Bug 96926 [quick fix] Change method return type quick fix gives invalid proposal for wildcard types
Against I20050527-0010: Code: void a() { ArrayList<? extends Number> b = null; return b.get(0); } Ask for a quick fix on the compile error. Three things happen: 1) BAD: The quick fix is entitled "Change method return type to '? extends Number'". 2) GOOD: The correct return type, Number, is shown originally. 3) BAD: However, the top completion proposal, and the one chosen if the user simply hits return, is "? extends Number", which creates a compile error.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/correction/ASTResolving.java
public static boolean isUseableTypeInContext(ITypeBinding type, IBinding context, boolean noWildcards) {
		if (type.isArray()) {
			type= type.getElementType();
		}
		if (type.isAnonymous()) {
			return false;
		}
		if (type.isRawType() || type.isPrimitive()) {
			return true;
		}
		if (type.isTypeVariable()) {
			return isVariableDefinedInContext(context, type);
		}
		if (type.isGenericType()) {
			ITypeBinding[] typeParameters= type.getTypeParameters();
			for (int i= 0; i < typeParameters.length; i++) {
				if (!isUseableTypeInContext(typeParameters[i], context, noWildcards)) {
					return false;
				}
			}
			return true;
		}
		if (type.isParameterizedType()) {
			ITypeBinding[] typeArguments= type.getTypeArguments();
			for (int i= 0; i < typeArguments.length; i++) {
				if (!isUseableTypeInContext(typeArguments[i], context, noWildcards)) {
					return false;
				}
			}
			return true;