Auto merge of #66208 - JohnTitor:rollup-2umgjer, r=JohnTitor

Rollup of 8 pull requests

Successful merges:

 - #65554 (Enhance the documentation of BufReader for potential data loss)
 - #65580 (Add `MaybeUninit` methods `uninit_array`, `slice_get_ref`, `slice_get_mut`)
 - #66049 (consistent handling of missing sysroot spans)
 - #66056 (rustc_metadata: Some reorganization of the module structure)
 - #66123 (No more hidden elements)
 - #66157 (Improve math log documentation examples)
 - #66165 (Ignore these tests ,since the called commands doesn't exist in VxWorks)
 - #66190 (rustc_target: inline abi::FloatTy into abi::Primitive.)

Failed merges:

 - #66188 (`MethodSig` -> `FnSig` & Use it in `ItemKind::Fn`)

r? @ghost

Author: bors

Diff for: src/etc/generate-deriving-span-tests.py

@@ -14,8 +14,7 @@
     os.path.join(os.path.dirname(__file__), '../test/ui/derives/'))
 
 TEMPLATE = """\
-// ignore-x86
-// ^ due to stderr output differences
+// ignore-x86 FIXME: missing sysroot spans (#53081)
 // This file was auto-generated using 'src/etc/generate-deriving-span-tests.py'
 
 {error_deriving}

Diff for: src/libcore/mem/maybe_uninit.rs

@@ -260,6 +260,43 @@ impl<T> MaybeUninit<T> {
         MaybeUninit { uninit: () }
     }
 
+    /// Create a new array of `MaybeUninit<T>` items, in an uninitialized state.
+    ///
+    /// Note: in a future Rust version this method may become unnecessary
+    /// when array literal syntax allows
+    /// [repeating const expressions](https://github.com/rust-lang/rust/issues/49147).
+    /// The example below could then use `let mut buf = [MaybeUninit::<u8>::uninit(); 32];`.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// #![feature(maybe_uninit_uninit_array, maybe_uninit_extra, maybe_uninit_slice_assume_init)]
+    ///
+    /// use std::mem::MaybeUninit;
+    ///
+    /// extern "C" {
+    ///     fn read_into_buffer(ptr: *mut u8, max_len: usize) -> usize;
+    /// }
+    ///
+    /// /// Returns a (possibly smaller) slice of data that was actually read
+    /// fn read(buf: &mut [MaybeUninit<u8>]) -> &[u8] {
+    ///     unsafe {
+    ///         let len = read_into_buffer(buf.as_mut_ptr() as *mut u8, buf.len());
+    ///         MaybeUninit::slice_get_ref(&buf[..len])
+    ///     }
+    /// }
+    ///
+    /// let mut buf: [MaybeUninit<u8>; 32] = MaybeUninit::uninit_array();
+    /// let data = read(&mut buf);
+    /// ```
+    #[unstable(feature = "maybe_uninit_uninit_array", issue = "0")]
+    #[inline(always)]
+    pub fn uninit_array<const LEN: usize>() -> [Self; LEN] {
+        unsafe {
+            MaybeUninit::<[MaybeUninit<T>; LEN]>::uninit().assume_init()
+        }
+    }
+
     /// A promotable constant, equivalent to `uninit()`.
     #[unstable(feature = "internal_uninit_const", issue = "0",
         reason = "hack to work around promotability")]
@@ -692,6 +729,32 @@ impl<T> MaybeUninit<T> {
         &mut *self.value
     }
 
+    /// Assuming all the elements are initialized, get a slice to them.
+    ///
+    /// # Safety
+    ///
+    /// It is up to the caller to guarantee that the `MaybeUninit<T>` elements
+    /// really are in an initialized state.
+    /// Calling this when the content is not yet fully initialized causes undefined behavior.
+    #[unstable(feature = "maybe_uninit_slice_assume_init", issue = "0")]
+    #[inline(always)]
+    pub unsafe fn slice_get_ref(slice: &[Self]) -> &[T] {
+        &*(slice as *const [Self] as *const [T])
+    }
+
+    /// Assuming all the elements are initialized, get a mutable slice to them.
+    ///
+    /// # Safety
+    ///
+    /// It is up to the caller to guarantee that the `MaybeUninit<T>` elements
+    /// really are in an initialized state.
+    /// Calling this when the content is not yet fully initialized causes undefined behavior.
+    #[unstable(feature = "maybe_uninit_slice_assume_init", issue = "0")]
+    #[inline(always)]
+    pub unsafe fn slice_get_mut(slice: &mut [Self]) -> &mut [T] {
+        &mut *(slice as *mut [Self] as *mut [T])
+    }
+
     /// Gets a pointer to the first element of the array.
     #[unstable(feature = "maybe_uninit_slice", issue = "63569")]
     #[inline(always)]

Diff for: src/librustc/ich/impls_syntax.rs

@@ -162,7 +162,6 @@ impl_stable_hash_for_spanned!(::syntax::ast::LitKind);
 impl_stable_hash_for!(enum ::syntax::ast::IntTy { Isize, I8, I16, I32, I64, I128 });
 impl_stable_hash_for!(enum ::syntax::ast::UintTy { Usize, U8, U16, U32, U64, U128 });
 impl_stable_hash_for!(enum ::syntax::ast::FloatTy { F32, F64 });
-impl_stable_hash_for!(enum ::rustc_target::abi::FloatTy { F32, F64 });
 impl_stable_hash_for!(enum ::syntax::ast::Unsafety { Unsafe, Normal });
 impl_stable_hash_for!(enum ::syntax::ast::Constness { Const, NotConst });
 impl_stable_hash_for!(enum ::syntax::ast::Defaultness { Default, Final });

Diff for: src/librustc/ty/layout.rs

@@ -132,8 +132,8 @@ impl PrimitiveExt for Primitive {
     fn to_ty<'tcx>(&self, tcx: TyCtxt<'tcx>) -> Ty<'tcx> {
         match *self {
             Int(i, signed) => i.to_ty(tcx, signed),
-            Float(FloatTy::F32) => tcx.types.f32,
-            Float(FloatTy::F64) => tcx.types.f64,
+            F32 => tcx.types.f32,
+            F64 => tcx.types.f64,
             Pointer => tcx.mk_mut_ptr(tcx.mk_unit()),
         }
     }
@@ -144,7 +144,7 @@ impl PrimitiveExt for Primitive {
         match *self {
             Int(i, signed) => i.to_ty(tcx, signed),
             Pointer => tcx.types.usize,
-            Float(..) => bug!("floats do not have an int type"),
+            F32 | F64 => bug!("floats do not have an int type"),
         }
     }
 }
@@ -538,10 +538,10 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
             ty::Uint(ity) => {
                 scalar(Int(Integer::from_attr(dl, attr::UnsignedInt(ity)), false))
             }
-            ty::Float(fty) => scalar(Float(match fty {
-                ast::FloatTy::F32 => FloatTy::F32,
-                ast::FloatTy::F64 => FloatTy::F64,
-            })),
+            ty::Float(fty) => scalar(match fty {
+                ast::FloatTy::F32 => F32,
+                ast::FloatTy::F64 => F64,
+            }),
             ty::FnPtr(_) => {
                 let mut ptr = scalar_unit(Pointer);
                 ptr.valid_range = 1..=*ptr.valid_range.end();
@@ -2457,7 +2457,8 @@ impl_stable_hash_for!(enum crate::ty::layout::Integer {
 
 impl_stable_hash_for!(enum crate::ty::layout::Primitive {
     Int(integer, signed),
-    Float(fty),
+    F32,
+    F64,
     Pointer
 });
 

Diff for: src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -1904,8 +1904,8 @@ fn prepare_enum_metadata(
 
             let discr_type = match discr.value {
                 layout::Int(t, _) => t,
-                layout::Float(layout::FloatTy::F32) => Integer::I32,
-                layout::Float(layout::FloatTy::F64) => Integer::I64,
+                layout::F32 => Integer::I32,
+                layout::F64 => Integer::I64,
                 layout::Pointer => cx.data_layout().ptr_sized_integer(),
             }.to_ty(cx.tcx, false);
 

Diff for: src/librustc_codegen_llvm/intrinsic.rs

@@ -18,7 +18,7 @@ use rustc::ty::layout::{self, LayoutOf, HasTyCtxt, Primitive};
 use rustc::mir::interpret::GlobalId;
 use rustc_codegen_ssa::common::{IntPredicate, TypeKind};
 use rustc::hir;
-use rustc_target::abi::{FloatTy, HasDataLayout};
+use rustc_target::abi::HasDataLayout;
 use syntax::ast;
 
 use rustc_codegen_ssa::common::span_invalid_monomorphization_error;
@@ -163,12 +163,12 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
                                     emit_va_arg(self, args[0], ret_ty)
                                 }
                             }
-                            Primitive::Float(FloatTy::F64) |
+                            Primitive::F64 |
                             Primitive::Pointer => {
                                 emit_va_arg(self, args[0], ret_ty)
                             }
                             // `va_arg` should never be used with the return type f32.
-                            Primitive::Float(FloatTy::F32) => {
+                            Primitive::F32 => {
                                 bug!("the va_arg intrinsic does not work with `f32`")
                             }
                         }

Diff for: src/librustc_codegen_llvm/type_of.rs

@@ -3,7 +3,7 @@ use crate::common::*;
 use crate::type_::Type;
 use rustc::ty::{self, Ty, TypeFoldable};
 use rustc::ty::layout::{self, Align, LayoutOf, FnAbiExt, PointeeInfo, Size, TyLayout};
-use rustc_target::abi::{FloatTy, TyLayoutMethods};
+use rustc_target::abi::TyLayoutMethods;
 use rustc::ty::print::obsolete::DefPathBasedNames;
 use rustc_codegen_ssa::traits::*;
 
@@ -300,8 +300,8 @@ impl<'tcx> LayoutLlvmExt<'tcx> for TyLayout<'tcx> {
                                scalar: &layout::Scalar, offset: Size) -> &'a Type {
         match scalar.value {
             layout::Int(i, _) => cx.type_from_integer( i),
-            layout::Float(FloatTy::F32) => cx.type_f32(),
-            layout::Float(FloatTy::F64) => cx.type_f64(),
+            layout::F32 => cx.type_f32(),
+            layout::F64 => cx.type_f64(),
             layout::Pointer => {
                 // If we know the alignment, pick something better than i8.
                 let pointee = if let Some(pointee) = self.pointee_info_at(cx, offset) {

Diff for: src/librustc_metadata/creader.rs

@@ -2,7 +2,7 @@
 
 use crate::cstore::{self, CStore, MetadataBlob};
 use crate::locator::{self, CratePaths};
-use crate::schema::{CrateRoot, CrateDep};
+use crate::rmeta::{CrateRoot, CrateDep};
 use rustc_data_structures::sync::{Lock, Once, AtomicCell};
 
 use rustc::hir::def_id::CrateNum;

Diff for: src/librustc_metadata/cstore.rs

@@ -1,7 +1,7 @@
 // The crate store - a central repo for information collected about external
 // crates and libraries
 
-use crate::schema;
+use crate::rmeta;
 use rustc::dep_graph::DepNodeIndex;
 use rustc::hir::def_id::{CrateNum, DefIndex};
 use rustc::hir::map::definitions::DefPathTable;
@@ -17,7 +17,7 @@ use syntax_expand::base::SyntaxExtension;
 use syntax_pos;
 use proc_macro::bridge::client::ProcMacro;
 
-pub use crate::cstore_impl::{provide, provide_extern};
+pub use crate::rmeta::{provide, provide_extern};
 
 // A map from external crate numbers (as decoded from some crate file) to
 // local crate numbers (as generated during this session). Each external
@@ -49,7 +49,7 @@ crate struct CrateMetadata {
     /// lifetime is only used behind `Lazy`, and therefore acts like an
     /// universal (`for<'tcx>`), that is paired up with whichever `TyCtxt`
     /// is being used to decode those values.
-    crate root: schema::CrateRoot<'static>,
+    crate root: rmeta::CrateRoot<'static>,
     /// For each definition in this crate, we encode a key. When the
     /// crate is loaded, we read all the keys and put them in this
     /// hashmap, which gives the reverse mapping. This allows us to
@@ -59,7 +59,7 @@ crate struct CrateMetadata {
     /// Trait impl data.
     /// FIXME: Used only from queries and can use query cache,
     /// so pre-decoding can probably be avoided.
-    crate trait_impls: FxHashMap<(u32, DefIndex), schema::Lazy<[DefIndex]>>,
+    crate trait_impls: FxHashMap<(u32, DefIndex), rmeta::Lazy<[DefIndex]>>,
     /// Proc macro descriptions for this crate, if it's a proc macro crate.
     crate raw_proc_macros: Option<&'static [ProcMacro]>,
     /// Source maps for code from the crate.

Diff for: src/librustc_metadata/lib.rs

@@ -26,15 +26,11 @@ extern crate rustc_data_structures;
 
 pub mod error_codes;
 
-mod encoder;
-mod decoder;
 mod dependency_format;
-mod cstore_impl;
 mod foreign_modules;
 mod link_args;
 mod native_libs;
-mod schema;
-mod table;
+mod rmeta;
 
 pub mod creader;
 pub mod cstore;

Diff for: src/librustc_metadata/locator.rs

@@ -214,7 +214,7 @@
 
 use crate::cstore::MetadataBlob;
 use crate::creader::Library;
-use crate::schema::{METADATA_HEADER, rustc_version};
+use crate::rmeta::{METADATA_HEADER, rustc_version};
 
 use rustc_data_structures::fx::FxHashSet;
 use rustc_data_structures::svh::Svh;