Auto merge of #72756 - RalfJung:rollup-tbjmtx2, r=RalfJung

Rollup of 9 pull requests

Successful merges:

 - #67460 (Tweak impl signature mismatch errors involving `RegionKind::ReVar` lifetimes)
 - #71095 (impl From<[T; N]> for Box<[T]>)
 - #71500 (Make pointer offset methods/intrinsics const)
 - #71804 (linker: Support `-static-pie` and `-static -shared`)
 - #71862 (Implement RFC 2585: unsafe blocks in unsafe fn)
 - #72103 (borrowck `DefId` -> `LocalDefId`)
 - #72407 (Various minor improvements to Ipv6Addr::Display)
 - #72413 (impl Step for char (make Range*<char> iterable))
 - #72439 (NVPTX support for new asm!)

Failed merges:

r? @ghost

src/doc/unstable-book/src/library-features/asm.md

@@ -468,12 +468,17 @@ Here is the list of currently supported register classes:
 | ARM | `qreg` | `q[0-15]` | `w` |
 | ARM | `qreg_low8` | `q[0-7]` | `t` |
 | ARM | `qreg_low4` | `q[0-3]` | `x` |
+| NVPTX | `reg16` | None\* | `h` |
+| NVPTX | `reg32` | None\* | `r` |
+| NVPTX | `reg64` | None\* | `l` |
 | RISC-V | `reg` | `x1`, `x[5-7]`, `x[9-15]`, `x[16-31]` (non-RV32E) | `r` |
 | RISC-V | `freg` | `f[0-31]` | `f` |
 
 > **Note**: On x86 we treat `reg_byte` differently from `reg` because the compiler can allocate `al` and `ah` separately whereas `reg` reserves the whole register.
 >
 > Note #2: On x86-64 the high byte registers (e.g. `ah`) are only available when used as an explicit register. Specifying the `reg_byte` register class for an operand will always allocate a low byte register.
+>
+> Note #3: NVPTX doesn't have a fixed register set, so named registers are not supported.
 
 Additional register classes may be added in the future based on demand (e.g. MMX, x87, etc).
 
@@ -495,6 +500,9 @@ Each register class has constraints on which value types they can be used with.
 | ARM | `sreg` | `vfp2` | `i32`, `f32` |
 | ARM | `dreg` | `vfp2` | `i64`, `f64`, `i8x8`, `i16x4`, `i32x2`, `i64x1`, `f32x2` |
 | ARM | `qreg` | `neon` | `i8x16`, `i16x8`, `i32x4`, `i64x2`, `f32x4` |
+| NVPTX | `reg16` | None | `i8`, `i16` |
+| NVPTX | `reg32` | None | `i8`, `i16`, `i32`, `f32` |
+| NVPTX | `reg64` | None | `i8`, `i16`, `i32`, `f32`, `i64`, `f64` |
 | RISC-V32 | `reg` | None | `i8`, `i16`, `i32`, `f32` |
 | RISC-V64 | `reg` | None | `i8`, `i16`, `i32`, `f32`, `i64`, `f64` |
 | RISC-V | `freg` | `f` | `f32` |
@@ -610,6 +618,9 @@ The supported modifiers are a subset of LLVM's (and GCC's) [asm template argumen
 | ARM | `dreg` | None | `d0` | `P` |
 | ARM | `qreg` | None | `q0` | `q` |
 | ARM | `qreg` | `e` / `f` | `d0` / `d1` | `e` / `f` |
+| NVPTX | `reg16` | None | `rs0` | None |
+| NVPTX | `reg32` | None | `r0` | None |
+| NVPTX | `reg64` | None | `rd0` | None |
 | RISC-V | `reg` | None | `x1` | None |
 | RISC-V | `freg` | None | `f0` | None |
 

src/liballoc/boxed.rs

@@ -865,6 +865,25 @@ impl From<Box<str>> for Box<[u8]> {
     }
 }
 
+#[stable(feature = "box_from_array", since = "1.45.0")]
+impl<T, const N: usize> From<[T; N]> for Box<[T]>
+where
+    [T; N]: LengthAtMost32,
+{
+    /// Converts a `[T; N]` into a `Box<[T]>`
+    ///
+    /// This conversion moves the array to newly heap-allocated memory.
+    ///
+    /// # Examples
+    /// ```rust
+    /// let boxed: Box<[u8]> = Box::from([4, 2]);
+    /// println!("{:?}", boxed);
+    /// ```
+    fn from(array: [T; N]) -> Box<[T]> {
+        box array
+    }
+}
+
 #[stable(feature = "boxed_slice_try_from", since = "1.43.0")]
 impl<T, const N: usize> TryFrom<Box<[T]>> for Box<[T; N]>
 where

src/libcore/intrinsics.rs

@@ -1314,6 +1314,7 @@ extern "rust-intrinsic" {
     /// The stabilized version of this intrinsic is
     /// [`std::pointer::offset`](../../std/primitive.pointer.html#method.offset).
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     pub fn offset<T>(dst: *const T, offset: isize) -> *const T;
 
     /// Calculates the offset from a pointer, potentially wrapping.
@@ -1331,6 +1332,7 @@ extern "rust-intrinsic" {
     /// The stabilized version of this intrinsic is
     /// [`std::pointer::wrapping_offset`](../../std/primitive.pointer.html#method.wrapping_offset).
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     pub fn arith_offset<T>(dst: *const T, offset: isize) -> *const T;
 
     /// Equivalent to the appropriate `llvm.memcpy.p0i8.0i8.*` intrinsic, with

src/libcore/iter/range.rs

@@ -1,3 +1,4 @@
+use crate::char;
 use crate::convert::TryFrom;
 use crate::mem;
 use crate::ops::{self, Add, Sub, Try};
@@ -400,6 +401,73 @@ step_integer_impls! {
     wider than usize: [u32 i32], [u64 i64], [u128 i128];
 }
 
+#[unstable(feature = "step_trait", reason = "recently redesigned", issue = "42168")]
+unsafe impl Step for char {
+    #[inline]
+    fn steps_between(&start: &char, &end: &char) -> Option<usize> {
+        let start = start as u32;
+        let end = end as u32;
+        if start <= end {
+            let count = end - start;
+            if start < 0xD800 && 0xE000 <= end {
+                usize::try_from(count - 0x800).ok()
+            } else {
+                usize::try_from(count).ok()
+            }
+        } else {
+            None
+        }
+    }
+
+    #[inline]
+    fn forward_checked(start: char, count: usize) -> Option<char> {
+        let start = start as u32;
+        let mut res = Step::forward_checked(start, count)?;
+        if start < 0xD800 && 0xD800 <= res {
+            res = Step::forward_checked(res, 0x800)?;
+        }
+        if res <= char::MAX as u32 {
+            // SAFETY: res is a valid unicode scalar
+            // (below 0x110000 and not in 0xD800..0xE000)
+            Some(unsafe { char::from_u32_unchecked(res) })
+        } else {
+            None
+        }
+    }
+
+    #[inline]
+    fn backward_checked(start: char, count: usize) -> Option<char> {
+        let start = start as u32;
+        let mut res = Step::backward_checked(start, count)?;
+        if start >= 0xE000 && 0xE000 > res {
+            res = Step::backward_checked(res, 0x800)?;
+        }
+        // SAFETY: res is a valid unicode scalar
+        // (below 0x110000 and not in 0xD800..0xE000)
+        Some(unsafe { char::from_u32_unchecked(res) })
+    }
+
+    #[inline]
+    unsafe fn forward_unchecked(start: char, count: usize) -> char {
+        let start = start as u32;
+        let mut res = Step::forward_unchecked(start, count);
+        if start < 0xD800 && 0xD800 <= res {
+            res = Step::forward_unchecked(res, 0x800);
+        }
+        char::from_u32_unchecked(res)
+    }
+
+    #[inline]
+    unsafe fn backward_unchecked(start: char, count: usize) -> char {
+        let start = start as u32;
+        let mut res = Step::backward_unchecked(start, count);
+        if start >= 0xE000 && 0xE000 > res {
+            res = Step::backward_unchecked(res, 0x800);
+        }
+        char::from_u32_unchecked(res)
+    }
+}
+
 macro_rules! range_exact_iter_impl {
     ($($t:ty)*) => ($(
         #[stable(feature = "rust1", since = "1.0.0")]
@@ -582,7 +650,11 @@ impl<A: Step> Iterator for ops::RangeInclusive<A> {
         }
         let is_iterating = self.start < self.end;
         Some(if is_iterating {
-            let n = Step::forward(self.start.clone(), 1);
+            // SAFETY: just checked precondition
+            // We use the unchecked version here, because
+            // otherwise `for _ in '\0'..=char::MAX`
+            // does not successfully remove panicking code.
+            let n = unsafe { Step::forward_unchecked(self.start.clone(), 1) };
             mem::replace(&mut self.start, n)
         } else {
             self.exhausted = true;

src/libcore/lib.rs

@@ -85,6 +85,7 @@
 #![feature(const_panic)]
 #![feature(const_fn_union)]
 #![feature(const_generics)]
+#![feature(const_ptr_offset)]
 #![feature(const_ptr_offset_from)]
 #![feature(const_result)]
 #![feature(const_slice_from_raw_parts)]

src/libcore/ptr/const_ptr.rs

@@ -151,8 +151,9 @@ impl<T: ?Sized> *const T {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub unsafe fn offset(self, count: isize) -> *const T
+    pub const unsafe fn offset(self, count: isize) -> *const T
     where
         T: Sized,
     {
@@ -210,8 +211,9 @@ impl<T: ?Sized> *const T {
     /// ```
     #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub fn wrapping_offset(self, count: isize) -> *const T
+    pub const fn wrapping_offset(self, count: isize) -> *const T
     where
         T: Sized,
     {
@@ -393,8 +395,9 @@ impl<T: ?Sized> *const T {
     /// ```
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub unsafe fn add(self, count: usize) -> Self
+    pub const unsafe fn add(self, count: usize) -> Self
     where
         T: Sized,
     {
@@ -455,8 +458,9 @@ impl<T: ?Sized> *const T {
     /// ```
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub unsafe fn sub(self, count: usize) -> Self
+    pub const unsafe fn sub(self, count: usize) -> Self
     where
         T: Sized,
     {
@@ -511,8 +515,9 @@ impl<T: ?Sized> *const T {
     /// ```
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub fn wrapping_add(self, count: usize) -> Self
+    pub const fn wrapping_add(self, count: usize) -> Self
     where
         T: Sized,
     {
@@ -567,8 +572,9 @@ impl<T: ?Sized> *const T {
     /// ```
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub fn wrapping_sub(self, count: usize) -> Self
+    pub const fn wrapping_sub(self, count: usize) -> Self
     where
         T: Sized,
     {

src/libcore/ptr/mut_ptr.rs

@@ -145,8 +145,9 @@ impl<T: ?Sized> *mut T {
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub unsafe fn offset(self, count: isize) -> *mut T
+    pub const unsafe fn offset(self, count: isize) -> *mut T
     where
         T: Sized,
     {
@@ -203,8 +204,9 @@ impl<T: ?Sized> *mut T {
     /// ```
     #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub fn wrapping_offset(self, count: isize) -> *mut T
+    pub const fn wrapping_offset(self, count: isize) -> *mut T
     where
         T: Sized,
     {
@@ -439,8 +441,9 @@ impl<T: ?Sized> *mut T {
     /// ```
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub unsafe fn add(self, count: usize) -> Self
+    pub const unsafe fn add(self, count: usize) -> Self
     where
         T: Sized,
     {
@@ -501,8 +504,9 @@ impl<T: ?Sized> *mut T {
     /// ```
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub unsafe fn sub(self, count: usize) -> Self
+    pub const unsafe fn sub(self, count: usize) -> Self
     where
         T: Sized,
     {
@@ -557,8 +561,9 @@ impl<T: ?Sized> *mut T {
     /// ```
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub fn wrapping_add(self, count: usize) -> Self
+    pub const fn wrapping_add(self, count: usize) -> Self
     where
         T: Sized,
     {
@@ -613,8 +618,9 @@ impl<T: ?Sized> *mut T {
     /// ```
     #[stable(feature = "pointer_methods", since = "1.26.0")]
     #[must_use = "returns a new pointer rather than modifying its argument"]
+    #[rustc_const_unstable(feature = "const_ptr_offset", issue = "71499")]
     #[inline]
-    pub fn wrapping_sub(self, count: usize) -> Self
+    pub const fn wrapping_sub(self, count: usize) -> Self
     where
         T: Sized,
     {

src/libcore/tests/iter.rs

@@ -1956,6 +1956,18 @@ fn test_range() {
     );
 }
 
+#[test]
+fn test_char_range() {
+    use std::char;
+    assert!(('\0'..=char::MAX).eq((0..=char::MAX as u32).filter_map(char::from_u32)));
+    assert!(('\0'..=char::MAX).rev().eq((0..=char::MAX as u32).filter_map(char::from_u32).rev()));
+
+    assert_eq!(('\u{D7FF}'..='\u{E000}').count(), 2);
+    assert_eq!(('\u{D7FF}'..='\u{E000}').size_hint(), (2, Some(2)));
+    assert_eq!(('\u{D7FF}'..'\u{E000}').count(), 1);
+    assert_eq!(('\u{D7FF}'..'\u{E000}').size_hint(), (1, Some(1)));
+}
+
 #[test]
 fn test_range_exhaustion() {
     let mut r = 10..10;

src/librustc_codegen_llvm/asm.rs

@@ -254,6 +254,7 @@ impl AsmBuilderMethods<'tcx> for Builder<'a, 'll, 'tcx> {
                     ]);
                 }
                 InlineAsmArch::RiscV32 | InlineAsmArch::RiscV64 => {}
+                InlineAsmArch::Nvptx64 => {}
             }
         }
         if !options.contains(InlineAsmOptions::NOMEM) {
@@ -410,6 +411,9 @@ fn reg_to_llvm(reg: InlineAsmRegOrRegClass) -> String {
             | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg_low4) => "x",
             InlineAsmRegClass::Arm(ArmInlineAsmRegClass::dreg)
             | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg) => "w",
+            InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg16) => "h",
+            InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg32) => "r",
+            InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg64) => "l",
             InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::reg) => "r",
             InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::freg) => "f",
             InlineAsmRegClass::X86(X86InlineAsmRegClass::reg) => "r",
@@ -452,6 +456,7 @@ fn modifier_to_llvm(
                 modifier
             }
         }
+        InlineAsmRegClass::Nvptx(_) => None,
         InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::reg)
         | InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::freg) => None,
         InlineAsmRegClass::X86(X86InlineAsmRegClass::reg)
@@ -502,6 +507,9 @@ fn dummy_output_type(cx: &CodegenCx<'ll, 'tcx>, reg: InlineAsmRegClass) -> &'ll
         | InlineAsmRegClass::Arm(ArmInlineAsmRegClass::qreg_low4) => {
             cx.type_vector(cx.type_i64(), 2)
         }
+        InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg16) => cx.type_i16(),
+        InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg32) => cx.type_i32(),
+        InlineAsmRegClass::Nvptx(NvptxInlineAsmRegClass::reg64) => cx.type_i64(),
         InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::reg) => cx.type_i32(),
         InlineAsmRegClass::RiscV(RiscVInlineAsmRegClass::freg) => cx.type_f32(),
         InlineAsmRegClass::X86(X86InlineAsmRegClass::reg)