Add tests for -Z cross-lang-lto.

src/test/run-make/cross-lang-lto/Makefile

@@ -0,0 +1,49 @@
+# This test makes sure that the expected .llvmbc sections for use by
+# linker-based LTO are available in object files when compiling with
+# -Z cross-lang-lto
+
+-include ../../run-make-fulldeps/tools.mk
+
+LLVMBC_SECTION_NAME=\\.llvmbc
+
+ifeq ($(UNAME),Darwin)
+	LLVMBC_SECTION_NAME=__LLVM,__bitcode
+endif
+
+
+OBJDUMP=$(HOST_RPATH_DIR)/../../llvm/bin/llvm-objdump
+SECTION_HEADERS=$(OBJDUMP) -section-headers
+
+BUILD_LIB=$(RUSTC) lib.rs -Copt-level=2 -Z cross-lang-lto -Ccodegen-units=1
+
+BUILD_EXE=$(RUSTC) main.rs -Copt-level=2 -Z cross-lang-lto -Ccodegen-units=1 --emit=obj
+
+all: staticlib staticlib-fat-lto staticlib-thin-lto rlib exe cdylib rdylib
+
+staticlib: lib.rs
+	$(BUILD_LIB) --crate-type=staticlib
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/liblib.a | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+staticlib-fat-lto: lib.rs
+	$(BUILD_LIB) --crate-type=staticlib -o $(TMPDIR)/liblib-fat-lto.a -Clto=fat
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/liblib-fat-lto.a | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+staticlib-thin-lto: lib.rs
+	$(BUILD_LIB) --crate-type=staticlib -o $(TMPDIR)/liblib-thin-lto.a -Clto=thin
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/liblib-thin-lto.a | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+rlib: lib.rs
+	$(BUILD_LIB) --crate-type=rlib
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/liblib.rlib | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+cdylib: lib.rs
+	$(BUILD_LIB) --crate-type=cdylib --emit=obj -o $(TMPDIR)/cdylib.o
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/cdylib.o | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+rdylib: lib.rs
+	$(BUILD_LIB) --crate-type=dylib --emit=obj -o $(TMPDIR)/rdylib.o
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/rdylib.o | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]
+
+exe: lib.rs
+	$(BUILD_EXE) -o $(TMPDIR)/exe.o
+	[ "$$($(SECTION_HEADERS) $(TMPDIR)/exe.o | grep -c $(LLVMBC_SECTION_NAME))" -ne "0" ]

src/test/run-make/cross-lang-lto/lib.rs

@@ -0,0 +1,14 @@
+// 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.
+
+#[no_mangle]
+pub extern "C" fn foo() {
+    println!("abc");
+}

src/test/run-make/cross-lang-lto/main.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.
+
+fn main() {
+    println!("Hello World");
+}