Rollup of 8 pull requests

compiler/rustc_interface/src/tests.rs

@@ -633,6 +633,7 @@ fn test_debugging_options_tracking_hash() {
     untracked!(dump_mir_graphviz, true);
     untracked!(emit_future_incompat_report, true);
     untracked!(emit_stack_sizes, true);
+    untracked!(future_incompat_test, true);
     untracked!(hir_stats, true);
     untracked!(identify_regions, true);
     untracked!(incremental_ignore_spans, true);

compiler/rustc_middle/src/ich/impls_syntax.rs

@@ -6,6 +6,7 @@ use crate::ich::StableHashingContext;
 use rustc_ast as ast;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
 use rustc_span::{BytePos, NormalizedPos, SourceFile};
+use std::assert::assert_matches;
 
 use smallvec::SmallVec;
 

compiler/rustc_middle/src/lint.rs

@@ -8,7 +8,7 @@ use rustc_hir::HirId;
 use rustc_index::vec::IndexVec;
 use rustc_session::lint::{
     builtin::{self, FORBIDDEN_LINT_GROUPS},
-    FutureIncompatibilityReason, FutureIncompatibleInfo, Level, Lint, LintId,
+    FutureIncompatibilityReason, Level, Lint, LintId,
 };
 use rustc_session::{DiagnosticMessageId, Session};
 use rustc_span::hygiene::MacroKind;
@@ -223,12 +223,12 @@ pub fn struct_lint_level<'s, 'd>(
         let lint_id = LintId::of(lint);
         let future_incompatible = lint.future_incompatible;
 
-        let has_future_breakage = matches!(
-            future_incompatible,
-            Some(FutureIncompatibleInfo {
-                reason: FutureIncompatibilityReason::FutureReleaseErrorReportNow,
-                ..
-            })
+        let has_future_breakage = future_incompatible.map_or(
+            // Default allow lints trigger too often for testing.
+            sess.opts.debugging_opts.future_incompat_test && lint.default_level != Level::Allow,
+            |incompat| {
+                matches!(incompat.reason, FutureIncompatibilityReason::FutureReleaseErrorReportNow)
+            },
         );
 
         let mut err = match (level, span) {

compiler/rustc_mir/src/interpret/memory.rs

@@ -6,6 +6,7 @@
 //! integer. It is crucial that these operations call `check_align` *before*
 //! short-circuiting the empty case!
 
+use std::assert::assert_matches;
 use std::borrow::Cow;
 use std::collections::VecDeque;
 use std::convert::{TryFrom, TryInto};

compiler/rustc_resolve/src/diagnostics.rs

@@ -502,14 +502,14 @@ impl<'a> Resolver<'a> {
 
                 err
             }
-            ResolutionError::SelfInTyParamDefault => {
+            ResolutionError::SelfInGenericParamDefault => {
                 let mut err = struct_span_err!(
                     self.session,
                     span,
                     E0735,
-                    "type parameters cannot use `Self` in their defaults"
+                    "generic parameters cannot use `Self` in their defaults"
                 );
-                err.span_label(span, "`Self` in type parameter default".to_string());
+                err.span_label(span, "`Self` in generic parameter default".to_string());
                 err
             }
             ResolutionError::UnreachableLabel { name, definition_span, suggestion } => {

compiler/rustc_resolve/src/lib.rs

@@ -249,7 +249,7 @@ enum ResolutionError<'a> {
     /// This error is only emitted when using `min_const_generics`.
     ParamInNonTrivialAnonConst { name: Symbol, is_type: bool },
     /// Error E0735: generic parameters with a default cannot use `Self`
-    SelfInTyParamDefault,
+    SelfInGenericParamDefault,
     /// Error E0767: use of unreachable label
     UnreachableLabel { name: Symbol, definition_span: Span, suggestion: Option<LabelSuggestion> },
 }
@@ -2643,7 +2643,7 @@ impl<'a> Resolver<'a> {
         if let ForwardGenericParamBanRibKind = all_ribs[rib_index].kind {
             if record_used {
                 let res_error = if rib_ident.name == kw::SelfUpper {
-                    ResolutionError::SelfInTyParamDefault
+                    ResolutionError::SelfInGenericParamDefault
                 } else {
                     ResolutionError::ForwardDeclaredGenericParam
                 };

compiler/rustc_session/src/options.rs

@@ -1084,6 +1084,8 @@ options! {
         "set the optimization fuel quota for a crate"),
     function_sections: Option<bool> = (None, parse_opt_bool, [TRACKED],
         "whether each function should go in its own section"),
+    future_incompat_test: bool = (false, parse_bool, [UNTRACKED],
+        "forces all lints to be future incompatible, used for internal testing (default: no)"),
     gcc_ld: Option<LdImpl> = (None, parse_gcc_ld, [TRACKED], "implementation of ld used by cc"),
     graphviz_dark_mode: bool = (false, parse_bool, [UNTRACKED],
         "use dark-themed colors in graphviz output (default: no)"),

library/alloc/src/sync.rs

@@ -19,7 +19,6 @@ use core::marker::{PhantomData, Unpin, Unsize};
 use core::mem::size_of_val;
 use core::mem::{self, align_of_val_raw};
 use core::ops::{CoerceUnsized, Deref, DispatchFromDyn, Receiver};
-#[cfg(not(no_global_oom_handling))]
 use core::pin::Pin;
 use core::ptr::{self, NonNull};
 #[cfg(not(no_global_oom_handling))]
@@ -494,6 +493,13 @@ impl<T> Arc<T> {
         unsafe { Pin::new_unchecked(Arc::new(data)) }
     }
 
+    /// Constructs a new `Pin<Arc<T>>`, return an error if allocation fails.
+    #[unstable(feature = "allocator_api", issue = "32838")]
+    #[inline]
+    pub fn try_pin(data: T) -> Result<Pin<Arc<T>>, AllocError> {
+        unsafe { Ok(Pin::new_unchecked(Arc::try_new(data)?)) }
+    }
+
     /// Constructs a new `Arc<T>`, returning an error if allocation fails.
     ///
     /// # Examples

library/core/src/lib.rs

@@ -179,6 +179,16 @@ use prelude::v1::*;
 #[macro_use]
 mod macros;
 
+// We don't export this through #[macro_export] for now, to avoid breakage.
+// See https://github.com/rust-lang/rust/issues/82913
+#[cfg(not(test))]
+#[unstable(feature = "assert_matches", issue = "82775")]
+/// Unstable module containing the unstable `assert_matches` macro.
+pub mod assert {
+    #[unstable(feature = "assert_matches", issue = "82775")]
+    pub use crate::macros::{assert_matches, debug_assert_matches};
+}
+
 #[macro_use]
 mod internal_macros;
 

library/core/src/macros/mod.rs

@@ -127,6 +127,8 @@ macro_rules! assert_ne {
 /// ```
 /// #![feature(assert_matches)]
 ///
+/// use std::assert::assert_matches;
+///
 /// let a = 1u32.checked_add(2);
 /// let b = 1u32.checked_sub(2);
 /// assert_matches!(a, Some(_));
@@ -135,10 +137,10 @@ macro_rules! assert_ne {
 /// let c = Ok("abc".to_string());
 /// assert_matches!(c, Ok(x) | Err(x) if x.len() < 100);
 /// ```
-#[macro_export]
 #[unstable(feature = "assert_matches", issue = "82775")]
 #[allow_internal_unstable(core_panic)]
-macro_rules! assert_matches {
+#[rustc_macro_transparency = "semitransparent"]
+pub macro assert_matches {
     ($left:expr, $( $pattern:pat_param )|+ $( if $guard: expr )? $(,)?) => ({
         match $left {
             $( $pattern )|+ $( if $guard )? => {}
@@ -150,7 +152,7 @@ macro_rules! assert_matches {
                 );
             }
         }
-    });
+    }),
     ($left:expr, $( $pattern:pat_param )|+ $( if $guard: expr )?, $($arg:tt)+) => ({
         match $left {
             $( $pattern )|+ $( if $guard )? => {}
@@ -162,7 +164,7 @@ macro_rules! assert_matches {
                 );
             }
         }
-    });
+    }),
 }
 
 /// Asserts that a boolean expression is `true` at runtime.
@@ -284,6 +286,8 @@ macro_rules! debug_assert_ne {
 /// ```
 /// #![feature(assert_matches)]
 ///
+/// use std::assert::debug_assert_matches;
+///
 /// let a = 1u32.checked_add(2);
 /// let b = 1u32.checked_sub(2);
 /// debug_assert_matches!(a, Some(_));
@@ -295,8 +299,9 @@ macro_rules! debug_assert_ne {
 #[macro_export]
 #[unstable(feature = "assert_matches", issue = "82775")]
 #[allow_internal_unstable(assert_matches)]
-macro_rules! debug_assert_matches {
-    ($($arg:tt)*) => (if $crate::cfg!(debug_assertions) { $crate::assert_matches!($($arg)*); })
+#[rustc_macro_transparency = "semitransparent"]
+pub macro debug_assert_matches($($arg:tt)*) {
+    if $crate::cfg!(debug_assertions) { $crate::assert::assert_matches!($($arg)*); }
 }
 
 /// Returns whether the given expression matches any of the given patterns.

library/core/src/slice/rotate.rs

@@ -1,5 +1,3 @@
-// ignore-tidy-undocumented-unsafe
-
 use crate::cmp;
 use crate::mem::{self, MaybeUninit};
 use crate::ptr;
@@ -79,8 +77,10 @@ pub unsafe fn ptr_rotate<T>(mut left: usize, mut mid: *mut T, mut right: usize)
             // the way until about `left + right == 32`, but the worst case performance breaks even
             // around 16. 24 was chosen as middle ground. If the size of `T` is larger than 4
             // `usize`s, this algorithm also outperforms other algorithms.
+            // SAFETY: callers must ensure `mid - left` is valid for reading and writing.
             let x = unsafe { mid.sub(left) };
             // beginning of first round
+            // SAFETY: see previous comment.
             let mut tmp: T = unsafe { x.read() };
             let mut i = right;
             // `gcd` can be found before hand by calculating `gcd(left + right, right)`,
@@ -92,6 +92,21 @@ pub unsafe fn ptr_rotate<T>(mut left: usize, mut mid: *mut T, mut right: usize)
             // the very end. This is possibly due to the fact that swapping or replacing temporaries
             // uses only one memory address in the loop instead of needing to manage two.
             loop {
+                // [long-safety-expl]
+                // SAFETY: callers must ensure `[left, left+mid+right)` are all valid for reading and
+                // writing.
+                //
+                // - `i` start with `right` so `mid-left <= x+i = x+right = mid-left+right < mid+right`
+                // - `i <= left+right-1` is always true
+                //   - if `i < left`, `right` is added so `i < left+right` and on the next
+                //     iteration `left` is removed from `i` so it doesn't go further
+                //   - if `i >= left`, `left` is removed immediately and so it doesn't go further.
+                // - overflows cannot happen for `i` since the function's safety contract ask for
+                //   `mid+right-1 = x+left+right` to be valid for writing
+                // - underflows cannot happen because `i` must be bigger or equal to `left` for
+                //   a substraction of `left` to happen.
+                //
+                // So `x+i` is valid for reading and writing if the caller respected the contract
                 tmp = unsafe { x.add(i).replace(tmp) };
                 // instead of incrementing `i` and then checking if it is outside the bounds, we
                 // check if `i` will go outside the bounds on the next increment. This prevents
@@ -100,6 +115,8 @@ pub unsafe fn ptr_rotate<T>(mut left: usize, mut mid: *mut T, mut right: usize)
                     i -= left;
                     if i == 0 {
                         // end of first round
+                        // SAFETY: tmp has been read from a valid source and x is valid for writing
+                        // according to the caller.
                         unsafe { x.write(tmp) };
                         break;
                     }
@@ -113,13 +130,24 @@ pub unsafe fn ptr_rotate<T>(mut left: usize, mut mid: *mut T, mut right: usize)
             }
             // finish the chunk with more rounds
             for start in 1..gcd {
+                // SAFETY: `gcd` is at most equal to `right` so all values in `1..gcd` are valid for
+                // reading and writing as per the function's safety contract, see [long-safety-expl]
+                // above
                 tmp = unsafe { x.add(start).read() };
+                // [safety-expl-addition]
+                //
+                // Here `start < gcd` so `start < right` so `i < right+right`: `right` being the
+                // greatest common divisor of `(left+right, right)` means that `left = right` so
+                // `i < left+right` so `x+i = mid-left+i` is always valid for reading and writing
+                // according to the function's safety contract.
                 i = start + right;
                 loop {
+                    // SAFETY: see [long-safety-expl] and [safety-expl-addition]
                     tmp = unsafe { x.add(i).replace(tmp) };
                     if i >= left {
                         i -= left;
                         if i == start {
+                            // SAFETY: see [long-safety-expl] and [safety-expl-addition]
                             unsafe { x.add(start).write(tmp) };
                             break;
                         }
@@ -135,14 +163,30 @@ pub unsafe fn ptr_rotate<T>(mut left: usize, mut mid: *mut T, mut right: usize)
             // The `[T; 0]` here is to ensure this is appropriately aligned for T
             let mut rawarray = MaybeUninit::<(BufType, [T; 0])>::uninit();
             let buf = rawarray.as_mut_ptr() as *mut T;
+            // SAFETY: `mid-left <= mid-left+right < mid+right`
             let dim = unsafe { mid.sub(left).add(right) };
             if left <= right {
+                // SAFETY:
+                //
+                // 1) The `else if` condition about the sizes ensures `[mid-left; left]` will fit in
+                //    `buf` without overflow and `buf` was created just above and so cannot be
+                //    overlapped with any value of `[mid-left; left]`
+                // 2) [mid-left, mid+right) are all valid for reading and writing and we don't care
+                //    about overlaps here.
+                // 3) The `if` condition about `left <= right` ensures writing `left` elements to
+                //    `dim = mid-left+right` is valid because:
+                //    - `buf` is valid and `left` elements were written in it in 1)
+                //    - `dim+left = mid-left+right+left = mid+right` and we write `[dim, dim+left)`
                 unsafe {
+                    // 1)
                     ptr::copy_nonoverlapping(mid.sub(left), buf, left);
+                    // 2)
                     ptr::copy(mid, mid.sub(left), right);
+                    // 3)
                     ptr::copy_nonoverlapping(buf, dim, left);
                 }
             } else {
+                // SAFETY: same reasoning as above but with `left` and `right` reversed
                 unsafe {
                     ptr::copy_nonoverlapping(mid, buf, right);
                     ptr::copy(mid.sub(left), dim, left);
@@ -156,6 +200,10 @@ pub unsafe fn ptr_rotate<T>(mut left: usize, mut mid: *mut T, mut right: usize)
             // of this algorithm would be, and swapping using that last chunk instead of swapping
             // adjacent chunks like this algorithm is doing, but this way is still faster.
             loop {
+                // SAFETY:
+                // `left >= right` so `[mid-right, mid+right)` is valid for reading and writing
+                // Substracting `right` from `mid` each turn is counterbalanced by the addition and
+                // check after it.
                 unsafe {
                     ptr::swap_nonoverlapping(mid.sub(right), mid, right);
                     mid = mid.sub(right);
@@ -168,6 +216,10 @@ pub unsafe fn ptr_rotate<T>(mut left: usize, mut mid: *mut T, mut right: usize)
         } else {
             // Algorithm 3, `left < right`
             loop {
+                // SAFETY: `[mid-left, mid+left)` is valid for reading and writing because
+                // `left < right` so `mid+left < mid+right`.
+                // Adding `left` to `mid` each turn is counterbalanced by the substraction and check
+                // after it.
                 unsafe {
                     ptr::swap_nonoverlapping(mid.sub(left), mid, left);
                     mid = mid.add(left);

library/std/src/lib.rs

@@ -548,8 +548,8 @@ pub use std_detect::{
 #[stable(feature = "rust1", since = "1.0.0")]
 #[allow(deprecated, deprecated_in_future)]
 pub use core::{
-    assert_eq, assert_matches, assert_ne, debug_assert, debug_assert_eq, debug_assert_matches,
-    debug_assert_ne, matches, r#try, todo, unimplemented, unreachable, write, writeln,
+    assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne, matches, r#try, todo,
+    unimplemented, unreachable, write, writeln,
 };
 
 // Re-export built-in macros defined through libcore.

library/std/src/os/wasi/fs.rs

@@ -1,7 +1,7 @@
 //! WASI-specific extensions to primitives in the `std::fs` module.
 
 #![deny(unsafe_op_in_unsafe_fn)]
-#![unstable(feature = "wasi_ext", issue = "none")]
+#![unstable(feature = "wasi_ext", issue = "71213")]
 
 use crate::ffi::OsStr;
 use crate::fs::{self, File, Metadata, OpenOptions};

library/std/src/os/wasi/io.rs

@@ -1,7 +1,7 @@
 //! WASI-specific extensions to general I/O primitives
 
 #![deny(unsafe_op_in_unsafe_fn)]
-#![unstable(feature = "wasi_ext", issue = "none")]
+#![unstable(feature = "wasi_ext", issue = "71213")]
 
 use crate::fs;
 use crate::io;

src/librustdoc/html/markdown.rs

@@ -621,8 +621,7 @@ impl<'a, I: Iterator<Item = SpannedEvent<'a>>> Iterator for Footnotes<'a, I> {
                                 is_paragraph = true;
                             }
                             html::push_html(&mut ret, content.into_iter());
-                            write!(ret, "&nbsp;<a href=\"#fnref{}\" rev=\"footnote\">↩</a>", id)
-                                .unwrap();
+                            write!(ret, "&nbsp;<a href=\"#fnref{}\">↩</a>", id).unwrap();
                             if is_paragraph {
                                 ret.push_str("</p>");
                             }

src/test/ui/const-generics/defaults/default-const-param-cannot-reference-self.rs

@@ -0,0 +1,16 @@
+#![feature(const_generics_defaults)]
+
+struct Struct<const N: usize = { Self; 10 }>;
+//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735]
+
+enum Enum<const N: usize = { Self; 10 }> { }
+//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735]
+
+union Union<const N: usize = { Self; 10 }> { not_empty: () }
+//~^ ERROR generic parameters cannot use `Self` in their defaults [E0735]
+
+fn main() {
+    let _: Struct;
+    let _: Enum;
+    let _: Union;
+}