Experimental feature gate proposal crabi

compiler/rustc_feature/src/active.rs

@@ -359,6 +359,8 @@ declare_features! (
     (active, const_trait_impl, "1.42.0", Some(67792), None),
     /// Allows the `?` operator in const contexts.
     (active, const_try, "1.56.0", Some(74935), None),
+    /// Allows using `extern "crabi"` and `repr(crabi)`
+    (incomplete, crabi, "CURRENT_RUSTC_VERSION", Some(111423), None),
     /// Allows non-builtin attributes in inner attribute position.
     (active, custom_inner_attributes, "1.30.0", Some(54726), None),
     /// Allows custom test frameworks with `#![test_runner]` and `#[test_case]`.

compiler/rustc_middle/src/ty/layout.rs

@@ -1228,6 +1228,7 @@ pub fn fn_can_unwind(tcx: TyCtxt<'_>, fn_def_id: Option<DefId>, abi: SpecAbi) ->
         | Wasm
         | RustIntrinsic
         | PlatformIntrinsic
+        | Crabi
         | Unadjusted => false,
         Rust | RustCall | RustCold => tcx.sess.panic_strategy() == PanicStrategy::Unwind,
     }

compiler/rustc_mir_transform/src/ffi_unwind_calls.rs

@@ -32,6 +32,7 @@ fn abi_can_unwind(abi: Abi) -> bool {
         | Wasm
         | RustIntrinsic
         | PlatformIntrinsic
+        | Crabi
         | Unadjusted => false,
         Rust | RustCall | RustCold => true,
     }

compiler/rustc_span/src/symbol.rs

@@ -555,6 +555,7 @@ symbols! {
         cosf64,
         count,
         cr,
+        crabi,
         crate_id,
         crate_in_paths,
         crate_local,

compiler/rustc_target/src/spec/abi.rs

@@ -38,6 +38,7 @@ pub enum Abi {
     PlatformIntrinsic,
     Unadjusted,
     RustCold,
+    Crabi,
 }
 
 impl Abi {
@@ -107,6 +108,7 @@ const AbiDatas: &[AbiData] = &[
     AbiData { abi: Abi::PlatformIntrinsic, name: "platform-intrinsic" },
     AbiData { abi: Abi::Unadjusted, name: "unadjusted" },
     AbiData { abi: Abi::RustCold, name: "rust-cold" },
+    AbiData { abi: Abi::Crabi, name: "crabi" },
 ];
 
 /// Returns the ABI with the given name (if any).
@@ -246,6 +248,10 @@ pub fn is_stable(name: &str) -> Result<(), AbiDisabled> {
             feature: sym::wasm_abi,
             explain: "wasm ABI is experimental and subject to change",
         }),
+        "crabi" => Err(AbiDisabled::Unstable {
+            feature: sym::crabi,
+            explain: "crABI is experimental and subject to change",
+        }),
         _ => Err(AbiDisabled::Unrecognized),
     }
 }
@@ -298,6 +304,7 @@ impl Abi {
             PlatformIntrinsic => 32,
             Unadjusted => 33,
             RustCold => 34,
+            Crabi => 35,
         };
         debug_assert!(
             AbiDatas

compiler/rustc_target/src/spec/mod.rs

@@ -2075,6 +2075,8 @@ impl Target {
             Vectorcall { .. } if ["x86", "x86_64"].contains(&&self.arch[..]) => true,
             // Return a `None` for other cases so that we know to emit a future compat lint.
             Stdcall { .. } | Fastcall { .. } | Vectorcall { .. } => return None,
+            // Not yet implemented
+            Crabi => false,
         })
     }
 

compiler/rustc_ty_utils/src/abi.rs

@@ -192,6 +192,7 @@ fn conv_from_spec_abi(tcx: TyCtxt<'_>, abi: SpecAbi) -> Conv {
         AvrInterrupt => Conv::AvrInterrupt,
         AvrNonBlockingInterrupt => Conv::AvrNonBlockingInterrupt,
         Wasm => Conv::C,
+        Crabi => bug!("crABI is not yet implemented"),
 
         // These API constants ought to be more specific...
         Cdecl { .. } => Conv::C,

tests/ui/feature-gates/feature-gate-crabi.rs

@@ -0,0 +1,12 @@
+// Test that the `crabi` ABI is feature-gated, and cannot be used when the `crabi` feature gate is
+// not used.
+
+extern "crabi" {
+//~^ ERROR crABI is experimental and subject to change [E0658]
+//~| ERROR `"crabi"` is not a supported ABI for the current target [E0570]
+    fn f();
+}
+
+fn main() {
+    f();
+}

tests/ui/feature-gates/feature-gate-crabi.stderr

@@ -0,0 +1,23 @@
+error[E0658]: crABI is experimental and subject to change
+  --> $DIR/feature-gate-crabi.rs:4:8
+   |
+LL | extern "crabi" {
+   |        ^^^^^^^
+   |
+   = note: see issue #111423 <https://github.com/rust-lang/rust/issues/111423> for more information
+   = help: add `#![feature(crabi)]` to the crate attributes to enable
+
+error[E0570]: `"crabi"` is not a supported ABI for the current target
+  --> $DIR/feature-gate-crabi.rs:4:1
+   |
+LL | / extern "crabi" {
+LL | |
+LL | |
+LL | |     fn f();
+LL | | }
+   | |_^
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0570, E0658.
+For more information about an error, try `rustc --explain E0570`.