rustbuild: Tweak how we cross-compile LLVM

In preparation for upgrading to LLVM 5.0 it looks like we need to tweak how we
cross compile LLVM slightly. It's using `CMAKE_SYSTEM_NAME` to infer whether to
build libFuzzer which only works on some platforms, and then once we configure
that it needs to apparently reach into the host build area to try to compile
`llvm-config` as well. Once these are both configured, though, it looks like we
can successfully cross-compile LLVM.

1 files changed, 8 insertions, 0 deletions

diff --git a/src/bootstrap/native.rs b/src/bootstrap/native.rs
index f0dfd857ab6..bb80674c887 100644
--- a/src/bootstrap/native.rs
+++ b/src/bootstrap/native.rs
@@ -154,6 +154,14 @@ impl Step for Llvm {
             let host = build.llvm_out(build.build).join("bin/llvm-tblgen");
             cfg.define("CMAKE_CROSSCOMPILING", "True")
                .define("LLVM_TABLEGEN", &host);
+
+            if target.contains("netbsd") {
+               cfg.define("CMAKE_SYSTEM_NAME", "NetBSD");
+            } else if target.contains("freebsd") {
+               cfg.define("CMAKE_SYSTEM_NAME", "FreeBSD");
+            }
+
+            cfg.define("LLVM_NATIVE_BUILD", build.llvm_out(build.build).join("build"));
         }
 
         let sanitize_cc = |cc: &Path| {