Auto merge of #70062 - Centril:rollup-synwle8, r=Centril

Rollup of 7 pull requests

Successful merges:

 - #69811 (resolve: Print import chains on privacy errors)
 - #69870 (expand: Implement something similar to `#[cfg(accessible(path))]`)
 - #69881 (VariantSizeDifferences: bail on SizeOverflow)
 - #70000 (resolve: Fix regression in resolution of raw keywords in paths)
 - #70029 (Bump the bootstrap compiler)
 - #70046 (Use sublice patterns to avoid computing the len)
 - #70049 (Fiddle `ParamEnv` through to a place that used to use `ParamEnv::empty` in a buggy manner)

Failed merges:

r? @ghost

src/bootstrap/builder.rs

@@ -725,7 +725,7 @@ impl<'a> Builder<'a> {
             self.clear_if_dirty(&my_out, &rustdoc);
         }
 
-        cargo.env("CARGO_TARGET_DIR", &out_dir).arg(cmd).arg("-Zconfig-profile");
+        cargo.env("CARGO_TARGET_DIR", &out_dir).arg(cmd);
 
         let profile_var = |name: &str| {
             let profile = if self.config.rust_optimize { "RELEASE" } else { "DEV" };
@@ -847,13 +847,7 @@ impl<'a> Builder<'a> {
             rustflags.arg("-Zforce-unstable-if-unmarked");
         }
 
-        // cfg(bootstrap): the flag was renamed from `-Zexternal-macro-backtrace`
-        // to `-Zmacro-backtrace`, keep only the latter after beta promotion.
-        if stage == 0 {
-            rustflags.arg("-Zexternal-macro-backtrace");
-        } else {
-            rustflags.arg("-Zmacro-backtrace");
-        }
+        rustflags.arg("-Zmacro-backtrace");
 
         let want_rustdoc = self.doc_tests != DocTests::No;
 

src/bootstrap/channel.rs

@@ -13,7 +13,7 @@ use build_helper::output;
 use crate::Build;
 
 // The version number
-pub const CFG_RELEASE_NUM: &str = "1.43.0";
+pub const CFG_RELEASE_NUM: &str = "1.44.0";
 
 pub struct GitInfo {
     inner: Option<Info>,

src/liballoc/boxed.rs

@@ -1105,29 +1105,6 @@ impl<T: ?Sized> AsMut<T> for Box<T> {
 #[stable(feature = "pin", since = "1.33.0")]
 impl<T: ?Sized> Unpin for Box<T> {}
 
-#[cfg(bootstrap)]
-#[unstable(feature = "generator_trait", issue = "43122")]
-impl<G: ?Sized + Generator + Unpin> Generator for Box<G> {
-    type Yield = G::Yield;
-    type Return = G::Return;
-
-    fn resume(mut self: Pin<&mut Self>) -> GeneratorState<Self::Yield, Self::Return> {
-        G::resume(Pin::new(&mut *self))
-    }
-}
-
-#[cfg(bootstrap)]
-#[unstable(feature = "generator_trait", issue = "43122")]
-impl<G: ?Sized + Generator> Generator for Pin<Box<G>> {
-    type Yield = G::Yield;
-    type Return = G::Return;
-
-    fn resume(mut self: Pin<&mut Self>) -> GeneratorState<Self::Yield, Self::Return> {
-        G::resume((*self).as_mut())
-    }
-}
-
-#[cfg(not(bootstrap))]
 #[unstable(feature = "generator_trait", issue = "43122")]
 impl<G: ?Sized + Generator<R> + Unpin, R> Generator<R> for Box<G> {
     type Yield = G::Yield;
@@ -1138,7 +1115,6 @@ impl<G: ?Sized + Generator<R> + Unpin, R> Generator<R> for Box<G> {
     }
 }
 
-#[cfg(not(bootstrap))]
 #[unstable(feature = "generator_trait", issue = "43122")]
 impl<G: ?Sized + Generator<R>, R> Generator<R> for Pin<Box<G>> {
     type Yield = G::Yield;

src/libcore/cell.rs

@@ -1569,7 +1569,7 @@ impl<T: ?Sized + fmt::Display> fmt::Display for RefMut<'_, T> {
 #[lang = "unsafe_cell"]
 #[stable(feature = "rust1", since = "1.0.0")]
 #[repr(transparent)]
-#[cfg_attr(not(bootstrap), repr(no_niche))] // rust-lang/rust#68303.
+#[repr(no_niche)] // rust-lang/rust#68303.
 pub struct UnsafeCell<T: ?Sized> {
     value: T,
 }

src/libcore/lib.rs

@@ -140,7 +140,7 @@
 #![feature(associated_type_bounds)]
 #![feature(const_type_id)]
 #![feature(const_caller_location)]
-#![cfg_attr(not(bootstrap), feature(no_niche))] // rust-lang/rust#68303
+#![feature(no_niche)] // rust-lang/rust#68303
 
 #[prelude_import]
 #[allow(unused)]

src/libcore/macros/mod.rs

@@ -1404,6 +1404,18 @@ pub(crate) mod builtin {
         /* compiler built-in */
     }
 
+    /// Keeps the item it's applied to if the passed path is accessible, and removes it otherwise.
+    #[cfg(not(bootstrap))]
+    #[unstable(
+        feature = "cfg_accessible",
+        issue = "64797",
+        reason = "`cfg_accessible` is not fully implemented"
+    )]
+    #[rustc_builtin_macro]
+    pub macro cfg_accessible($item:item) {
+        /* compiler built-in */
+    }
+
     /// Unstable implementation detail of the `rustc` compiler, do not use.
     #[rustc_builtin_macro]
     #[stable(feature = "rust1", since = "1.0.0")]

src/libcore/ops/generator.rs

@@ -67,7 +67,7 @@ pub enum GeneratorState<Y, R> {
 #[lang = "generator"]
 #[unstable(feature = "generator_trait", issue = "43122")]
 #[fundamental]
-pub trait Generator<#[cfg(not(bootstrap))] R = ()> {
+pub trait Generator<R = ()> {
     /// The type of value this generator yields.
     ///
     /// This associated type corresponds to the `yield` expression and the
@@ -110,35 +110,9 @@ pub trait Generator<#[cfg(not(bootstrap))] R = ()> {
     /// been returned previously. While generator literals in the language are
     /// guaranteed to panic on resuming after `Complete`, this is not guaranteed
     /// for all implementations of the `Generator` trait.
-    fn resume(
-        self: Pin<&mut Self>,
-        #[cfg(not(bootstrap))] arg: R,
-    ) -> GeneratorState<Self::Yield, Self::Return>;
+    fn resume(self: Pin<&mut Self>, arg: R) -> GeneratorState<Self::Yield, Self::Return>;
 }
 
-#[cfg(bootstrap)]
-#[unstable(feature = "generator_trait", issue = "43122")]
-impl<G: ?Sized + Generator> Generator for Pin<&mut G> {
-    type Yield = G::Yield;
-    type Return = G::Return;
-
-    fn resume(mut self: Pin<&mut Self>) -> GeneratorState<Self::Yield, Self::Return> {
-        G::resume((*self).as_mut())
-    }
-}
-
-#[cfg(bootstrap)]
-#[unstable(feature = "generator_trait", issue = "43122")]
-impl<G: ?Sized + Generator + Unpin> Generator for &mut G {
-    type Yield = G::Yield;
-    type Return = G::Return;
-
-    fn resume(mut self: Pin<&mut Self>) -> GeneratorState<Self::Yield, Self::Return> {
-        G::resume(Pin::new(&mut *self))
-    }
-}
-
-#[cfg(not(bootstrap))]
 #[unstable(feature = "generator_trait", issue = "43122")]
 impl<G: ?Sized + Generator<R>, R> Generator<R> for Pin<&mut G> {
     type Yield = G::Yield;
@@ -149,7 +123,6 @@ impl<G: ?Sized + Generator<R>, R> Generator<R> for Pin<&mut G> {
     }
 }
 
-#[cfg(not(bootstrap))]
 #[unstable(feature = "generator_trait", issue = "43122")]
 impl<G: ?Sized + Generator<R> + Unpin, R> Generator<R> for &mut G {
     type Yield = G::Yield;

src/libcore/prelude/v1.rs

@@ -67,3 +67,12 @@ pub use crate::{
 pub use crate::macros::builtin::{
     bench, global_allocator, test, test_case, RustcDecodable, RustcEncodable,
 };
+
+#[cfg(not(bootstrap))]
+#[unstable(
+    feature = "cfg_accessible",
+    issue = "64797",
+    reason = "`cfg_accessible` is not fully implemented"
+)]
+#[doc(no_inline)]
+pub use crate::macros::builtin::cfg_accessible;

src/librustc/ty/inhabitedness/mod.rs

@@ -90,30 +90,46 @@ impl<'tcx> TyCtxt<'tcx> {
     /// ```
     /// This code should only compile in modules where the uninhabitedness of Foo is
     /// visible.
-    pub fn is_ty_uninhabited_from(self, module: DefId, ty: Ty<'tcx>) -> bool {
+    pub fn is_ty_uninhabited_from(
+        self,
+        module: DefId,
+        ty: Ty<'tcx>,
+        param_env: ty::ParamEnv<'tcx>,
+    ) -> bool {
         // To check whether this type is uninhabited at all (not just from the
         // given node), you could check whether the forest is empty.
         // ```
         // forest.is_empty()
         // ```
-        ty.uninhabited_from(self).contains(self, module)
+        ty.uninhabited_from(self, param_env).contains(self, module)
     }
 
-    pub fn is_ty_uninhabited_from_any_module(self, ty: Ty<'tcx>) -> bool {
-        !ty.uninhabited_from(self).is_empty()
+    pub fn is_ty_uninhabited_from_any_module(
+        self,
+        ty: Ty<'tcx>,
+        param_env: ty::ParamEnv<'tcx>,
+    ) -> bool {
+        !ty.uninhabited_from(self, param_env).is_empty()
     }
 }
 
 impl<'tcx> AdtDef {
     /// Calculates the forest of `DefId`s from which this ADT is visibly uninhabited.
-    fn uninhabited_from(&self, tcx: TyCtxt<'tcx>, substs: SubstsRef<'tcx>) -> DefIdForest {
+    fn uninhabited_from(
+        &self,
+        tcx: TyCtxt<'tcx>,
+        substs: SubstsRef<'tcx>,
+        param_env: ty::ParamEnv<'tcx>,
+    ) -> DefIdForest {
         // Non-exhaustive ADTs from other crates are always considered inhabited.
         if self.is_variant_list_non_exhaustive() && !self.did.is_local() {
             DefIdForest::empty()
         } else {
             DefIdForest::intersection(
                 tcx,
-                self.variants.iter().map(|v| v.uninhabited_from(tcx, substs, self.adt_kind())),
+                self.variants
+                    .iter()
+                    .map(|v| v.uninhabited_from(tcx, substs, self.adt_kind(), param_env)),
             )
         }
     }
@@ -126,6 +142,7 @@ impl<'tcx> VariantDef {
         tcx: TyCtxt<'tcx>,
         substs: SubstsRef<'tcx>,
         adt_kind: AdtKind,
+        param_env: ty::ParamEnv<'tcx>,
     ) -> DefIdForest {
         let is_enum = match adt_kind {
             // For now, `union`s are never considered uninhabited.
@@ -140,7 +157,7 @@ impl<'tcx> VariantDef {
         } else {
             DefIdForest::union(
                 tcx,
-                self.fields.iter().map(|f| f.uninhabited_from(tcx, substs, is_enum)),
+                self.fields.iter().map(|f| f.uninhabited_from(tcx, substs, is_enum, param_env)),
             )
         }
     }
@@ -153,8 +170,9 @@ impl<'tcx> FieldDef {
         tcx: TyCtxt<'tcx>,
         substs: SubstsRef<'tcx>,
         is_enum: bool,
+        param_env: ty::ParamEnv<'tcx>,
     ) -> DefIdForest {
-        let data_uninhabitedness = move || self.ty(tcx, substs).uninhabited_from(tcx);
+        let data_uninhabitedness = move || self.ty(tcx, substs).uninhabited_from(tcx, param_env);
         // FIXME(canndrew): Currently enum fields are (incorrectly) stored with
         // `Visibility::Invisible` so we need to override `self.vis` if we're
         // dealing with an enum.
@@ -176,20 +194,21 @@ impl<'tcx> FieldDef {
 
 impl<'tcx> TyS<'tcx> {
     /// Calculates the forest of `DefId`s from which this type is visibly uninhabited.
-    fn uninhabited_from(&self, tcx: TyCtxt<'tcx>) -> DefIdForest {
+    fn uninhabited_from(&self, tcx: TyCtxt<'tcx>, param_env: ty::ParamEnv<'tcx>) -> DefIdForest {
         match self.kind {
-            Adt(def, substs) => def.uninhabited_from(tcx, substs),
+            Adt(def, substs) => def.uninhabited_from(tcx, substs, param_env),
 
             Never => DefIdForest::full(tcx),
 
-            Tuple(ref tys) => {
-                DefIdForest::union(tcx, tys.iter().map(|ty| ty.expect_ty().uninhabited_from(tcx)))
-            }
+            Tuple(ref tys) => DefIdForest::union(
+                tcx,
+                tys.iter().map(|ty| ty.expect_ty().uninhabited_from(tcx, param_env)),
+            ),
 
-            Array(ty, len) => match len.try_eval_usize(tcx, ty::ParamEnv::empty()) {
+            Array(ty, len) => match len.try_eval_usize(tcx, param_env) {
                 // If the array is definitely non-empty, it's uninhabited if
                 // the type of its elements is uninhabited.
-                Some(n) if n != 0 => ty.uninhabited_from(tcx),
+                Some(n) if n != 0 => ty.uninhabited_from(tcx, param_env),
                 _ => DefIdForest::empty(),
             },
 

src/librustc_builtin_macros/cfg_accessible.rs

@@ -0,0 +1,54 @@
+//! Implementation of the `#[cfg_accessible(path)]` attribute macro.
+
+use rustc_ast::ast;
+use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, MultiItemModifier};
+use rustc_feature::AttributeTemplate;
+use rustc_parse::validate_attr;
+use rustc_span::symbol::sym;
+use rustc_span::Span;
+
+crate struct Expander;
+
+fn validate_input<'a>(ecx: &mut ExtCtxt<'_>, mi: &'a ast::MetaItem) -> Option<&'a ast::Path> {
+    match mi.meta_item_list() {
+        None => {}
+        Some([]) => ecx.span_err(mi.span, "`cfg_accessible` path is not specified"),
+        Some([_, .., l]) => ecx.span_err(l.span(), "multiple `cfg_accessible` paths are specified"),
+        Some([nmi]) => match nmi.meta_item() {
+            None => ecx.span_err(nmi.span(), "`cfg_accessible` path cannot be a literal"),
+            Some(mi) => {
+                if !mi.is_word() {
+                    ecx.span_err(mi.span, "`cfg_accessible` path cannot accept arguments");
+                }
+                return Some(&mi.path);
+            }
+        },
+    }
+    None
+}
+
+impl MultiItemModifier for Expander {
+    fn expand(
+        &self,
+        ecx: &mut ExtCtxt<'_>,
+        _span: Span,
+        meta_item: &ast::MetaItem,
+        item: Annotatable,
+    ) -> ExpandResult<Vec<Annotatable>, Annotatable> {
+        let template = AttributeTemplate { list: Some("path"), ..Default::default() };
+        let attr = &ecx.attribute(meta_item.clone());
+        validate_attr::check_builtin_attribute(ecx.parse_sess, attr, sym::cfg_accessible, template);
+
+        let path = match validate_input(ecx, meta_item) {
+            Some(path) => path,
+            None => return ExpandResult::Ready(Vec::new()),
+        };
+
+        let failure_msg = "cannot determine whether the path is accessible or not";
+        match ecx.resolver.cfg_accessible(ecx.current_expansion.id, path) {
+            Ok(true) => ExpandResult::Ready(vec![item]),
+            Ok(false) => ExpandResult::Ready(Vec::new()),
+            Err(_) => ExpandResult::Retry(item, failure_msg.into()),
+        }
+    }
+}

src/librustc_builtin_macros/deriving/mod.rs

@@ -2,7 +2,7 @@
 
 use rustc_ast::ast::{self, ItemKind, MetaItem};
 use rustc_ast::ptr::P;
-use rustc_expand::base::{Annotatable, ExtCtxt, MultiItemModifier};
+use rustc_expand::base::{Annotatable, ExpandResult, ExtCtxt, MultiItemModifier};
 use rustc_span::symbol::{sym, Symbol};
 use rustc_span::Span;
 
@@ -48,13 +48,13 @@ impl MultiItemModifier for BuiltinDerive {
         span: Span,
         meta_item: &MetaItem,
         item: Annotatable,
-    ) -> Vec<Annotatable> {
+    ) -> ExpandResult<Vec<Annotatable>, Annotatable> {
         // FIXME: Built-in derives often forget to give spans contexts,
         // so we are doing it here in a centralized way.
         let span = ecx.with_def_site_ctxt(span);
         let mut items = Vec::new();
         (self.0)(ecx, span, meta_item, &item, &mut |a| items.push(a));
-        items
+        ExpandResult::Ready(items)
     }
 }
 

src/librustc_builtin_macros/lib.rs

@@ -22,6 +22,7 @@ use rustc_span::symbol::sym;
 mod asm;
 mod assert;
 mod cfg;
+mod cfg_accessible;
 mod compile_error;
 mod concat;
 mod concat_idents;
@@ -85,6 +86,7 @@ pub fn register_builtin_macros(resolver: &mut dyn Resolver, edition: Edition) {
 
     register_attr! {
         bench: test::expand_bench,
+        cfg_accessible: cfg_accessible::Expander,
         global_allocator: global_allocator::expand,
         test: test::expand_test,
         test_case: test::expand_test_case,

src/librustc_builtin_macros/util.rs

@@ -6,7 +6,7 @@ use rustc_span::Symbol;
 
 pub fn check_builtin_macro_attribute(ecx: &ExtCtxt<'_>, meta_item: &MetaItem, name: Symbol) {
     // All the built-in macro attributes are "words" at the moment.
-    let template = AttributeTemplate::only_word();
+    let template = AttributeTemplate { word: true, ..Default::default() };
     let attr = ecx.attribute(meta_item.clone());
     validate_attr::check_builtin_attribute(ecx.parse_sess, &attr, name, template);
 }