Auto merge of rust-lang#71566 - Dylan-DPC:rollup-9xoz6fg, r=Dylan-DPC

Rollup of 5 pull requests

Successful merges:

 - rust-lang#70043 (Add all remaining `DefKind`s.)
 - rust-lang#71140 ([breaking change] Disallow statics initializing themselves)
 - rust-lang#71392 (Don't hold the predecessor cache lock longer than necessary)
 - rust-lang#71541 (Add regression test for rust-lang#26376)
 - rust-lang#71554 (Replace thread_local with generator resume arguments in box_region.)

Failed merges:

r? @ghost

src/librustc_codegen_ssa/mir/mod.rs

@@ -157,7 +157,7 @@ pub fn codegen_mir<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
     let cleanup_kinds = analyze::cleanup_kinds(&mir);
     // Allocate a `Block` for every basic block, except
     // the start block, if nothing loops back to it.
-    let reentrant_start_block = !mir.predecessors_for(mir::START_BLOCK).is_empty();
+    let reentrant_start_block = !mir.predecessors()[mir::START_BLOCK].is_empty();
     let block_bxs: IndexVec<mir::BasicBlock, Bx::BasicBlock> = mir
         .basic_blocks()
         .indices()

src/librustc_data_structures/box_region.rs

@@ -1,4 +1,15 @@
-use std::cell::Cell;
+//! This module provides a way to deal with self-referential data.
+//!
+//! The main idea is to allocate such data in a generator frame and then
+//! give access to it by executing user-provided closures inside that generator.
+//! The module provides a safe abstraction for the latter task.
+//!
+//! The interface consists of two exported macros meant to be used together:
+//! * `declare_box_region_type` wraps a generator inside a struct with `access`
+//!   method which accepts closures.
+//! * `box_region_allow_access` is a helper which should be called inside
+//!   a generator to actually execute those closures.
+
 use std::marker::PhantomData;
 use std::ops::{Generator, GeneratorState};
 use std::pin::Pin;
@@ -14,24 +25,23 @@ impl AccessAction {
 
 #[derive(Copy, Clone)]
 pub enum Action {
+    Initial,
     Access(AccessAction),
     Complete,
 }
 
-thread_local!(pub static BOX_REGION_ARG: Cell<Action> = Cell::new(Action::Complete));
-
 pub struct PinnedGenerator<I, A, R> {
-    generator: Pin<Box<dyn Generator<Yield = YieldType<I, A>, Return = R>>>,
+    generator: Pin<Box<dyn Generator<Action, Yield = YieldType<I, A>, Return = R>>>,
 }
 
 impl<I, A, R> PinnedGenerator<I, A, R> {
-    pub fn new<T: Generator<Yield = YieldType<I, A>, Return = R> + 'static>(
+    pub fn new<T: Generator<Action, Yield = YieldType<I, A>, Return = R> + 'static>(
         generator: T,
     ) -> (I, Self) {
         let mut result = PinnedGenerator { generator: Box::pin(generator) };
 
         // Run it to the first yield to set it up
-        let init = match Pin::new(&mut result.generator).resume(()) {
+        let init = match Pin::new(&mut result.generator).resume(Action::Initial) {
             GeneratorState::Yielded(YieldType::Initial(y)) => y,
             _ => panic!(),
         };
@@ -40,21 +50,17 @@ impl<I, A, R> PinnedGenerator<I, A, R> {
     }
 
     pub unsafe fn access(&mut self, closure: *mut dyn FnMut()) {
-        BOX_REGION_ARG.with(|i| {
-            i.set(Action::Access(AccessAction(closure)));
-        });
-
-        // Call the generator, which in turn will call the closure in BOX_REGION_ARG
-        if let GeneratorState::Complete(_) = Pin::new(&mut self.generator).resume(()) {
+        // Call the generator, which in turn will call the closure
+        if let GeneratorState::Complete(_) =
+            Pin::new(&mut self.generator).resume(Action::Access(AccessAction(closure)))
+        {
             panic!()
         }
     }
 
     pub fn complete(&mut self) -> R {
         // Tell the generator we want it to complete, consuming it and yielding a result
-        BOX_REGION_ARG.with(|i| i.set(Action::Complete));
-
-        let result = Pin::new(&mut self.generator).resume(());
+        let result = Pin::new(&mut self.generator).resume(Action::Complete);
         if let GeneratorState::Complete(r) = result { r } else { panic!() }
     }
 }
@@ -89,7 +95,7 @@ macro_rules! declare_box_region_type {
         >);
 
         impl $name {
-            fn new<T: ::std::ops::Generator<Yield = $yield_type, Return = $retc> + 'static>(
+            fn new<T: ::std::ops::Generator<$crate::box_region::Action, Yield = $yield_type, Return = $retc> + 'static>(
                 generator: T
             ) -> ($reti, Self) {
                 let (initial, pinned) = $crate::box_region::PinnedGenerator::new(generator);
@@ -98,7 +104,7 @@ macro_rules! declare_box_region_type {
 
             $v fn access<F: for<$($lifetimes)*> FnOnce($($args,)*) -> R, R>(&mut self, f: F) -> R {
                 // Turn the FnOnce closure into *mut dyn FnMut()
-                // so we can pass it in to the generator using the BOX_REGION_ARG thread local
+                // so we can pass it in to the generator
                 let mut r = None;
                 let mut f = Some(f);
                 let mut_f: &mut dyn for<$($lifetimes)*> FnMut(($($args,)*)) =
@@ -140,9 +146,9 @@ macro_rules! declare_box_region_type {
 #[macro_export]
 #[allow_internal_unstable(fn_traits)]
 macro_rules! box_region_allow_access {
-    (for($($lifetimes:tt)*), ($($args:ty),*), ($($exprs:expr),*) ) => {
+    (for($($lifetimes:tt)*), ($($args:ty),*), ($($exprs:expr),*), $action:ident) => {
         loop {
-            match $crate::box_region::BOX_REGION_ARG.with(|i| i.get()) {
+            match $action {
                 $crate::box_region::Action::Access(accessor) => {
                     let accessor: &mut dyn for<$($lifetimes)*> FnMut($($args),*) = unsafe {
                         ::std::mem::transmute(accessor.get())
@@ -152,10 +158,11 @@ macro_rules! box_region_allow_access {
                         let marker = $crate::box_region::Marker::<
                             for<$($lifetimes)*> fn(($($args,)*))
                         >::new();
-                        yield $crate::box_region::YieldType::Accessor(marker)
+                        $action = yield $crate::box_region::YieldType::Accessor(marker);
                     };
                 }
                 $crate::box_region::Action::Complete => break,
+                $crate::box_region::Action::Initial => panic!("unexpected box_region action: Initial"),
             }
         }
     }

src/librustc_hir/def.rs

@@ -77,6 +77,18 @@ pub enum DefKind {
 
     // Macro namespace
     Macro(MacroKind),
+
+    // Not namespaced (or they are, but we don't treat them so)
+    ExternCrate,
+    Use,
+    ForeignMod,
+    AnonConst,
+    Field,
+    LifetimeParam,
+    GlobalAsm,
+    Impl,
+    Closure,
+    Generator,
 }
 
 impl DefKind {
@@ -113,6 +125,16 @@ impl DefKind {
             DefKind::TyParam => "type parameter",
             DefKind::ConstParam => "const parameter",
             DefKind::Macro(macro_kind) => macro_kind.descr(),
+            DefKind::LifetimeParam => "lifetime parameter",
+            DefKind::Use => "import",
+            DefKind::ForeignMod => "foreign module",
+            DefKind::AnonConst => "constant expression",
+            DefKind::Field => "field",
+            DefKind::Impl => "implementation",
+            DefKind::Closure => "closure",
+            DefKind::Generator => "generator",
+            DefKind::ExternCrate => "extern crate",
+            DefKind::GlobalAsm => "global assembly block",
         }
     }
 
@@ -124,7 +146,10 @@ impl DefKind {
             | DefKind::AssocOpaqueTy
             | DefKind::AssocFn
             | DefKind::Enum
-            | DefKind::OpaqueTy => "an",
+            | DefKind::OpaqueTy
+            | DefKind::Impl
+            | DefKind::Use
+            | DefKind::ExternCrate => "an",
             DefKind::Macro(macro_kind) => macro_kind.article(),
             _ => "a",
         }
@@ -155,6 +180,18 @@ impl DefKind {
             | DefKind::AssocConst => ns == Namespace::ValueNS,
 
             DefKind::Macro(..) => ns == Namespace::MacroNS,
+
+            // Not namespaced.
+            DefKind::AnonConst
+            | DefKind::Field
+            | DefKind::LifetimeParam
+            | DefKind::ExternCrate
+            | DefKind::Closure
+            | DefKind::Generator
+            | DefKind::Use
+            | DefKind::ForeignMod
+            | DefKind::GlobalAsm
+            | DefKind::Impl => false,
         }
     }
 }

src/librustc_hir/hir.rs

@@ -2452,27 +2452,6 @@ pub enum ItemKind<'hir> {
 }
 
 impl ItemKind<'_> {
-    pub fn descr(&self) -> &str {
-        match *self {
-            ItemKind::ExternCrate(..) => "extern crate",
-            ItemKind::Use(..) => "`use` import",
-            ItemKind::Static(..) => "static item",
-            ItemKind::Const(..) => "constant item",
-            ItemKind::Fn(..) => "function",
-            ItemKind::Mod(..) => "module",
-            ItemKind::ForeignMod(..) => "extern block",
-            ItemKind::GlobalAsm(..) => "global asm item",
-            ItemKind::TyAlias(..) => "type alias",
-            ItemKind::OpaqueTy(..) => "opaque type",
-            ItemKind::Enum(..) => "enum",
-            ItemKind::Struct(..) => "struct",
-            ItemKind::Union(..) => "union",
-            ItemKind::Trait(..) => "trait",
-            ItemKind::TraitAlias(..) => "trait alias",
-            ItemKind::Impl { .. } => "implementation",
-        }
-    }
-
     pub fn generics(&self) -> Option<&Generics<'_>> {
         Some(match *self {
             ItemKind::Fn(_, ref generics, _)
@@ -2551,16 +2530,6 @@ pub enum ForeignItemKind<'hir> {
     Type,
 }
 
-impl ForeignItemKind<'hir> {
-    pub fn descriptive_variant(&self) -> &str {
-        match *self {
-            ForeignItemKind::Fn(..) => "foreign function",
-            ForeignItemKind::Static(..) => "foreign static item",
-            ForeignItemKind::Type => "foreign type",
-        }
-    }
-}
-
 /// A variable captured by a closure.
 #[derive(Debug, Copy, Clone, RustcEncodable, RustcDecodable, HashStable_Generic)]
 pub struct Upvar {

src/librustc_infer/infer/error_reporting/need_type_info.rs

@@ -207,12 +207,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                         .get_opt_name()
                         .map(|parent_symbol| parent_symbol.to_string());
 
-                    let type_parent_desc = self
-                        .tcx
-                        .def_kind(parent_def_id)
-                        .map(|parent_def_kind| parent_def_kind.descr(parent_def_id));
-
-                    (parent_name, type_parent_desc)
+                    (parent_name, Some(self.tcx.def_kind(parent_def_id).descr(parent_def_id)))
                 } else {
                     (None, None)
                 };

src/librustc_interface/passes.rs

@@ -109,7 +109,8 @@ pub fn configure_and_expand(
     // its contents but the results of name resolution on those contents. Hopefully we'll push
     // this back at some point.
     let crate_name = crate_name.to_string();
-    let (result, resolver) = BoxedResolver::new(static move || {
+    let (result, resolver) = BoxedResolver::new(static move |mut action| {
+        let _ = action;
         let sess = &*sess;
         let resolver_arenas = Resolver::arenas();
         let res = configure_and_expand_inner(
@@ -126,11 +127,11 @@ pub fn configure_and_expand(
                 panic!()
             }
             Ok((krate, resolver)) => {
-                yield BoxedResolver::initial_yield(Ok(krate));
+                action = yield BoxedResolver::initial_yield(Ok(krate));
                 resolver
             }
         };
-        box_region_allow_access!(for(), (&mut Resolver<'_>), (&mut resolver));
+        box_region_allow_access!(for(), (&mut Resolver<'_>), (&mut resolver), action);
         resolver.into_outputs()
     });
     result.map(|k| (k, resolver))

src/librustc_metadata/rmeta/decoder.rs

@@ -562,8 +562,8 @@ impl MetadataBlob {
 }
 
 impl EntryKind {
-    fn def_kind(&self) -> Option<DefKind> {
-        Some(match *self {
+    fn def_kind(&self) -> DefKind {
+        match *self {
             EntryKind::Const(..) => DefKind::Const,
             EntryKind::AssocConst(..) => DefKind::AssocConst,
             EntryKind::ImmStatic
@@ -587,14 +587,13 @@ impl EntryKind {
             EntryKind::Enum(..) => DefKind::Enum,
             EntryKind::MacroDef(_) => DefKind::Macro(MacroKind::Bang),
             EntryKind::ForeignType => DefKind::ForeignTy,
-
-            EntryKind::ForeignMod
-            | EntryKind::GlobalAsm
-            | EntryKind::Impl(_)
-            | EntryKind::Field
-            | EntryKind::Generator(_)
-            | EntryKind::Closure => return None,
-        })
+            EntryKind::Impl(_) => DefKind::Impl,
+            EntryKind::Closure => DefKind::Closure,
+            EntryKind::ForeignMod => DefKind::ForeignMod,
+            EntryKind::GlobalAsm => DefKind::GlobalAsm,
+            EntryKind::Field => DefKind::Field,
+            EntryKind::Generator(_) => DefKind::Generator,
+        }
     }
 }
 
@@ -679,11 +678,11 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
         }
     }
 
-    fn def_kind(&self, index: DefIndex) -> Option<DefKind> {
+    fn def_kind(&self, index: DefIndex) -> DefKind {
         if !self.is_proc_macro(index) {
             self.kind(index).def_kind()
         } else {
-            Some(DefKind::Macro(macro_kind(self.raw_proc_macro(index))))
+            DefKind::Macro(macro_kind(self.raw_proc_macro(index)))
         }
     }
 
@@ -1009,20 +1008,19 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
                             .get(self, child_index)
                             .unwrap_or(Lazy::empty());
                         for child_index in child_children.decode((self, sess)) {
-                            if let Some(kind) = self.def_kind(child_index) {
-                                callback(Export {
-                                    res: Res::Def(kind, self.local_def_id(child_index)),
-                                    ident: self.item_ident(child_index, sess),
-                                    vis: self.get_visibility(child_index),
-                                    span: self
-                                        .root
-                                        .tables
-                                        .span
-                                        .get(self, child_index)
-                                        .unwrap()
-                                        .decode((self, sess)),
-                                });
-                            }
+                            let kind = self.def_kind(child_index);
+                            callback(Export {
+                                res: Res::Def(kind, self.local_def_id(child_index)),
+                                ident: self.item_ident(child_index, sess),
+                                vis: self.get_visibility(child_index),
+                                span: self
+                                    .root
+                                    .tables
+                                    .span
+                                    .get(self, child_index)
+                                    .unwrap()
+                                    .decode((self, sess)),
+                            });
                         }
                         continue;
                     }
@@ -1033,10 +1031,8 @@ impl<'a, 'tcx> CrateMetadataRef<'a> {
 
                 let def_key = self.def_key(child_index);
                 let span = self.get_span(child_index, sess);
-                if let (Some(kind), true) = (
-                    self.def_kind(child_index),
-                    def_key.disambiguated_data.data.get_opt_name().is_some(),
-                ) {
+                if def_key.disambiguated_data.data.get_opt_name().is_some() {
+                    let kind = self.def_kind(child_index);
                     let ident = self.item_ident(child_index, sess);
                     let vis = self.get_visibility(child_index);
                     let def_id = self.local_def_id(child_index);