[Issue 21748] Return value of forward-referenced auto ref function mistakenly treated as lvalue

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=21748

--- Comment #3 from uplink.coder at googlemail.com ---
This diff would fix it in a hacky way!
BUT that does not address the systemic issue that the ast is in unstable states
depending on resolve ordering! 

--- a/src/dmd/expression.d
+++ b/src/dmd/expression.d
@@ -5081,6 +5081,24 @@ extern (C++) final class CallExp : UnaExp
         if (tb.ty == Tdelegate || tb.ty == Tpointer)
             tb = tb.nextOf();
         auto tf = tb.isTypeFunction();
+
+        // the real ref-ness of the function might not be inferred yet
+        // therefore we need to get the function out if there is one
+        if (tf)
+        {
+            if (auto ve = e1.isVarExp())
+            {
+                if (ve.var)
+                {
+                    if (auto fd = ve.var.isFuncDeclaration())
+                    {
+                        fd.functionSemantic();
+                        fd.functionSemantic3();
+                    }
+                }
+            }
+        }

--