2085 – CTFE fails if the function is forward referenced

Related to 2080.
----
const s = foo();
pragma(msg, s);
char[] foo()
{ 
 return "Hi from foo";
}
----
Error: cannot evaluate ... you know :)
Worked around by placing s declaration and pragma after foo definition

another example
----
enum { a=b() }
int b(){ return 0; }
----

This bug is hit regularly when porting C to D.
It's a shame that C macros don't suffer from this ordering bug :)
---
#define a b(0)
#define b(c) (c+1)
---

Here's patch that invokes the semantic on the function if referenced. Additioally, it needs to avoid duplicate semantic to be run later.
This patch also fixes #3499
Index: expression.c
===================================================================
--- expression.c	(revision 421)
+++ expression.c	(working copy)
@@ -2427,7 +2427,8 @@
 f = s->isFuncDeclaration();
 if (f)
 {	//printf("'%s' is a function\n", f->toChars());
-
+	if (!f->originalType && f->scope) // semantic not yet run
+	 f->semantic(f->scope);
 	if (!f->type->deco)
 	{
 	 error("forward reference to %s", toChars());
Index: func.c
===================================================================
--- func.c	(revision 421)
+++ func.c	(working copy)
@@ -134,7 +134,7 @@
 parent = sc->parent;
 Dsymbol *parent = toParent();
 
- if (semanticRun == PASSsemanticdone)
+ if (semanticRun >= PASSsemanticdone) // BUG 2085
 {
 	if (!parent->isClassDeclaration())
 	 return;

Although bug 4075 appears similar to this one, the patch doesn't fix it.

changeset 478

*** Issue 2513 has been marked as a duplicate of this issue. ***

dlang/dub pull request #2098 "Fix #2085: [visuald] spurious library project" was merged into master:
- d2e8c03f89c52b6b57d12449acb87e1b67cd831b by Bastiaan Veelo:
 If no output is generated (TargetType.none) then don't generate a project configuration.
 
 This prevents VS from attempting to build a library with no name from no sources.
 Fixes #2085.
- cf4a049bf8755fb988a1adf3adbf709dc025841b by Bastiaan Veelo:
 Test issue #2085.
https://github.com/dlang/dub/pull/2098