Rollup merge of #132385 - workingjubilee:move-abi-to-rustc-abi, r=jieyouxu,compiler-errors

compiler: Move `rustc_target::spec::abi::Abi` to `rustc_abi::ExternAbi`

Lift `enum Abi` from its rather odd place in the middle of rustc_target, and make it available again from rustc_abi. You know, the crate where you would expect the enum that describes all the ABIs to be? The platform-neutral ones, at least. This will help further refactoring of how we handle ABIs in the near future[^0].

Rename `Abi` to `ExternAbi` because quite a lot of the compiler overloads the concept of "ABI" enough that the existing name is imprecise and it is often renamed _anyway_. Often this was to avoid conflicts with the *other* type formerly known as `Abi` (now named BackendRepr[^1]), but sometimes it is just for clarity, and this name seems more self-explanatory. It does get reexported, though, using its old name, to reduce the odds of merge-conflicting over the entire tree.

All of `ExternAbi`'s friends come along for the ride, which costs adding some optional dependencies to the rustc_abi crate. However, all of this also allows simply moving three crates entirely off rustc_target:
- rustc_hir_pretty
- rustc_lint_defs
- rustc_mir_build

This odd selection is mostly to demonstrate a secondary motivation: The majority of the front-end of the compiler should be as target-agnostic as possible, and it is easier to assure this if they simply don't depend on the crate that describes targets. Note that I didn't migrate crates that don't benefit from it in this way yet, and I didn't survey every last crate.

[^0]: This is being undertaken as part of https://github.com/rust-lang/rust/issues/119183
[^1]: https://github.com/rust-lang/rust/pull/132246

Cargo.lock

@@ -3204,9 +3204,11 @@ dependencies = [
  "rand",
  "rand_xoshiro",
  "rustc_data_structures",
+ "rustc_feature",
  "rustc_index",
  "rustc_macros",
  "rustc_serialize",
+ "rustc_span",
  "tracing",
 ]
 
@@ -3749,11 +3751,11 @@ dependencies = [
 name = "rustc_hir_pretty"
 version = "0.0.0"
 dependencies = [
+ "rustc_abi",
  "rustc_ast",
  "rustc_ast_pretty",
  "rustc_hir",
  "rustc_span",
- "rustc_target",
 ]
 
 [[package]]
@@ -3938,6 +3940,7 @@ dependencies = [
 name = "rustc_lint_defs"
 version = "0.0.0"
 dependencies = [
+ "rustc_abi",
  "rustc_ast",
  "rustc_data_structures",
  "rustc_error_messages",
@@ -3945,7 +3948,6 @@ dependencies = [
  "rustc_macros",
  "rustc_serialize",
  "rustc_span",
- "rustc_target",
  "serde",
 ]
 
@@ -4054,6 +4056,7 @@ version = "0.0.0"
 dependencies = [
  "either",
  "itertools",
+ "rustc_abi",
  "rustc_apfloat",
  "rustc_arena",
  "rustc_ast",
@@ -4069,7 +4072,6 @@ dependencies = [
  "rustc_pattern_analysis",
  "rustc_session",
  "rustc_span",
- "rustc_target",
  "rustc_trait_selection",
  "tracing",
 ]

compiler/rustc_abi/Cargo.toml

@@ -9,9 +9,11 @@ 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  }
+rustc_span = { path = "../rustc_span", optional = true }
 tracing = "0.1"
 # tidy-alphabetical-end
 
@@ -22,8 +24,10 @@ 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",
     "rustc_index/nightly",
 ]
 randomize = ["dep:rand", "dep:rand_xoshiro", "nightly"]

compiler/rustc_abi/src/extern_abi/mod.rs

@@ -7,9 +7,11 @@ use rustc_span::{Span, Symbol};
 #[cfg(test)]
 mod tests;
 
+use ExternAbi as Abi;
+
 #[derive(PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy, Debug)]
 #[derive(HashStable_Generic, Encodable, Decodable)]
-pub enum Abi {
+pub enum ExternAbi {
     // Some of the ABIs come first because every time we add a new ABI, we have to re-bless all the
     // hashing tests. These are used in many places, so giving them stable values reduces test
     // churn. The specific values are meaningless.

compiler/rustc_abi/src/lib.rs

@@ -1,6 +1,7 @@
 // tidy-alphabetical-start
 #![cfg_attr(feature = "nightly", allow(internal_features))]
 #![cfg_attr(feature = "nightly", doc(rust_logo))]
+#![cfg_attr(feature = "nightly", feature(assert_matches))]
 #![cfg_attr(feature = "nightly", feature(rustc_attrs))]
 #![cfg_attr(feature = "nightly", feature(rustdoc_internals))]
 #![cfg_attr(feature = "nightly", feature(step_trait))]
@@ -28,8 +29,15 @@ mod layout;
 #[cfg(test)]
 mod tests;
 
+#[cfg(feature = "nightly")]
+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,
+};
+#[cfg(feature = "nightly")]
 pub use layout::{FIRST_VARIANT, FieldIdx, Layout, TyAbiInterface, TyAndLayout, VariantIdx};
 pub use layout::{LayoutCalculator, LayoutCalculatorError};
 

compiler/rustc_hir_pretty/Cargo.toml

@@ -5,9 +5,9 @@ edition = "2021"
 
 [dependencies]
 # tidy-alphabetical-start
+rustc_abi = { path = "../rustc_abi" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_ast_pretty = { path = "../rustc_ast_pretty" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_span = { path = "../rustc_span" }
-rustc_target = { path = "../rustc_target" }
 # tidy-alphabetical-end

compiler/rustc_hir_pretty/src/lib.rs

@@ -9,6 +9,7 @@
 use std::cell::Cell;
 use std::vec;
 
+use rustc_abi::ExternAbi;
 use rustc_ast::util::parser::{self, AssocOp, Fixity};
 use rustc_ast_pretty::pp::Breaks::{Consistent, Inconsistent};
 use rustc_ast_pretty::pp::{self, Breaks};
@@ -20,7 +21,6 @@ use rustc_hir::{
 use rustc_span::FileName;
 use rustc_span::source_map::SourceMap;
 use rustc_span::symbol::{Ident, Symbol, kw};
-use rustc_target::spec::abi::Abi;
 use {rustc_ast as ast, rustc_hir as hir};
 
 pub fn id_to_string(map: &dyn rustc_hir::intravisit::Map<'_>, hir_id: HirId) -> String {
@@ -2240,7 +2240,7 @@ impl<'a> State<'a> {
 
     fn print_ty_fn(
         &mut self,
-        abi: Abi,
+        abi: ExternAbi,
         safety: hir::Safety,
         decl: &hir::FnDecl<'_>,
         name: Option<Symbol>,
@@ -2276,7 +2276,7 @@ impl<'a> State<'a> {
 
         self.print_safety(header.safety);
 
-        if header.abi != Abi::Rust {
+        if header.abi != ExternAbi::Rust {
             self.word_nbsp("extern");
             self.word_nbsp(header.abi.to_string());
         }

compiler/rustc_lint_defs/Cargo.toml

@@ -5,6 +5,7 @@ edition = "2021"
 
 [dependencies]
 # tidy-alphabetical-start
+rustc_abi = { path = "../rustc_abi" }
 rustc_ast = { path = "../rustc_ast" }
 rustc_data_structures = { path = "../rustc_data_structures" }
 rustc_error_messages = { path = "../rustc_error_messages" }
@@ -12,6 +13,5 @@ rustc_hir = { path = "../rustc_hir" }
 rustc_macros = { path = "../rustc_macros" }
 rustc_serialize = { path = "../rustc_serialize" }
 rustc_span = { path = "../rustc_span" }
-rustc_target = { path = "../rustc_target" }
 serde = { version = "1.0.125", features = ["derive"] }
 # tidy-alphabetical-end

compiler/rustc_lint_defs/src/lib.rs

@@ -2,6 +2,7 @@
 #![warn(unreachable_pub)]
 // tidy-alphabetical-end
 
+use rustc_abi::ExternAbi;
 use rustc_ast::node_id::NodeId;
 use rustc_ast::{AttrId, Attribute};
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
@@ -15,7 +16,6 @@ use rustc_macros::{Decodable, Encodable, HashStable_Generic};
 pub use rustc_span::edition::Edition;
 use rustc_span::symbol::{Ident, MacroRulesNormalizedIdent};
 use rustc_span::{Span, Symbol, sym};
-use rustc_target::spec::abi::Abi;
 use serde::{Deserialize, Serialize};
 
 pub use self::Level::*;
@@ -602,7 +602,7 @@ pub enum BuiltinLintDiag {
         path: String,
         since_kind: DeprecatedSinceKind,
     },
-    MissingAbi(Span, Abi),
+    MissingAbi(Span, ExternAbi),
     UnusedDocComment(Span),
     UnusedBuiltinAttribute {
         attr_name: Symbol,

compiler/rustc_mir_build/Cargo.toml

@@ -7,6 +7,8 @@ edition = "2021"
 # tidy-alphabetical-start
 either = "1.5.0"
 itertools = "0.12"
+
+rustc_abi = { path = "../rustc_abi" }
 rustc_apfloat = "0.2.0"
 rustc_arena = { path = "../rustc_arena" }
 rustc_ast = { path = "../rustc_ast" }
@@ -22,7 +24,6 @@ rustc_middle = { path = "../rustc_middle" }
 rustc_pattern_analysis = { path = "../rustc_pattern_analysis" }
 rustc_session = { path = "../rustc_session" }
 rustc_span = { path = "../rustc_span" }
-rustc_target = { path = "../rustc_target" }
 rustc_trait_selection = { path = "../rustc_trait_selection" }
 tracing = "0.1"
 # tidy-alphabetical-end

compiler/rustc_mir_build/src/build/custom/parse/instruction.rs

@@ -1,3 +1,4 @@
+use rustc_abi::{FieldIdx, VariantIdx};
 use rustc_middle::mir::interpret::Scalar;
 use rustc_middle::mir::tcx::PlaceTy;
 use rustc_middle::mir::*;
@@ -6,7 +7,6 @@ use rustc_middle::ty;
 use rustc_middle::ty::cast::mir_cast_kind;
 use rustc_span::Span;
 use rustc_span::source_map::Spanned;
-use rustc_target::abi::{FieldIdx, VariantIdx};
 
 use super::{PResult, ParseCtxt, parse_by_kind};
 use crate::build::custom::ParseError;

compiler/rustc_mir_build/src/build/expr/as_constant.rs

@@ -1,5 +1,6 @@
 //! See docs in build/expr/mod.rs
 
+use rustc_abi::Size;
 use rustc_ast as ast;
 use rustc_hir::LangItem;
 use rustc_middle::mir::interpret::{
@@ -11,7 +12,6 @@ use rustc_middle::ty::{
     self, CanonicalUserType, CanonicalUserTypeAnnotation, Ty, TyCtxt, UserTypeAnnotationIndex,
 };
 use rustc_middle::{bug, mir, span_bug};
-use rustc_target::abi::Size;
 use tracing::{instrument, trace};
 
 use crate::build::{Builder, parse_float_into_constval};

compiler/rustc_mir_build/src/build/expr/as_place.rs

@@ -3,6 +3,7 @@
 use std::assert_matches::assert_matches;
 use std::iter;
 
+use rustc_abi::{FIRST_VARIANT, FieldIdx, VariantIdx};
 use rustc_hir::def_id::LocalDefId;
 use rustc_middle::hir::place::{Projection as HirProjection, ProjectionKind as HirProjectionKind};
 use rustc_middle::middle::region;
@@ -12,7 +13,6 @@ use rustc_middle::thir::*;
 use rustc_middle::ty::{self, AdtDef, CanonicalUserTypeAnnotation, Ty, Variance};
 use rustc_middle::{bug, span_bug};
 use rustc_span::Span;
-use rustc_target::abi::{FIRST_VARIANT, FieldIdx, VariantIdx};
 use tracing::{debug, instrument, trace};
 
 use crate::build::ForGuard::{OutsideGuard, RefWithinGuard};

compiler/rustc_mir_build/src/build/expr/as_rvalue.rs

@@ -1,5 +1,6 @@
 //! See docs in `build/expr/mod.rs`.
 
+use rustc_abi::{BackendRepr, FieldIdx, Primitive};
 use rustc_hir::lang_items::LangItem;
 use rustc_index::{Idx, IndexVec};
 use rustc_middle::bug;
@@ -13,7 +14,6 @@ use rustc_middle::ty::util::IntTypeExt;
 use rustc_middle::ty::{self, Ty, UpvarArgs};
 use rustc_span::source_map::Spanned;
 use rustc_span::{DUMMY_SP, Span};
-use rustc_target::abi::{BackendRepr, FieldIdx, Primitive};
 use tracing::debug;
 
 use crate::build::expr::as_place::PlaceBase;

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -5,6 +5,7 @@
 //! This also includes code for pattern bindings in `let` statements and
 //! function parameters.
 
+use rustc_abi::VariantIdx;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir::{BindingMode, ByRef};
@@ -15,7 +16,6 @@ use rustc_middle::thir::{self, *};
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty};
 use rustc_span::symbol::Symbol;
 use rustc_span::{BytePos, Pos, Span};
-use rustc_target::abi::VariantIdx;
 use tracing::{debug, instrument};
 
 use crate::build::ForGuard::{self, OutsideGuard, RefWithinGuard};

compiler/rustc_mir_build/src/build/mod.rs

@@ -1,4 +1,5 @@
 use itertools::Itertools;
+use rustc_abi::{ExternAbi, FieldIdx};
 use rustc_apfloat::Float;
 use rustc_apfloat::ieee::{Double, Half, Quad, Single};
 use rustc_ast::attr;
@@ -20,8 +21,6 @@ use rustc_middle::ty::{self, ScalarInt, Ty, TyCtxt, TypeVisitableExt, TypingMode
 use rustc_middle::{bug, span_bug};
 use rustc_span::symbol::sym;
 use rustc_span::{Span, Symbol};
-use rustc_target::abi::FieldIdx;
-use rustc_target::spec::abi::Abi;
 
 use super::lints;
 use crate::build::expr::as_place::PlaceBuilder;
@@ -467,7 +466,7 @@ fn construct_fn<'tcx>(
     if let DefKind::Closure = tcx.def_kind(fn_def) {
         // HACK(eddyb) Avoid having RustCall on closures,
         // as it adds unnecessary (and wrong) auto-tupling.
-        abi = Abi::Rust;
+        abi = ExternAbi::Rust;
     }
 
     let arguments = &thir.params;
@@ -540,7 +539,7 @@ fn construct_fn<'tcx>(
 
     let mut body = builder.finish();
 
-    body.spread_arg = if abi == Abi::RustCall {
+    body.spread_arg = if abi == ExternAbi::RustCall {
         // RustCall pseudo-ABI untuples the last argument.
         Some(Local::new(arguments.len()))
     } else {

compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -1,4 +1,5 @@
 use itertools::Itertools;
+use rustc_abi::{FIRST_VARIANT, FieldIdx};
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_hir as hir;
 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
@@ -18,7 +19,6 @@ use rustc_middle::ty::{
 };
 use rustc_middle::{bug, span_bug};
 use rustc_span::{Span, sym};
-use rustc_target::abi::{FIRST_VARIANT, FieldIdx};
 use tracing::{debug, info, instrument, trace};
 
 use crate::errors;

compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs

@@ -1,4 +1,5 @@
 use either::Either;
+use rustc_abi::{FieldIdx, VariantIdx};
 use rustc_apfloat::Float;
 use rustc_hir as hir;
 use rustc_index::Idx;
@@ -9,7 +10,6 @@ use rustc_middle::mir::interpret::ErrorHandled;
 use rustc_middle::thir::{FieldPat, Pat, PatKind};
 use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt, TypingMode, ValTree};
 use rustc_span::Span;
-use rustc_target::abi::{FieldIdx, VariantIdx};
 use rustc_trait_selection::traits::ObligationCause;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use tracing::{debug, instrument, trace};

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -5,6 +5,7 @@ mod const_to_pat;
 
 use std::cmp::Ordering;
 
+use rustc_abi::{FieldIdx, Integer};
 use rustc_errors::codes::*;
 use rustc_hir::def::{CtorOf, DefKind, Res};
 use rustc_hir::pat_util::EnumerateAndAdjustIterator;
@@ -20,7 +21,6 @@ use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt, TypeVisita
 use rustc_middle::{bug, span_bug};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::{ErrorGuaranteed, Span};
-use rustc_target::abi::{FieldIdx, Integer};
 use tracing::{debug, instrument};
 
 pub(crate) use self::check_match::check_match;

compiler/rustc_target/src/spec/mod.rs

@@ -55,9 +55,15 @@ use crate::json::{Json, ToJson};
 use crate::spec::abi::Abi;
 use crate::spec::crt_objects::CrtObjects;
 
-pub mod abi;
 pub mod crt_objects;
 
+pub mod abi {
+    pub use rustc_abi::{
+        AbiDisabled, AbiUnsupported, ExternAbi as Abi, all_names, enabled_names, is_enabled,
+        is_stable, lookup,
+    };
+}
+
 mod base;
 pub use base::apple::{
     deployment_target_for_target as current_apple_deployment_target,