Ban non-extern rust intrinsics

Intrinsics can only be defined by the compiler.

src/librustc_typeck/check/mod.rs

@@ -1088,6 +1088,8 @@ fn check_fn<'a, 'tcx>(
 
     let span = body.value.span;
 
+    fn_maybe_err(fcx.tcx, span, fn_sig.abi);
+
     if body.generator_kind.is_some() && can_be_generator.is_some() {
         let yield_ty = fcx.next_ty_var(TypeVariableOrigin {
             kind: TypeVariableOriginKind::TypeInference,
@@ -1439,6 +1441,14 @@ fn check_opaque_for_cycles<'tcx>(
     }
 }
 
+// Forbid defining intrinsics in Rust code,
+// as they must always be defined by the compiler.
+fn fn_maybe_err(tcx: TyCtxt<'_>, sp: Span, abi: Abi) {
+    if let Abi::RustIntrinsic | Abi::PlatformIntrinsic = abi {
+        tcx.sess.span_err(sp, "intrinsic must be in `extern \"rust-intrinsic\" { ... }` block");
+    }
+}
+
 pub fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, it: &'tcx hir::Item) {
     debug!(
         "check_item_type(it.hir_id={}, it.name={})",
@@ -1475,9 +1485,17 @@ pub fn check_item_type<'tcx>(tcx: TyCtxt<'tcx>, it: &'tcx hir::Item) {
                 check_on_unimplemented(tcx, trait_def_id, it);
             }
         }
-        hir::ItemKind::Trait(..) => {
+        hir::ItemKind::Trait(_, _, _, _, ref items) => {
             let def_id = tcx.hir().local_def_id(it.hir_id);
             check_on_unimplemented(tcx, def_id, it);
+
+            for item in items.iter() {
+                let item = tcx.hir().trait_item(item.id);
+                if let hir::TraitItemKind::Method(sig, _) = &item.node {
+                    let abi = sig.header.abi;
+                    fn_maybe_err(tcx, item.ident.span, abi);
+                }
+            }
         }
         hir::ItemKind::Struct(..) => {
             check_struct(tcx, it.hir_id, it.span);

src/test/incremental/hashes/function_interfaces.rs

@@ -11,7 +11,6 @@
 
 
 #![allow(warnings)]
-#![feature(intrinsics)]
 #![feature(linkage)]
 #![feature(rustc_attrs)]
 #![crate_type = "rlib"]
@@ -99,15 +98,15 @@ pub fn make_extern() {}
 pub extern "C" fn make_extern() {}
 
 
-// Extern C Extern Rust-Intrinsic ----------------------------------------------
+// Extern C Extern stdcall ----------------------------------------------
 
 #[cfg(cfail1)]
-pub extern "C" fn make_intrinsic() {}
+pub extern "C" fn make_stdcall() {}
 
 #[cfg(not(cfail1))]
 #[rustc_clean(cfg = "cfail2", except = "Hir, HirBody, typeck_tables_of, fn_sig")]
 #[rustc_clean(cfg = "cfail3")]
-pub extern "rust-intrinsic" fn make_intrinsic() {}
+pub extern "stdcall" fn make_stdcall() {}
 
 
 // Type Parameter --------------------------------------------------------------

src/test/incremental/hashes/trait_defs.rs

@@ -18,7 +18,6 @@
 #![feature(rustc_attrs)]
 #![crate_type="rlib"]
 #![feature(associated_type_defaults)]
-#![feature(intrinsics)]
 
 
 // Change trait visibility
@@ -318,7 +317,7 @@ trait TraitAddExternModifier {
 
 
 
-// Change extern "C" to extern "rust-intrinsic"
+// Change extern "C" to extern "stdcall"
 #[cfg(cfail1)]
 trait TraitChangeExternCToRustIntrinsic {
     extern "C" fn method();
@@ -330,7 +329,7 @@ trait TraitChangeExternCToRustIntrinsic {
 trait TraitChangeExternCToRustIntrinsic {
     #[rustc_dirty(label="Hir", cfg="cfail2")]
     #[rustc_clean(label="Hir", cfg="cfail3")]
-    extern "rust-intrinsic" fn method();
+    extern "stdcall" fn method();
 }
 
 

src/test/ui/feature-gates/feature-gate-abi.rs

@@ -10,7 +10,9 @@
 
 // Functions
 extern "rust-intrinsic" fn f1() {} //~ ERROR intrinsics are subject to change
+//~^ ERROR intrinsic must be in
 extern "platform-intrinsic" fn f2() {} //~ ERROR platform intrinsics are experimental
+//~^ ERROR intrinsic must be in
 extern "vectorcall" fn f3() {} //~ ERROR vectorcall is experimental and subject to change
 extern "rust-call" fn f4() {} //~ ERROR rust-call ABI is subject to change
 extern "msp430-interrupt" fn f5() {} //~ ERROR msp430-interrupt ABI is experimental
@@ -22,7 +24,9 @@ extern "amdgpu-kernel" fn f9() {} //~ ERROR amdgpu-kernel ABI is experimental an
 // Methods in trait definition
 trait Tr {
     extern "rust-intrinsic" fn m1(); //~ ERROR intrinsics are subject to change
+    //~^ ERROR intrinsic must be in
     extern "platform-intrinsic" fn m2(); //~ ERROR platform intrinsics are experimental
+    //~^ ERROR intrinsic must be in
     extern "vectorcall" fn m3(); //~ ERROR vectorcall is experimental and subject to change
     extern "rust-call" fn m4(); //~ ERROR rust-call ABI is subject to change
     extern "msp430-interrupt" fn m5(); //~ ERROR msp430-interrupt ABI is experimental
@@ -31,8 +35,6 @@ trait Tr {
     extern "thiscall" fn m8(); //~ ERROR thiscall is experimental and subject to change
     extern "amdgpu-kernel" fn m9(); //~ ERROR amdgpu-kernel ABI is experimental and subject to change
 
-    extern "rust-intrinsic" fn dm1() {} //~ ERROR intrinsics are subject to change
-    extern "platform-intrinsic" fn dm2() {} //~ ERROR platform intrinsics are experimental
     extern "vectorcall" fn dm3() {} //~ ERROR vectorcall is experimental and subject to change
     extern "rust-call" fn dm4() {} //~ ERROR rust-call ABI is subject to change
     extern "msp430-interrupt" fn dm5() {} //~ ERROR msp430-interrupt ABI is experimental
@@ -47,7 +49,9 @@ struct S;
 // Methods in trait impl
 impl Tr for S {
     extern "rust-intrinsic" fn m1() {} //~ ERROR intrinsics are subject to change
+    //~^ ERROR intrinsic must be in
     extern "platform-intrinsic" fn m2() {} //~ ERROR platform intrinsics are experimental
+    //~^ ERROR intrinsic must be in
     extern "vectorcall" fn m3() {} //~ ERROR vectorcall is experimental and subject to change
     extern "rust-call" fn m4() {} //~ ERROR rust-call ABI is subject to change
     extern "msp430-interrupt" fn m5() {} //~ ERROR msp430-interrupt ABI is experimental
@@ -60,7 +64,9 @@ impl Tr for S {
 // Methods in inherent impl
 impl S {
     extern "rust-intrinsic" fn im1() {} //~ ERROR intrinsics are subject to change
+    //~^ ERROR intrinsic must be in
     extern "platform-intrinsic" fn im2() {} //~ ERROR platform intrinsics are experimental
+    //~^ ERROR intrinsic must be in
     extern "vectorcall" fn im3() {} //~ ERROR vectorcall is experimental and subject to change
     extern "rust-call" fn im4() {} //~ ERROR rust-call ABI is subject to change
     extern "msp430-interrupt" fn im5() {} //~ ERROR msp430-interrupt ABI is experimental