diff --git a/COMPILER_TESTS.md b/COMPILER_TESTS.md
index 91975c1f9ed9a..58df1aae6d3f0 100644
--- a/COMPILER_TESTS.md
+++ b/COMPILER_TESTS.md
@@ -45,6 +45,10 @@ whole, instead of just a few lines inside the test.
 * `should-fail` indicates that the test should fail; used for "meta testing",
   where we test the compiletest program itself to check that it will generate
   errors in appropriate scenarios. This header is ignored for pretty-printer tests.
+* `gate-test-X` where `X` is a feature marks the test as "gate test" for feature X.
+  Such tests are supposed to ensure that the compiler errors when usage of a gated
+  feature is attempted without the proper `#![feature(X)]` tag.
+  Each unstable lang feature is required to have a gate test.
 
 ## Revisions
 
diff --git a/src/test/compile-fail/asm-gated.rs b/src/test/compile-fail/asm-gated.rs
index 8d053bdae789b..cd9cc22370149 100644
--- a/src/test/compile-fail/asm-gated.rs
+++ b/src/test/compile-fail/asm-gated.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-asm
+
 fn main() {
     unsafe {
         asm!(""); //~ ERROR inline assembly is not stable enough
diff --git a/src/test/compile-fail/asm-gated2.rs b/src/test/compile-fail/asm-gated2.rs
index d2ee01109f8d8..222190de9fe9c 100644
--- a/src/test/compile-fail/asm-gated2.rs
+++ b/src/test/compile-fail/asm-gated2.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-asm
+
 fn main() {
     unsafe {
         println!("{}", asm!("")); //~ ERROR inline assembly is not stable
diff --git a/src/test/compile-fail/attr-on-generic-formals-wo-feature-gate.rs b/src/test/compile-fail/attr-on-generic-formals-wo-feature-gate.rs
index 944802f450a6d..b341f7c78257a 100644
--- a/src/test/compile-fail/attr-on-generic-formals-wo-feature-gate.rs
+++ b/src/test/compile-fail/attr-on-generic-formals-wo-feature-gate.rs
@@ -16,6 +16,8 @@
 // using `rustc_attrs` feature. There is a separate compile-fail/ test
 // ensuring that the attribute feature-gating works in this context.)
 
+// gate-test-generic_param_attrs
+
 #![feature(rustc_attrs)]
 #![allow(dead_code)]
 
diff --git a/src/test/compile-fail/check-static-values-constraints.rs b/src/test/compile-fail/check-static-values-constraints.rs
index df22e2ea4de13..f65968e0e1192 100644
--- a/src/test/compile-fail/check-static-values-constraints.rs
+++ b/src/test/compile-fail/check-static-values-constraints.rs
@@ -10,6 +10,8 @@
 
 // Verifies all possible restrictions for statics values.
 
+// gate-test-drop_types_in_const
+
 #![feature(box_syntax)]
 
 use std::marker;
diff --git a/src/test/compile-fail/concat_idents-gate.rs b/src/test/compile-fail/concat_idents-gate.rs
index f4d97445725cd..5b125d0e51c08 100644
--- a/src/test/compile-fail/concat_idents-gate.rs
+++ b/src/test/compile-fail/concat_idents-gate.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-concat_idents
+
 const XY_1: i32 = 10;
 
 fn main() {
diff --git a/src/test/compile-fail/concat_idents-gate2.rs b/src/test/compile-fail/concat_idents-gate2.rs
index d8f8f803edcc8..5a9ffe98c93ca 100644
--- a/src/test/compile-fail/concat_idents-gate2.rs
+++ b/src/test/compile-fail/concat_idents-gate2.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-concat_idents
+
 const XY_1: i32 = 10;
 
 fn main() {
diff --git a/src/test/compile-fail/const-fn-stability.rs b/src/test/compile-fail/const-fn-stability.rs
index 9913c2fa12c4a..436244525e1c2 100644
--- a/src/test/compile-fail/const-fn-stability.rs
+++ b/src/test/compile-fail/const-fn-stability.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-const_fn
+
 // Test use of const fn without feature gate.
 
 const fn foo() -> usize { 0 } //~ ERROR const fn is unstable
diff --git a/src/test/compile-fail/feature-gate-abi.rs b/src/test/compile-fail/feature-gate-abi.rs
index 0c01f955c063b..c0fb94e8c42c9 100644
--- a/src/test/compile-fail/feature-gate-abi.rs
+++ b/src/test/compile-fail/feature-gate-abi.rs
@@ -8,6 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-intrinsics
+// gate-test-platform_intrinsics
+// gate-test-abi_vectorcall
+
 // Functions
 extern "rust-intrinsic" fn f1() {} //~ ERROR intrinsics are subject to change
 extern "platform-intrinsic" fn f2() {} //~ ERROR platform intrinsics are experimental
diff --git a/src/test/compile-fail/feature-gate-advanced-slice-features.rs b/src/test/compile-fail/feature-gate-advanced-slice-features.rs
index 1daca371b3409..dc9b4e634ab72 100644
--- a/src/test/compile-fail/feature-gate-advanced-slice-features.rs
+++ b/src/test/compile-fail/feature-gate-advanced-slice-features.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-advanced_slice_patterns
+
 #![feature(slice_patterns)]
 
 fn main() {
diff --git a/src/test/compile-fail/feature-gate-allow-internal-unstable-nested-macro.rs b/src/test/compile-fail/feature-gate-allow-internal-unstable-nested-macro.rs
index 9ebf8a9b74a6c..1aabe6b87dff5 100644
--- a/src/test/compile-fail/feature-gate-allow-internal-unstable-nested-macro.rs
+++ b/src/test/compile-fail/feature-gate-allow-internal-unstable-nested-macro.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-allow_internal_unstable
+
 macro_rules! bar {
     () => {
         // more layers don't help:
diff --git a/src/test/compile-fail/feature-gate-assoc-type-defaults.rs b/src/test/compile-fail/feature-gate-assoc-type-defaults.rs
index fc4871a712dff..de3521eb0f20b 100644
--- a/src/test/compile-fail/feature-gate-assoc-type-defaults.rs
+++ b/src/test/compile-fail/feature-gate-assoc-type-defaults.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-associated_type_defaults
+
 trait Foo {
     type Bar = u8; //~ ERROR associated type defaults are unstable
 }
diff --git a/src/test/compile-fail/feature-gate-box-expr.rs b/src/test/compile-fail/feature-gate-box-expr.rs
index f1bb5c0dea21d..65d437d0c0d31 100644
--- a/src/test/compile-fail/feature-gate-box-expr.rs
+++ b/src/test/compile-fail/feature-gate-box-expr.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-box_syntax
+
 // Check that `box EXPR` is feature-gated.
 //
 // See also feature-gate-placement-expr.rs
diff --git a/src/test/compile-fail/feature-gate-box-pat.rs b/src/test/compile-fail/feature-gate-box-pat.rs
index e64081823e74c..c30f3952dbfbe 100644
--- a/src/test/compile-fail/feature-gate-box-pat.rs
+++ b/src/test/compile-fail/feature-gate-box-pat.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-box_patterns
+
 fn main() {
     let box x = Box::new('c'); //~ ERROR box pattern syntax is experimental
     println!("x: {}", x);
diff --git a/src/test/compile-fail/feature-gate-dropck-ugeh.rs b/src/test/compile-fail/feature-gate-dropck-ugeh.rs
index aa479a987a35b..7c290b3c9c262 100644
--- a/src/test/compile-fail/feature-gate-dropck-ugeh.rs
+++ b/src/test/compile-fail/feature-gate-dropck-ugeh.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-dropck_parametricity
+
 // Ensure that attempts to use the unsafe attribute are feature-gated.
 
 // Example adapted from RFC 1238 text (just left out the feature gate).
diff --git a/src/test/compile-fail/feature-gate-may-dangle.rs b/src/test/compile-fail/feature-gate-may-dangle.rs
index 23f8ead0ca9dc..0bf1e93d9aace 100644
--- a/src/test/compile-fail/feature-gate-may-dangle.rs
+++ b/src/test/compile-fail/feature-gate-may-dangle.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-dropck_eyepatch
+
 // Check that `may_dangle` is rejected if `dropck_eyepatch` feature gate is absent.
 
 #![feature(generic_param_attrs)]
diff --git a/src/test/compile-fail/feature-gate-placement-expr.rs b/src/test/compile-fail/feature-gate-placement-expr.rs
index 080364c08554f..e3478876763b4 100644
--- a/src/test/compile-fail/feature-gate-placement-expr.rs
+++ b/src/test/compile-fail/feature-gate-placement-expr.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-placement_in_syntax
+
 // Check that `in PLACE { EXPR }` is feature-gated.
 //
 // See also feature-gate-box-expr.rs
diff --git a/src/test/compile-fail/gated-associated_consts.rs b/src/test/compile-fail/gated-associated_consts.rs
index cfa75ff9763e9..ee4422faf3a24 100644
--- a/src/test/compile-fail/gated-associated_consts.rs
+++ b/src/test/compile-fail/gated-associated_consts.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-associated_consts
+
 trait MyTrait {
     const C: bool;
     //~^ associated constants are experimental
diff --git a/src/test/compile-fail/gated-attr-literals.rs b/src/test/compile-fail/gated-attr-literals.rs
index f3132d5593e62..04abc44caecd7 100644
--- a/src/test/compile-fail/gated-attr-literals.rs
+++ b/src/test/compile-fail/gated-attr-literals.rs
@@ -10,6 +10,8 @@
 
 // Check that literals in attributes don't parse without the feature gate.
 
+// gate-test-attr_literals
+
 #![feature(rustc_attrs)]
 #![allow(dead_code)]
 #![allow(unused_variables)]
diff --git a/src/test/compile-fail/gated-box-syntax.rs b/src/test/compile-fail/gated-box-syntax.rs
index a2643fe02b8f7..9a68ddb305960 100644
--- a/src/test/compile-fail/gated-box-syntax.rs
+++ b/src/test/compile-fail/gated-box-syntax.rs
@@ -10,6 +10,8 @@
 
 // Test that the use of the box syntax is gated by `box_syntax` feature gate.
 
+// gate-test-box_syntax
+
 fn main() {
     let x = box 3;
     //~^ ERROR box expression syntax is experimental; you can call `Box::new` instead.
diff --git a/src/test/compile-fail/gated-concat_idents.rs b/src/test/compile-fail/gated-concat_idents.rs
index 054e70f382268..af288a9790440 100644
--- a/src/test/compile-fail/gated-concat_idents.rs
+++ b/src/test/compile-fail/gated-concat_idents.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-concat_idents
+
 fn main() {
     concat_idents!(a, b); //~ ERROR `concat_idents` is not stable enough
 }
diff --git a/src/test/compile-fail/gated-link-args.rs b/src/test/compile-fail/gated-link-args.rs
index 7b1405c913f6b..d34057e290eba 100644
--- a/src/test/compile-fail/gated-link-args.rs
+++ b/src/test/compile-fail/gated-link-args.rs
@@ -11,6 +11,8 @@
 // Test that `#[link_args]` attribute is gated by `link_args`
 // feature gate.
 
+// gate-test-link_args
+
 #[link_args = "aFdEfSeVEEE"]
 extern {}
 //~^ ERROR the `link_args` attribute is not portable across platforms
diff --git a/src/test/compile-fail/gated-link-llvm-intrinsics.rs b/src/test/compile-fail/gated-link-llvm-intrinsics.rs
index 92a1b071437e6..681824ae71dd0 100644
--- a/src/test/compile-fail/gated-link-llvm-intrinsics.rs
+++ b/src/test/compile-fail/gated-link-llvm-intrinsics.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-link_llvm_intrinsics
+
 extern {
     #[link_name = "llvm.sqrt.f32"]
     fn sqrt(x: f32) -> f32;
diff --git a/src/test/compile-fail/gated-naked_functions.rs b/src/test/compile-fail/gated-naked_functions.rs
index ceb475e119217..5eb4118102768 100644
--- a/src/test/compile-fail/gated-naked_functions.rs
+++ b/src/test/compile-fail/gated-naked_functions.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-naked_functions
+
 #[naked]
 //~^ the `#[naked]` attribute is an experimental feature
 fn naked() {}
diff --git a/src/test/compile-fail/gated-no-core.rs b/src/test/compile-fail/gated-no-core.rs
index 0a55a8a78ce5a..66b9c2e56705f 100644
--- a/src/test/compile-fail/gated-no-core.rs
+++ b/src/test/compile-fail/gated-no-core.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-no_core
+
 #![no_core] //~ ERROR no_core is experimental
 
 fn main() {}
diff --git a/src/test/compile-fail/gated-non-ascii-idents.rs b/src/test/compile-fail/gated-non-ascii-idents.rs
index 9e042c3a7d50e..1dff22839ad87 100644
--- a/src/test/compile-fail/gated-non-ascii-idents.rs
+++ b/src/test/compile-fail/gated-non-ascii-idents.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-non_ascii_idents
+
 extern crate core as bäz; //~ ERROR non-ascii idents
 
 use föö::bar; //~ ERROR non-ascii idents
diff --git a/src/test/compile-fail/gated-plugin_registrar.rs b/src/test/compile-fail/gated-plugin_registrar.rs
index 9cdebde7b7b98..8d185d183b419 100644
--- a/src/test/compile-fail/gated-plugin_registrar.rs
+++ b/src/test/compile-fail/gated-plugin_registrar.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-plugin_registrar
+
 // Test that `#[plugin_registrar]` attribute is gated by `plugin_registrar`
 // feature gate.
 
diff --git a/src/test/compile-fail/gated-target_feature.rs b/src/test/compile-fail/gated-target_feature.rs
index da2e41a0f5e42..02db8a71d5340 100644
--- a/src/test/compile-fail/gated-target_feature.rs
+++ b/src/test/compile-fail/gated-target_feature.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-target_feature
+
 #[target_feature = "+sse2"]
 //~^ the `#[target_feature]` attribute is an experimental feature
 fn foo() {}
diff --git a/src/test/compile-fail/gated-thread-local.rs b/src/test/compile-fail/gated-thread-local.rs
index f355c6562c8b0..b02ce9b7ecb81 100644
--- a/src/test/compile-fail/gated-thread-local.rs
+++ b/src/test/compile-fail/gated-thread-local.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-thread_local
+
 // Test that `#[thread_local]` attribute is gated by `thread_local`
 // feature gate.
 //
diff --git a/src/test/compile-fail/gated-trace_macros.rs b/src/test/compile-fail/gated-trace_macros.rs
index 19b08ce655c06..0b85b19f176d7 100644
--- a/src/test/compile-fail/gated-trace_macros.rs
+++ b/src/test/compile-fail/gated-trace_macros.rs
@@ -8,6 +8,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-trace_macros
 
 fn main() {
     trace_macros!(true); //~ ERROR: `trace_macros` is not stable
diff --git a/src/test/compile-fail/i128-feature-2.rs b/src/test/compile-fail/i128-feature-2.rs
index 4a76d39921842..d3bd810ceb2b4 100644
--- a/src/test/compile-fail/i128-feature-2.rs
+++ b/src/test/compile-fail/i128-feature-2.rs
@@ -7,6 +7,9 @@
 // <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.
+
+// gate-test-i128_type
+
 fn test1() -> i128 { //~ ERROR 128-bit type is unstable
     0
 }
diff --git a/src/test/compile-fail/i128-feature.rs b/src/test/compile-fail/i128-feature.rs
index 87dda469f9390..e94fd14a42163 100644
--- a/src/test/compile-fail/i128-feature.rs
+++ b/src/test/compile-fail/i128-feature.rs
@@ -7,6 +7,9 @@
 // <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.
+
+// gate-test-i128_type
+
 fn test2() {
     0i128; //~ ERROR 128-bit integers are not stable
 }
diff --git a/src/test/compile-fail/impl-trait/feature-gate.rs b/src/test/compile-fail/impl-trait/feature-gate.rs
index 8239b06f2b4a3..f171b6becc4b7 100644
--- a/src/test/compile-fail/impl-trait/feature-gate.rs
+++ b/src/test/compile-fail/impl-trait/feature-gate.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-conservative_impl_trait
+
 fn foo() -> impl Fn() { || {} }
 //~^ ERROR `impl Trait` is experimental
 
diff --git a/src/test/compile-fail/link-cfg-gated.rs b/src/test/compile-fail/link-cfg-gated.rs
index 27918a27caf50..bb6fb9e356352 100644
--- a/src/test/compile-fail/link-cfg-gated.rs
+++ b/src/test/compile-fail/link-cfg-gated.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-link_cfg
+
 #[link(name = "foo", cfg(foo))]
 //~^ ERROR: is feature gated
 extern {}
diff --git a/src/test/compile-fail/linkage1.rs b/src/test/compile-fail/linkage1.rs
index 555cc2b9a7aad..1cf208f021588 100644
--- a/src/test/compile-fail/linkage1.rs
+++ b/src/test/compile-fail/linkage1.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-linkage
+
 extern {
     #[linkage = "extern_weak"] static foo: isize;
     //~^ ERROR: the `linkage` attribute is experimental and not portable
diff --git a/src/test/compile-fail/log-syntax-gate.rs b/src/test/compile-fail/log-syntax-gate.rs
index 63c66e53c5ee8..b9688af35dc90 100644
--- a/src/test/compile-fail/log-syntax-gate.rs
+++ b/src/test/compile-fail/log-syntax-gate.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-log_syntax
+
 fn main() {
     log_syntax!() //~ ERROR `log_syntax!` is not stable enough
 }
diff --git a/src/test/compile-fail/log-syntax-gate2.rs b/src/test/compile-fail/log-syntax-gate2.rs
index bb19e97ab0fa8..dcbe7eefee52c 100644
--- a/src/test/compile-fail/log-syntax-gate2.rs
+++ b/src/test/compile-fail/log-syntax-gate2.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-log_syntax
+
 fn main() {
     println!("{}", log_syntax!()); //~ ERROR `log_syntax!` is not stable
 }
diff --git a/src/test/compile-fail/never-disabled.rs b/src/test/compile-fail/never-disabled.rs
index 11b9f412957eb..fb6b34fcbb676 100644
--- a/src/test/compile-fail/never-disabled.rs
+++ b/src/test/compile-fail/never-disabled.rs
@@ -10,6 +10,8 @@
 
 // Test that ! errors when used in illegal positions with feature(never_type) disabled
 
+// gate-test-never_type
+
 trait Foo {
     type Wub;
 }
diff --git a/src/test/compile-fail/no-core-gated.rs b/src/test/compile-fail/no-core-gated.rs
index dbaa4177e1429..27f8fda98ab34 100644
--- a/src/test/compile-fail/no-core-gated.rs
+++ b/src/test/compile-fail/no-core-gated.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-no_core
+
 #![no_core] //~ ERROR no_core is experimental
 
 fn main() {}
diff --git a/src/test/compile-fail/numeric-fields-feature-gate.rs b/src/test/compile-fail/numeric-fields-feature-gate.rs
index 3ce85813a9b51..bd8ec16ef8826 100644
--- a/src/test/compile-fail/numeric-fields-feature-gate.rs
+++ b/src/test/compile-fail/numeric-fields-feature-gate.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-relaxed_adts
+
 struct S(u8);
 
 fn main() {
diff --git a/src/test/compile-fail/panic-runtime/needs-gate.rs b/src/test/compile-fail/panic-runtime/needs-gate.rs
index 02f3da58f1da8..1b3b978c40811 100644
--- a/src/test/compile-fail/panic-runtime/needs-gate.rs
+++ b/src/test/compile-fail/panic-runtime/needs-gate.rs
@@ -8,6 +8,9 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-needs_panic_runtime
+// gate-test-panic_runtime
+
 #![panic_runtime] //~ ERROR: is an experimental feature
 #![needs_panic_runtime] //~ ERROR: is an experimental feature
 
diff --git a/src/test/compile-fail/privacy/restricted/feature-gate.rs b/src/test/compile-fail/privacy/restricted/feature-gate.rs
index 53ae439867f98..e81e1e30d1750 100644
--- a/src/test/compile-fail/privacy/restricted/feature-gate.rs
+++ b/src/test/compile-fail/privacy/restricted/feature-gate.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-pub_restricted
+
 pub(crate) //~ ERROR experimental
 mod foo {}
 
diff --git a/src/test/compile-fail/rfc1445/feature-gate.rs b/src/test/compile-fail/rfc1445/feature-gate.rs
index 1f2d7819e26d8..b51ee3d8b5ed8 100644
--- a/src/test/compile-fail/rfc1445/feature-gate.rs
+++ b/src/test/compile-fail/rfc1445/feature-gate.rs
@@ -14,6 +14,8 @@
 
 // revisions: with_gate no_gate
 
+// gate-test-structural_match
+
 #![allow(dead_code)]
 #![deny(future_incompatible)]
 #![feature(rustc_attrs)]
diff --git a/src/test/compile-fail/single-derive-attr.rs b/src/test/compile-fail/single-derive-attr.rs
index 0b1b3141f5bf7..cd37611aceda9 100644
--- a/src/test/compile-fail/single-derive-attr.rs
+++ b/src/test/compile-fail/single-derive-attr.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-custom_derive
+
 #[derive_Clone]
 //~^ ERROR attributes of the form `#[derive_*]` are reserved
 struct Test;
diff --git a/src/test/compile-fail/specialization/specialization-feature-gate-default.rs b/src/test/compile-fail/specialization/specialization-feature-gate-default.rs
index e7c194ce84df9..3a01ecdf9db6f 100644
--- a/src/test/compile-fail/specialization/specialization-feature-gate-default.rs
+++ b/src/test/compile-fail/specialization/specialization-feature-gate-default.rs
@@ -10,6 +10,8 @@
 
 // Check that specialization must be ungated to use the `default` keyword
 
+// gate-test-specialization
+
 trait Foo {
     fn foo(&self);
 }
diff --git a/src/test/compile-fail/specialization/specialization-feature-gate-overlap.rs b/src/test/compile-fail/specialization/specialization-feature-gate-overlap.rs
index d11ab56ff7e87..5eb48eab15e52 100644
--- a/src/test/compile-fail/specialization/specialization-feature-gate-overlap.rs
+++ b/src/test/compile-fail/specialization/specialization-feature-gate-overlap.rs
@@ -10,6 +10,8 @@
 
 // Check that writing an overlapping impl is not allow unless specialization is ungated.
 
+// gate-test-specialization
+
 trait Foo {
     fn foo(&self);
 }
diff --git a/src/test/compile-fail/static-mut-not-constant.rs b/src/test/compile-fail/static-mut-not-constant.rs
index 9b83c42609aa5..7c37abf765769 100644
--- a/src/test/compile-fail/static-mut-not-constant.rs
+++ b/src/test/compile-fail/static-mut-not-constant.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-drop_types_in_const
+
 #![feature(box_syntax)]
 
 static mut a: Box<isize> = box 3;
diff --git a/src/test/compile-fail/struct-field-attr-feature-gate.rs b/src/test/compile-fail/struct-field-attr-feature-gate.rs
index 665c3fd67f48f..47495be4ad2c9 100644
--- a/src/test/compile-fail/struct-field-attr-feature-gate.rs
+++ b/src/test/compile-fail/struct-field-attr-feature-gate.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-struct_field_attributes
+
 struct Foo {
     present: (),
 }
diff --git a/src/test/compile-fail/type-ascription-feature-gate.rs b/src/test/compile-fail/type-ascription-feature-gate.rs
index d3c07d653f40c..bf4ca03069c57 100644
--- a/src/test/compile-fail/type-ascription-feature-gate.rs
+++ b/src/test/compile-fail/type-ascription-feature-gate.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-type_ascription
+
 // Type ascription is feature gated
 
 fn main() {
diff --git a/src/test/compile-fail/unadjusted-unstable.rs b/src/test/compile-fail/unadjusted-unstable.rs
index 501f4451ed8d5..2c23050085d88 100644
--- a/src/test/compile-fail/unadjusted-unstable.rs
+++ b/src/test/compile-fail/unadjusted-unstable.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-abi_unadjusted
+
 extern "unadjusted" fn foo() {
 //~^ ERROR: unadjusted ABI is an implementation detail and perma-unstable
 }
diff --git a/src/test/compile-fail/union/union-feature-gate.rs b/src/test/compile-fail/union/union-feature-gate.rs
index abfc4d909218b..0c2165871f6db 100644
--- a/src/test/compile-fail/union/union-feature-gate.rs
+++ b/src/test/compile-fail/union/union-feature-gate.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-untagged_unions
+
 union U { //~ ERROR unions are unstable and possibly buggy
     a: u8,
 }
diff --git a/src/test/compile-fail/windows-subsystem-gated.rs b/src/test/compile-fail/windows-subsystem-gated.rs
index 4b563e78e55c8..63f891a2af7bf 100644
--- a/src/test/compile-fail/windows-subsystem-gated.rs
+++ b/src/test/compile-fail/windows-subsystem-gated.rs
@@ -8,6 +8,8 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+// gate-test-windows_subsystem
+
 #![windows_subsystem = "console"]
 //~^ ERROR: the windows subsystem attribute is currently unstable
 
diff --git a/src/tools/tidy/src/features.rs b/src/tools/tidy/src/features.rs
index ac5dff0980c08..b0da6647eb900 100644
--- a/src/tools/tidy/src/features.rs
+++ b/src/tools/tidy/src/features.rs
@@ -16,6 +16,7 @@
 //! * The set of library features is disjoint from the set of language features
 //! * Library features have at most one stability level
 //! * Library features have at most one `since` value
+//! * All unstable lang features have tests to ensure they are actually unstable
 
 use std::collections::HashMap;
 use std::fmt;
@@ -26,6 +27,7 @@ use std::path::Path;
 #[derive(PartialEq)]
 enum Status {
     Stable,
+    Removed,
     Unstable,
 }
 
@@ -34,27 +36,22 @@ impl fmt::Display for Status {
         let as_str = match *self {
             Status::Stable => "stable",
             Status::Unstable => "unstable",
+            Status::Removed => "removed",
         };
         fmt::Display::fmt(as_str, f)
     }
 }
 
-
 struct Feature {
-    name: String,
-    level: Status,
-    since: String,
-}
-
-struct LibFeature {
     level: Status,
     since: String,
+    has_gate_test: bool,
 }
 
 pub fn check(path: &Path, bad: &mut bool) {
-    let features = collect_lang_features(&path.join("libsyntax/feature_gate.rs"));
+    let mut features = collect_lang_features(&path.join("libsyntax/feature_gate.rs"));
     assert!(!features.is_empty());
-    let mut lib_features = HashMap::<String, LibFeature>::new();
+    let mut lib_features = HashMap::<String, Feature>::new();
 
     let mut contents = String::new();
     super::walk(path,
@@ -97,7 +94,7 @@ pub fn check(path: &Path, bad: &mut bool) {
                 None => "None",
             };
 
-            if features.iter().any(|f| f.name == feature_name) {
+            if features.contains_key(feature_name) {
                 err("duplicating a lang feature");
             }
             if let Some(ref s) = lib_features.get(feature_name) {
@@ -110,21 +107,105 @@ pub fn check(path: &Path, bad: &mut bool) {
                 continue;
             }
             lib_features.insert(feature_name.to_owned(),
-                                LibFeature {
+                                Feature {
                                     level: level,
                                     since: since.to_owned(),
+                                    has_gate_test: false,
                                 });
         }
     });
 
+    super::walk(&path.join("test/compile-fail"),
+                &mut |path| super::filter_dirs(path),
+                &mut |file| {
+        let filename = file.file_name().unwrap().to_string_lossy();
+        if !filename.ends_with(".rs") || filename == "features.rs" ||
+           filename == "diagnostic_list.rs" {
+            return;
+        }
+
+        let filen_underscore = filename.replace("-","_").replace(".rs","");
+        test_filen_gate(&filen_underscore, &mut features);
+
+        contents.truncate(0);
+        t!(t!(File::open(&file), &file).read_to_string(&mut contents));
+
+        for (i, line) in contents.lines().enumerate() {
+            let mut err = |msg: &str| {
+                println!("{}:{}: {}", file.display(), i + 1, msg);
+                *bad = true;
+            };
+
+            let gate_test_str = "gate-test-";
+
+            if !line.contains(gate_test_str) {
+                continue;
+            }
+
+            let feature_name = match line.find(gate_test_str) {
+                Some(i) => {
+                    &line[i+gate_test_str.len()..line[i+1..].find(' ').unwrap_or(line.len())]
+                },
+                None => continue,
+            };
+            let found_feature = features.get_mut(feature_name)
+                                        .map(|v| { v.has_gate_test = true; () })
+                                        .is_some();
+
+            let found_lib_feature = features.get_mut(feature_name)
+                                            .map(|v| { v.has_gate_test = true; () })
+                                            .is_some();
+
+            if !(found_feature || found_lib_feature) {
+                err(&format!("gate-test test found referencing a nonexistent feature '{}'",
+                             feature_name));
+            }
+        }
+    });
+
+    // FIXME get this whitelist empty.
+    let whitelist = vec![
+        "abi_ptx", "simd", "safe_suggestion", "macro_reexport",
+        "more_struct_aliases", "static_recursion", "reflect",
+        "quote", "cfg_target_has_atomic", "custom_attribute",
+        "default_type_parameter_fallback", "pushpop_unsafe",
+        "use_extern_macros", "staged_api", "const_indexing",
+        "unboxed_closures", "stmt_expr_attributes",
+        "cfg_target_thread_local", "unwind_attributes",
+        "inclusive_range_syntax"
+    ];
+
+    // Only check the number of lang features.
+    // Obligatory testing for library features is dumb.
+    let gate_untested = features.iter()
+                                .filter(|&(_, f)| f.level == Status::Unstable)
+                                .filter(|&(_, f)| !f.has_gate_test)
+                                .filter(|&(n, _)| !whitelist.contains(&n.as_str()))
+                                .collect::<Vec<_>>();
+
+    for &(name, _) in gate_untested.iter() {
+        println!("Expected a gate test for the feature '{}'.", name);
+        println!("Hint: create a file named 'feature-gate-{}.rs' in the compile-fail\
+                \n      test suite, with its failures due to missing usage of\
+                \n      #![feature({})].", name, name);
+        println!("Hint: If you already have such a test and don't want to rename it,\
+                \n      you can also add a // gate-test-{} line to the test file.",
+                 name);
+    }
+
+    if gate_untested.len() > 0 {
+        println!("Found {} features without a gate test.", gate_untested.len());
+        *bad = true;
+    }
+
     if *bad {
         return;
     }
 
     let mut lines = Vec::new();
-    for feature in features {
+    for (name, feature) in features.iter() {
         lines.push(format!("{:<32} {:<8} {:<12} {:<8}",
-                           feature.name,
+                           name,
                            "lang",
                            feature.level,
                            feature.since));
@@ -150,7 +231,20 @@ fn find_attr_val<'a>(line: &'a str, attr: &str) -> Option<&'a str> {
         .map(|(i, j)| &line[i..j])
 }
 
-fn collect_lang_features(path: &Path) -> Vec<Feature> {
+fn test_filen_gate(filen_underscore: &str,
+                   features: &mut HashMap<String, Feature>) -> bool {
+    if filen_underscore.starts_with("feature_gate") {
+        for (n, f) in features.iter_mut() {
+            if filen_underscore == format!("feature_gate_{}", n) {
+                f.has_gate_test = true;
+                return true;
+            }
+        }
+    }
+    return false;
+}
+
+fn collect_lang_features(path: &Path) -> HashMap<String, Feature> {
     let mut contents = String::new();
     t!(t!(File::open(path)).read_to_string(&mut contents));
 
@@ -159,17 +253,18 @@ fn collect_lang_features(path: &Path) -> Vec<Feature> {
             let mut parts = line.trim().split(",");
             let level = match parts.next().map(|l| l.trim().trim_left_matches('(')) {
                 Some("active") => Status::Unstable,
-                Some("removed") => Status::Unstable,
+                Some("removed") => Status::Removed,
                 Some("accepted") => Status::Stable,
                 _ => return None,
             };
             let name = parts.next().unwrap().trim();
             let since = parts.next().unwrap().trim().trim_matches('"');
-            Some(Feature {
-                name: name.to_owned(),
-                level: level,
-                since: since.to_owned(),
-            })
+            Some((name.to_owned(),
+                Feature {
+                    level: level,
+                    since: since.to_owned(),
+                    has_gate_test: false,
+                }))
         })
         .collect()
 }