Auto merge of #125144 - fmease:rollup-4uft293, r=fmease

Rollup of 6 pull requests

Successful merges:

 - #124307 (Optimize character escaping.)
 - #124975 (Use an helper to move the files)
 - #125027 (Migrate `run-make/c-link-to-rust-staticlib` to `rmake`)
 - #125038 (Invert comparison in `uN::checked_sub`)
 - #125104 (Migrate `run-make/no-cdylib-as-rdylib` to `rmake`)
 - #125137 (MIR operators: clarify Shl/Shr handling of negative offsets)

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

compiler/rustc_middle/src/mir/syntax.rs

@@ -1480,13 +1480,17 @@ pub enum BinOp {
     BitOr,
     /// The `<<` operator (shift left)
     ///
-    /// The offset is truncated to the size of the first operand and made unsigned before shifting.
+    /// The offset is (uniquely) determined as follows:
+    /// - it is "equal modulo LHS::BITS" to the RHS
+    /// - it is in the range `0..LHS::BITS`
     Shl,
     /// Like `Shl`, but is UB if the RHS >= LHS::BITS or RHS < 0
     ShlUnchecked,
     /// The `>>` operator (shift right)
     ///
-    /// The offset is truncated to the size of the first operand and made unsigned before shifting.
+    /// The offset is (uniquely) determined as follows:
+    /// - it is "equal modulo LHS::BITS" to the RHS
+    /// - it is in the range `0..LHS::BITS`
     ///
     /// This is an arithmetic shift if the LHS is signed
     /// and a logical shift if the LHS is unsigned.

library/core/src/ascii.rs

@@ -91,17 +91,21 @@
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn escape_default(c: u8) -> EscapeDefault {
-    let mut data = [Char::Null; 4];
+    EscapeDefault::new(c)
-    let range = escape::escape_ascii_into(&mut data, c);
-    EscapeDefault(escape::EscapeIterInner::new(data, range))
 }
 
 impl EscapeDefault {
-    pub(crate) fn empty() -> Self {
+    #[inline]
-        let data = [Char::Null; 4];
+    pub(crate) const fn new(c: u8) -> Self {
-        EscapeDefault(escape::EscapeIterInner::new(data, 0..0))
+        Self(escape::EscapeIterInner::ascii(c))
     }
 
+    #[inline]
+    pub(crate) fn empty() -> Self {
+        Self(escape::EscapeIterInner::empty())
+    }
+
+    #[inline]
     pub(crate) fn as_str(&self) -> &str {
         self.0.as_str()
     }

library/core/src/char/methods.rs

@@ -449,10 +449,10 @@ pub(crate) fn escape_debug_ext(self, args: EscapeDebugExtArgs) -> EscapeDebug {
             '\"' if args.escape_double_quote => EscapeDebug::backslash(ascii::Char::QuotationMark),
             '\'' if args.escape_single_quote => EscapeDebug::backslash(ascii::Char::Apostrophe),
             _ if args.escape_grapheme_extended && self.is_grapheme_extended() => {
-                EscapeDebug::from_unicode(self.escape_unicode())
+                EscapeDebug::unicode(self)
             }
             _ if is_printable(self) => EscapeDebug::printable(self),
-            _ => EscapeDebug::from_unicode(self.escape_unicode()),
+            _ => EscapeDebug::unicode(self),
         }
     }
 
@@ -555,9 +555,9 @@ pub fn escape_default(self) -> EscapeDefault {
             '\t' => EscapeDefault::backslash(ascii::Char::SmallT),
             '\r' => EscapeDefault::backslash(ascii::Char::SmallR),
             '\n' => EscapeDefault::backslash(ascii::Char::SmallN),
-            '\\' | '\'' | '"' => EscapeDefault::backslash(self.as_ascii().unwrap()),
+            '\\' | '\'' | '\"' => EscapeDefault::backslash(self.as_ascii().unwrap()),
             '\x20'..='\x7e' => EscapeDefault::printable(self.as_ascii().unwrap()),
-            _ => EscapeDefault::from_unicode(self.escape_unicode()),
+            _ => EscapeDefault::unicode(self),
         }
     }
 

library/core/src/char/mod.rs

@@ -152,10 +152,9 @@ pub const fn from_digit(num: u32, radix: u32) -> Option<char> {
 pub struct EscapeUnicode(escape::EscapeIterInner<10>);
 
 impl EscapeUnicode {
-    fn new(chr: char) -> Self {
+    #[inline]
-        let mut data = [ascii::Char::Null; 10];
+    const fn new(c: char) -> Self {
-        let range = escape::escape_unicode_into(&mut data, chr);
+        Self(escape::EscapeIterInner::unicode(c))
-        Self(escape::EscapeIterInner::new(data, range))
     }
 }
 
@@ -219,18 +218,19 @@ fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
 pub struct EscapeDefault(escape::EscapeIterInner<10>);
 
 impl EscapeDefault {
-    fn printable(chr: ascii::Char) -> Self {
+    #[inline]
-        let data = [chr];
+    const fn printable(c: ascii::Char) -> Self {
-        Self(escape::EscapeIterInner::from_array(data))
+        Self(escape::EscapeIterInner::ascii(c.to_u8()))
     }
 
-    fn backslash(chr: ascii::Char) -> Self {
+    #[inline]
-        let data = [ascii::Char::ReverseSolidus, chr];
+    const fn backslash(c: ascii::Char) -> Self {
-        Self(escape::EscapeIterInner::from_array(data))
+        Self(escape::EscapeIterInner::backslash(c))
     }
 
-    fn from_unicode(esc: EscapeUnicode) -> Self {
+    #[inline]
-        Self(esc.0)
+    const fn unicode(c: char) -> Self {
+        Self(escape::EscapeIterInner::unicode(c))
     }
 }
 
@@ -304,23 +304,24 @@ enum EscapeDebugInner {
 }
 
 impl EscapeDebug {
-    fn printable(chr: char) -> Self {
+    #[inline]
+    const fn printable(chr: char) -> Self {
         Self(EscapeDebugInner::Char(chr))
     }
 
-    fn backslash(chr: ascii::Char) -> Self {
+    #[inline]
-        let data = [ascii::Char::ReverseSolidus, chr];
+    const fn backslash(c: ascii::Char) -> Self {
-        let iter = escape::EscapeIterInner::from_array(data);
+        Self(EscapeDebugInner::Bytes(escape::EscapeIterInner::backslash(c)))
-        Self(EscapeDebugInner::Bytes(iter))
     }
 
-    fn from_unicode(esc: EscapeUnicode) -> Self {
+    #[inline]
-        Self(EscapeDebugInner::Bytes(esc.0))
+    const fn unicode(c: char) -> Self {
+        Self(EscapeDebugInner::Bytes(escape::EscapeIterInner::unicode(c)))
     }
 
+    #[inline]
     fn clear(&mut self) {
-        let bytes = escape::EscapeIterInner::from_array([]);
+        self.0 = EscapeDebugInner::Bytes(escape::EscapeIterInner::empty());
-        self.0 = EscapeDebugInner::Bytes(bytes);
     }
 }
 
@@ -339,6 +340,7 @@ fn next(&mut self) -> Option<char> {
         }
     }
 
+    #[inline]
     fn size_hint(&self) -> (usize, Option<usize>) {
         let n = self.len();
         (n, Some(n))

library/core/src/escape.rs

@@ -6,56 +6,79 @@
 
 const HEX_DIGITS: [ascii::Char; 16] = *b"0123456789abcdef".as_ascii().unwrap();
 
-/// Escapes a byte into provided buffer; returns length of escaped
+#[inline]
-/// representation.
+const fn backslash<const N: usize>(a: ascii::Char) -> ([ascii::Char; N], Range<u8>) {
-pub(crate) fn escape_ascii_into(output: &mut [ascii::Char; 4], byte: u8) -> Range<u8> {
+    const { assert!(N >= 2) };
-    #[inline]
-    fn backslash(a: ascii::Char) -> ([ascii::Char; 4], u8) {
-        ([ascii::Char::ReverseSolidus, a, ascii::Char::Null, ascii::Char::Null], 2)
-    }
 
-    let (data, len) = match byte {
+    let mut output = [ascii::Char::Null; N];
+
+    output[0] = ascii::Char::ReverseSolidus;
+    output[1] = a;
+
+    (output, 0..2)
+}
+
+/// Escapes an ASCII character.
+///
+/// Returns a buffer and the length of the escaped representation.
+const fn escape_ascii<const N: usize>(byte: u8) -> ([ascii::Char; N], Range<u8>) {
+    const { assert!(N >= 4) };
+
+    match byte {
         b'\t' => backslash(ascii::Char::SmallT),
         b'\r' => backslash(ascii::Char::SmallR),
         b'\n' => backslash(ascii::Char::SmallN),
         b'\\' => backslash(ascii::Char::ReverseSolidus),
         b'\'' => backslash(ascii::Char::Apostrophe),
         b'\"' => backslash(ascii::Char::QuotationMark),
-        _ => {
+        byte => {
-            if let Some(a) = byte.as_ascii()
+            let mut output = [ascii::Char::Null; N];
+
+            if let Some(c) = byte.as_ascii()
                 && !byte.is_ascii_control()
             {
-                ([a, ascii::Char::Null, ascii::Char::Null, ascii::Char::Null], 1)
+                output[0] = c;
+                (output, 0..1)
             } else {
-                let hi = HEX_DIGITS[usize::from(byte >> 4)];
+                let hi = HEX_DIGITS[(byte >> 4) as usize];
-                let lo = HEX_DIGITS[usize::from(byte & 0xf)];
+                let lo = HEX_DIGITS[(byte & 0xf) as usize];
-                ([ascii::Char::ReverseSolidus, ascii::Char::SmallX, hi, lo], 4)
+
+                output[0] = ascii::Char::ReverseSolidus;
+                output[1] = ascii::Char::SmallX;
+                output[2] = hi;
+                output[3] = lo;
+
+                (output, 0..4)
             }
         }
-    };
+    }
-    *output = data;
-    0..len
 }
 
-/// Escapes a character into provided buffer using `\u{NNNN}` representation.
+/// Escapes a character `\u{NNNN}` representation.
-pub(crate) fn escape_unicode_into(output: &mut [ascii::Char; 10], ch: char) -> Range<u8> {
+///
+/// Returns a buffer and the length of the escaped representation.
+const fn escape_unicode<const N: usize>(c: char) -> ([ascii::Char; N], Range<u8>) {
+    const { assert!(N >= 10 && N < u8::MAX as usize) };
+
+    let c = u32::from(c);
+
+    // OR-ing `1` ensures that for `c == 0` the code computes that
+    // one digit should be printed.
+    let start = (c | 1).leading_zeros() as usize / 4 - 2;
+
+    let mut output = [ascii::Char::Null; N];
+    output[3] = HEX_DIGITS[((c >> 20) & 15) as usize];
+    output[4] = HEX_DIGITS[((c >> 16) & 15) as usize];
+    output[5] = HEX_DIGITS[((c >> 12) & 15) as usize];
+    output[6] = HEX_DIGITS[((c >> 8) & 15) as usize];
+    output[7] = HEX_DIGITS[((c >> 4) & 15) as usize];
+    output[8] = HEX_DIGITS[((c >> 0) & 15) as usize];
     output[9] = ascii::Char::RightCurlyBracket;
+    output[start + 0] = ascii::Char::ReverseSolidus;
+    output[start + 1] = ascii::Char::SmallU;
+    output[start + 2] = ascii::Char::LeftCurlyBracket;
 
-    let ch = ch as u32;
+    (output, (start as u8)..(N as u8))
-    output[3] = HEX_DIGITS[((ch >> 20) & 15) as usize];
-    output[4] = HEX_DIGITS[((ch >> 16) & 15) as usize];
-    output[5] = HEX_DIGITS[((ch >> 12) & 15) as usize];
-    output[6] = HEX_DIGITS[((ch >> 8) & 15) as usize];
-    output[7] = HEX_DIGITS[((ch >> 4) & 15) as usize];
-    output[8] = HEX_DIGITS[((ch >> 0) & 15) as usize];
-
-    // or-ing 1 ensures that for ch==0 the code computes that one digit should
-    // be printed.
-    let start = (ch | 1).leading_zeros() as usize / 4 - 2;
-    const UNICODE_ESCAPE_PREFIX: &[ascii::Char; 3] = b"\\u{".as_ascii().unwrap();
-    output[start..][..3].copy_from_slice(UNICODE_ESCAPE_PREFIX);
-
-    (start as u8)..10
 }
 
 /// An iterator over an fixed-size array.
@@ -65,45 +88,63 @@
 #[derive(Clone, Debug)]
 pub(crate) struct EscapeIterInner<const N: usize> {
     // The element type ensures this is always ASCII, and thus also valid UTF-8.
-    pub(crate) data: [ascii::Char; N],
+    data: [ascii::Char; N],
 
-    // Invariant: alive.start <= alive.end <= N.
+    // Invariant: `alive.start <= alive.end <= N`
-    pub(crate) alive: Range<u8>,
+    alive: Range<u8>,
 }
 
 impl<const N: usize> EscapeIterInner<N> {
-    pub fn new(data: [ascii::Char; N], alive: Range<u8>) -> Self {
+    pub const fn backslash(c: ascii::Char) -> Self {
-        const { assert!(N < 256) };
+        let (data, range) = backslash(c);
-        debug_assert!(alive.start <= alive.end && usize::from(alive.end) <= N, "{alive:?}");
+        Self { data, alive: range }
-        Self { data, alive }
     }
 
-    pub fn from_array<const M: usize>(array: [ascii::Char; M]) -> Self {
+    pub const fn ascii(c: u8) -> Self {
-        const { assert!(M <= N) };
+        let (data, range) = escape_ascii(c);
-
+        Self { data, alive: range }
-        let mut data = [ascii::Char::Null; N];
-        data[..M].copy_from_slice(&array);
-        Self::new(data, 0..M as u8)
     }
 
+    pub const fn unicode(c: char) -> Self {
+        let (data, range) = escape_unicode(c);
+        Self { data, alive: range }
+    }
+
+    #[inline]
+    pub const fn empty() -> Self {
+        Self { data: [ascii::Char::Null; N], alive: 0..0 }
+    }
+
+    #[inline]
     pub fn as_ascii(&self) -> &[ascii::Char] {
-        &self.data[usize::from(self.alive.start)..usize::from(self.alive.end)]
+        // SAFETY: `self.alive` is guaranteed to be a valid range for indexing `self.data`.
+        unsafe {
+            self.data.get_unchecked(usize::from(self.alive.start)..usize::from(self.alive.end))
+        }
     }
 
+    #[inline]
     pub fn as_str(&self) -> &str {
         self.as_ascii().as_str()
     }
 
+    #[inline]
     pub fn len(&self) -> usize {
         usize::from(self.alive.end - self.alive.start)
     }
 
     pub fn next(&mut self) -> Option<u8> {
-        self.alive.next().map(|i| self.data[usize::from(i)].to_u8())
+        let i = self.alive.next()?;
+
+        // SAFETY: `i` is guaranteed to be a valid index for `self.data`.
+        unsafe { Some(self.data.get_unchecked(usize::from(i)).to_u8()) }
     }
 
     pub fn next_back(&mut self) -> Option<u8> {
-        self.alive.next_back().map(|i| self.data[usize::from(i)].to_u8())
+        let i = self.alive.next_back()?;
+
+        // SAFETY: `i` is guaranteed to be a valid index for `self.data`.
+        unsafe { Some(self.data.get_unchecked(usize::from(i)).to_u8()) }
     }
 
     pub fn advance_by(&mut self, n: usize) -> Result<(), NonZero<usize>> {

library/core/src/num/uint_macros.rs

@@ -584,11 +584,11 @@ pub const fn checked_sub(self, rhs: Self) -> Option<Self> {
             // Thus, rather than using `overflowing_sub` that produces a wrapping
             // subtraction, check it ourself so we can use an unchecked one.
 
-            if self >= rhs {
+            if self < rhs {
+                None
+            } else {
                 // SAFETY: just checked this can't overflow
                 Some(unsafe { intrinsics::unchecked_sub(self, rhs) })
-            } else {
-                None
             }
         }
 

src/bootstrap/src/core/build_steps/dist.rs

@@ -26,7 +26,9 @@
 use crate::core::builder::{Builder, Kind, RunConfig, ShouldRun, Step};
 use crate::core::config::TargetSelection;
 use crate::utils::channel::{self, Info};
-use crate::utils::helpers::{exe, is_dylib, output, t, target_supports_cranelift_backend, timeit};
+use crate::utils::helpers::{
+    exe, is_dylib, move_file, output, t, target_supports_cranelift_backend, timeit,
+};
 use crate::utils::tarball::{GeneratedTarball, OverlayKind, Tarball};
 use crate::{Compiler, DependencyType, Mode, LLVM_TOOLS};
 
@@ -2024,7 +2026,7 @@ fn filter(contents: &str, marker: &str) -> String {
             builder.run(&mut cmd);
 
             if !builder.config.dry_run() {
-                t!(fs::rename(exe.join(&filename), distdir(builder).join(&filename)));
+                t!(move_file(exe.join(&filename), distdir(builder).join(&filename)));
             }
         }
     }

src/bootstrap/src/core/download.rs

@@ -12,7 +12,7 @@
 use build_helper::stage0_parser::VersionMetadata;
 use xz2::bufread::XzDecoder;
 
-use crate::utils::helpers::{check_run, exe, program_out_of_date};
+use crate::utils::helpers::{check_run, exe, move_file, program_out_of_date};
 use crate::{core::build_steps::llvm::detect_llvm_sha, utils::helpers::hex_encode};
 use crate::{t, Config};
 
@@ -209,7 +209,7 @@ fn download_file(&self, url: &str, dest_path: &Path, help_on_error: &str) {
             None => panic!("no protocol in {url}"),
         }
         t!(
-            std::fs::rename(&tempfile, dest_path),
+            move_file(&tempfile, dest_path),
             format!("failed to rename {tempfile:?} to {dest_path:?}")
         );
     }
@@ -313,7 +313,7 @@ fn unpack(&self, tarball: &Path, dst: &Path, pattern: &str) {
             if src_path.is_dir() && dst_path.exists() {
                 continue;
             }
-            t!(fs::rename(src_path, dst_path));
+            t!(move_file(src_path, dst_path));
         }
         let dst_dir = dst.join(directory_prefix);
         if dst_dir.exists() {

src/bootstrap/src/utils/helpers.rs

@@ -150,6 +150,21 @@ fn symlink_dir_inner(target: &Path, junction: &Path) -> io::Result<()> {
     }
 }
 
+/// Rename a file if from and to are in the same filesystem or
+/// copy and remove the file otherwise
+pub fn move_file<P: AsRef<Path>, Q: AsRef<Path>>(from: P, to: Q) -> io::Result<()> {
+    match fs::rename(&from, &to) {
+        // FIXME: Once `ErrorKind::CrossesDevices` is stabilized use
+        // if e.kind() == io::ErrorKind::CrossesDevices {
+        #[cfg(unix)]
+        Err(e) if e.raw_os_error() == Some(libc::EXDEV) => {
+            std::fs::copy(&from, &to)?;
+            std::fs::remove_file(&from)
+        }
+        r => r,
+    }
+}
+
 pub fn forcing_clang_based_tests() -> bool {
     if let Some(var) = env::var_os("RUSTBUILD_FORCE_CLANG_BASED_TESTS") {
         match &var.to_string_lossy().to_lowercase()[..] {

src/bootstrap/src/utils/tarball.rs

@@ -13,7 +13,7 @@
 use crate::core::builder::Builder;
 use crate::core::{build_steps::dist::distdir, builder::Kind};
 use crate::utils::channel;
-use crate::utils::helpers::t;
+use crate::utils::helpers::{move_file, t};
 
 #[derive(Copy, Clone)]
 pub(crate) enum OverlayKind {
@@ -284,7 +284,7 @@ pub(crate) fn bare(self) -> GeneratedTarball {
         // name, not "image". We rename the image directory just before passing
         // into rust-installer.
         let dest = self.temp_dir.join(self.package_name());
-        t!(std::fs::rename(&self.image_dir, &dest));
+        t!(move_file(&self.image_dir, &dest));
 
         self.run(|this, cmd| {
             let distdir = distdir(this.builder);

src/tools/tidy/src/allowed_run_make_makefiles.txt

@@ -8,7 +8,6 @@ run-make/branch-protection-check-IBT/Makefile
 run-make/c-dynamic-dylib/Makefile
 run-make/c-dynamic-rlib/Makefile
 run-make/c-link-to-rust-dylib/Makefile
-run-make/c-link-to-rust-staticlib/Makefile
 run-make/c-static-dylib/Makefile
 run-make/c-static-rlib/Makefile
 run-make/c-unwind-abi-catch-lib-panic/Makefile
@@ -179,7 +178,6 @@ run-make/native-link-modifier-whole-archive/Makefile
 run-make/no-alloc-shim/Makefile
 run-make/no-builtins-attribute/Makefile
 run-make/no-builtins-lto/Makefile
-run-make/no-cdylib-as-rdylib/Makefile
 run-make/no-duplicate-libs/Makefile
 run-make/no-intermediate-extras/Makefile
 run-make/obey-crate-type-flag/Makefile

tests/run-make/c-link-to-rust-staticlib/Makefile

@@ -1,16 +0,0 @@
-# This test checks that C linking with Rust does not encounter any errors, with static libraries.
-# See https://github.com/rust-lang/rust/issues/10434
-
-# ignore-cross-compile
-include ../tools.mk
-
-# ignore-freebsd
-# FIXME
-
-all:
-	$(RUSTC) foo.rs
-	$(CC) bar.c $(call STATICLIB,foo) $(call OUT_EXE,bar) \
-		$(EXTRACFLAGS) $(EXTRACXXFLAGS)
-	$(call RUN,bar)
-	rm $(call STATICLIB,foo)
-	$(call RUN,bar)

tests/run-make/c-link-to-rust-staticlib/rmake.rs

@@ -0,0 +1,15 @@
+// This test checks that C linking with Rust does not encounter any errors, with a static library.
+// See https://github.com/rust-lang/rust/issues/10434
+
+//@ ignore-cross-compile
+
+use run_make_support::{cc, extra_c_flags, run, rustc, static_lib};
+use std::fs;
+
+fn main() {
+    rustc().input("foo.rs").run();
+    cc().input("bar.c").input(static_lib("foo")).out_exe("bar").args(&extra_c_flags()).run();
+    run("bar");
+    fs::remove_file(static_lib("foo"));
+    run("bar");
+}

tests/run-make/no-cdylib-as-rdylib/Makefile

@@ -1,16 +0,0 @@
-# ignore-cross-compile
-include ../tools.mk
-
-# Test that rustc will not attempt to link against a cdylib as if
-# it is a rust dylib when an rlib for the same crate is available.
-# Previously rustc didn't actually check if any further formats of
-# a crate which has been loaded are of the same version and if
-# they are actually valid. This caused a cdylib to be interpreted
-# as rust dylib as soon as the corresponding rlib was loaded. As
-# cdylibs don't export any rust symbols, linking would fail if
-# rustc decides to link against the cdylib rather than the rlib.
-
-all:
-	$(RUSTC) bar.rs --crate-type=rlib --crate-type=cdylib
-	$(RUSTC) foo.rs -C prefer-dynamic
-	$(call RUN,foo)

tests/run-make/no-cdylib-as-rdylib/rmake.rs

@@ -0,0 +1,16 @@
+// This test produces an rlib and a cdylib from bar.rs.
+// Then, foo.rs attempts to link to the bar library.
+// If the test passes, that means rustc favored the rlib and ignored the cdylib.
+// If the test fails, that is because the cdylib was picked, which does not export
+// any Rust symbols.
+// See https://github.com/rust-lang/rust/pull/113695
+
+//@ ignore-cross-compile
+
+use run_make_support::{run, rustc};
+
+fn main() {
+    rustc().input("bar.rs").crate_type("rlib").crate_type("cdylib").run();
+    rustc().input("foo.rs").arg("-Cprefer-dynamic").run();
+    run("foo");
+}