Add test case for including upstream object files in staticlibs when doing cross-lang LTO.

src/test/run-make-fulldeps/cross-lang-lto-upstream-rlibs/Makefile

@@ -0,0 +1,23 @@
+
+-include ../tools.mk
+
+# This test makes sure that we don't loose upstream object files when compiling
+# staticlibs with -Zcross-lang-lto
+
+all: staticlib.rs upstream.rs
+	$(RUSTC) upstream.rs -Z cross-lang-lto -Ccodegen-units=1
+
+	# Check No LTO
+	$(RUSTC) staticlib.rs -Z cross-lang-lto -Ccodegen-units=1 -L. -o $(TMPDIR)/staticlib.a
+	(cd $(TMPDIR); llvm-ar x ./staticlib.a)
+	# Make sure the upstream object file was included
+	ls upstream.*.rcgu.o
+
+	# Cleanup
+	rm $(TMPDIR)/*
+
+	# Check ThinLTO
+	$(RUSTC) upstream.rs -Z cross-lang-lto -Ccodegen-units=1 -Clto=thin
+	$(RUSTC) staticlib.rs -Z cross-lang-lto -Ccodegen-units=1 -Clto=thin -L. -o $(TMPDIR)/staticlib.a
+	(cd $(TMPDIR); llvm-ar x ./staticlib.a)
+	ls upstream.*.rcgu.o

src/test/run-make-fulldeps/cross-lang-lto-upstream-rlibs/staticlib.rs

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+// Copyright 2018 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.
+
+#![crate_type="staticlib"]
+
+extern crate upstream;
+
+#[no_mangle]
+pub extern fn bar() {
+    upstream::foo();
+}

src/test/run-make-fulldeps/cross-lang-lto-upstream-rlibs/upstream.rs

@@ -0,0 +1,13 @@
+// Copyright 2018 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.
+
+#![crate_type = "rlib"]
+
+pub fn foo() {}