Bug 484959 - Instantiate return expression of constexpr function

template

Change-Id: I3abec0f3bac58db77aacd61bd985c94c2185e3a8
Signed-off-by: Nathan Ridge <zeratul976@hotmail.com>

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

@@ -8752,6 +8752,24 @@ public class AST2TemplateTests extends AST2TestBase {
 	public void testConstexprFunctionCallWithNonConstexprArguments_429891() throws Exception {
 		parseAndCheckBindings();
 	}
+	
+	//	template <typename>
+	//	struct S;
+	//
+	//	template <>
+	//	struct S<int> {
+	//		static const int value = 42;
+	//	};
+	//
+	//	template <typename T>
+	//	constexpr int foo() {
+	//		return S<T>::value;
+	//	}
+	//
+	//	constexpr int waldo = foo<int>();
+	public void testInstantiationOfReturnExpression_484959() throws Exception {
+		getAssertionHelper().assertVariableValue("waldo", 42);
+	}
 
 	//	template <typename> class A {};
 	//	template <int>      class B {};

core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/core/parser/tests/ast2/AST2TestBase.java

@@ -776,9 +776,7 @@ public class AST2TestBase extends BaseTestCase {
     	
     	public void assertVariableValue(String variableName, long expectedValue) {
     		IVariable var = assertNonProblem(variableName);
-    		assertNotNull(var.getInitialValue());
+    		BaseTestCase.assertVariableValue(var, expectedValue);
-    		assertNotNull(var.getInitialValue().numericalValue());
-    		assertEquals(expectedValue, var.getInitialValue().numericalValue().longValue());
     	}
 
 		public <T, U extends T> U assertType(T obj, Class... cs) {

core/org.eclipse.cdt.core.tests/parser/org/eclipse/cdt/internal/index/tests/IndexCPPTemplateResolutionTest.java

@@ -2644,6 +2644,25 @@ public class IndexCPPTemplateResolutionTest extends IndexBindingResolutionTestBa
 	public void testSpecializationOfConstexprFunction_420995() throws Exception {
 		checkBindings();
 	}
+	
+	//	template <typename>
+	//	struct S;
+	//
+	//	template <>
+	//	struct S<int> {
+	//		static const int value = 42;
+	//	};
+	//
+	//	template <typename T>
+	//	constexpr int foo() {
+	//		return S<T>::value;
+	//	}
+	
+	//	constexpr int waldo = foo<int>();
+	public void testInstantiationOfReturnExpression_484959() throws Exception {
+		ICPPVariable waldo = getBindingFromASTName("waldo", 5);
+		assertVariableValue(waldo, 42);
+	}
 
 	//	template <class TYPE>
 	//	class waldo {

core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/testplugin/util/BaseTestCase.java

@@ -32,6 +32,7 @@ import junit.framework.TestResult;
 import junit.framework.TestSuite;
 
 import org.eclipse.cdt.core.CCorePlugin;
+import org.eclipse.cdt.core.dom.ast.IVariable;
 import org.eclipse.cdt.core.index.IIndex;
 import org.eclipse.cdt.core.model.CoreModel;
 import org.eclipse.cdt.core.model.ElementChangedEvent;
@@ -349,4 +350,10 @@ public class BaseTestCase extends TestCase {
 		}
 		return clazz.cast(o);
 	}
+	
+	protected static void assertVariableValue(IVariable var, long expectedValue) {
+		assertNotNull(var.getInitialValue());
+		assertNotNull(var.getInitialValue().numericalValue());
+		assertEquals(expectedValue, var.getInitialValue().numericalValue().longValue());
+	}
 }

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

@@ -35,6 +35,8 @@ import org.eclipse.cdt.core.dom.ast.cpp.ICPPTemplateParameterMap;
 import org.eclipse.cdt.core.index.IIndexBinding;
 import org.eclipse.cdt.internal.core.dom.parser.ASTInternal;
 import org.eclipse.cdt.internal.core.dom.parser.ASTQueries;
+import org.eclipse.cdt.internal.core.dom.parser.Value;
+import org.eclipse.cdt.internal.core.dom.parser.cpp.semantics.CPPTemplates;
 import org.eclipse.cdt.internal.core.dom.parser.cpp.semantics.CPPVisitor;
 
 /**
@@ -330,7 +332,18 @@ public class CPPFunctionSpecialization extends CPPSpecialization implements ICPP
 		}
 		IBinding f = getSpecializedBinding();
 		if (f instanceof ICPPComputableFunction) {
-			return ((ICPPComputableFunction) f).getReturnExpression();
+			ICPPEvaluation eval = ((ICPPComputableFunction) f).getReturnExpression();
+			if (eval != null) {
+				// TODO: Should we instead do this when the CPPFunctionSpecialization is created?
+				// It would mean getting a more accurate point of instantiation, but it would also
+				// mean doing the instantiation when we might never need it.
+				IASTNode point = f instanceof ICPPInternalFunction 
+						? ((ICPPInternalFunction) f).getDefinition()
+						: null;
+				eval = eval.instantiate(getTemplateParameterMap(), -1, 
+						CPPTemplates.getSpecializationContext(getOwner()), Value.MAX_RECURSION_DEPTH, point);
+			}
+			return eval;
 		}
 		return null;
 	}

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

@@ -39,9 +39,6 @@ public class CPPTemplateNonTypeArgument implements ICPPTemplateArgument {
 			IValue value = evaluation.getValue(point);
 			if (value == Value.ERROR) {
 				fEvaluation = EvalFixed.INCOMPLETE; 
-			} else if (value.getEvaluation() instanceof EvalFixed) {
-				// Avoid nesting EvalFixed's as nesting causes the signature to be different.
-				fEvaluation = value.getEvaluation();
 			} else {
 				fEvaluation= new EvalFixed(evaluation.getType(point),
 						evaluation.getValueCategory(point), value);

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

@@ -45,6 +45,14 @@ public class EvalFixed extends CPPEvaluation {
 	private boolean fCheckedIsValueDependent;
 
 	public EvalFixed(IType type, ValueCategory cat, IValue value) {
+		// Avoid nesting EvalFixed's as nesting causes the signature to be different.
+		if (value.getEvaluation() instanceof EvalFixed) {
+			EvalFixed inner = (EvalFixed) value.getEvaluation();
+			type = inner.fType;
+			cat = inner.fValueCategory;
+			value = inner.fValue;
+		}
+		
 		if (type instanceof CPPBasicType) {
 			Long num = value.numericalValue();
 			if (num != null) {
@@ -57,7 +65,7 @@ public class EvalFixed extends CPPEvaluation {
 		fValueCategory= cat;
 		fValue= value;
 	}
-
+	
 	public IType getType() {
 		return fType;
 	}