From 995f0bdb9b999056667e6dff7ebc9712ac79cc5b Mon Sep 17 00:00:00 2001
From: MaulingMonkey <git@maulingmonkey.com>
Date: Sun, 10 Sep 2017 19:37:59 -0700
Subject: [PATCH] Skip passing /natvis to lld-link until supported.

LLVM 5.0.0's lld-link frontend errors out if passed /natvis.
LLVM 6 (maybe earlier?) should at least ignore the flag.
Hopefully LLVM will eventually support the flag, at which point
this workaround can perhaps be simply removed, if 6? is old enough.
---
 src/librustc_trans/back/linker.rs | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/librustc_trans/back/linker.rs b/src/librustc_trans/back/linker.rs
index 487d9e059458c..de2b5905d6f78 100644
--- a/src/librustc_trans/back/linker.rs
+++ b/src/librustc_trans/back/linker.rs
@@ -498,6 +498,18 @@ impl<'a> Linker for MsvcLinker<'a> {
         let sysroot = self.sess.sysroot();
         let natvis_dir_path = sysroot.join("lib\\rustlib\\etc");
         if let Ok(natvis_dir) = fs::read_dir(&natvis_dir_path) {
+            // LLVM 5.0.0's lld-link frontend doesn't yet recognize, and chokes
+            // on, the /NATVIS:... flags.  LLVM 6 (or earlier) should at worst ignore
+            // them, eventually mooting this workaround, per this landed patch:
+            // https://github.com/llvm-mirror/lld/commit/27b9c4285364d8d76bb43839daa100
+            if let Some(ref linker_path) = self.sess.opts.cg.linker {
+                if let Some(linker_name) = Path::new(&linker_path).file_stem() {
+                    if linker_name.to_str().unwrap().to_lowercase() == "lld-link" {
+                        self.sess.warn("not embedding natvis: lld-link may not support the flag");
+                        return;
+                    }
+                }
+            }
             for entry in natvis_dir {
                 match entry {
                     Ok(entry) => {