Auto merge of rust-lang#95573 - cjgillot:lower-query, r=michaelwoerister

Make lowering a query

Split from rust-lang#88186.

This PR refactors the relationship between lowering and the resolver outputs in order to make lowering itself a query.
In a first part, lowering is changed to avoid modifying resolver outputs, by maintaining its own data structures for creating new `NodeId`s and so.

Then, the `TyCtxt` is modified to allow creating new `LocalDefId`s from inside it. This is done by:
- enclosing `Definitions` in a lock, so as to allow modification;
- creating a query `register_def` whose purpose is to declare a `LocalDefId` to the query system.

See `TyCtxt::create_def` and `TyCtxt::iter_local_def_id` for more detailed explanations of the design.

Author: bors

Cargo.lock

@@ -3869,6 +3869,7 @@ name = "rustc_hir"
 version = "0.0.0"
 dependencies = [
  "odht",
+ "rustc_arena",
  "rustc_ast",
  "rustc_data_structures",
  "rustc_error_messages",

compiler/rustc_ast_lowering/src/asm.rs

@@ -24,10 +24,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     ) -> &'hir hir::InlineAsm<'hir> {
         // Rustdoc needs to support asm! from foreign architectures: don't try
         // lowering the register constraints in this case.
-        let asm_arch = if self.sess.opts.actually_rustdoc { None } else { self.sess.asm_arch };
-        if asm_arch.is_none() && !self.sess.opts.actually_rustdoc {
-            struct_span_err!(self.sess, sp, E0472, "inline assembly is unsupported on this target")
-                .emit();
+        let asm_arch =
+            if self.tcx.sess.opts.actually_rustdoc { None } else { self.tcx.sess.asm_arch };
+        if asm_arch.is_none() && !self.tcx.sess.opts.actually_rustdoc {
+            struct_span_err!(
+                self.tcx.sess,
+                sp,
+                E0472,
+                "inline assembly is unsupported on this target"
+            )
+            .emit();
         }
         if let Some(asm_arch) = asm_arch {
             // Inline assembly is currently only stable for these architectures.
@@ -40,9 +46,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                     | asm::InlineAsmArch::RiscV32
                     | asm::InlineAsmArch::RiscV64
             );
-            if !is_stable && !self.sess.features_untracked().asm_experimental_arch {
+            if !is_stable && !self.tcx.features().asm_experimental_arch {
                 feature_err(
-                    &self.sess.parse_sess,
+                    &self.tcx.sess.parse_sess,
                     sym::asm_experimental_arch,
                     sp,
                     "inline assembly is not stable yet on this architecture",
@@ -52,17 +58,16 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         }
         if asm.options.contains(InlineAsmOptions::ATT_SYNTAX)
             && !matches!(asm_arch, Some(asm::InlineAsmArch::X86 | asm::InlineAsmArch::X86_64))
-            && !self.sess.opts.actually_rustdoc
+            && !self.tcx.sess.opts.actually_rustdoc
         {
-            self.sess
+            self.tcx
+                .sess
                 .struct_span_err(sp, "the `att_syntax` option is only supported on x86")
                 .emit();
         }
-        if asm.options.contains(InlineAsmOptions::MAY_UNWIND)
-            && !self.sess.features_untracked().asm_unwind
-        {
+        if asm.options.contains(InlineAsmOptions::MAY_UNWIND) && !self.tcx.features().asm_unwind {
             feature_err(
-                &self.sess.parse_sess,
+                &self.tcx.sess.parse_sess,
                 sym::asm_unwind,
                 sp,
                 "the `may_unwind` option is unstable",
@@ -73,20 +78,20 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         let mut clobber_abis = FxHashMap::default();
         if let Some(asm_arch) = asm_arch {
             for (abi_name, abi_span) in &asm.clobber_abis {
-                match asm::InlineAsmClobberAbi::parse(asm_arch, &self.sess.target, *abi_name) {
+                match asm::InlineAsmClobberAbi::parse(asm_arch, &self.tcx.sess.target, *abi_name) {
                     Ok(abi) => {
                         // If the abi was already in the list, emit an error
                         match clobber_abis.get(&abi) {
                             Some((prev_name, prev_sp)) => {
-                                let mut err = self.sess.struct_span_err(
+                                let mut err = self.tcx.sess.struct_span_err(
                                     *abi_span,
                                     &format!("`{}` ABI specified multiple times", prev_name),
                                 );
                                 err.span_label(*prev_sp, "previously specified here");
 
                                 // Multiple different abi names may actually be the same ABI
                                 // If the specified ABIs are not the same name, alert the user that they resolve to the same ABI
-                                let source_map = self.sess.source_map();
+                                let source_map = self.tcx.sess.source_map();
                                 if source_map.span_to_snippet(*prev_sp)
                                     != source_map.span_to_snippet(*abi_span)
                                 {
@@ -101,16 +106,19 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         }
                     }
                     Err(&[]) => {
-                        self.sess
+                        self.tcx
+                            .sess
                             .struct_span_err(
                                 *abi_span,
                                 "`clobber_abi` is not supported on this target",
                             )
                             .emit();
                     }
                     Err(supported_abis) => {
-                        let mut err =
-                            self.sess.struct_span_err(*abi_span, "invalid ABI for `clobber_abi`");
+                        let mut err = self
+                            .tcx
+                            .sess
+                            .struct_span_err(*abi_span, "invalid ABI for `clobber_abi`");
                         let mut abis = format!("`{}`", supported_abis[0]);
                         for m in &supported_abis[1..] {
                             let _ = write!(abis, ", `{}`", m);
@@ -128,7 +136,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         // Lower operands to HIR. We use dummy register classes if an error
         // occurs during lowering because we still need to be able to produce a
         // valid HIR.
-        let sess = self.sess;
+        let sess = self.tcx.sess;
         let mut operands: Vec<_> = asm
             .operands
             .iter()
@@ -184,9 +192,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         }
                     }
                     InlineAsmOperand::Const { ref anon_const } => {
-                        if !self.sess.features_untracked().asm_const {
+                        if !self.tcx.features().asm_const {
                             feature_err(
-                                &self.sess.parse_sess,
+                                &sess.parse_sess,
                                 sym::asm_const,
                                 *op_sp,
                                 "const operands for inline assembly are unstable",
@@ -198,9 +206,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                         }
                     }
                     InlineAsmOperand::Sym { ref sym } => {
-                        if !self.sess.features_untracked().asm_sym {
+                        if !self.tcx.features().asm_sym {
                             feature_err(
-                                &self.sess.parse_sess,
+                                &sess.parse_sess,
                                 sym::asm_sym,
                                 *op_sp,
                                 "sym operands for inline assembly are unstable",

compiler/rustc_ast_lowering/src/block.rs

@@ -159,9 +159,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
             span,
             kind: hir::ExprKind::If(let_expr, then_expr, Some(else_expr)),
         });
-        if !self.sess.features_untracked().let_else {
+        if !self.tcx.features().let_else {
             feature_err(
-                &self.sess.parse_sess,
+                &self.tcx.sess.parse_sess,
                 sym::let_else,
                 local.span,
                 "`let...else` statements are unstable",

compiler/rustc_ast_lowering/src/expr.rs

@@ -46,7 +46,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                             let hir_id = self.lower_node_id(e.id);
                             return hir::Expr { hir_id, kind, span: self.lower_span(e.span) };
                         } else {
-                            self.sess
+                            self.tcx.sess
                                 .struct_span_err(
                                     e.span,
                                     "#[rustc_box] requires precisely one argument \
@@ -207,8 +207,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     self.lower_expr_range(e.span, e1.as_deref(), e2.as_deref(), lims)
                 }
                 ExprKind::Underscore => {
-                    self.sess
-                        .struct_span_err(
+                    self.tcx
+                        .sess.struct_span_err(
                             e.span,
                             "in expressions, `_` can only be used on the left-hand side of an assignment",
                         )
@@ -245,7 +245,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     let rest = match &se.rest {
                         StructRest::Base(e) => Some(self.lower_expr(e)),
                         StructRest::Rest(sp) => {
-                            self.sess
+                            self.tcx
+                                .sess
                                 .struct_span_err(*sp, "base expression required after `..`")
                                 .span_label(*sp, "add a base expression here")
                                 .emit();
@@ -474,7 +475,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             } else {
                 let try_span = this.mark_span_with_reason(
                     DesugaringKind::TryBlock,
-                    this.sess.source_map().end_point(body.span),
+                    this.tcx.sess.source_map().end_point(body.span),
                     this.allow_try_trait.clone(),
                 );
 
@@ -653,7 +654,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             Some(hir::GeneratorKind::Async(_)) => {}
             Some(hir::GeneratorKind::Gen) | None => {
                 let mut err = struct_span_err!(
-                    self.sess,
+                    self.tcx.sess,
                     dot_await_span,
                     E0728,
                     "`await` is only allowed inside `async` functions and blocks"
@@ -878,7 +879,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             Some(hir::GeneratorKind::Gen) => {
                 if decl.inputs.len() > 1 {
                     struct_span_err!(
-                        self.sess,
+                        self.tcx.sess,
                         fn_decl_span,
                         E0628,
                         "too many parameters for a generator (expected 0 or 1 parameters)"
@@ -892,8 +893,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
             }
             None => {
                 if movability == Movability::Static {
-                    struct_span_err!(self.sess, fn_decl_span, E0697, "closures cannot be static")
-                        .emit();
+                    struct_span_err!(
+                        self.tcx.sess,
+                        fn_decl_span,
+                        E0697,
+                        "closures cannot be static"
+                    )
+                    .emit();
                 }
                 None
             }
@@ -916,7 +922,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             // FIXME(cramertj): allow `async` non-`move` closures with arguments.
             if capture_clause == CaptureBy::Ref && !decl.inputs.is_empty() {
                 struct_span_err!(
-                    this.sess,
+                    this.tcx.sess,
                     fn_decl_span,
                     E0708,
                     "`async` non-`move` closures with parameters are not currently supported",
@@ -1163,7 +1169,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
                 );
                 let fields_omitted = match &se.rest {
                     StructRest::Base(e) => {
-                        self.sess
+                        self.tcx
+                            .sess
                             .struct_span_err(
                                 e.span,
                                 "functional record updates are not allowed in destructuring \
@@ -1371,7 +1378,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             Some(hir::GeneratorKind::Gen) => {}
             Some(hir::GeneratorKind::Async(_)) => {
                 struct_span_err!(
-                    self.sess,
+                    self.tcx.sess,
                     span,
                     E0727,
                     "`async` generators are not yet supported"
@@ -1516,7 +1523,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             span,
             self.allow_try_trait.clone(),
         );
-        let try_span = self.sess.source_map().end_point(span);
+        let try_span = self.tcx.sess.source_map().end_point(span);
         let try_span = self.mark_span_with_reason(
             DesugaringKind::QuestionMark,
             try_span,

compiler/rustc_ast_lowering/src/item.rs

@@ -1,7 +1,6 @@
 use super::ResolverAstLoweringExt;
 use super::{AstOwner, ImplTraitContext, ImplTraitPosition};
-use super::{LoweringContext, ParamMode};
-use crate::{Arena, FnDeclKind};
+use super::{FnDeclKind, LoweringContext, ParamMode};
 
 use rustc_ast::ptr::P;
 use rustc_ast::visit::AssocCtxt;
@@ -12,12 +11,9 @@ use rustc_errors::struct_span_err;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
-use rustc_hir::definitions::Definitions;
 use rustc_hir::PredicateOrigin;
 use rustc_index::vec::{Idx, IndexVec};
-use rustc_middle::ty::{ResolverAstLowering, ResolverOutputs};
-use rustc_session::cstore::CrateStoreDyn;
-use rustc_session::Session;
+use rustc_middle::ty::{DefIdTree, ResolverAstLowering, TyCtxt};
 use rustc_span::source_map::DesugaringKind;
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::Span;
@@ -27,12 +23,8 @@ use smallvec::{smallvec, SmallVec};
 use std::iter;
 
 pub(super) struct ItemLowerer<'a, 'hir> {
-    pub(super) sess: &'a Session,
-    pub(super) definitions: &'a mut Definitions,
-    pub(super) cstore: &'a CrateStoreDyn,
-    pub(super) resolutions: &'a ResolverOutputs,
+    pub(super) tcx: TyCtxt<'hir>,
     pub(super) resolver: &'a mut ResolverAstLowering,
-    pub(super) arena: &'hir Arena<'hir>,
     pub(super) ast_index: &'a IndexVec<LocalDefId, AstOwner<'a>>,
     pub(super) owners: &'a mut IndexVec<LocalDefId, hir::MaybeOwner<&'hir hir::OwnerInfo<'hir>>>,
 }
@@ -65,12 +57,9 @@ impl<'a, 'hir> ItemLowerer<'a, 'hir> {
     ) {
         let mut lctx = LoweringContext {
             // Pseudo-globals.
-            sess: &self.sess,
-            definitions: self.definitions,
-            cstore: self.cstore,
-            resolutions: self.resolutions,
+            tcx: self.tcx,
             resolver: self.resolver,
-            arena: self.arena,
+            arena: self.tcx.hir_arena,
 
             // HirId handling.
             bodies: Vec::new(),
@@ -144,12 +133,7 @@ impl<'a, 'hir> ItemLowerer<'a, 'hir> {
     fn lower_assoc_item(&mut self, item: &AssocItem, ctxt: AssocCtxt) {
         let def_id = self.resolver.node_id_to_def_id[&item.id];
 
-        let parent_id = {
-            let parent = self.definitions.def_key(def_id).parent;
-            let local_def_index = parent.unwrap();
-            LocalDefId { local_def_index }
-        };
-
+        let parent_id = self.tcx.local_parent(def_id);
         let parent_hir = self.lower_node(parent_id).unwrap();
         self.with_lctx(item.id, |lctx| {
             // Evaluate with the lifetimes in `params` in-scope.
@@ -1278,7 +1262,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     }
 
     fn error_on_invalid_abi(&self, abi: StrLit) {
-        struct_span_err!(self.sess, abi.span, E0703, "invalid ABI: found `{}`", abi.symbol)
+        struct_span_err!(self.tcx.sess, abi.span, E0703, "invalid ABI: found `{}`", abi.symbol)
             .span_label(abi.span, "invalid ABI")
             .help(&format!("valid ABIs: {}", abi::all_names().join(", ")))
             .emit();