Rollup merge of rust-lang#136603 - workingjubilee:move-abi-versioning…

…-into-ast, r=compiler-errors

compiler: gate `extern "{abi}"` in ast_lowering

I don't believe low-level crates like `rustc_abi` should have to know or care about higher-level concerns like whether the ABI string is stable for users. These implementation details can be made less open to public inspection. This way the code that governs stability is near the code that enforces stability, and compiled together.

It also abstracts away certain error messages instead of constantly repeating them.

A few error messages are simply deleted outright, instead of made uniform, because they are either too dated to be useful or redundant with other diagnostic improvements we could make. These can be pursued in followups: my first concern was making sure there wasn't unnecessary diagnostics-related code in `rustc_abi`, which is not well-positioned to understand what kind of errors are going to be generated based on how it is used.

r? `@ghost`

Cargo.lock

@@ -3317,7 +3317,6 @@ dependencies = [
  "rand 0.8.5",
  "rand_xoshiro",
  "rustc_data_structures",
- "rustc_feature",
  "rustc_index",
  "rustc_macros",
  "rustc_serialize",
@@ -3379,6 +3378,7 @@ dependencies = [
  "rustc_ast_pretty",
  "rustc_data_structures",
  "rustc_errors",
+ "rustc_feature",
  "rustc_fluent_macro",
  "rustc_hir",
  "rustc_index",
@@ -3683,6 +3683,7 @@ version = "0.0.0"
 dependencies = [
  "ctrlc",
  "libc",
+ "rustc_abi",
  "rustc_ast",
  "rustc_ast_lowering",
  "rustc_ast_passes",
@@ -4337,6 +4338,7 @@ version = "0.0.0"
 dependencies = [
  "rustc_abi",
  "rustc_ast",
+ "rustc_ast_lowering",
  "rustc_ast_pretty",
  "rustc_attr_parsing",
  "rustc_data_structures",

compiler/rustc_abi/Cargo.toml

@@ -9,7 +9,6 @@ bitflags = "2.4.1"
 rand = { version = "0.8.4", default-features = false, optional = true }
 rand_xoshiro = { version = "0.6.0", optional = true }
 rustc_data_structures = { path = "../rustc_data_structures", optional = true  }
-rustc_feature = { path = "../rustc_feature", optional = true }
 rustc_index = { path = "../rustc_index", default-features = false }
 rustc_macros = { path = "../rustc_macros", optional = true }
 rustc_serialize = { path = "../rustc_serialize", optional = true  }
@@ -24,7 +23,6 @@ default = ["nightly", "randomize"]
 # without depending on rustc_data_structures, rustc_macros and rustc_serialize
 nightly = [
     "dep:rustc_data_structures",
-    "dep:rustc_feature",
     "dep:rustc_macros",
     "dep:rustc_serialize",
     "dep:rustc_span",

compiler/rustc_abi/src/callconv.rs

@@ -1,6 +1,5 @@
 #[cfg(feature = "nightly")]
-use crate::{BackendRepr, FieldsShape, TyAbiInterface, TyAndLayout};
-use crate::{Primitive, Size, Variants};
+use crate::{BackendRepr, FieldsShape, Primitive, Size, TyAbiInterface, TyAndLayout, Variants};
 
 mod reg;
 

compiler/rustc_abi/src/extern_abi.rs

@@ -1,7 +1,6 @@
 use std::fmt;
 
 use rustc_macros::{Decodable, Encodable, HashStable_Generic};
-use rustc_span::{Span, Symbol, sym};
 
 #[cfg(test)]
 mod tests;
@@ -95,14 +94,14 @@ impl Abi {
 
 #[derive(Copy, Clone)]
 pub struct AbiData {
-    abi: Abi,
+    pub abi: Abi,
 
     /// Name of this ABI as we like it called.
-    name: &'static str,
+    pub name: &'static str,
 }
 
 #[allow(non_upper_case_globals)]
-const AbiDatas: &[AbiData] = &[
+pub const AbiDatas: &[AbiData] = &[
     AbiData { abi: Abi::Rust, name: "Rust" },
     AbiData { abi: Abi::C { unwind: false }, name: "C" },
     AbiData { abi: Abi::C { unwind: true }, name: "C-unwind" },
@@ -142,129 +141,18 @@ const AbiDatas: &[AbiData] = &[
 ];
 
 #[derive(Copy, Clone, Debug)]
-pub enum AbiUnsupported {
-    Unrecognized,
-    Reason { explain: &'static str },
-}
-
+pub struct AbiUnsupported {}
 /// Returns the ABI with the given name (if any).
 pub fn lookup(name: &str) -> Result<Abi, AbiUnsupported> {
-    AbiDatas.iter().find(|abi_data| name == abi_data.name).map(|&x| x.abi).ok_or_else(|| match name {
-        "riscv-interrupt" => AbiUnsupported::Reason {
-            explain: "please use one of riscv-interrupt-m or riscv-interrupt-s for machine- or supervisor-level interrupts, respectively",
-        },
-        "riscv-interrupt-u" => AbiUnsupported::Reason {
-            explain: "user-mode interrupt handlers have been removed from LLVM pending standardization, see: https://reviews.llvm.org/D149314",
-        },
-        "wasm" => AbiUnsupported::Reason {
-            explain: "non-standard wasm ABI is no longer supported",
-        },
-
-        _ => AbiUnsupported::Unrecognized,
-
-    })
-}
-
-pub fn all_names() -> Vec<&'static str> {
-    AbiDatas.iter().map(|d| d.name).collect()
-}
-
-pub fn enabled_names(features: &rustc_feature::Features, span: Span) -> Vec<&'static str> {
     AbiDatas
         .iter()
-        .map(|d| d.name)
-        .filter(|name| is_enabled(features, span, name).is_ok())
-        .collect()
+        .find(|abi_data| name == abi_data.name)
+        .map(|&x| x.abi)
+        .ok_or_else(|| AbiUnsupported {})
 }
 
-pub enum AbiDisabled {
-    Unstable { feature: Symbol, explain: &'static str },
-    Unrecognized,
-}
-
-pub fn is_enabled(
-    features: &rustc_feature::Features,
-    span: Span,
-    name: &str,
-) -> Result<(), AbiDisabled> {
-    let s = is_stable(name);
-    if let Err(AbiDisabled::Unstable { feature, .. }) = s {
-        if features.enabled(feature) || span.allows_unstable(feature) {
-            return Ok(());
-        }
-    }
-    s
-}
-
-/// Returns whether the ABI is stable to use.
-///
-/// Note that there is a separate check determining whether the ABI is even supported
-/// on the current target; see `fn is_abi_supported` in `rustc_target::spec`.
-pub fn is_stable(name: &str) -> Result<(), AbiDisabled> {
-    match name {
-        // Stable
-        "Rust" | "C" | "C-unwind" | "cdecl" | "cdecl-unwind" | "stdcall" | "stdcall-unwind"
-        | "fastcall" | "fastcall-unwind" | "aapcs" | "aapcs-unwind" | "win64" | "win64-unwind"
-        | "sysv64" | "sysv64-unwind" | "system" | "system-unwind" | "efiapi" | "thiscall"
-        | "thiscall-unwind" => Ok(()),
-        "rust-intrinsic" => Err(AbiDisabled::Unstable {
-            feature: sym::intrinsics,
-            explain: "intrinsics are subject to change",
-        }),
-        "vectorcall" => Err(AbiDisabled::Unstable {
-            feature: sym::abi_vectorcall,
-            explain: "vectorcall is experimental and subject to change",
-        }),
-        "vectorcall-unwind" => Err(AbiDisabled::Unstable {
-            feature: sym::abi_vectorcall,
-            explain: "vectorcall-unwind ABI is experimental and subject to change",
-        }),
-        "rust-call" => Err(AbiDisabled::Unstable {
-            feature: sym::unboxed_closures,
-            explain: "rust-call ABI is subject to change",
-        }),
-        "rust-cold" => Err(AbiDisabled::Unstable {
-            feature: sym::rust_cold_cc,
-            explain: "rust-cold is experimental and subject to change",
-        }),
-        "ptx-kernel" => Err(AbiDisabled::Unstable {
-            feature: sym::abi_ptx,
-            explain: "PTX ABIs are experimental and subject to change",
-        }),
-        "unadjusted" => Err(AbiDisabled::Unstable {
-            feature: sym::abi_unadjusted,
-            explain: "unadjusted ABI is an implementation detail and perma-unstable",
-        }),
-        "msp430-interrupt" => Err(AbiDisabled::Unstable {
-            feature: sym::abi_msp430_interrupt,
-            explain: "msp430-interrupt ABI is experimental and subject to change",
-        }),
-        "x86-interrupt" => Err(AbiDisabled::Unstable {
-            feature: sym::abi_x86_interrupt,
-            explain: "x86-interrupt ABI is experimental and subject to change",
-        }),
-        "gpu-kernel" => Err(AbiDisabled::Unstable {
-            feature: sym::abi_gpu_kernel,
-            explain: "gpu-kernel ABI is experimental and subject to change",
-        }),
-        "avr-interrupt" | "avr-non-blocking-interrupt" => Err(AbiDisabled::Unstable {
-            feature: sym::abi_avr_interrupt,
-            explain: "avr-interrupt and avr-non-blocking-interrupt ABIs are experimental and subject to change",
-        }),
-        "riscv-interrupt-m" | "riscv-interrupt-s" => Err(AbiDisabled::Unstable {
-            feature: sym::abi_riscv_interrupt,
-            explain: "riscv-interrupt ABIs are experimental and subject to change",
-        }),
-        "C-cmse-nonsecure-call" => Err(AbiDisabled::Unstable {
-            feature: sym::abi_c_cmse_nonsecure_call,
-            explain: "C-cmse-nonsecure-call ABI is experimental and subject to change",
-        }),
-        "C-cmse-nonsecure-entry" => Err(AbiDisabled::Unstable {
-            feature: sym::cmse_nonsecure_entry,
-            explain: "C-cmse-nonsecure-entry ABI is experimental and subject to change",
-        }),
-        _ => Err(AbiDisabled::Unrecognized),
-    }
+pub fn all_names() -> Vec<&'static str> {
+    AbiDatas.iter().map(|d| d.name).collect()
 }
 
 impl Abi {

compiler/rustc_abi/src/extern_abi/tests.rs

@@ -18,7 +18,7 @@ fn lookup_cdecl() {
 #[test]
 fn lookup_baz() {
     let abi = lookup("baz");
-    assert_matches!(abi, Err(AbiUnsupported::Unrecognized));
+    assert_matches!(abi, Err(AbiUnsupported {}));
 }
 
 #[test]

compiler/rustc_abi/src/lib.rs

@@ -66,9 +66,7 @@ mod extern_abi;
 
 pub use callconv::{Heterogeneous, HomogeneousAggregate, Reg, RegKind};
 #[cfg(feature = "nightly")]
-pub use extern_abi::{
-    AbiDisabled, AbiUnsupported, ExternAbi, all_names, enabled_names, is_enabled, is_stable, lookup,
-};
+pub use extern_abi::{AbiDatas, AbiUnsupported, ExternAbi, all_names, lookup};
 #[cfg(feature = "nightly")]
 pub use layout::{FIRST_VARIANT, FieldIdx, Layout, TyAbiInterface, TyAndLayout, VariantIdx};
 pub use layout::{LayoutCalculator, LayoutCalculatorError};

compiler/rustc_ast_lowering/Cargo.toml

@@ -13,6 +13,7 @@ rustc_ast = { path = "../rustc_ast" }
 rustc_ast_pretty = { path = "../rustc_ast_pretty" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_errors = { path = "../rustc_errors" }
+rustc_feature = { path = "../rustc_feature" }
 rustc_fluent_macro = { path = "../rustc_fluent_macro" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_index = { path = "../rustc_index" }

compiler/rustc_ast_lowering/src/delegation.rs

@@ -41,13 +41,13 @@ use std::iter;
 use ast::visit::Visitor;
 use hir::def::{DefKind, PartialRes, Res};
 use hir::{BodyId, HirId};
+use rustc_abi::ExternAbi;
 use rustc_ast::*;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir::def_id::DefId;
 use rustc_middle::span_bug;
 use rustc_middle::ty::{Asyncness, ResolverAstLowering};
 use rustc_span::{Ident, Span};
-use rustc_target::spec::abi;
 use {rustc_ast as ast, rustc_hir as hir};
 
 use super::{GenericArgsMode, ImplTraitContext, LoweringContext, ParamMode};
@@ -398,7 +398,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             safety: hir::Safety::Safe.into(),
             constness: hir::Constness::NotConst,
             asyncness: hir::IsAsync::NotAsync,
-            abi: abi::Abi::Rust,
+            abi: ExternAbi::Rust,
         }
     }
 

compiler/rustc_ast_lowering/src/errors.rs

@@ -1,5 +1,5 @@
+use rustc_errors::DiagArgFromDisplay;
 use rustc_errors::codes::*;
-use rustc_errors::{Diag, DiagArgFromDisplay, EmissionGuarantee, SubdiagMessageOp, Subdiagnostic};
 use rustc_macros::{Diagnostic, Subdiagnostic};
 use rustc_span::{Ident, Span, Symbol};
 
@@ -32,8 +32,6 @@ pub(crate) struct InvalidAbi {
     pub abi: Symbol,
     pub command: String,
     #[subdiagnostic]
-    pub explain: Option<InvalidAbiReason>,
-    #[subdiagnostic]
     pub suggestion: Option<InvalidAbiSuggestion>,
 }
 
@@ -45,19 +43,6 @@ pub(crate) struct TupleStructWithDefault {
     pub span: Span,
 }
 
-pub(crate) struct InvalidAbiReason(pub &'static str);
-
-impl Subdiagnostic for InvalidAbiReason {
-    fn add_to_diag_with<G: EmissionGuarantee, F: SubdiagMessageOp<G>>(
-        self,
-        diag: &mut Diag<'_, G>,
-        _: &F,
-    ) {
-        #[allow(rustc::untranslatable_diagnostic)]
-        diag.note(self.0);
-    }
-}
-
 #[derive(Subdiagnostic)]
 #[suggestion(
     ast_lowering_invalid_abi_suggestion,

compiler/rustc_ast_lowering/src/item.rs

@@ -17,9 +17,9 @@ use thin_vec::ThinVec;
 use tracing::instrument;
 
 use super::errors::{
-    InvalidAbi, InvalidAbiReason, InvalidAbiSuggestion, MisplacedRelaxTraitBound,
-    TupleStructWithDefault,
+    InvalidAbi, InvalidAbiSuggestion, MisplacedRelaxTraitBound, TupleStructWithDefault,
 };
+use super::stability::{enabled_names, gate_unstable_abi};
 use super::{
     AstOwner, FnDeclKind, ImplTraitContext, ImplTraitPosition, LoweringContext, ParamMode,
     ResolverAstLoweringExt,
@@ -1479,11 +1479,16 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    pub(super) fn lower_abi(&mut self, abi: StrLit) -> ExternAbi {
-        rustc_abi::lookup(abi.symbol_unescaped.as_str()).unwrap_or_else(|err| {
-            self.error_on_invalid_abi(abi, err);
+    pub(super) fn lower_abi(&mut self, abi_str: StrLit) -> ExternAbi {
+        let ast::StrLit { symbol_unescaped, span, .. } = abi_str;
+        let extern_abi = rustc_abi::lookup(symbol_unescaped.as_str()).unwrap_or_else(|_| {
+            self.error_on_invalid_abi(abi_str);
             ExternAbi::Rust
-        })
+        });
+        let sess = self.tcx.sess;
+        let features = self.tcx.features();
+        gate_unstable_abi(sess, features, span, extern_abi);
+        extern_abi
     }
 
     pub(super) fn lower_extern(&mut self, ext: Extern) -> ExternAbi {
@@ -1494,19 +1499,15 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn error_on_invalid_abi(&self, abi: StrLit, err: rustc_abi::AbiUnsupported) {
-        let abi_names = rustc_abi::enabled_names(self.tcx.features(), abi.span)
+    fn error_on_invalid_abi(&self, abi: StrLit) {
+        let abi_names = enabled_names(self.tcx.features(), abi.span)
             .iter()
             .map(|s| Symbol::intern(s))
             .collect::<Vec<_>>();
         let suggested_name = find_best_match_for_name(&abi_names, abi.symbol_unescaped, None);
         self.dcx().emit_err(InvalidAbi {
             abi: abi.symbol_unescaped,
             span: abi.span,
-            explain: match err {
-                rustc_abi::AbiUnsupported::Reason { explain } => Some(InvalidAbiReason(explain)),
-                _ => None,
-            },
             suggestion: suggested_name.map(|suggested_name| InvalidAbiSuggestion {
                 span: abi.span,
                 suggestion: format!("\"{suggested_name}\""),

compiler/rustc_ast_lowering/src/lib.rs

@@ -84,6 +84,7 @@ mod index;
 mod item;
 mod pat;
 mod path;
+pub mod stability;
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }