Rollup merge of #132574 - workingjubilee:abi-in-compiler, r=compiler-errors

compiler: Directly use rustc_abi almost everywhere

Use rustc_abi instead of rustc_target where applicable. This is mostly described by the following substitutions:
```rust
match path_substring {
    rustc_target::spec::abi::Abi => rustc_abi::ExternAbi,
    rustc_target::abi::call => rustc_target::callconv,
    rustc_target::abi => rustc_abi,
}
```

A number of spot-fixes make that not quite the whole story.

The main exception is in 33edc68 where I get a lot more persnickety about how things are imported, especially in `rustc_middle::ty::layout`, not just from where. This includes putting an end to a reexport of `rustc_middle::ty::ReprOptions`, for the same reason that the rest of this change is happening: reexports mostly confound things.

This notably omits rustc_passes and the ast crates, as I'm still examining a question I have about how they do stability checking of `extern "Abi"` strings and if I can simplify their logic. The rustc_abi and rustc_target crates also go untouched because they will be entangled in that cleanup.

r? compiler-errors

Author: workingjubilee

compiler/rustc_codegen_ssa/src/debuginfo/mod.rs

@@ -1,7 +1,7 @@
+use rustc_abi::{Integer, Primitive, Size, TagEncoding, Variants};
 use rustc_middle::bug;
 use rustc_middle::ty::layout::{IntegerExt, PrimitiveExt, TyAndLayout};
 use rustc_middle::ty::{self, Ty, TyCtxt};
-use rustc_target::abi::{Integer, Primitive, Size, TagEncoding, Variants};
 
 // FIXME(eddyb) find a place for this (or a way to replace it).
 pub mod type_names;

compiler/rustc_codegen_ssa/src/debuginfo/type_names.rs

@@ -13,6 +13,7 @@
 
 use std::fmt::Write;
 
+use rustc_abi::Integer;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::stable_hasher::{Hash64, HashStable, StableHasher};
 use rustc_hir::def_id::DefId;
@@ -23,7 +24,6 @@ use rustc_middle::ty::layout::{IntegerExt, TyAndLayout};
 use rustc_middle::ty::{
     self, ExistentialProjection, GenericArgKind, GenericArgsRef, ParamEnv, Ty, TyCtxt,
 };
-use rustc_target::abi::Integer;
 use smallvec::SmallVec;
 
 use crate::debuginfo::wants_c_like_enum_debuginfo;
@@ -364,7 +364,7 @@ fn push_debuginfo_type_name<'tcx>(
             } else {
                 output.push_str(sig.safety.prefix_str());
 
-                if sig.abi != rustc_target::spec::abi::Abi::Rust {
+                if sig.abi != rustc_abi::ExternAbi::Rust {
                     output.push_str("extern \"");
                     output.push_str(sig.abi.name());
                     output.push_str("\" ");

compiler/rustc_codegen_ssa/src/meth.rs

@@ -2,7 +2,7 @@ use rustc_middle::bug;
 use rustc_middle::ty::{self, GenericArgKind, Ty};
 use rustc_session::config::Lto;
 use rustc_symbol_mangling::typeid_for_trait_ref;
-use rustc_target::abi::call::FnAbi;
+use rustc_target::callconv::FnAbi;
 use tracing::{debug, instrument};
 
 use crate::traits::*;