Rollup merge of #115934 - oli-obk:smir_identity, r=spastorino

Split out the stable part of smir into its own crate to prevent accidental usage of forever unstable things

Some groundwork for being able to work on rust-lang/project-stable-mir#27 at all

r? `@spastorino`

Cargo.lock

@@ -3245,6 +3245,7 @@ dependencies = [
  "rustc_driver",
  "rustc_driver_impl",
  "rustc_smir",
+ "stable_mir",
 ]
 
 [[package]]
@@ -4409,7 +4410,7 @@ dependencies = [
  "rustc_session",
  "rustc_span",
  "rustc_target",
- "scoped-tls",
+ "stable_mir",
  "tracing",
 ]
 
@@ -4946,6 +4947,14 @@ version = "1.2.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a8f112729512f8e442d81f95a8a7ddf2b7c6b8a1a6f509a95864142b30cab2d3"
 
+[[package]]
+name = "stable_mir"
+version = "0.1.0-preview"
+dependencies = [
+ "scoped-tls",
+ "tracing",
+]
+
 [[package]]
 name = "stacker"
 version = "0.1.15"

compiler/rustc/Cargo.toml

@@ -13,6 +13,7 @@ rustc_codegen_ssa = { path = "../rustc_codegen_ssa" }
 # Make sure rustc_smir ends up in the sysroot, because this
 # crate is intended to be used by stable MIR consumers, which are not in-tree
 rustc_smir = { path = "../rustc_smir" }
+stable_mir = { path = "../stable_mir" }
 
 [dependencies.jemalloc-sys]
 version = "0.5.0"

compiler/rustc_smir/Cargo.toml

@@ -4,24 +4,14 @@ version = "0.0.0"
 edition = "2021"
 
 [dependencies]
-# Use optional dependencies for rustc_* in order to support building this crate separately.
-rustc_hir = { path = "../rustc_hir", optional = true }
-rustc_middle = { path = "../rustc_middle", optional = true }
-rustc_span = { path = "../rustc_span", optional = true }
-rustc_target = { path = "../rustc_target", optional = true }
-rustc_driver = { path = "../rustc_driver", optional = true }
-rustc_interface = { path = "../rustc_interface", optional = true}
-rustc_session = {path = "../rustc_session", optional = true}
+rustc_hir = { path = "../rustc_hir" }
+rustc_middle = { path = "../rustc_middle" }
+rustc_span = { path = "../rustc_span" }
+rustc_target = { path = "../rustc_target" }
+rustc_driver = { path = "../rustc_driver" }
+rustc_interface = { path = "../rustc_interface" }
+rustc_session = {path = "../rustc_session" }
 tracing = "0.1"
-scoped-tls = "1.0"
+stable_mir = {path = "../stable_mir" }
 
 [features]
-default = [
-    "rustc_hir",
-    "rustc_middle",
-    "rustc_span",
-    "rustc_target",
-    "rustc_driver",
-    "rustc_interface",
-    "rustc_session",
-]

compiler/rustc_smir/src/lib.rs

@@ -10,26 +10,12 @@
     html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/",
     test(attr(allow(unused_variables), deny(warnings)))
 )]
-#![cfg_attr(not(feature = "default"), feature(rustc_private))]
+#![feature(rustc_private)]
 #![feature(ptr_metadata)]
 #![feature(type_alias_impl_trait)] // Used to define opaque types.
 #![feature(intra_doc_pointers)]
 
-// Declare extern rustc_* crates to enable building this crate separately from the compiler.
-#[cfg(not(feature = "default"))]
-extern crate rustc_hir;
-#[cfg(not(feature = "default"))]
-extern crate rustc_middle;
-#[cfg(not(feature = "default"))]
-extern crate rustc_span;
-#[cfg(not(feature = "default"))]
-extern crate rustc_target;
-
 pub mod rustc_internal;
-pub mod stable_mir;
 
 // Make this module private for now since external users should not call these directly.
 mod rustc_smir;
-
-#[macro_use]
-extern crate scoped_tls;

compiler/rustc_smir/src/rustc_internal/mod.rs

@@ -3,75 +3,17 @@
 //! For that, we define APIs that will temporarily be public to 3P that exposes rustc internal APIs
 //! until stable MIR is complete.
 
-use std::fmt::Debug;
 use std::ops::{ControlFlow, Index};
 
 use crate::rustc_internal;
-use crate::stable_mir::CompilerError;
-use crate::{
-    rustc_smir::Tables,
-    stable_mir::{self, with},
-};
+use crate::rustc_smir::Tables;
 use rustc_driver::{Callbacks, Compilation, RunCompiler};
 use rustc_interface::{interface, Queries};
 use rustc_middle::mir::interpret::AllocId;
 use rustc_middle::ty::TyCtxt;
 pub use rustc_span::def_id::{CrateNum, DefId};
 use rustc_span::Span;
-
-fn with_tables<R>(mut f: impl FnMut(&mut Tables<'_>) -> R) -> R {
-    let mut ret = None;
-    with(|tables| tables.rustc_tables(&mut |t| ret = Some(f(t))));
-    ret.unwrap()
-}
-
-pub fn item_def_id(item: &stable_mir::CrateItem) -> DefId {
-    with_tables(|t| t[item.0])
-}
-
-pub fn crate_item(did: DefId) -> stable_mir::CrateItem {
-    with_tables(|t| t.crate_item(did))
-}
-
-pub fn adt_def(did: DefId) -> stable_mir::ty::AdtDef {
-    with_tables(|t| t.adt_def(did))
-}
-
-pub fn foreign_def(did: DefId) -> stable_mir::ty::ForeignDef {
-    with_tables(|t| t.foreign_def(did))
-}
-
-pub fn fn_def(did: DefId) -> stable_mir::ty::FnDef {
-    with_tables(|t| t.fn_def(did))
-}
-
-pub fn closure_def(did: DefId) -> stable_mir::ty::ClosureDef {
-    with_tables(|t| t.closure_def(did))
-}
-
-pub fn generator_def(did: DefId) -> stable_mir::ty::GeneratorDef {
-    with_tables(|t| t.generator_def(did))
-}
-
-pub fn alias_def(did: DefId) -> stable_mir::ty::AliasDef {
-    with_tables(|t| t.alias_def(did))
-}
-
-pub fn param_def(did: DefId) -> stable_mir::ty::ParamDef {
-    with_tables(|t| t.param_def(did))
-}
-
-pub fn br_named_def(did: DefId) -> stable_mir::ty::BrNamedDef {
-    with_tables(|t| t.br_named_def(did))
-}
-
-pub fn trait_def(did: DefId) -> stable_mir::ty::TraitDef {
-    with_tables(|t| t.trait_def(did))
-}
-
-pub fn impl_def(did: DefId) -> stable_mir::ty::ImplDef {
-    with_tables(|t| t.impl_def(did))
-}
+use stable_mir::CompilerError;
 
 impl<'tcx> Index<stable_mir::DefId> for Tables<'tcx> {
     type Output = DefId;
@@ -82,6 +24,15 @@ impl<'tcx> Index<stable_mir::DefId> for Tables<'tcx> {
     }
 }
 
+impl<'tcx> Index<stable_mir::ty::Span> for Tables<'tcx> {
+    type Output = Span;
+
+    #[inline(always)]
+    fn index(&self, index: stable_mir::ty::Span) -> &Self::Output {
+        &self.spans[index.0]
+    }
+}
+
 impl<'tcx> Tables<'tcx> {
     pub fn crate_item(&mut self, did: DefId) -> stable_mir::CrateItem {
         stable_mir::CrateItem(self.create_def_id(did))
@@ -178,32 +129,12 @@ pub fn crate_num(item: &stable_mir::Crate) -> CrateNum {
 }
 
 pub fn run(tcx: TyCtxt<'_>, f: impl FnOnce()) {
-    crate::stable_mir::run(
+    stable_mir::run(
         Tables { tcx, def_ids: vec![], alloc_ids: vec![], spans: vec![], types: vec![] },
         f,
     );
 }
 
-/// A type that provides internal information but that can still be used for debug purpose.
-#[derive(Clone)]
-pub struct Opaque(String);
-
-impl std::fmt::Display for Opaque {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{}", self.0)
-    }
-}
-
-impl std::fmt::Debug for Opaque {
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        write!(f, "{:?}", self.0)
-    }
-}
-
-pub(crate) fn opaque<T: Debug>(value: &T) -> Opaque {
-    Opaque(format!("{value:?}"))
-}
-
 pub struct StableMir<B = (), C = ()>
 where
     B: Send,

compiler/rustc_smir/src/rustc_smir/alloc.rs

@@ -3,11 +3,9 @@ use rustc_middle::mir::{
     ConstValue,
 };
 
-use crate::{
-    rustc_smir::{Stable, Tables},
-    stable_mir::mir::Mutability,
-    stable_mir::ty::{Allocation, ProvenanceMap},
-};
+use crate::rustc_smir::{Stable, Tables};
+use stable_mir::mir::Mutability;
+use stable_mir::ty::{Allocation, ProvenanceMap};
 
 /// Creates new empty `Allocation` from given `Align`.
 fn new_empty_allocation(align: rustc_target::abi::Align) -> Allocation {