From ecd8a2ac07033fc8f4d4ec8b4aaae1f5a0bd19d3 Mon Sep 17 00:00:00 2001
From: Tomas Lindquist Olsen <tomas.l.olsen@gmail.com>
Date: Mon, 6 Oct 2008 14:06:55 +0200
Subject: [PATCH] Support structs that are merely a forward reference. See
 mini/forwdecl1.d

---
 gen/structs.cpp        | 12 +++++++++---
 gen/toir.cpp           |  6 +++---
 tests/mini/forwdecl1.d | 12 ++++++++++++
 3 files changed, 24 insertions(+), 6 deletions(-)
 create mode 100644 tests/mini/forwdecl1.d

diff --git a/gen/structs.cpp b/gen/structs.cpp
index bdaa070a..1c74a104 100644
--- a/gen/structs.cpp
+++ b/gen/structs.cpp
@@ -131,11 +131,17 @@ void DtoResolveStruct(StructDeclaration* sd)
     Logger::println("DtoResolveStruct(%s): %s", sd->toChars(), sd->loc.toChars());
     LOG_SCOPE;
 
-    if (sd->prot() == PROTprivate && sd->getModule() != gIR->dmodule)
-        Logger::println("using a private struct from outside its module");
-
     TypeStruct* ts = (TypeStruct*)sd->type->toBasetype();
 
+    // this struct is a forward declaration
+    // didn't even know had those ...
+    if (sd->sizeok != 1)
+    {
+        sd->ir.irStruct = new IrStruct(ts);
+        ts->ir.type = new llvm::PATypeHolder(llvm::OpaqueType::get());
+        return;
+    }
+
     bool ispacked = (ts->alignsize() == 1);
 
     IrStruct* irstruct = new IrStruct(ts);
diff --git a/gen/toir.cpp b/gen/toir.cpp
index 1d4d99d1..089615d0 100644
--- a/gen/toir.cpp
+++ b/gen/toir.cpp
@@ -129,10 +129,10 @@ DValue* VarExp::toElem(IRState* p)
             if (vd->isDataseg() || (vd->storage_class & STCextern)) {
                 vd->toObjFile(0); // TODO: multiobj
             }
-            if (!vd->ir.isSet() || !vd->ir.getIrValue() || DtoType(vd->type)->isAbstract()) {
-                error("global variable %s not resolved", vd->toChars());
+            if (!vd->ir.isSet() || !vd->ir.getIrValue()) {
+                error("variable %s not resolved", vd->toChars());
                 if (Logger::enabled())
-                    Logger::cout() << "unresolved global had type: " << *DtoType(vd->type) << '\n';
+                    Logger::cout() << "unresolved variable had type: " << *DtoType(vd->type) << '\n';
                 fatal();
             }
             if (vd->isDataseg() || (vd->storage_class & STCextern)) {
diff --git a/tests/mini/forwdecl1.d b/tests/mini/forwdecl1.d
new file mode 100644
index 00000000..c8674067
--- /dev/null
+++ b/tests/mini/forwdecl1.d
@@ -0,0 +1,12 @@
+struct Foo;
+
+Foo* foo()
+{
+    return null;
+}
+
+void main()
+{
+    Foo* f = foo();
+    assert(f is null);
+}