +148,14 @@ public class CPPUnknownTypeScope implements ICPPInternalUnknownScope {
 	@Override
 	public final IBinding[] getBindings(ScopeLookupData lookup) {
     	if (lookup.isPrefixLookup()) {
-    		if (fScopeType instanceof ICPPDeferredClassInstance) {
+			// If name lookup is performed for the purpose of code completion in a dependent context,
-	    		ICPPDeferredClassInstance instance = (ICPPDeferredClassInstance) fScopeType;
+			// try to give some useful results heuristically.
-				IScope scope = instance.getClassTemplate().getCompositeScope();
+			IScope scope = CPPSemantics.heuristicallyFindConcreteScopeForType(fScopeType, 
-				if (scope != null) {
+					lookup.getLookupPoint());
-					return scope.getBindings(lookup);
+			if (scope != null) {
-				}
+				return scope.getBindings(lookup);
-    		}
+			}
-    		return IBinding.EMPTY_BINDING_ARRAY;
+			return IBinding.EMPTY_BINDING_ARRAY;
     	}
     	IASTName lookupName= lookup.getLookupName();
     	if (lookupName != null)

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

@@ -22,7 +22,6 @@ import org.eclipse.cdt.core.dom.ast.IType;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPAliasTemplateInstance;
 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.ICPPClassSpecialization;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPClassTemplatePartialSpecialization;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPClassType;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPFunction;
@@ -278,9 +277,9 @@ public class AccessContext {
 				if (scopeType instanceof ICPPDeferredClassInstance) {
 					return ((ICPPDeferredClassInstance) scopeType).getClassTemplate();
 				}
-			} else {
-				scope = CPPSemantics.getParentScope(scope, data.getTranslationUnit());
 			}
+
+			scope = CPPSemantics.getParentScope(scope, data.getTranslationUnit());
 		}
 		if (scope instanceof ICPPClassScope) {
 			return ((ICPPClassScope) scope).getClassType();

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

@@ -83,6 +83,7 @@ import org.eclipse.cdt.core.dom.ast.IASTTypeId;
 import org.eclipse.cdt.core.dom.ast.IASTTypeIdExpression;
 import org.eclipse.cdt.core.dom.ast.IASTTypeIdInitializerExpression;
 import org.eclipse.cdt.core.dom.ast.IASTUnaryExpression;
+import org.eclipse.cdt.core.dom.ast.IField;
 import org.eclipse.cdt.core.dom.ast.IBasicType.Kind;
 import org.eclipse.cdt.core.dom.ast.IBinding;
 import org.eclipse.cdt.core.dom.ast.ICompositeType;
@@ -3951,4 +3952,48 @@ public class CPPSemantics {
 
 		return binding;
 	}
+	
+	/**
+	 * Given a dependent type, heuristically try to find a concrete scope (i.e. not an unknown scope) for it.
+	 * @param point the point of instantiation for name lookups
+	 */
+	public static IScope heuristicallyFindConcreteScopeForType(IType type, IASTNode point) {
+		if (type instanceof ICPPDeferredClassInstance) {
+			// If this scope is for a deferred-class-instance, use the scope of the primary template.
+			ICPPDeferredClassInstance instance = (ICPPDeferredClassInstance) type;
+			return instance.getClassTemplate().getCompositeScope();
+		} else if (type instanceof TypeOfDependentExpression) {
+			// If this scope is for the id-expression of a field reference, and the field owner
+			// is a deferred-class-instance, look up the field in the scope of the primary template,
+			// and use the scope of the resulting field type.
+			ICPPEvaluation evaluation = ((TypeOfDependentExpression) type).getEvaluation();
+			if (evaluation instanceof EvalID) {
+				EvalID evalId = (EvalID) evaluation;
+				ICPPEvaluation fieldOwner = evalId.getFieldOwner();
+				if (fieldOwner != null) {
+					IType fieldOwnerType = fieldOwner.getTypeOrFunctionSet(point);
+					if (fieldOwnerType instanceof ICPPDeferredClassInstance) {
+						ICPPDeferredClassInstance instance = (ICPPDeferredClassInstance) fieldOwnerType;
+						IScope scope = instance.getClassTemplate().getCompositeScope();
+						LookupData lookup = new LookupData(evalId.getName(), evalId.getTemplateArgs(), point);
+						lookup.qualified = evalId.isQualified();
+						try {
+							CPPSemantics.lookup(lookup, scope);
+						} catch (DOMException e) {
+							return null;
+						}
+						IBinding[] bindings = lookup.getFoundBindings();
+						if (bindings.length == 1 && bindings[0] instanceof IField) {
+							IType fieldType = ((IField) bindings[0]).getType();
+							if (fieldType instanceof ICompositeType) {
+								return ((ICompositeType) fieldType).getCompositeScope(); 
+							}
+						}
+					}
+				}
+			}
+		}
+		// TODO(nathanridge): Handle more cases.
+		return null;
+	}
 }

core/org.eclipse.cdt.ui.tests/ui/org/eclipse/cdt/ui/tests/text/contentassist2/CompletionTests.java

@@ -1668,4 +1668,22 @@ public class CompletionTests extends AbstractContentAssistTest {
 		final String[] expectedDisplay = { "other_tpl<typename T1, typename T2 = tpl<T1>>" };
 		assertContentAssistResults(fCursorOffset, expectedDisplay, true, DISPLAY);
 	}
+	
+	//	struct A {
+	//	    void foo();
+	//	};
+	//
+	//	template <typename>
+	//	struct B {
+	//	    A val;
+	//	};
+	//
+	//	template <typename T>
+	//	void test(B<T> b) {
+	//	    b.val./*cursor*/
+	//	}
+	public void testFieldOfDeferredClassInstance_Bug402617() throws Exception {
+		final String[] expected = { "A", "foo(void)" };
+		assertContentAssistResults(fCursorOffset, expected, true, ID);
+	}
 }