[eclipse-cdt#455] If constructor arguments fail to resolve, propagate…

… failure

This change prevents invalid partial specialisations from being chosen
when
instantiating a template in cases where the expression for the
type/value of a template parameter involves a constructor call.

core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TemplateTests.java

@@ -6865,6 +6865,44 @@ public void testSfinae_b() throws Exception {
 		parseAndCheckBindings();
 	}
 
+	// template <class, typename = void>
+	// struct A
+	// {
+	//     using type = int *;
+	// };
+	//
+	// template <class T>
+	// struct A<T, decltype(void(typename T::p()))>
+	// {
+	//     using type = typename T::p;
+	// };
+	//
+	// class d { };
+	//
+	// class B {
+	// public:
+	//     using p = typename A<d>::type;
+	//
+	// public:
+	//     explicit B(p) {}
+	// };
+	//
+	// int *ip = nullptr;
+	// B b1 { ip };
+	// B::p jp = nullptr;
+	public void testSfinae_c() throws Exception {
+		BindingAssertionHelper bh = getAssertionHelper();
+
+		IVariable varB1 = bh.assertNonProblem("b1");
+		IType bcls = bh.assertNonProblem("B");
+		IVariable varJp = bh.assertNonProblem("jp");
+		IVariable varIp = bh.assertNonProblem("ip");
+
+		assertFalse(varB1.getInitialValue() instanceof IProblemBinding);
+		assertTrue(varB1.getType().isSameType(bcls));
+		assertTrue(varIp.getType().isSameType(varJp.getType()));
+	}
+
 	//	template<typename T>
 	//	struct is_pod {
 	//	  static const bool value = __is_pod(T);

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

@@ -218,6 +218,7 @@
 import org.eclipse.cdt.internal.core.dom.parser.ITypeContainer;
 import org.eclipse.cdt.internal.core.dom.parser.IntegralValue;
 import org.eclipse.cdt.internal.core.dom.parser.ProblemBinding;
+import org.eclipse.cdt.internal.core.dom.parser.ProblemType;
 import org.eclipse.cdt.internal.core.dom.parser.SizeofCalculator;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPASTIdExpression;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPASTLiteralExpression;
@@ -5067,6 +5068,8 @@ public static boolean isUsingPromiscuousBindingResolution() {
 	 */
 	public static IType getDeclTypeForEvaluation(ICPPEvaluation eval) {
 		IType expressionType = eval.getType();
+		if (expressionType instanceof ProblemType)
+			return expressionType;
 		boolean namedEntity = eval instanceof EvalBinding || eval instanceof EvalMemberAccess;
 		if (!namedEntity && !(expressionType instanceof ICPPReferenceType)) {
 			switch (eval.getValueCategory()) {

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

@@ -26,6 +26,7 @@
 import org.eclipse.cdt.core.dom.ast.IASTNode;
 import org.eclipse.cdt.core.dom.ast.IBinding;
 import org.eclipse.cdt.core.dom.ast.IProblemBinding;
+import org.eclipse.cdt.core.dom.ast.IProblemType;
 import org.eclipse.cdt.core.dom.ast.ISemanticProblem;
 import org.eclipse.cdt.core.dom.ast.IType;
 import org.eclipse.cdt.core.dom.ast.IValue;
@@ -42,6 +43,7 @@
 import org.eclipse.cdt.internal.core.dom.parser.DependentValue;
 import org.eclipse.cdt.internal.core.dom.parser.ITypeMarshalBuffer;
 import org.eclipse.cdt.internal.core.dom.parser.IntegralValue;
+import org.eclipse.cdt.internal.core.dom.parser.ProblemBinding;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPFunction;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPPointerType;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.ClassTypeHelper;
@@ -416,6 +418,15 @@ public ICPPEvaluation instantiate(InstantiationContext context, int maxDepth) {
 		if (args == fArguments && type == fInputType)
 			return this;
 
+		// If type or arguments failed to resolve, return INCOMPLETE for SFINAE purposes
+		if (type instanceof ProblemBinding)
+			return EvalFixed.INCOMPLETE;
+		for (ICPPEvaluation arg : args) {
+			if (arg.getType() instanceof IProblemType) {
+				return EvalFixed.INCOMPLETE;
+			}
+		}
+
 		EvalTypeId result = new EvalTypeId(type, getTemplateDefinition(), fRepresentsNewExpression, fUsesBracedInitList,
 				args);