diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/CompositeValue.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/CompositeValue.java
index 362920b8ad3..d3435a01260 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/CompositeValue.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/CompositeValue.java
@@ -16,6 +16,7 @@ import java.util.TreeSet;
 
 import org.eclipse.cdt.core.CCorePlugin;
 import org.eclipse.cdt.core.dom.ast.ASTTypeUtil;
+import org.eclipse.cdt.core.dom.ast.IASTExpression.ValueCategory;
 import org.eclipse.cdt.core.dom.ast.IArrayType;
 import org.eclipse.cdt.core.dom.ast.IBinding;
 import org.eclipse.cdt.core.dom.ast.ICompositeType;
@@ -147,13 +148,24 @@ public final class CompositeValue implements IValue {
 		ICPPEvaluation[] values = new ICPPEvaluation[fields.length];
 		ICPPEvaluation[] clauses = initList.getClauses();
 		for (int i = 0; i < fields.length; i++) {
-			if (i == clauses.length)
-				break;
 			IField field = fields[i];
-			ICPPEvaluation eval = clauses[i];
 			IType fieldType = field.getType();
-			IValue value = getValue(fieldType, eval);
-			values[i] = new EvalFixed(fieldType, eval.getValueCategory(), value);
+			IValue value;
+			ValueCategory valueCategory;
+			if (i < clauses.length) {
+				ICPPEvaluation eval = clauses[i];
+				value = getValue(fieldType, eval);
+				valueCategory = eval.getValueCategory();
+			} else {
+				// (dcl.init.aggr-7) from brace-or-equal-initializer or from {}
+				value = field.getInitialValue();
+				// Writing IntegralValue.UNKNOWN to PDOM stores null, convert it back
+				if (value == null || value == IntegralValue.UNKNOWN) {
+					value = IntegralValue.create(0);
+				}
+				valueCategory = ValueCategory.PRVALUE;
+			}
+			values[i] = new EvalFixed(fieldType, valueCategory, value);
 		}
 		return new CompositeValue(initList, values);
 	}
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/AggregateInitialization.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/AggregateInitialization.java
index d32481d3087..0f6eae40b77 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/AggregateInitialization.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/AggregateInitialization.java
@@ -99,7 +99,7 @@ class AggregateInitialization {
 		}
 
 		Cost costWithoutElision = Conversions.checkImplicitConversionSequence(nestedType, initializer.getType(),
-				initializer.getValueCategory(), UDCMode.ALLOWED, Context.ORDINARY);
+				initializer.getValueCategory(), UDCMode.ALLOWED, Context.ORDINARY, false);
 		if (costWithoutElision.converts()) {
 			// p3: The elements of the initializer list are taken as initializers for the elements
 			//     of the aggregate, in order.
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPEvaluation.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPEvaluation.java
index c25776b0255..8c6e88e63a3 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPEvaluation.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPEvaluation.java
@@ -195,7 +195,7 @@ public abstract class CPPEvaluation implements ICPPEvaluation {
 			ValueCategory valueCategory = argument.getValueCategory();
 			if (uqType instanceof ICPPClassType) {
 				Cost cost = Conversions.initializationByConversion(valueCategory, type, (ICPPClassType) uqType,
-						targetType, false, allowContextualConversion);
+						targetType, false, allowContextualConversion, false);
 				ICPPFunction conversion = cost.getUserDefinedConversion();
 				if (conversion != null) {
 					if (onlyConstexprConversion && !conversion.isConstexpr()) {
@@ -210,7 +210,7 @@ public abstract class CPPEvaluation implements ICPPEvaluation {
 			// Source type is not a class type, or is but a conversion operator wasn't used.
 			// Check for standard conversions.
 			Cost cost = Conversions.checkImplicitConversionSequence(targetType, type, valueCategory, UDCMode.FORBIDDEN,
-					Context.ORDINARY);
+					Context.ORDINARY, false);
 			if (!cost.converts()) {
 				return EvalFixed.INCOMPLETE;
 			} else if (cost.getRank() == Rank.CONVERSION) {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
index b804175003e..b6d65d2112d 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPSemantics.java
@@ -3169,7 +3169,14 @@ public class CPPSemantics {
 
 		if (potentialCosts != null) {
 			for (FunctionCost fnCost : potentialCosts) {
-				if (!fnCost.mustBeWorse(bestFnCost) && fnCost.performUDC()) {
+				if (!fnCost.mustBeWorse(bestFnCost) && fnCost.performUDC(data.fNoNarrowing)) {
+					if (data.fNoNarrowing) {
+						for (int i = 0; i < fnCost.getLength(); ++i) {
+							if (fnCost.getCost(i).isNarrowingConversion()) {
+								continue;
+							}
+						}
+					}
 					int cmp = fnCost.compareTo(tu, bestFnCost, data.getFunctionArgumentCount());
 					if (cmp < 0) {
 						bestFnCost = fnCost;
@@ -3473,7 +3480,7 @@ public class CPPSemantics {
 				Context context = ftype.hasRefQualifier() ? Context.IMPLICIT_OBJECT_FOR_METHOD_WITH_REF_QUALIFIER
 						: Context.IMPLICIT_OBJECT_FOR_METHOD_WITHOUT_REF_QUALIFIER;
 				cost = Conversions.checkImplicitConversionSequence(implicitParameterType, impliedObjectType,
-						impliedObjectValueCategory, UDCMode.FORBIDDEN, context);
+						impliedObjectValueCategory, UDCMode.FORBIDDEN, context, data.fNoNarrowing);
 				if (cost.converts()) {
 					cost.setImpliedObject();
 				} else {
@@ -3530,7 +3537,9 @@ public class CPPSemantics {
 						}
 					}
 				}
-				cost = Conversions.checkImplicitConversionSequence(paramType, argType, argValueCategory, udc, ctx);
+				cost = Conversions.checkImplicitConversionSequence(paramType, argType, argValueCategory, udc, ctx,
+						data.fNoNarrowing);
+				// TODO: see if isNarrowingConversion() is re-checked while performing UDC again later
 				if (data.fNoNarrowing && cost.isNarrowingConversion()) {
 					cost = Cost.NO_CONVERSION;
 				}
@@ -4118,10 +4127,16 @@ public class CPPSemantics {
 				if (initializer == null) {
 					IASTDeclSpecifier declSpec = ((IASTSimpleDeclaration) parent).getDeclSpecifier();
 					parent = parent.getParent();
-					if (parent instanceof IASTCompositeTypeSpecifier
+					// (c++11:class.base.init 12.6.2-8) [..no initializer..]
+					//  if the entity is an anonymous union or a variant member, no initialization is performed
+					//  otherwise the entity is default-initialized
+					// (c++11:dcl.init 8.5-7)
+					// if T is a (possibly cv-qualified) class type .. the default constructor for T is called
+					if ((parent instanceof IASTCompositeTypeSpecifier compositeType
+							&& compositeType.getKey() == ICompositeType.k_union)
 							|| declSpec.getStorageClass() == IASTDeclSpecifier.sc_extern) {
-						// No initialization is performed for class members and extern declarations
-						// without an initializer.
+						// No initialization is performed for class members which are of union type,
+						// and for extern declarations without an initializer.
 						return null;
 					}
 				}
@@ -4182,6 +4197,20 @@ public class CPPSemantics {
 		return null;
 	}
 
+	public static IBinding findConstructorForDirectListInitialization(ICPPClassType type, EvalInitList eval,
+			IASTNode typeId) throws DOMException {
+		Cost c = Conversions.listInitializationSequence(eval, type, UDCMode.ALLOWED, true);
+		if (c.converts()) {
+			ICPPFunction f = c.getUserDefinedConversion();
+			if (f instanceof ICPPConstructor) {
+				return f;
+			}
+		} else {
+			return new ProblemBinding(null, typeId, ISemanticProblem.BINDING_NOT_FOUND, type.getConstructors());
+		}
+		return null;
+	}
+
 	private static IBinding findImplicitlyCalledConstructor(ICPPClassType type, IASTInitializer initializer,
 			IASTNode typeId) {
 		pushLookupPoint(typeId);
@@ -4207,10 +4236,10 @@ public class CPPSemantics {
 					}
 					Cost c;
 					if (calculateInheritanceDepth(sourceType, type) >= 0) {
-						c = Conversions.copyInitializationOfClass(isLValue, sourceType, type, false);
+						c = Conversions.copyInitializationOfClass(isLValue, sourceType, type, false, false);
 					} else {
 						c = Conversions.checkImplicitConversionSequence(type, sourceType, isLValue, UDCMode.ALLOWED,
-								Context.ORDINARY);
+								Context.ORDINARY, false);
 					}
 					if (c.converts()) {
 						ICPPFunction f = c.getUserDefinedConversion();
@@ -4225,7 +4254,7 @@ public class CPPSemantics {
 			} else if (initializer instanceof ICPPASTInitializerList) {
 				// List initialization.
 				ICPPEvaluation eval = ((ICPPASTInitializerClause) initializer).getEvaluation();
-				if (eval instanceof EvalInitList) {
+				if (eval instanceof EvalInitList evalInitList) {
 					if (CPPTemplates.isDependentType(eval.getType())) {
 						ICPPEvaluation[] clauses = ((EvalInitList) eval).getClauses();
 						IType[] tmp = new IType[clauses.length];
@@ -4235,14 +4264,9 @@ public class CPPSemantics {
 						setTargetedFunctionsToUnknown(tmp);
 						return CPPDeferredFunction.createForCandidates(type.getConstructors());
 					}
-					Cost c = Conversions.listInitializationSequence((EvalInitList) eval, type, UDCMode.ALLOWED, true);
-					if (c.converts()) {
-						ICPPFunction f = c.getUserDefinedConversion();
-						if (f instanceof ICPPConstructor)
-							return f;
-					} else {
-						return new ProblemBinding(null, typeId, ISemanticProblem.BINDING_NOT_FOUND,
-								type.getConstructors());
+					IBinding b = findConstructorForDirectListInitialization(type, evalInitList, typeId);
+					if (b != null) {
+						return b;
 					}
 				}
 			} else if (initializer instanceof ICPPASTConstructorInitializer) {
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPTemplates.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPTemplates.java
index 78d43af320a..3f08893f8ba 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPTemplates.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/CPPTemplates.java
@@ -2983,7 +2983,8 @@ public class CPPTemplates {
 			}
 		}
 
-		Cost cost = Conversions.checkImplicitConversionSequence(p, a, LVALUE, UDCMode.FORBIDDEN, Context.ORDINARY);
+		Cost cost = Conversions.checkImplicitConversionSequence(p, a, LVALUE, UDCMode.FORBIDDEN, Context.ORDINARY,
+				false);
 		if (cost == null || !cost.converts()) {
 			ICPPEvaluation eval = arg.getNonTypeEvaluation();
 			ICPPEvaluation newEval = CPPEvaluation.maybeApplyConversion(eval, p, false, true);
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/Conversions.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/Conversions.java
index 91c53594dc9..f49459ecaa8 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/Conversions.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/Conversions.java
@@ -99,7 +99,7 @@ public class Conversions {
 	 * @throws DOMException
 	 */
 	public static Cost checkImplicitConversionSequence(IType target, IType exprType, ValueCategory valueCat,
-			UDCMode udc, Context ctx) throws DOMException {
+			UDCMode udc, Context ctx, boolean noNarrowing) throws DOMException {
 		final boolean isImpliedObject = ctx == Context.IMPLICIT_OBJECT_FOR_METHOD_WITHOUT_REF_QUALIFIER
 				|| ctx == Context.IMPLICIT_OBJECT_FOR_METHOD_WITH_REF_QUALIFIER;
 		if (isImpliedObject)
@@ -211,7 +211,7 @@ public class Conversions {
 
 			// 13.3.3.1.7 no temporary object when converting the implicit object parameter
 			if (!isImpliedObject && ctx != Context.REQUIRE_DIRECT_BINDING) {
-				Cost cost = nonReferenceConversion(valueCat, cv2T2, T1, udc);
+				Cost cost = nonReferenceConversion(valueCat, cv2T2, T1, udc, noNarrowing);
 				if (cost.converts()) {
 					cost.setReferenceBinding(refBindingType);
 				}
@@ -232,7 +232,7 @@ public class Conversions {
 		}
 
 		// Non-reference binding
-		return nonReferenceConversion(valueCat, exprType, T1, udc);
+		return nonReferenceConversion(valueCat, exprType, T1, udc, noNarrowing);
 	}
 
 	/**
@@ -297,8 +297,8 @@ public class Conversions {
 	/**
 	 * 8.5-16
 	 */
-	private static Cost nonReferenceConversion(ValueCategory valueCat, IType source, IType target, UDCMode udc)
-			throws DOMException {
+	private static Cost nonReferenceConversion(ValueCategory valueCat, IType source, IType target, UDCMode udc,
+			boolean noNarrowing) throws DOMException {
 		if (source instanceof InitializerListType) {
 			return listInitializationSequence(((InitializerListType) source).getEvaluation(), target, udc, false);
 		}
@@ -321,7 +321,8 @@ public class Conversions {
 			if (udc == UDCMode.FORBIDDEN)
 				return Cost.NO_CONVERSION;
 
-			return copyInitializationOfClass(valueCat, source, (ICPPClassType) uqTarget, udc == UDCMode.DEFER);
+			return copyInitializationOfClass(valueCat, source, (ICPPClassType) uqTarget, udc == UDCMode.DEFER,
+					noNarrowing);
 		}
 
 		if (uqSource instanceof ICPPClassType) {
@@ -329,7 +330,7 @@ public class Conversions {
 				return Cost.NO_CONVERSION;
 
 			return initializationByConversion(valueCat, source, (ICPPClassType) uqSource, target, udc == UDCMode.DEFER,
-					false);
+					false, noNarrowing);
 		}
 
 		return checkStandardConversionSequence(uqSource, target);
@@ -352,7 +353,7 @@ public class Conversions {
 			Cost worstCost = new Cost(arg.getType(), target, Rank.IDENTITY);
 			for (ICPPEvaluation clause : arg.getClauses()) {
 				Cost cost = checkImplicitConversionSequence(listType, clause.getType(), clause.getValueCategory(),
-						UDCMode.ALLOWED, Context.ORDINARY);
+						UDCMode.ALLOWED, Context.ORDINARY, false);
 				if (!cost.converts())
 					return cost;
 				if (cost.isNarrowingConversion()) {
@@ -389,7 +390,7 @@ public class Conversions {
 			final ICPPEvaluation firstArg = args[0];
 			if (!firstArg.isInitializerList()) {
 				Cost cost = checkImplicitConversionSequence(target, firstArg.getType(), firstArg.getValueCategory(),
-						udc, Context.ORDINARY);
+						udc, Context.ORDINARY, false);
 				if (cost.isNarrowingConversion()) {
 					return Cost.NO_CONVERSION;
 				}
@@ -614,24 +615,7 @@ public class Conversions {
 		data.fNoNarrowing = true;
 
 		// 13.3.3.1.4
-		ICPPConstructor[] filteredConstructors = constructors;
-		if (expandedArgs.length == 1) {
-			filteredConstructors = new ICPPConstructor[constructors.length];
-			int j = 0;
-			for (ICPPConstructor ctor : constructors) {
-				if (ctor.getRequiredArgumentCount() < 2) {
-					IType[] ptypes = ctor.getType().getParameterTypes();
-					if (ptypes.length > 0) {
-						IType ptype = getNestedType(ptypes[0], TDEF | REF | CVTYPE);
-						if (!t.isSameType(ptype)) {
-							filteredConstructors[j++] = ctor;
-						}
-					}
-				}
-			}
-		}
-
-		final IBinding result = CPPSemantics.resolveFunction(data, filteredConstructors, true, false);
+		final IBinding result = CPPSemantics.resolveFunction(data, constructors, true, false);
 		final Cost c;
 		if (result instanceof ICPPMethod) {
 			if (!isDirect && ((ICPPMethod) result).isExplicit()) {
@@ -658,8 +642,8 @@ public class Conversions {
 	/**
 	 * 13.3.1.4 Copy-initialization of class by user-defined conversion [over.match.copy]
 	 */
-	static final Cost copyInitializationOfClass(ValueCategory valueCat, IType source, ICPPClassType t, boolean deferUDC)
-			throws DOMException {
+	static final Cost copyInitializationOfClass(ValueCategory valueCat, IType source, ICPPClassType t, boolean deferUDC,
+			boolean noNarrowing) throws DOMException {
 		if (deferUDC) {
 			Cost c = new Cost(source, t, Rank.USER_DEFINED_CONVERSION);
 			c.setDeferredUDC(DeferredUDC.COPY_INIT_OF_CLASS);
@@ -698,8 +682,14 @@ public class Conversions {
 					if (ctor.getRequiredArgumentCount() > 1)
 						continue;
 
-					c1 = new FunctionCost(ctor, checkImplicitConversionSequence(ptype, source, valueCat,
-							UDCMode.FORBIDDEN, Context.ORDINARY));
+					Cost cost = checkImplicitConversionSequence(ptype, source, valueCat, UDCMode.FORBIDDEN,
+							Context.ORDINARY, noNarrowing);
+
+					if (noNarrowing && cost.isNarrowingConversion()) {
+						cost = Cost.NO_CONVERSION;
+					}
+
+					c1 = new FunctionCost(ctor, cost);
 				}
 				int cmp = c1.compareTo(null, cost1, 1);
 				if (cmp <= 0) {
@@ -761,7 +751,7 @@ public class Conversions {
 	 * 13.3.1.5 Initialization by conversion function [over.match.conv]
 	 */
 	static Cost initializationByConversion(ValueCategory valueCat, IType source, ICPPClassType uqSource, IType target,
-			boolean deferUDC, boolean allowExplicitConversion) throws DOMException {
+			boolean deferUDC, boolean allowExplicitConversion, boolean noNarrowing) throws DOMException {
 		if (deferUDC) {
 			Cost c = new Cost(source, target, Rank.USER_DEFINED_CONVERSION);
 			c.setDeferredUDC(DeferredUDC.INIT_BY_CONVERSION);
@@ -783,7 +773,7 @@ public class Conversions {
 				final IType returnType = functionType.getReturnType();
 				IType uqReturnType = getNestedType(returnType, TDEF | ALLCVQ);
 				Cost c2 = checkImplicitConversionSequence(target, uqReturnType,
-						valueCategoryFromReturnType(uqReturnType), UDCMode.FORBIDDEN, Context.ORDINARY);
+						valueCategoryFromReturnType(uqReturnType), UDCMode.FORBIDDEN, Context.ORDINARY, noNarrowing);
 				if (c2.converts()) {
 					if (isExplicitConversion && c2.getRank() != Rank.IDENTITY)
 						continue;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalConditional.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalConditional.java
index 49cc3df4639..b0e471ae08a 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalConditional.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalConditional.java
@@ -306,7 +306,7 @@ public class EvalConditional extends CPPDependentEvaluation {
 			if (vcat2.isGLValue()) {
 				IType target = new CPPReferenceType(t2, vcat2 == XVALUE);
 				Cost c = Conversions.checkImplicitConversionSequence(target, t1, vcat1, UDCMode.ALLOWED,
-						Context.REQUIRE_DIRECT_BINDING);
+						Context.REQUIRE_DIRECT_BINDING, false);
 				if (c.converts()) {
 					fType = t2;
 					fValueCategory = vcat2;
@@ -333,7 +333,8 @@ public class EvalConditional extends CPPDependentEvaluation {
 			if (vcat2 != PRVALUE) {
 				t2 = Conversions.lvalue_to_rvalue(t2, false);
 			}
-			Cost c = Conversions.checkImplicitConversionSequence(t2, t1, vcat1, UDCMode.ALLOWED, Context.ORDINARY);
+			Cost c = Conversions.checkImplicitConversionSequence(t2, t1, vcat1, UDCMode.ALLOWED, Context.ORDINARY,
+					false);
 			if (c.converts()) {
 				fType = t2;
 				fValueCategory = PRVALUE;
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalTypeId.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalTypeId.java
index 09533b43e4a..2ddd4282b44 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalTypeId.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/EvalTypeId.java
@@ -35,7 +35,6 @@ import org.eclipse.cdt.core.dom.ast.cpp.ICPPClassTemplate;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPClassType;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPConstructor;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPFunction;
-import org.eclipse.cdt.core.dom.ast.cpp.ICPPMethod;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPSpecialization;
 import org.eclipse.cdt.core.dom.ast.cpp.ICPPTemplateParameterMap;
 import org.eclipse.cdt.core.parser.util.ArrayUtil;
@@ -234,7 +233,9 @@ public class EvalTypeId extends CPPDependentEvaluation {
 	}
 
 	private boolean computeIsConstantExpression() {
-		if (getConstructor() == null && fArguments.length == 1) {
+		ICPPFunction constructor = getConstructor();
+
+		if (constructor == null && fArguments.length == 1) {
 			// maybe EvalTypeID represents a conversion
 			ICPPEvaluation conversionEval = maybeApplyConversion(fArguments[0], fInputType, false, false);
 			if (isEquivalentTo(conversionEval)) {
@@ -244,9 +245,13 @@ public class EvalTypeId extends CPPDependentEvaluation {
 
 			if (!conversionEval.isConstantExpression())
 				return false;
+		} else if (constructor == AGGREGATE_INITIALIZATION) {
+			// A literal type is one for which it might be possible to create an object within a constant expression.
+			// See also CPPImplicitConstructor.isConstExpr()
+			return getInputType() instanceof ICPPClassType classType && TypeTraits.isLiteralClass(classType);
 		}
-		return !fRepresentsNewExpression && areAllConstantExpressions(fArguments)
-				&& isNullOrConstexprFunc(getConstructor());
+
+		return !fRepresentsNewExpression && areAllConstantExpressions(fArguments) && isNullOrConstexprFunc(constructor);
 	}
 
 	@Override
@@ -285,38 +290,35 @@ public class EvalTypeId extends CPPDependentEvaluation {
 			return null;
 
 		IType simplifiedType = SemanticUtil.getNestedType(fInputType, TDEF | CVTYPE);
-		if (simplifiedType instanceof ICPPClassType) {
-			ICPPClassType classType = (ICPPClassType) simplifiedType;
-			ICPPEvaluation[] arguments = fArguments;
-			ICPPConstructor[] constructors = classType.getConstructors();
-			if (fUsesBracedInitList && arguments.length > 0) {
-				// List-initialization of a class (dcl.init.list-3).
-				// e.g. A{1,2}
-				ICPPConstructor[] ctors = getInitializerListConstructors(constructors);
-				if (ctors.length != 0) {
-					constructors = ctors;
-					arguments = new EvalInitList[] { new EvalInitList(arguments, getTemplateDefinition()) };
-				}
-			} else if (arguments.length == 1 && arguments[0] instanceof EvalInitList && !fUsesBracedInitList) {
-				// List-initialization of a class (dcl.init.list-3).
-				// e.g. A({1,2})
-				if (TypeTraits.isAggregateClass(classType)) {
-					// Pretend that aggregate initialization is calling the default constructor.
-					return findDefaultConstructor(classType, constructors);
-				}
-				if (((EvalInitList) arguments[0]).getClauses().length == 0) {
-					ICPPMethod ctor = findDefaultConstructor(classType, constructors);
-					if (ctor != null)
-						return ctor;
-				}
-				ICPPConstructor[] ctors = getInitializerListConstructors(constructors);
-				if (ctors.length != 0) {
-					constructors = ctors;
-				} else {
-					arguments = ((EvalInitList) arguments[0]).getClauses();
+		if (simplifiedType instanceof ICPPClassType classType) {
+			if (fUsesBracedInitList) {
+				// (dcl.init.list)
+				EvalInitList evalInitList = new EvalInitList(fArguments, getTemplateDefinition());
+
+				try {
+					// List-initialization of a class (dcl.init.list-3).
+					// e.g. A{1,2}
+					IBinding binding = CPPSemantics.findConstructorForDirectListInitialization(classType, evalInitList,
+							null);
+					if (binding instanceof ICPPConstructor constructor) {
+						return constructor;
+					} else if (binding instanceof IProblemBinding) {
+						return new CPPFunction.CPPFunctionProblem(null, ISemanticProblem.BINDING_NOT_FOUND,
+								classType.getNameCharArray());
+					} else if (TypeTraits.isAggregateClass(classType)) {
+						// If Conversions.listInitializationSequence() did not returned problem binding,
+						// this is a list-initialization of aggregate class, and there is no constructor.
+						return AGGREGATE_INITIALIZATION;
+					}
+				} catch (DOMException e) {
+					CCorePlugin.log(e);
 				}
+
+				return null;
 			}
 
+			ICPPEvaluation[] arguments = fArguments;
+			ICPPConstructor[] constructors = classType.getConstructors();
 			LookupData data = new LookupData(classType.getNameCharArray(), null, CPPSemantics.getCurrentLookupPoint());
 			data.foundItems = constructors;
 			data.setFunctionArguments(false, arguments);
diff --git a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/FunctionCost.java b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/FunctionCost.java
index d77b19e72fd..578f76c0470 100644
--- a/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/FunctionCost.java
+++ b/core/org.eclipse.cdt.core/parser/org/eclipse/cdt/internal/core/dom/parser/cpp/semantics/FunctionCost.java
@@ -98,7 +98,7 @@ class FunctionCost {
 		return false;
 	}
 
-	public boolean performUDC() throws DOMException {
+	public boolean performUDC(boolean noNarrowing) throws DOMException {
 		for (int i = 0; i < fCosts.length; i++) {
 			Cost cost = fCosts[i];
 			Cost udcCost = null;
@@ -107,12 +107,12 @@ class FunctionCost {
 				continue;
 			case COPY_INIT_OF_CLASS:
 				udcCost = Conversions.copyInitializationOfClass(fValueCategories[i], cost.source,
-						(ICPPClassType) cost.target, false);
+						(ICPPClassType) cost.target, false, noNarrowing);
 				break;
 			case INIT_BY_CONVERSION:
 				IType uqSource = getNestedType(cost.source, TDEF | REF | CVTYPE);
 				udcCost = Conversions.initializationByConversion(fValueCategories[i], cost.source,
-						(ICPPClassType) uqSource, cost.target, false, allowsContextualBooleanConversion());
+						(ICPPClassType) uqSource, cost.target, false, allowsContextualBooleanConversion(), noNarrowing);
 				break;
 			case LIST_INIT_OF_CLASS:
 				udcCost = Conversions.listInitializationOfClass(((InitializerListType) cost.source).getEvaluation(),
@@ -126,6 +126,7 @@ class FunctionCost {
 				return false;
 			}
 			fCosts[i] = udcCost;
+
 			if (!udcCost.converts()) {
 				return false;
 			}
diff --git a/core/org.eclipse.cdt.ui/META-INF/MANIFEST.MF b/core/org.eclipse.cdt.ui/META-INF/MANIFEST.MF
index cb839628c20..89440b66807 100644
--- a/core/org.eclipse.cdt.ui/META-INF/MANIFEST.MF
+++ b/core/org.eclipse.cdt.ui/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.cdt.ui; singleton:=true
-Bundle-Version: 8.1.200.qualifier
+Bundle-Version: 8.1.300.qualifier
 Bundle-Activator: org.eclipse.cdt.ui.CUIPlugin
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
@@ -104,7 +104,7 @@ Export-Package: org.eclipse.cdt.internal.corext;x-internal:=true,
  org.eclipse.cdt.ui.wizards.conversion,
  org.eclipse.cdt.utils.ui.controls
 Import-Package: org.apache.commons.io;version="[2.8.0,3.0.0)"
-Require-Bundle: org.eclipse.cdt.core;bundle-version="[8.3.0,9.0.0)",
+Require-Bundle: org.eclipse.cdt.core;bundle-version="[8.4.0,9.0.0)",
  org.eclipse.compare;bundle-version="[3.8.500,4.0.0)",
  org.eclipse.core.expressions;bundle-version="[3.8.200,4.0.0)",
  org.eclipse.core.filesystem;bundle-version="[1.9.500,2.0.0)",
diff --git a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/contentassist/ParameterGuesser.java b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/contentassist/ParameterGuesser.java
index fbf2a093db9..5ae96c95e1c 100644
--- a/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/contentassist/ParameterGuesser.java
+++ b/core/org.eclipse.cdt.ui/src/org/eclipse/cdt/internal/ui/text/contentassist/ParameterGuesser.java
@@ -180,7 +180,7 @@ public class ParameterGuesser {
 	private boolean isImplicitlyConvertible(IType orginType, IType candidateType) {
 		try {
 			Cost cost = Conversions.checkImplicitConversionSequence(orginType, candidateType, ValueCategory.LVALUE,
-					UDCMode.ALLOWED, Context.ORDINARY);
+					UDCMode.ALLOWED, Context.ORDINARY, false);
 			if (cost.converts())
 				return true;
 		} catch (DOMException e) {