Auto merge of #28612 - gandro:targetvendor, r=alexcrichton

This adds a new target property, `target_vendor`. It is to be be used as a matcher for conditional compilation. The vendor is part of the [autoconf target triple](http://llvm.org/docs/doxygen/html/classllvm_1_1Triple.html#details): `<arch><sub>-<vendor>-<os>-<env>`. `arch`, `target_os` and `target_env` are already supported by Rust.

This change was suggested in PR #28593. It enables conditional compilation based on the vendor. This is needed for the rumprun target, which needs to match against both, target_os and target_vendor.

The default value for `target_vendor` is "unknown", "apple" and "pc" are other common values.

Matching against the `target_vendor` is introduced behind the feature gate `#![feature(cfg_target_vendor)]`.

This is the first time I messed around with rustc internals. I just added the my code where I found the existing `target_*` variables, hopefully I haven't missed anything. Please review with care. :)

r? @alexcrichton 

36 files changed, 95 insertions, 3 deletions

diff --git a/src/doc/reference.md b/src/doc/reference.md
index cd24e33a232..eeae2de827a 100644
--- a/src/doc/reference.md
+++ b/src/doc/reference.md
@@ -2093,6 +2093,8 @@ The following configurations must be defined by the implementation:
 * `target_pointer_width = "..."` - Target pointer width in bits. This is set
   to `"32"` for targets with 32-bit pointers, and likewise set to `"64"` for
   64-bit pointers.
+* `target_vendor = "..."` - Vendor of the target, for example `apple`, `pc`, or
+  simply `"unknown"`.
 * `test` - Enabled when compiling the test harness (using the `--test` flag).
 * `unix` - See `target_family`.
 * `windows` - See `target_family`.
@@ -2269,7 +2271,7 @@ The currently implemented features of the reference compiler are:
 * `advanced_slice_patterns` - See the [match expressions](#match-expressions)
                               section for discussion; the exact semantics of
                               slice patterns are subject to change, so some types
-			      are still unstable.
+                              are still unstable.
 
 * `slice_patterns` - OK, actually, slice patterns are just scary and
                      completely unstable.
@@ -2290,6 +2292,9 @@ The currently implemented features of the reference compiler are:
 * `box_syntax` - Allows use of `box` expressions, the exact semantics of which
                  is subject to change.
 
+* `cfg_target_vendor` - Allows conditional compilation using the `target_vendor`
+                        matcher which is subject to change.
+
 * `concat_idents` - Allows use of the `concat_idents` macro, which is in many
                     ways insufficient for concatenating identifiers, and may be
                     removed entirely for something more wholesome.
diff --git a/src/librustc/session/config.rs b/src/librustc/session/config.rs
index 30f43baabba..dcc4ca137ea 100644
--- a/src/librustc/session/config.rs
+++ b/src/librustc/session/config.rs
@@ -617,6 +617,7 @@ pub fn default_configuration(sess: &Session) -> ast::CrateConfig {
     let wordsz = &sess.target.target.target_pointer_width;
     let os = &sess.target.target.target_os;
     let env = &sess.target.target.target_env;
+    let vendor = &sess.target.target.target_vendor;
 
     let fam = match sess.target.target.options.is_like_windows {
         true  => InternedString::new("windows"),
@@ -632,6 +633,7 @@ pub fn default_configuration(sess: &Session) -> ast::CrateConfig {
          mk(InternedString::new("target_endian"), intern(end)),
          mk(InternedString::new("target_pointer_width"), intern(wordsz)),
          mk(InternedString::new("target_env"), intern(env)),
+         mk(InternedString::new("target_vendor"), intern(vendor)),
     ];
     if sess.opts.debug_assertions {
         ret.push(attr::mk_word_item(InternedString::new("debug_assertions")));
diff --git a/src/librustc_back/target/aarch64_apple_ios.rs b/src/librustc_back/target/aarch64_apple_ios.rs
index e87cb43128d..e1242560e62 100644
--- a/src/librustc_back/target/aarch64_apple_ios.rs
+++ b/src/librustc_back/target/aarch64_apple_ios.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         arch: "aarch64".to_string(),
         target_os: "ios".to_string(),
         target_env: "".to_string(),
+        target_vendor: "apple".to_string(),
         options: TargetOptions {
             features: "+neon,+fp-armv8,+cyclone".to_string(),
             eliminate_frame_pointer: false,
diff --git a/src/librustc_back/target/aarch64_linux_android.rs b/src/librustc_back/target/aarch64_linux_android.rs
index 8c350e8b287..c6901a4cc42 100644
--- a/src/librustc_back/target/aarch64_linux_android.rs
+++ b/src/librustc_back/target/aarch64_linux_android.rs
@@ -18,6 +18,7 @@ pub fn target() -> Target {
         arch: "aarch64".to_string(),
         target_os: "android".to_string(),
         target_env: "".to_string(),
+        target_vendor: "unknown".to_string(),
         options: super::android_base::opts(),
     }
 }
diff --git a/src/librustc_back/target/aarch64_unknown_linux_gnu.rs b/src/librustc_back/target/aarch64_unknown_linux_gnu.rs
index ed79caf4869..51abab6609a 100644
--- a/src/librustc_back/target/aarch64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/aarch64_unknown_linux_gnu.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         target_env: "gnu".to_string(),
         arch: "aarch64".to_string(),
         target_os: "linux".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/arm_linux_androideabi.rs b/src/librustc_back/target/arm_linux_androideabi.rs
index 0770fe70e8a..732f1a353a8 100644
--- a/src/librustc_back/target/arm_linux_androideabi.rs
+++ b/src/librustc_back/target/arm_linux_androideabi.rs
@@ -21,6 +21,7 @@ pub fn target() -> Target {
         arch: "arm".to_string(),
         target_os: "android".to_string(),
         target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/arm_unknown_linux_gnueabi.rs b/src/librustc_back/target/arm_unknown_linux_gnueabi.rs
index 084f989277f..7c35b43fd4b 100644
--- a/src/librustc_back/target/arm_unknown_linux_gnueabi.rs
+++ b/src/librustc_back/target/arm_unknown_linux_gnueabi.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         arch: "arm".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnueabi".to_string(),
+        target_vendor: "unknown".to_string(),
 
         options: TargetOptions {
             features: "+v6".to_string(),
diff --git a/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs b/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs
index 08f1aa5ade8..a99ec45996c 100644
--- a/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs
+++ b/src/librustc_back/target/arm_unknown_linux_gnueabihf.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         arch: "arm".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnueabihf".to_string(),
+        target_vendor: "unknown".to_string(),
 
         options: TargetOptions {
             features: "+v6,+vfp2".to_string(),
diff --git a/src/librustc_back/target/armv7_apple_ios.rs b/src/librustc_back/target/armv7_apple_ios.rs
index a6d649ea162..d3064800291 100644
--- a/src/librustc_back/target/armv7_apple_ios.rs
+++ b/src/librustc_back/target/armv7_apple_ios.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         arch: "arm".to_string(),
         target_os: "ios".to_string(),
         target_env: "".to_string(),
+        target_vendor: "apple".to_string(),
         options: TargetOptions {
             features: "+v7,+vfp3,+neon".to_string(),
             .. opts(Arch::Armv7)
diff --git a/src/librustc_back/target/armv7s_apple_ios.rs b/src/librustc_back/target/armv7s_apple_ios.rs
index 264385512ad..66ec6efca0e 100644
--- a/src/librustc_back/target/armv7s_apple_ios.rs
+++ b/src/librustc_back/target/armv7s_apple_ios.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         arch: "arm".to_string(),
         target_os: "ios".to_string(),
         target_env: "".to_string(),
+        target_vendor: "apple".to_string(),
         options: TargetOptions {
             features: "+v7,+vfp4,+neon".to_string(),
             .. opts(Arch::Armv7s)
diff --git a/src/librustc_back/target/i386_apple_ios.rs b/src/librustc_back/target/i386_apple_ios.rs
index d17aa915461..52b5901192c 100644
--- a/src/librustc_back/target/i386_apple_ios.rs
+++ b/src/librustc_back/target/i386_apple_ios.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         arch: "x86".to_string(),
         target_os: "ios".to_string(),
         target_env: "".to_string(),
+        target_vendor: "apple".to_string(),
         options: opts(Arch::I386)
     }
 }
diff --git a/src/librustc_back/target/i686_apple_darwin.rs b/src/librustc_back/target/i686_apple_darwin.rs
index 9fe15e76942..98f4654ecab 100644
--- a/src/librustc_back/target/i686_apple_darwin.rs
+++ b/src/librustc_back/target/i686_apple_darwin.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         arch: "x86".to_string(),
         target_os: "macos".to_string(),
         target_env: "".to_string(),
+        target_vendor: "apple".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/i686_linux_android.rs b/src/librustc_back/target/i686_linux_android.rs
index 708e7756b94..f548fdad3cb 100644
--- a/src/librustc_back/target/i686_linux_android.rs
+++ b/src/librustc_back/target/i686_linux_android.rs
@@ -21,6 +21,7 @@ pub fn target() -> Target {
         arch: "x86".to_string(),
         target_os: "android".to_string(),
         target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/i686_pc_windows_gnu.rs b/src/librustc_back/target/i686_pc_windows_gnu.rs
index ae1b4d450a5..c825f6043d2 100644
--- a/src/librustc_back/target/i686_pc_windows_gnu.rs
+++ b/src/librustc_back/target/i686_pc_windows_gnu.rs
@@ -30,6 +30,7 @@ pub fn target() -> Target {
         arch: "x86".to_string(),
         target_os: "windows".to_string(),
         target_env: "gnu".to_string(),
+        target_vendor: "pc".to_string(),
         options: options,
     }
 }
diff --git a/src/librustc_back/target/i686_pc_windows_msvc.rs b/src/librustc_back/target/i686_pc_windows_msvc.rs
index d8c1c79b47f..96b2d37ab20 100644
--- a/src/librustc_back/target/i686_pc_windows_msvc.rs
+++ b/src/librustc_back/target/i686_pc_windows_msvc.rs
@@ -21,6 +21,7 @@ pub fn target() -> Target {
         arch: "x86".to_string(),
         target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
+        target_vendor: "pc".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/i686_unknown_dragonfly.rs b/src/librustc_back/target/i686_unknown_dragonfly.rs
index f2478e6d0db..32a15b9f2d4 100644
--- a/src/librustc_back/target/i686_unknown_dragonfly.rs
+++ b/src/librustc_back/target/i686_unknown_dragonfly.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         arch: "x86".to_string(),
         target_os: "dragonfly".to_string(),
         target_env: "".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/i686_unknown_freebsd.rs b/src/librustc_back/target/i686_unknown_freebsd.rs
index 6b2d9b5053c..812ba11cd79 100644
--- a/src/librustc_back/target/i686_unknown_freebsd.rs
+++ b/src/librustc_back/target/i686_unknown_freebsd.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         arch: "x86".to_string(),
         target_os: "freebsd".to_string(),
         target_env: "".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/i686_unknown_linux_gnu.rs b/src/librustc_back/target/i686_unknown_linux_gnu.rs
index 074d5b2b9ed..ac2af0c64fd 100644
--- a/src/librustc_back/target/i686_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/i686_unknown_linux_gnu.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         arch: "x86".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/mips_unknown_linux_gnu.rs b/src/librustc_back/target/mips_unknown_linux_gnu.rs
index 3f3da6d6c91..357499c48ec 100644
--- a/src/librustc_back/target/mips_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/mips_unknown_linux_gnu.rs
@@ -18,6 +18,7 @@ pub fn target() -> Target {
         arch: "mips".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
         options: super::linux_base::opts()
     }
 }
diff --git a/src/librustc_back/target/mipsel_unknown_linux_gnu.rs b/src/librustc_back/target/mipsel_unknown_linux_gnu.rs
index d7f286c8aa4..3d0088add0d 100644
--- a/src/librustc_back/target/mipsel_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/mipsel_unknown_linux_gnu.rs
@@ -18,6 +18,7 @@ pub fn target() -> Target {
         arch: "mips".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
 
         options: super::linux_base::opts()
     }
diff --git a/src/librustc_back/target/mod.rs b/src/librustc_back/target/mod.rs
index e7c1c3fb258..b5847b98af1 100644
--- a/src/librustc_back/target/mod.rs
+++ b/src/librustc_back/target/mod.rs
@@ -77,6 +77,8 @@ pub struct Target {
     pub target_os: String,
     /// Environment name to use for conditional compilation.
     pub target_env: String,
+    /// Vendor name to use for conditional compilation.
+    pub target_vendor: String,
     /// Architecture to use for ABI considerations. Valid options: "x86", "x86_64", "arm",
     /// "aarch64", "mips", and "powerpc". "mips" includes "mipsel".
     pub arch: String,
@@ -260,14 +262,20 @@ impl Target {
             }
         };
 
+        let get_opt_field = |name: &str, default: &str| {
+            obj.find(name).and_then(|s| s.as_string())
+               .map(|s| s.to_string())
+               .unwrap_or(default.to_string())
+        };
+
         let mut base = Target {
             llvm_target: get_req_field("llvm-target"),
             target_endian: get_req_field("target-endian"),
             target_pointer_width: get_req_field("target-pointer-width"),
             arch: get_req_field("arch"),
             target_os: get_req_field("os"),
-            target_env: obj.find("env").and_then(|s| s.as_string())
-                           .map(|s| s.to_string()).unwrap_or(String::new()),
+            target_env: get_opt_field("env", ""),
+            target_vendor: get_opt_field("vendor", "unknown"),
             options: Default::default(),
         };
 
diff --git a/src/librustc_back/target/powerpc_unknown_linux_gnu.rs b/src/librustc_back/target/powerpc_unknown_linux_gnu.rs
index 896824eba0e..6664abf5458 100644
--- a/src/librustc_back/target/powerpc_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/powerpc_unknown_linux_gnu.rs
@@ -21,6 +21,7 @@ pub fn target() -> Target {
         arch: "powerpc".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_apple_darwin.rs b/src/librustc_back/target/x86_64_apple_darwin.rs
index ef40c2f2006..3e19e148290 100644
--- a/src/librustc_back/target/x86_64_apple_darwin.rs
+++ b/src/librustc_back/target/x86_64_apple_darwin.rs
@@ -23,6 +23,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "macos".to_string(),
         target_env: "".to_string(),
+        target_vendor: "apple".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_apple_ios.rs b/src/librustc_back/target/x86_64_apple_ios.rs
index 7aca8c554da..63234c0baee 100644
--- a/src/librustc_back/target/x86_64_apple_ios.rs
+++ b/src/librustc_back/target/x86_64_apple_ios.rs
@@ -19,6 +19,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "ios".to_string(),
         target_env: "".to_string(),
+        target_vendor: "apple".to_string(),
         options: opts(Arch::X86_64)
     }
 }
diff --git a/src/librustc_back/target/x86_64_pc_windows_gnu.rs b/src/librustc_back/target/x86_64_pc_windows_gnu.rs
index aef1d7471b8..2bd363e46bb 100644
--- a/src/librustc_back/target/x86_64_pc_windows_gnu.rs
+++ b/src/librustc_back/target/x86_64_pc_windows_gnu.rs
@@ -25,6 +25,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "windows".to_string(),
         target_env: "gnu".to_string(),
+        target_vendor: "pc".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_pc_windows_msvc.rs b/src/librustc_back/target/x86_64_pc_windows_msvc.rs
index 85756db9606..5030a1ff448 100644
--- a/src/librustc_back/target/x86_64_pc_windows_msvc.rs
+++ b/src/librustc_back/target/x86_64_pc_windows_msvc.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "windows".to_string(),
         target_env: "msvc".to_string(),
+        target_vendor: "pc".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_bitrig.rs b/src/librustc_back/target/x86_64_unknown_bitrig.rs
index 6ecf885aba3..04456b1b271 100644
--- a/src/librustc_back/target/x86_64_unknown_bitrig.rs
+++ b/src/librustc_back/target/x86_64_unknown_bitrig.rs
@@ -21,6 +21,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "bitrig".to_string(),
         target_env: "".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_dragonfly.rs b/src/librustc_back/target/x86_64_unknown_dragonfly.rs
index f0e665967ec..62654176aa4 100644
--- a/src/librustc_back/target/x86_64_unknown_dragonfly.rs
+++ b/src/librustc_back/target/x86_64_unknown_dragonfly.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "dragonfly".to_string(),
         target_env: "".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_freebsd.rs b/src/librustc_back/target/x86_64_unknown_freebsd.rs
index f742ebfde1d..888b7f58bff 100644
--- a/src/librustc_back/target/x86_64_unknown_freebsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_freebsd.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "freebsd".to_string(),
         target_env: "".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_linux_gnu.rs b/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
index 4749e481fd8..e3ccd9c4c7e 100644
--- a/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
+++ b/src/librustc_back/target/x86_64_unknown_linux_gnu.rs
@@ -22,6 +22,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "linux".to_string(),
         target_env: "gnu".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_linux_musl.rs b/src/librustc_back/target/x86_64_unknown_linux_musl.rs
index c66192c28b1..a5ac78cd5b6 100644
--- a/src/librustc_back/target/x86_64_unknown_linux_musl.rs
+++ b/src/librustc_back/target/x86_64_unknown_linux_musl.rs
@@ -76,6 +76,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "linux".to_string(),
         target_env: "musl".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_netbsd.rs b/src/librustc_back/target/x86_64_unknown_netbsd.rs
index e13e58e3a18..4101fabe734 100644
--- a/src/librustc_back/target/x86_64_unknown_netbsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_netbsd.rs
@@ -21,6 +21,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "netbsd".to_string(),
         target_env: "".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/librustc_back/target/x86_64_unknown_openbsd.rs b/src/librustc_back/target/x86_64_unknown_openbsd.rs
index a404db48b22..07a1e137b41 100644
--- a/src/librustc_back/target/x86_64_unknown_openbsd.rs
+++ b/src/librustc_back/target/x86_64_unknown_openbsd.rs
@@ -21,6 +21,7 @@ pub fn target() -> Target {
         arch: "x86_64".to_string(),
         target_os: "openbsd".to_string(),
         target_env: "".to_string(),
+        target_vendor: "unknown".to_string(),
         options: base,
     }
 }
diff --git a/src/libsyntax/feature_gate.rs b/src/libsyntax/feature_gate.rs
index eaf964a3c64..6643dad6a68 100644
--- a/src/libsyntax/feature_gate.rs
+++ b/src/libsyntax/feature_gate.rs
@@ -203,6 +203,9 @@ const KNOWN_FEATURES: &'static [(&'static str, &'static str, Option<u32>, Status
 
     // allow `#[omit_gdb_pretty_printer_section]`
     ("omit_gdb_pretty_printer_section", "1.5.0", None, Active),
+
+    // Allows cfg(target_vendor = "...").
+    ("cfg_target_vendor", "1.5.0", None, Active),
 ];
 // (changing above list without updating src/doc/reference.md makes @cmr sad)
 
@@ -377,6 +380,7 @@ macro_rules! cfg_fn {
 const GATED_CFGS: &'static [(&'static str, &'static str, fn(&Features) -> bool)] = &[
     // (name in cfg, feature, function to check if the feature is enabled)
     ("target_feature", "cfg_target_feature", cfg_fn!(|x| x.cfg_target_feature)),
+    ("target_vendor", "cfg_target_vendor", cfg_fn!(|x| x.cfg_target_vendor)),
 ];
 
 #[derive(Debug, Eq, PartialEq)]
@@ -471,6 +475,7 @@ pub struct Features {
     pub default_type_parameter_fallback: bool,
     pub type_macros: bool,
     pub cfg_target_feature: bool,
+    pub cfg_target_vendor: bool,
     pub augmented_assignments: bool,
 }
 
@@ -500,6 +505,7 @@ impl Features {
             default_type_parameter_fallback: false,
             type_macros: false,
             cfg_target_feature: false,
+            cfg_target_vendor: false,
             augmented_assignments: false,
         }
     }
@@ -1069,6 +1075,7 @@ fn check_crate_inner<F>(cm: &CodeMap, span_handler: &SpanHandler,
         default_type_parameter_fallback: cx.has_feature("default_type_parameter_fallback"),
         type_macros: cx.has_feature("type_macros"),
         cfg_target_feature: cx.has_feature("cfg_target_feature"),
+        cfg_target_vendor: cx.has_feature("cfg_target_vendor"),
         augmented_assignments: cx.has_feature("augmented_assignments"),
     }
 }
diff --git a/src/test/compile-fail/feature-gate-cfg-target-vendor.rs b/src/test/compile-fail/feature-gate-cfg-target-vendor.rs
new file mode 100644
index 00000000000..e68a84d3553
--- /dev/null
+++ b/src/test/compile-fail/feature-gate-cfg-target-vendor.rs
@@ -0,0 +1,21 @@
+// Copyright 2015 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.
+
+#[cfg(target_vendor = "x")] //~ ERROR `cfg(target_vendor)` is experimental
+#[cfg_attr(target_vendor = "x", x)] //~ ERROR `cfg(target_vendor)` is experimental
+struct Foo(u64, u64);
+
+#[cfg(not(any(all(target_vendor = "x"))))] //~ ERROR `cfg(target_vendor)` is experimental
+fn foo() {}
+
+fn main() {
+    cfg!(target_vendor = "x");
+    //~^ ERROR `cfg(target_vendor)` is experimental and subject to change
+}
diff --git a/src/test/run-pass/cfg-target-vendor.rs b/src/test/run-pass/cfg-target-vendor.rs
new file mode 100644
index 00000000000..787ae5289dd
--- /dev/null
+++ b/src/test/run-pass/cfg-target-vendor.rs
@@ -0,0 +1,19 @@
+// Copyright 2015 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(cfg_target_vendor)]
+
+#[cfg(target_vendor = "unknown")]
+pub fn main() {
+}
+
+#[cfg(not(target_vendor = "unknown"))]
+pub fn main() {
+}