Fix ICE trying to pass DST to C functions

Fixes #25581

src/librustc_trans/trans/callee.rs

@@ -846,7 +846,7 @@ pub fn trans_call_inner<'a, 'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
 
         let mut llargs = Vec::new();
         let arg_tys = match args {
-            ArgExprs(a) => a.iter().map(|x| common::expr_ty(bcx, &**x)).collect(),
+            ArgExprs(a) => a.iter().map(|x| common::expr_ty_adjusted(bcx, &**x)).collect(),
             _ => panic!("expected arg exprs.")
         };
         bcx = trans_args(bcx,

src/test/run-make/issue-25581/Makefile

@@ -0,0 +1,7 @@
+-include ../tools.mk
+
+all:
+	$(CC) -std=c99 test.c -c -o $(TMPDIR)/test.o
+	$(AR) rcs $(TMPDIR)/libtest.a $(TMPDIR)/test.o
+	$(RUSTC) test.rs -L $(TMPDIR)
+	$(call RUN,test) || exit 1

src/test/run-make/issue-25581/test.c

@@ -0,0 +1,16 @@
+// ignore-license
+#include <stddef.h>
+#include <stdint.h>
+
+struct ByteSlice {
+        uint8_t *data;
+        size_t len;
+};
+
+size_t slice_len(struct ByteSlice bs) {
+        return bs.len;
+}
+
+uint8_t slice_elem(struct ByteSlice bs, size_t idx) {
+        return bs.data[idx];
+}

src/test/run-make/issue-25581/test.rs

@@ -0,0 +1,32 @@
+// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![feature(libc)]
+
+extern crate libc;
+
+#[link(name = "test")]
+extern {
+    fn slice_len(s: &[u8]) -> libc::size_t;
+    fn slice_elem(s: &[u8], idx: libc::size_t) -> u8;
+}
+
+fn main() {
+    let data = [1,2,3,4,5];
+
+    unsafe {
+        assert_eq!(data.len(), slice_len(&data) as usize);
+        assert_eq!(data[0], slice_elem(&data, 0));
+        assert_eq!(data[1], slice_elem(&data, 1));
+        assert_eq!(data[2], slice_elem(&data, 2));
+        assert_eq!(data[3], slice_elem(&data, 3));
+        assert_eq!(data[4], slice_elem(&data, 4));
+    }
+}