Auto merge of #150500 - jhpratt:rollup-ei77kqi, r=jhpratt

Rollup of 3 pull requests

Successful merges:

 - #146792 (Implement `TryFrom<char>` for `usize`.)
 - #150484 (Mark set_times as unavailable for RTEMS target)
 - #150498 (mir_build: Remove several remnants of `#![feature(inline_const_pat)]`)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_middle/src/thir.rs

@@ -832,18 +832,18 @@ pub enum PatKind<'tcx> {
         value: ty::Value<'tcx>,
     },
 
-    /// Pattern obtained by converting a constant (inline or named) to its pattern
-    /// representation using `const_to_pat`. This is used for unsafety checking.
+    /// Wrapper node representing a named constant that was lowered to a pattern
+    /// using `const_to_pat`.
+    ///
+    /// This is used by some diagnostics for non-exhaustive matches, to map
+    /// the pattern node back to the `DefId` of its original constant.
+    ///
+    /// FIXME(#150498): Can we make this an `Option<DefId>` field on `Pat`
+    /// instead, so that non-diagnostic code can ignore it more easily?
     ExpandedConstant {
         /// [DefId] of the constant item.
         def_id: DefId,
         /// The pattern that the constant lowered to.
-        ///
-        /// HACK: we need to keep the `DefId` of inline constants around for unsafety checking;
-        /// therefore when a range pattern contains inline constants, we re-wrap the range pattern
-        /// with the `ExpandedConstant` nodes that correspond to the range endpoints. Hence
-        /// `subpattern` may actually be a range pattern, and `def_id` be the constant for one of
-        /// its endpoints.
         subpattern: Box<Pat<'tcx>>,
     },
 

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -410,14 +410,6 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
                 visit::walk_pat(self, pat);
                 self.inside_adt = old_inside_adt;
             }
-            PatKind::ExpandedConstant { def_id, .. } => {
-                if let Some(def) = def_id.as_local()
-                    && matches!(self.tcx.def_kind(def_id), DefKind::InlineConst)
-                {
-                    self.visit_inner_body(def);
-                }
-                visit::walk_pat(self, pat);
-            }
             _ => {
                 visit::walk_pat(self, pat);
             }

compiler/rustc_mir_build/src/thir/pattern/check_match.rs

@@ -5,7 +5,7 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_errors::codes::*;
 use rustc_errors::{Applicability, ErrorGuaranteed, MultiSpan, struct_span_code_err};
 use rustc_hir::def::*;
-use rustc_hir::def_id::LocalDefId;
+use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_hir::{self as hir, BindingMode, ByRef, HirId, MatchSource};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::Level;
@@ -687,12 +687,7 @@ impl<'p, 'tcx> MatchVisitor<'p, 'tcx> {
             unpeeled_pat = subpattern;
         }
 
-        if let PatKind::ExpandedConstant { def_id, .. } = unpeeled_pat.kind
-            && let DefKind::Const = self.tcx.def_kind(def_id)
-            && let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(pat.span)
-            // We filter out paths with multiple path::segments.
-            && snippet.chars().all(|c| c.is_alphanumeric() || c == '_')
-        {
+        if let Some(def_id) = is_const_pat_that_looks_like_binding(self.tcx, unpeeled_pat) {
             let span = self.tcx.def_span(def_id);
             let variable = self.tcx.item_name(def_id).to_string();
             // When we encounter a constant as the binding name, point at the `const` definition.
@@ -1209,6 +1204,26 @@ fn pat_is_catchall(pat: &DeconstructedPat<'_, '_>) -> bool {
     }
 }
 
+/// If the given pattern is a named constant that looks like it could have been
+/// intended to be a binding, returns the `DefId` of the named constant.
+///
+/// Diagnostics use this to give more detailed suggestions for non-exhaustive
+/// matches.
+fn is_const_pat_that_looks_like_binding<'tcx>(tcx: TyCtxt<'tcx>, pat: &Pat<'tcx>) -> Option<DefId> {
+    // The pattern must be a named constant, and the name that appears in
+    // the pattern's source text must resemble a plain identifier without any
+    // `::` namespace separators or other non-identifier characters.
+    if let PatKind::ExpandedConstant { def_id, .. } = pat.kind
+        && matches!(tcx.def_kind(def_id), DefKind::Const)
+        && let Ok(snippet) = tcx.sess.source_map().span_to_snippet(pat.span)
+        && snippet.chars().all(|c| c.is_alphanumeric() || c == '_')
+    {
+        Some(def_id)
+    } else {
+        None
+    }
+}
+
 /// Report that a match is not exhaustive.
 fn report_non_exhaustive_match<'p, 'tcx>(
     cx: &PatCtxt<'p, 'tcx>,
@@ -1303,12 +1318,7 @@ fn report_non_exhaustive_match<'p, 'tcx>(
 
     for &arm in arms {
         let arm = &thir.arms[arm];
-        if let PatKind::ExpandedConstant { def_id, .. } = arm.pattern.kind
-            && !matches!(cx.tcx.def_kind(def_id), DefKind::InlineConst)
-            && let Ok(snippet) = cx.tcx.sess.source_map().span_to_snippet(arm.pattern.span)
-            // We filter out paths with multiple path::segments.
-            && snippet.chars().all(|c| c.is_alphanumeric() || c == '_')
-        {
+        if let Some(def_id) = is_const_pat_that_looks_like_binding(cx.tcx, &arm.pattern) {
             let const_name = cx.tcx.item_name(def_id);
             err.span_label(
                 arm.pattern.span,

compiler/rustc_mir_build/src/thir/pattern/const_to_pat.rs

@@ -187,7 +187,7 @@ impl<'tcx> ConstToPat<'tcx> {
         }
 
         // Wrap the pattern in a marker node to indicate that it is the result of lowering a
-        // constant. This is used for diagnostics, and for unsafety checking of inline const blocks.
+        // constant. This is used for diagnostics.
         let kind = PatKind::ExpandedConstant { subpattern: inlined_const_as_pat, def_id: uv.def };
         Box::new(Pat { kind, ty, span: self.span })
     }

compiler/rustc_mir_build/src/thir/pattern/mod.rs

@@ -21,7 +21,6 @@ use rustc_middle::ty::adjustment::{PatAdjust, PatAdjustment};
 use rustc_middle::ty::layout::IntegerExt;
 use rustc_middle::ty::{self, CanonicalUserTypeAnnotation, Ty, TyCtxt};
 use rustc_middle::{bug, span_bug};
-use rustc_span::def_id::DefId;
 use rustc_span::{ErrorGuaranteed, Span};
 use tracing::{debug, instrument};
 
@@ -131,9 +130,8 @@ impl<'tcx> PatCtxt<'tcx> {
     fn lower_pattern_range_endpoint(
         &mut self,
         expr: Option<&'tcx hir::PatExpr<'tcx>>,
-        // Out-parameters collecting extra data to be reapplied by the caller
+        // Out-parameter collecting extra data to be reapplied by the caller
         ascriptions: &mut Vec<Ascription<'tcx>>,
-        expanded_consts: &mut Vec<DefId>,
     ) -> Result<Option<PatRangeBoundary<'tcx>>, ErrorGuaranteed> {
         let Some(expr) = expr else { return Ok(None) };
 
@@ -148,8 +146,10 @@ impl<'tcx> PatCtxt<'tcx> {
                     ascriptions.push(ascription);
                     kind = subpattern.kind;
                 }
-                PatKind::ExpandedConstant { def_id, subpattern } => {
-                    expanded_consts.push(def_id);
+                PatKind::ExpandedConstant { def_id: _, subpattern } => {
+                    // Expanded-constant nodes are currently only needed by
+                    // diagnostics that don't apply to range patterns, so we
+                    // can just discard them here.
                     kind = subpattern.kind;
                 }
                 _ => break,
@@ -227,10 +227,7 @@ impl<'tcx> PatCtxt<'tcx> {
 
         // Collect extra data while lowering the endpoints, to be reapplied later.
         let mut ascriptions = vec![];
-        let mut expanded_consts = vec![];
-
-        let mut lower_endpoint =
-            |expr| self.lower_pattern_range_endpoint(expr, &mut ascriptions, &mut expanded_consts);
+        let mut lower_endpoint = |expr| self.lower_pattern_range_endpoint(expr, &mut ascriptions);
 
         let lo = lower_endpoint(lo_expr)?.unwrap_or(PatRangeBoundary::NegInfinity);
         let hi = lower_endpoint(hi_expr)?.unwrap_or(PatRangeBoundary::PosInfinity);
@@ -282,10 +279,11 @@ impl<'tcx> PatCtxt<'tcx> {
             let subpattern = Box::new(Pat { span, ty, kind });
             kind = PatKind::AscribeUserType { ascription, subpattern };
         }
-        for def_id in expanded_consts {
-            let subpattern = Box::new(Pat { span, ty, kind });
-            kind = PatKind::ExpandedConstant { def_id, subpattern };
-        }
+        // `PatKind::ExpandedConstant` wrappers from range endpoints used to
+        // also be preserved here, but that was only needed for unsafeck of
+        // inline `const { .. }` patterns, which were removed by
+        // <https://github.com/rust-lang/rust/pull/138492>.
+
         Ok(kind)
     }
 

library/core/src/char/convert.rs

@@ -45,6 +45,7 @@ impl const From<char> for u32 {
     /// ```
     /// let c = 'c';
     /// let u = u32::from(c);
+    ///
     /// assert!(4 == size_of_val(&u))
     /// ```
     #[inline]
@@ -63,6 +64,7 @@ impl const From<char> for u64 {
     /// ```
     /// let c = '👤';
     /// let u = u64::from(c);
+    ///
     /// assert!(8 == size_of_val(&u))
     /// ```
     #[inline]
@@ -83,6 +85,7 @@ impl const From<char> for u128 {
     /// ```
     /// let c = '⚙';
     /// let u = u128::from(c);
+    ///
     /// assert!(16 == size_of_val(&u))
     /// ```
     #[inline]
@@ -93,8 +96,8 @@ impl const From<char> for u128 {
     }
 }
 
-/// Maps a `char` with code point in U+0000..=U+00FF to a byte in 0x00..=0xFF with same value,
-/// failing if the code point is greater than U+00FF.
+/// Maps a `char` with a code point from U+0000 to U+00FF (inclusive) to a byte in `0x00..=0xFF` with
+/// the same value, failing if the code point is greater than U+00FF.
 ///
 /// See [`impl From<u8> for char`](char#impl-From<u8>-for-char) for details on the encoding.
 #[stable(feature = "u8_from_char", since = "1.59.0")]
@@ -109,6 +112,7 @@ impl const TryFrom<char> for u8 {
     /// ```
     /// let a = 'ÿ'; // U+00FF
     /// let b = 'Ā'; // U+0100
+    ///
     /// assert_eq!(u8::try_from(a), Ok(0xFF_u8));
     /// assert!(u8::try_from(b).is_err());
     /// ```
@@ -122,8 +126,8 @@ impl const TryFrom<char> for u8 {
     }
 }
 
-/// Maps a `char` with code point in U+0000..=U+FFFF to a `u16` in 0x0000..=0xFFFF with same value,
-/// failing if the code point is greater than U+FFFF.
+/// Maps a `char` with a code point from U+0000 to U+FFFF (inclusive) to a `u16` in `0x0000..=0xFFFF`
+/// with the same value, failing if the code point is greater than U+FFFF.
 ///
 /// This corresponds to the UCS-2 encoding, as specified in ISO/IEC 10646:2003.
 #[stable(feature = "u16_from_char", since = "1.74.0")]
@@ -138,6 +142,7 @@ impl const TryFrom<char> for u16 {
     /// ```
     /// let trans_rights = '⚧'; // U+26A7
     /// let ninjas = '🥷'; // U+1F977
+    ///
     /// assert_eq!(u16::try_from(trans_rights), Ok(0x26A7_u16));
     /// assert!(u16::try_from(ninjas).is_err());
     /// ```
@@ -151,7 +156,45 @@ impl const TryFrom<char> for u16 {
     }
 }
 
-/// Maps a byte in 0x00..=0xFF to a `char` whose code point has the same value, in U+0000..=U+00FF.
+/// Maps a `char` with a code point from U+0000 to U+10FFFF (inclusive) to a `usize` in
+/// `0x0000..=0x10FFFF` with the same value, failing if the final value is unrepresentable by
+/// `usize`.
+///
+/// Generally speaking, this conversion can be seen as obtaining the character's corresponding
+/// UTF-32 code point to the extent representable by pointer addresses.
+#[stable(feature = "usize_try_from_char", since = "CURRENT_RUSTC_VERSION")]
+#[rustc_const_unstable(feature = "const_convert", issue = "143773")]
+impl const TryFrom<char> for usize {
+    type Error = TryFromCharError;
+
+    /// Tries to convert a [`char`] into a [`usize`].
+    ///
+    /// # Examples
+    ///
+    /// ```
+    /// let a = '\u{FFFF}'; // Always succeeds.
+    /// let b = '\u{10FFFF}'; // Conditionally succeeds.
+    ///
+    /// assert_eq!(usize::try_from(a), Ok(0xFFFF));
+    ///
+    /// if size_of::<usize>() >= size_of::<u32>() {
+    ///     assert_eq!(usize::try_from(b), Ok(0x10FFFF));
+    /// } else {
+    ///     assert!(matches!(usize::try_from(b), Err(_)));
+    /// }
+    /// ```
+    #[inline]
+    fn try_from(c: char) -> Result<usize, Self::Error> {
+        // FIXME(const-hack): this should use map_err instead
+        match usize::try_from(u32::from(c)) {
+            Ok(x) => Ok(x),
+            Err(_) => Err(TryFromCharError(())),
+        }
+    }
+}
+
+/// Maps a byte in `0x00..=0xFF` to a `char` whose code point has the same value from U+0000 to U+00FF
+/// (inclusive).
 ///
 /// Unicode is designed such that this effectively decodes bytes
 /// with the character encoding that IANA calls ISO-8859-1.
@@ -179,6 +222,7 @@ impl const From<u8> for char {
     /// ```
     /// let u = 32 as u8;
     /// let c = char::from(u);
+    ///
     /// assert!(4 == size_of_val(&c))
     /// ```
     #[inline]
@@ -246,7 +290,6 @@ const fn char_try_from_u32(i: u32) -> Result<char, CharTryFromError> {
     // Subtracting 0x800 causes 0x0000..0x0800 to wrap, meaning that a single
     // unsigned comparison against 0x110000 - 0x800 will detect both the wrapped
     // surrogate range as well as the numbers originally larger than 0x110000.
-    //
     if (i ^ 0xD800).wrapping_sub(0x800) >= 0x110000 - 0x800 {
         Err(CharTryFromError(()))
     } else {

library/std/src/sys/fs/unix.rs

@@ -2166,7 +2166,7 @@ fn open_from(from: &Path) -> io::Result<(crate::fs::File, crate::fs::Metadata)>
 
 fn set_times_impl(p: &CStr, times: FileTimes, follow_symlinks: bool) -> io::Result<()> {
     cfg_select! {
-       any(target_os = "redox", target_os = "espidf", target_os = "horizon", target_os = "nuttx", target_os = "vita") => {
+       any(target_os = "redox", target_os = "espidf", target_os = "horizon", target_os = "nuttx", target_os = "vita", target_os = "rtems") => {
             let _ = (p, times, follow_symlinks);
             Err(io::const_error!(
                 io::ErrorKind::Unsupported,