Enhancement: Base(child) class object upcast

compiler/src/dmd/expressionsem.d

@@ -6133,7 +6133,7 @@ private extern (C++) final class ExpressionSemanticVisitor : Visitor
                 }
                 // No constructor, look for overload of opCall
                 if (search_function(sd, Id.call))
-                    goto L1;
+                    goto LopCall;
                 // overload of opCall, therefore it's a call
                 if (exp.e1.op != EXP.type)
                 {
@@ -6171,7 +6171,17 @@ private extern (C++) final class ExpressionSemanticVisitor : Visitor
             }
             else if (t1.ty == Tclass)
             {
-            L1:
+                // upcast `Base(child)`
+                if (exp.e1.op == EXP.type && exp.arguments.length == 1 &&
+                    (*exp.arguments)[0].type.implicitConvTo(t1) &&
+                    !t1.isTypeClass().sym.symtab.lookup(Id.call))
+                {
+                    Expression e = new CastExp(exp.loc, (*exp.arguments)[0], t1);
+                    e = e.expressionSemantic(sc);
+                    result = e;
+                    return;
+                }
+            LopCall:
                 // Rewrite as e1.call(arguments)
                 Expression e = new DotIdExp(exp.loc, exp.e1, Id.call);
                 e = new CallExp(exp.loc, e, exp.arguments, exp.names);

compiler/test/compilable/type_call_expr.d

@@ -0,0 +1,10 @@
+enum A { B }
+static assert(is(typeof(A.B) == A));
+static assert(is(typeof(A(A.B)) == A));
+
+void main()
+{
+    Exception ex;
+    auto o = Object(ex);
+    static assert(is(typeof(o) == Object));
+}