Bug 568625 - "Invalid arguments" using __underlying_type outside template

ICPPUnaryTypeTransformation was meant to be used only when the
transformation is applied on a dependent type. But it was actually
always used when creating types for decl specifiers, regardless if a
dependent type was involved or not. The untransformed type was causing
issues because code dealing with ITypes doesn't apply the transformation
everywhere. It seems better to apply the transformation early when
possible and let the rest of the logic intact.

Change-Id: I1b6d77a857e901f71f00e935e75d24cea87c3118
Signed-off-by: Marc-Andre Laperle <malaperle@gmail.com>

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

@@ -11382,6 +11382,19 @@ public class AST2CPPTests extends AST2CPPTestBase {
 		parseAndCheckBindings(getAboveComment(), CPP, true /* use GNU extensions */);
 	}
 
+	//	enum class TestEnum : char {
+	//	};
+	//
+	//	void bar(__underlying_type(TestEnum) as) {
+	//	}
+	//
+	//	void foo() {
+	//	  bar('a'); // Invalid arguments 'Candidates are: void bar(@120932903)'
+	//	}
+	public void testUnderlyingType_568625() throws Exception {
+		parseAndCheckBindings(getAboveComment(), CPP, true /* use GNU extensions */);
+	}
+
 	//	void ptrFunc(void*);
 	//	void intFunc(int);
 	//	void foo(int* pi, unsigned i) {
@@ -13636,6 +13649,7 @@ public class AST2CPPTests extends AST2CPPTestBase {
 	//		Test<__is_same(Enum, Enum)>::true_val;
 	//		Test<__is_same(Enum, int)>::false_val;
 	//		Test<__is_same(EnumChar, char)>::false_val;
+	//		Test<__is_same(__underlying_type(EnumChar), char)>::true_val;
 	//
 	//		Test<TemplateArgs<int, bool>::Value>::false_val;
 	//		Test<TemplateArgs<int, int>::Value>::true_val;

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

@@ -1717,12 +1717,7 @@ public class CPPTemplates {
 			if (type instanceof ICPPUnaryTypeTransformation) {
 				ICPPUnaryTypeTransformation typeTransformation = (ICPPUnaryTypeTransformation) type;
 				IType operand = instantiateType(typeTransformation.getOperand(), context);
-				switch (typeTransformation.getOperator()) {
+				return SemanticUtil.applyTypeTransformation(typeTransformation.getOperator(), operand);
-				case underlying_type:
-					return TypeTraits.underlyingType(operand);
-				default:
-					return null; // shouldn't happen
-				}
 			}
 
 			if (type instanceof CPPClosureType) {

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

@@ -236,7 +236,6 @@ import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPTemplateNonTypeArgument;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPTemplateParameterMap;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPTemplateTypeArgument;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPTypedef;
-import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPUnaryTypeTransformation;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPUnknownTypeScope;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPVariable;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.CPPVariableTemplate;
@@ -2793,7 +2792,12 @@ public class CPPVisitor extends ASTQueries {
 			name = ((IASTEnumerationSpecifier) declSpec).getName();
 		} else if (declSpec instanceof ICPPASTTypeTransformationSpecifier) {
 			ICPPASTTypeTransformationSpecifier spec = (ICPPASTTypeTransformationSpecifier) declSpec;
-			return new CPPUnaryTypeTransformation(spec.getOperator(), createType(spec.getOperand()));
+			IType type = SemanticUtil.applyTypeTransformation(spec.getOperator(), createType(spec.getOperand()));
+			if (type != null)
+				return type;
+
+			return ProblemType.UNRESOLVED_NAME;
+
 		} else if (declSpec instanceof ICPPASTSimpleDeclSpecifier) {
 			ICPPASTSimpleDeclSpecifier spec = (ICPPASTSimpleDeclSpecifier) declSpec;
 			// Check for decltype(expr)

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

@@ -68,6 +68,7 @@ import org.eclipse.cdt.core.dom.ast.cpp.ICPPPointerToMemberType;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPReferenceType;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPSpecialization;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPTemplateArgument;
+import org.eclipse.cdt.core.dom.ast.cpp.ICPPUnaryTypeTransformation;
 import org.eclipse.cdt.core.index.IIndexBinding;
 import org.eclipse.cdt.core.parser.Keywords;
 import org.eclipse.cdt.core.parser.util.ArrayUtil;
@@ -945,4 +946,13 @@ public class SemanticUtil {
 		}
 		return result;
 	}
+
+	public static IType applyTypeTransformation(ICPPUnaryTypeTransformation.Operator operator, IType type) {
+		switch (operator) {
+		case underlying_type:
+			return TypeTraits.underlyingType(type);
+		default:
+			return null; // shouldn't happen
+		}
+	}
 }