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

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;