---

yaml
---
r: 273295
b: refs/heads/beta
c: 9a8b807
h: refs/heads/master
i:
  273293: 84e3ef5
  273291: 6137aaf
  273287: af21e1f
  273279: 737377e

Author: eddyb

[refs]

@@ -23,7 +23,7 @@ refs/tags/0.9: 36870b185fc5f5486636d4515f0e22677493f225
 refs/tags/0.10: ac33f2b15782272ae348dbd7b14b8257b2148b5a
 refs/tags/0.11.0: e1247cb1d0d681be034adb4b558b5a0c0d5720f9
 refs/tags/0.12.0: f0c419429ef30723ceaf6b42f9b5a2aeb5d2e2d1
-refs/heads/beta: 02a141a5506ae499367c67e147688d049dd96efb
+refs/heads/beta: 9a8b80762b4369772ae3f99a96efed1f3bdf8c1b
 refs/tags/1.0.0-alpha: e42bd6d93a1d3433c486200587f8f9e12590a4d7
 refs/heads/tmp: e06d2ad9fcd5027bcaac5b08fc9aa39a49d0ecd3
 refs/tags/1.0.0-alpha.2: 4c705f6bc559886632d3871b04f58aab093bfa2f

branches/beta/src/librustc_trans/trans/abi.rs

@@ -378,11 +378,27 @@ impl FnType {
         if abi == Abi::Rust || abi == Abi::RustCall ||
            abi == Abi::RustIntrinsic || abi == Abi::PlatformIntrinsic {
             let fixup = |arg: &mut ArgType| {
-                if !arg.ty.is_aggregate() {
+                let mut llty = arg.ty;
+
+                // Replace newtypes with their inner-most type.
+                while llty.kind() == llvm::TypeKind::Struct {
+                    let inner = llty.field_types();
+                    if inner.len() != 1 {
+                        break;
+                    }
+                    llty = inner[0];
+                }
+
+                if !llty.is_aggregate() {
                     // Scalars and vectors, always immediate.
+                    if llty != arg.ty {
+                        // Needs a cast as we've unpacked a newtype.
+                        arg.cast = Some(llty);
+                    }
                     return;
                 }
-                let size = llsize_of_real(ccx, arg.ty);
+
+                let size = llsize_of_real(ccx, llty);
                 if size > llsize_of_real(ccx, ccx.int_type()) {
                     arg.make_indirect(ccx);
                 } else if size > 0 {