Auto merge of #65804 - Centril:rollup-arlxgch, r=Centril

Rollup of 9 pull requests

Successful merges:

 - #64639 (Stabilize `#[non_exhaustive]` (RFC 2008))
 - #65074 (Fix the start/end byte positions in the compiler JSON output)
 - #65315 (Intern place projection)
 - #65685 (Fix check of `statx` and handle EPERM)
 - #65731 (Prevent unnecessary allocation in PathBuf::set_extension.)
 - #65740 (Fix default "disable-shortcuts" feature value)
 - #65787 (move panictry! to where it is used.)
 - #65789 (move Attribute::with_desugared_doc to librustdoc)
 - #65790 (move report_invalid_macro_expansion_item to item.rs)

Failed merges:

r? @ghost

src/libcore/lib.rs

@@ -121,7 +121,7 @@
 #![feature(hexagon_target_feature)]
 #![feature(const_int_conversion)]
 #![feature(const_transmute)]
-#![feature(non_exhaustive)]
+#![cfg_attr(bootstrap, feature(non_exhaustive))]
 #![feature(structural_match)]
 #![feature(abi_unadjusted)]
 #![feature(adx_target_feature)]

src/libproc_macro/lib.rs

@@ -25,7 +25,7 @@
 #![feature(extern_types)]
 #![feature(in_band_lifetimes)]
 #![feature(optin_builtin_traits)]
-#![feature(non_exhaustive)]
+#![cfg_attr(bootstrap, feature(non_exhaustive))]
 #![feature(rustc_attrs)]
 #![feature(specialization)]
 

src/librustc/error_codes.rs

@@ -2105,8 +2105,6 @@ on something other than a struct or enum.
 Examples of erroneous code:
 
 ```compile_fail,E0701
-# #![feature(non_exhaustive)]
-
 #[non_exhaustive]
 trait Foo { }
 ```

src/librustc/ich/impls_syntax.rs

@@ -425,6 +425,7 @@ impl<'a> HashStable<StableHashingContext<'a>> for SourceFile {
             ref lines,
             ref multibyte_chars,
             ref non_narrow_chars,
+            ref normalized_pos,
         } = *self;
 
         (name_hash as u64).hash_stable(hcx, hasher);
@@ -453,6 +454,12 @@ impl<'a> HashStable<StableHashingContext<'a>> for SourceFile {
         for &char_pos in non_narrow_chars.iter() {
             stable_non_narrow_char(char_pos, start_pos).hash_stable(hcx, hasher);
         }
+
+        normalized_pos.len().hash_stable(hcx, hasher);
+        for &char_pos in normalized_pos.iter() {
+            stable_normalized_pos(char_pos, start_pos).hash_stable(hcx, hasher);
+        }
+
     }
 }
 
@@ -482,6 +489,18 @@ fn stable_non_narrow_char(swc: ::syntax_pos::NonNarrowChar,
     (pos.0 - source_file_start.0, width as u32)
 }
 
+fn stable_normalized_pos(np: ::syntax_pos::NormalizedPos,
+                         source_file_start: ::syntax_pos::BytePos)
+                         -> (u32, u32) {
+    let ::syntax_pos::NormalizedPos {
+        pos,
+        diff
+    } = np;
+
+    (pos.0 - source_file_start.0, diff)
+}
+
+
 impl<'tcx> HashStable<StableHashingContext<'tcx>> for feature_gate::Features {
     fn hash_stable(&self, hcx: &mut StableHashingContext<'tcx>, hasher: &mut StableHasher) {
         // Unfortunately we cannot exhaustively list fields here, since the

src/librustc/lib.rs

@@ -41,7 +41,7 @@
 #![feature(overlapping_marker_traits)]
 #![feature(extern_types)]
 #![feature(nll)]
-#![feature(non_exhaustive)]
+#![cfg_attr(bootstrap, feature(non_exhaustive))]
 #![feature(optin_builtin_traits)]
 #![feature(option_expect_none)]
 #![feature(range_is_empty)]

src/librustc/mir/mod.rs

@@ -15,8 +15,7 @@ use crate::ty::layout::VariantIdx;
 use crate::ty::print::{FmtPrinter, Printer};
 use crate::ty::subst::{Subst, SubstsRef};
 use crate::ty::{
-    self, AdtDef, CanonicalUserTypeAnnotations, Region, Ty, TyCtxt,
-    UserTypeAnnotationIndex,
+    self, AdtDef, CanonicalUserTypeAnnotations, List, Region, Ty, TyCtxt, UserTypeAnnotationIndex,
 };
 
 use polonius_engine::Atom;
@@ -1712,15 +1711,17 @@ impl Debug for Statement<'_> {
 /// A path to a value; something that can be evaluated without
 /// changing or disturbing program state.
 #[derive(
-    Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, HashStable,
+    Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, HashStable,
 )]
 pub struct Place<'tcx> {
     pub base: PlaceBase<'tcx>,
 
     /// projection out of a place (access a field, deref a pointer, etc)
-    pub projection: Box<[PlaceElem<'tcx>]>,
+    pub projection: &'tcx List<PlaceElem<'tcx>>,
 }
 
+impl<'tcx> rustc_serialize::UseSpecializedDecodable for Place<'tcx> {}
+
 #[derive(
     Clone, PartialEq, Eq, PartialOrd, Ord, Hash, RustcEncodable, RustcDecodable, HashStable,
 )]
@@ -1824,6 +1825,8 @@ impl<V, T> ProjectionElem<V, T> {
 /// and the index is a local.
 pub type PlaceElem<'tcx> = ProjectionElem<Local, Ty<'tcx>>;
 
+impl<'tcx> Copy for PlaceElem<'tcx> { }
+
 // At least on 64 bit systems, `PlaceElem` should not be larger than two pointers.
 #[cfg(target_arch = "x86_64")]
 static_assert_size!(PlaceElem<'_>, 16);
@@ -1846,50 +1849,11 @@ pub struct PlaceRef<'a, 'tcx> {
 }
 
 impl<'tcx> Place<'tcx> {
-    // FIXME change this back to a const when projection is a shared slice.
-    //
-    // pub const RETURN_PLACE: Place<'tcx> = Place {
-    //     base: PlaceBase::Local(RETURN_PLACE),
-    //     projection: &[],
-    // };
+    // FIXME change this to a const fn by also making List::empty a const fn.
     pub fn return_place() -> Place<'tcx> {
         Place {
             base: PlaceBase::Local(RETURN_PLACE),
-            projection: Box::new([]),
-        }
-    }
-
-    pub fn field(self, f: Field, ty: Ty<'tcx>) -> Place<'tcx> {
-        self.elem(ProjectionElem::Field(f, ty))
-    }
-
-    pub fn deref(self) -> Place<'tcx> {
-        self.elem(ProjectionElem::Deref)
-    }
-
-    pub fn downcast(self, adt_def: &'tcx AdtDef, variant_index: VariantIdx) -> Place<'tcx> {
-        self.elem(ProjectionElem::Downcast(
-            Some(adt_def.variants[variant_index].ident.name),
-            variant_index,
-        ))
-    }
-
-    pub fn downcast_unnamed(self, variant_index: VariantIdx) -> Place<'tcx> {
-        self.elem(ProjectionElem::Downcast(None, variant_index))
-    }
-
-    pub fn index(self, index: Local) -> Place<'tcx> {
-        self.elem(ProjectionElem::Index(index))
-    }
-
-    pub fn elem(self, elem: PlaceElem<'tcx>) -> Place<'tcx> {
-        // FIXME(spastorino): revisit this again once projection is not a Box<[T]> anymore
-        let mut projection = self.projection.into_vec();
-        projection.push(elem);
-
-        Place {
-            base: self.base,
-            projection: projection.into_boxed_slice(),
+            projection: List::empty(),
         }
     }
 
@@ -1906,26 +1870,23 @@ impl<'tcx> Place<'tcx> {
     //
     // FIXME: can we safely swap the semantics of `fn base_local` below in here instead?
     pub fn local_or_deref_local(&self) -> Option<Local> {
-        match self {
-            Place {
-                base: PlaceBase::Local(local),
-                projection: box [],
+        match self.as_ref() {
+            PlaceRef {
+                base: &PlaceBase::Local(local),
+                projection: &[],
             } |
-            Place {
-                base: PlaceBase::Local(local),
-                projection: box [ProjectionElem::Deref],
-            } => Some(*local),
+            PlaceRef {
+                base: &PlaceBase::Local(local),
+                projection: &[ProjectionElem::Deref],
+            } => Some(local),
             _ => None,
         }
     }
 
     /// If this place represents a local variable like `_X` with no
     /// projections, return `Some(_X)`.
     pub fn as_local(&self) -> Option<Local> {
-        match self {
-            Place { projection: box [], base: PlaceBase::Local(l) } => Some(*l),
-            _ => None,
-        }
+        self.as_ref().as_local()
     }
 
     pub fn as_ref(&self) -> PlaceRef<'_, 'tcx> {
@@ -1940,7 +1901,7 @@ impl From<Local> for Place<'_> {
     fn from(local: Local) -> Self {
         Place {
             base: local.into(),
-            projection: Box::new([]),
+            projection: List::empty(),
         }
     }
 }
@@ -1969,6 +1930,15 @@ impl<'a, 'tcx> PlaceRef<'a, 'tcx> {
             _ => None,
         }
     }
+
+    /// If this place represents a local variable like `_X` with no
+    /// projections, return `Some(_X)`.
+    pub fn as_local(&self) -> Option<Local> {
+        match self {
+            PlaceRef { base: PlaceBase::Local(l), projection: [] } => Some(*l),
+            _ => None,
+        }
+    }
 }
 
 impl Debug for Place<'_> {
@@ -3182,6 +3152,17 @@ impl<'tcx> TypeFoldable<'tcx> for PlaceBase<'tcx> {
     }
 }
 
+impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::List<PlaceElem<'tcx>> {
+    fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
+        let v = self.iter().map(|t| t.fold_with(folder)).collect::<Vec<_>>();
+        folder.tcx().intern_place_elems(&v)
+    }
+
+    fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
+        self.iter().any(|t| t.visit_with(visitor))
+    }
+}
+
 impl<'tcx> TypeFoldable<'tcx> for Static<'tcx> {
     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
         Static {

src/librustc/mir/visit.rs

@@ -784,6 +784,8 @@ macro_rules! make_mir_visitor {
 
 macro_rules! visit_place_fns {
     (mut) => (
+        fn tcx<'a>(&'a self) -> TyCtxt<'tcx>;
+
         fn super_place(
             &mut self,
             place: &mut Place<'tcx>,
@@ -793,19 +795,21 @@ macro_rules! visit_place_fns {
             self.visit_place_base(&mut place.base, context, location);
 
             if let Some(new_projection) = self.process_projection(&place.projection) {
-                place.projection = new_projection;
+                place.projection = self.tcx().intern_place_elems(&new_projection);
             }
         }
 
         fn process_projection(
             &mut self,
             projection: &'a [PlaceElem<'tcx>],
-        ) -> Option<Box<[PlaceElem<'tcx>]>> {
+        ) -> Option<Vec<PlaceElem<'tcx>>> {
             let mut projection = Cow::Borrowed(projection);
 
             for i in 0..projection.len() {
                 if let Some(elem) = projection.get(i) {
                     if let Some(elem) = self.process_projection_elem(elem) {
+                        // This converts the borrowed projection into `Cow::Owned(_)` and returns a
+                        // clone of the projection so we can mutate and reintern later.
                         let vec = projection.to_mut();
                         vec[i] = elem;
                     }
@@ -814,7 +818,7 @@ macro_rules! visit_place_fns {
 
             match projection {
                 Cow::Borrowed(_) => None,
-                Cow::Owned(vec) => Some(vec.into_boxed_slice()),
+                Cow::Owned(vec) => Some(vec),
             }
         }