Rollup of 7 pull requests

src/libcore/alloc/mod.rs

@@ -33,9 +33,7 @@ impl fmt::Display for AllocErr {
 #[derive(Debug, Copy, Clone, PartialEq, Eq)]
 #[unstable(feature = "allocator_api", issue = "32838")]
 pub enum AllocInit {
-    /// The contents of the new memory are undefined.
-    ///
-    /// Reading uninitialized memory is Undefined Behavior; it must be initialized before use.
+    /// The contents of the new memory are uninitialized.
     Uninitialized,
     /// The new memory is guaranteed to be zeroed.
     Zeroed,
@@ -196,7 +194,11 @@ pub unsafe trait AllocRef {
     ///
     /// # Safety
     ///
-    /// `memory` must be a memory block returned by this allocator.
+    /// * `ptr` must be [*currently allocated*] via this allocator, and
+    /// * `layout` must [*fit*] the `ptr`.
+    ///
+    /// [*currently allocated*]: #currently-allocated-memory
+    /// [*fit*]: #memory-fitting
     unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout);
 
     /// Attempts to extend the memory block.
@@ -237,7 +239,7 @@ pub unsafe trait AllocRef {
     // * `new_size must be strictly greater than `memory.size` or both are zero
     /// * `new_size` must be greater than or equal to `layout.size()`
     /// * `new_size`, when rounded up to the nearest multiple of `layout.align()`, must not overflow
-    ///   (i.e., the rounded value must be less than `usize::MAX`).
+    ///   (i.e., the rounded value must be less than or equal to `usize::MAX`).
     ///
     /// [*currently allocated*]: #currently-allocated-memory
     /// [*fit*]: #memory-fitting

src/libcore/convert/num.rs

@@ -13,9 +13,9 @@ mod private {
 /// Typically doesn’t need to be used directly.
 #[unstable(feature = "convert_float_to_int", issue = "67057")]
 pub trait FloatToInt<Int>: private::Sealed + Sized {
-    #[unstable(feature = "float_approx_unchecked_to", issue = "67058")]
+    #[unstable(feature = "convert_float_to_int", issue = "67057")]
     #[doc(hidden)]
-    unsafe fn approx_unchecked(self) -> Int;
+    unsafe fn to_int_unchecked(self) -> Int;
 }
 
 macro_rules! impl_float_to_int {
@@ -27,8 +27,15 @@ macro_rules! impl_float_to_int {
             impl FloatToInt<$Int> for $Float {
                 #[doc(hidden)]
                 #[inline]
-                unsafe fn approx_unchecked(self) -> $Int {
-                    crate::intrinsics::float_to_int_approx_unchecked(self)
+                unsafe fn to_int_unchecked(self) -> $Int {
+                    #[cfg(bootstrap)]
+                    {
+                        crate::intrinsics::float_to_int_approx_unchecked(self)
+                    }
+                    #[cfg(not(bootstrap))]
+                    {
+                        crate::intrinsics::float_to_int_unchecked(self)
+                    }
                 }
             }
         )+

src/libcore/intrinsics.rs

@@ -1582,8 +1582,16 @@ extern "rust-intrinsic" {
     /// Convert with LLVM’s fptoui/fptosi, which may return undef for values out of range
     /// (<https://github.com/rust-lang/rust/issues/10184>)
     /// This is under stabilization at <https://github.com/rust-lang/rust/issues/67058>
+    #[cfg(bootstrap)]
     pub fn float_to_int_approx_unchecked<Float: Copy, Int: Copy>(value: Float) -> Int;
 
+    /// Convert with LLVM’s fptoui/fptosi, which may return undef for values out of range
+    /// (<https://github.com/rust-lang/rust/issues/10184>)
+    ///
+    /// Stabilized as `f32::to_int_unchecked` and `f64::to_int_unchecked`.
+    #[cfg(not(bootstrap))]
+    pub fn float_to_int_unchecked<Float: Copy, Int: Copy>(value: Float) -> Int;
+
     /// Returns the number of bits set in an integer type `T`
     ///
     /// The stabilized versions of this intrinsic are available on the integer

src/libcore/macros/mod.rs

@@ -1070,8 +1070,10 @@ pub(crate) mod builtin {
 
     /// Includes a utf8-encoded file as a string.
     ///
-    /// The file is located relative to the current file. (similarly to how
-    /// modules are found)
+    /// The file is located relative to the current file (similarly to how
+    /// modules are found). The provided path is interpreted in a platform-specific
+    /// way at compile time. So, for instance, an invocation with a Windows path
+    /// containing backslashes `\` would not compile correctly on Unix.
     ///
     /// This macro will yield an expression of type `&'static str` which is the
     /// contents of the file.
@@ -1108,8 +1110,10 @@ pub(crate) mod builtin {
 
     /// Includes a file as a reference to a byte array.
     ///
-    /// The file is located relative to the current file. (similarly to how
-    /// modules are found)
+    /// The file is located relative to the current file (similarly to how
+    /// modules are found). The provided path is interpreted in a platform-specific
+    /// way at compile time. So, for instance, an invocation with a Windows path
+    /// containing backslashes `\` would not compile correctly on Unix.
     ///
     /// This macro will yield an expression of type `&'static [u8; N]` which is
     /// the contents of the file.
@@ -1202,7 +1206,9 @@ pub(crate) mod builtin {
     /// Parses a file as an expression or an item according to the context.
     ///
     /// The file is located relative to the current file (similarly to how
-    /// modules are found).
+    /// modules are found). The provided path is interpreted in a platform-specific
+    /// way at compile time. So, for instance, an invocation with a Windows path
+    /// containing backslashes `\` would not compile correctly on Unix.
     ///
     /// Using this macro is often a bad idea, because if the file is
     /// parsed as an expression, it is going to be placed in the

src/libcore/num/f32.rs

@@ -464,14 +464,12 @@ impl f32 {
     /// assuming that the value is finite and fits in that type.
     ///
     /// ```
-    /// #![feature(float_approx_unchecked_to)]
-    ///
     /// let value = 4.6_f32;
-    /// let rounded = unsafe { value.approx_unchecked_to::<u16>() };
+    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
     /// assert_eq!(rounded, 4);
     ///
     /// let value = -128.9_f32;
-    /// let rounded = unsafe { value.approx_unchecked_to::<i8>() };
+    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
     /// assert_eq!(rounded, std::i8::MIN);
     /// ```
     ///
@@ -482,13 +480,13 @@ impl f32 {
     /// * Not be `NaN`
     /// * Not be infinite
     /// * Be representable in the return type `Int`, after truncating off its fractional part
-    #[unstable(feature = "float_approx_unchecked_to", issue = "67058")]
+    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
     #[inline]
-    pub unsafe fn approx_unchecked_to<Int>(self) -> Int
+    pub unsafe fn to_int_unchecked<Int>(self) -> Int
     where
         Self: FloatToInt<Int>,
     {
-        FloatToInt::<Int>::approx_unchecked(self)
+        FloatToInt::<Int>::to_int_unchecked(self)
     }
 
     /// Raw transmutation to `u32`.

src/libcore/num/f64.rs

@@ -478,14 +478,12 @@ impl f64 {
     /// assuming that the value is finite and fits in that type.
     ///
     /// ```
-    /// #![feature(float_approx_unchecked_to)]
-    ///
     /// let value = 4.6_f32;
-    /// let rounded = unsafe { value.approx_unchecked_to::<u16>() };
+    /// let rounded = unsafe { value.to_int_unchecked::<u16>() };
     /// assert_eq!(rounded, 4);
     ///
     /// let value = -128.9_f32;
-    /// let rounded = unsafe { value.approx_unchecked_to::<i8>() };
+    /// let rounded = unsafe { value.to_int_unchecked::<i8>() };
     /// assert_eq!(rounded, std::i8::MIN);
     /// ```
     ///
@@ -496,13 +494,13 @@ impl f64 {
     /// * Not be `NaN`
     /// * Not be infinite
     /// * Be representable in the return type `Int`, after truncating off its fractional part
-    #[unstable(feature = "float_approx_unchecked_to", issue = "67058")]
+    #[stable(feature = "float_approx_unchecked_to", since = "1.44.0")]
     #[inline]
-    pub unsafe fn approx_unchecked_to<Int>(self) -> Int
+    pub unsafe fn to_int_unchecked<Int>(self) -> Int
     where
         Self: FloatToInt<Int>,
     {
-        FloatToInt::<Int>::approx_unchecked(self)
+        FloatToInt::<Int>::to_int_unchecked(self)
     }
 
     /// Raw transmutation to `u64`.

src/libcore/num/mod.rs

@@ -4376,7 +4376,7 @@ impl u8 {
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_uppercase(&self) -> u8 {
-        // Unset the fith bit if this is a lowercase letter
+        // Unset the fifth bit if this is a lowercase letter
         *self & !((self.is_ascii_lowercase() as u8) << 5)
     }
 
@@ -4399,7 +4399,7 @@ impl u8 {
     #[stable(feature = "ascii_methods_on_intrinsics", since = "1.23.0")]
     #[inline]
     pub fn to_ascii_lowercase(&self) -> u8 {
-        // Set the fith bit if this is an uppercase letter
+        // Set the fifth bit if this is an uppercase letter
         *self | ((self.is_ascii_uppercase() as u8) << 5)
     }
 

src/librustc_codegen_llvm/intrinsic.rs

@@ -543,13 +543,13 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
                 }
             }
 
-            "float_to_int_approx_unchecked" => {
+            "float_to_int_unchecked" => {
                 if float_type_width(arg_tys[0]).is_none() {
                     span_invalid_monomorphization_error(
                         tcx.sess,
                         span,
                         &format!(
-                            "invalid monomorphization of `float_to_int_approx_unchecked` \
+                            "invalid monomorphization of `float_to_int_unchecked` \
                                   intrinsic: expected basic float type, \
                                   found `{}`",
                             arg_tys[0]
@@ -570,7 +570,7 @@ impl IntrinsicCallMethods<'tcx> for Builder<'a, 'll, 'tcx> {
                             tcx.sess,
                             span,
                             &format!(
-                                "invalid monomorphization of `float_to_int_approx_unchecked` \
+                                "invalid monomorphization of `float_to_int_unchecked` \
                                       intrinsic:  expected basic integer type, \
                                       found `{}`",
                                 ret_ty

src/librustc_mir/transform/simplify.rs

@@ -368,18 +368,22 @@ impl<'a, 'tcx> Visitor<'tcx> for DeclMarker<'a, 'tcx> {
             if location.statement_index != block.statements.len() {
                 let stmt = &block.statements[location.statement_index];
 
-                if let StatementKind::Assign(box (p, Rvalue::Use(Operand::Constant(c)))) =
-                    &stmt.kind
-                {
-                    match c.literal.val {
-                        // Keep assignments from unevaluated constants around, since the evaluation
-                        // may report errors, even if the use of the constant is dead code.
-                        ty::ConstKind::Unevaluated(..) => {}
-                        _ => {
-                            if !p.is_indirect() {
-                                trace!("skipping store of const value {:?} to {:?}", c, p);
-                                return;
+                if let StatementKind::Assign(box (dest, rvalue)) = &stmt.kind {
+                    if !dest.is_indirect() && dest.local == *local {
+                        if let Rvalue::Use(Operand::Constant(c)) = rvalue {
+                            match c.literal.val {
+                                // Keep assignments from unevaluated constants around, since the
+                                // evaluation may report errors, even if the use of the constant
+                                // is dead code.
+                                ty::ConstKind::Unevaluated(..) => {}
+                                _ => {
+                                    trace!("skipping store of const value {:?} to {:?}", c, dest);
+                                    return;
+                                }
                             }
+                        } else if let Rvalue::Discriminant(d) = rvalue {
+                            trace!("skipping store of discriminant value {:?} to {:?}", d, dest);
+                            return;
                         }
                     }
                 }

src/librustc_typeck/check/intrinsic.rs

@@ -275,7 +275,7 @@ pub fn check_intrinsic_type(tcx: TyCtxt<'_>, it: &hir::ForeignItem<'_>) {
             "fadd_fast" | "fsub_fast" | "fmul_fast" | "fdiv_fast" | "frem_fast" => {
                 (1, vec![param(0), param(0)], param(0))
             }
-            "float_to_int_approx_unchecked" => (2, vec![param(0)], param(1)),
+            "float_to_int_unchecked" => (2, vec![param(0)], param(1)),
 
             "assume" => (0, vec![tcx.types.bool], tcx.mk_unit()),
             "likely" => (0, vec![tcx.types.bool], tcx.types.bool),

src/librustc_typeck/collect/type_of.rs

@@ -655,7 +655,11 @@ fn infer_placeholder_type(
         }
     }
 
-    ty
+    // Typeck doesn't expect erased regions to be returned from `type_of`.
+    tcx.fold_regions(&ty, &mut false, |r, _| match r {
+        ty::ReErased => tcx.lifetimes.re_static,
+        _ => r,
+    })
 }
 
 fn report_assoc_ty_on_inherent_impl(tcx: TyCtxt<'_>, span: Span) {

src/libstd/fs.rs

@@ -734,7 +734,7 @@ impl OpenOptions {
     /// let file = options.read(true).open("foo.txt");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn new() -> OpenOptions {
+    pub fn new() -> Self {
         OpenOptions(fs_imp::OpenOptions::new())
     }
 
@@ -751,7 +751,7 @@ impl OpenOptions {
     /// let file = OpenOptions::new().read(true).open("foo.txt");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn read(&mut self, read: bool) -> &mut OpenOptions {
+    pub fn read(&mut self, read: bool) -> &mut Self {
         self.0.read(read);
         self
     }
@@ -772,7 +772,7 @@ impl OpenOptions {
     /// let file = OpenOptions::new().write(true).open("foo.txt");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn write(&mut self, write: bool) -> &mut OpenOptions {
+    pub fn write(&mut self, write: bool) -> &mut Self {
         self.0.write(write);
         self
     }
@@ -819,7 +819,7 @@ impl OpenOptions {
     /// let file = OpenOptions::new().append(true).open("foo.txt");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn append(&mut self, append: bool) -> &mut OpenOptions {
+    pub fn append(&mut self, append: bool) -> &mut Self {
         self.0.append(append);
         self
     }
@@ -839,7 +839,7 @@ impl OpenOptions {
     /// let file = OpenOptions::new().write(true).truncate(true).open("foo.txt");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn truncate(&mut self, truncate: bool) -> &mut OpenOptions {
+    pub fn truncate(&mut self, truncate: bool) -> &mut Self {
         self.0.truncate(truncate);
         self
     }
@@ -860,7 +860,7 @@ impl OpenOptions {
     /// let file = OpenOptions::new().write(true).create(true).open("foo.txt");
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
-    pub fn create(&mut self, create: bool) -> &mut OpenOptions {
+    pub fn create(&mut self, create: bool) -> &mut Self {
         self.0.create(create);
         self
     }
@@ -893,7 +893,7 @@ impl OpenOptions {
     ///                              .open("foo.txt");
     /// ```
     #[stable(feature = "expand_open_options2", since = "1.9.0")]
-    pub fn create_new(&mut self, create_new: bool) -> &mut OpenOptions {
+    pub fn create_new(&mut self, create_new: bool) -> &mut Self {
         self.0.create_new(create_new);
         self
     }

src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads.rs

@@ -0,0 +1,12 @@
+fn map(x: Option<Box<()>>) -> Option<Box<()>> {
+    match x {
+        None => None,
+        Some(x) => Some(x),
+    }
+}
+
+fn main() {
+    map(None);
+}
+
+// EMIT_MIR rustc.map.SimplifyLocals.diff

src/test/mir-opt/simplify-locals-removes-unused-discriminant-reads/rustc.map.SimplifyLocals.diff

@@ -0,0 +1,37 @@
+- // MIR for `map` before SimplifyLocals
++ // MIR for `map` after SimplifyLocals
+
+  fn map(_1: std::option::Option<std::boxed::Box<()>>) -> std::option::Option<std::boxed::Box<()>> {
+      debug x => _1;                       // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:1:8: 1:9
+      let mut _0: std::option::Option<std::boxed::Box<()>>; // return place in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:1:31: 1:46
+      let mut _2: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
+      let _3: std::boxed::Box<()>;         // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
+-     let mut _4: std::boxed::Box<()>;     // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:25: 4:26
+-     let mut _5: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
+-     let mut _6: isize;                   // in scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
+      scope 1 {
+          debug x => _3;                   // in scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:14: 4:15
+      }
+
+      bb0: {
+          _2 = discriminant(_1);           // bb0[0]: scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
+          switchInt(move _2) -> [0isize: bb2, otherwise: bb1]; // bb0[1]: scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:9: 3:13
+      }
+
+      bb1: {
+          _0 = move _1;                    // bb1[0]: scope 1 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:4:20: 4:27
+          goto -> bb3;                     // bb1[1]: scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:2:5: 5:6
+      }
+
+      bb2: {
+          discriminant(_0) = 0;            // bb2[0]: scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:3:17: 3:21
+          goto -> bb3;                     // bb2[1]: scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:2:5: 5:6
+      }
+
+      bb3: {
+-         _5 = discriminant(_1);           // bb3[0]: scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:1: 6:2
+-         return;                          // bb3[1]: scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:2: 6:2
++         return;                          // bb3[0]: scope 0 at $DIR/simplify-locals-removes-unused-discriminant-reads.rs:6:2: 6:2
+      }
+  }
+