Auto merge of rust-lang#102097 - Dylan-DPC:rollup-gc75oh4, r=Dylan-DPC

Rollup of 7 pull requests

Successful merges:

 - rust-lang#89891 (`alloc`: add unstable cfg features `no_rc` and `no_sync`)
 - rust-lang#101995 (Add another example for `uN::carrying_mul`)
 - rust-lang#102031 (Adding ignore fuchsia tests for Backtrace, ErrorKind cases)
 - rust-lang#102041 (Improve `-Zmeta-stats` some more)
 - rust-lang#102045 (fix ConstProp handling of written_only_inside_own_block_locals)
 - rust-lang#102058 (Clarify Path::extension() semantics in docs abstract)
 - rust-lang#102059 (Use rebind instead of dummy binder in `SameTypeModuloInfer` relation)

Failed merges:

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

Author: bors

compiler/rustc_infer/src/infer/error_reporting/mod.rs

@@ -2765,7 +2765,7 @@ impl<'tcx> TypeRelation<'tcx> for SameTypeModuloInfer<'_, 'tcx> {
     where
         T: relate::Relate<'tcx>,
     {
-        Ok(ty::Binder::dummy(self.relate(a.skip_binder(), b.skip_binder())?))
+        Ok(a.rebind(self.relate(a.skip_binder(), b.skip_binder())?))
     }
 
     fn consts(

compiler/rustc_metadata/src/rmeta/encoder.rs

@@ -1066,32 +1066,32 @@ impl<'tcx> MutVisitor<'tcx> for ConstPropagator<'_, 'tcx> {
         let source_info = terminator.source_info;
         self.source_info = Some(source_info);
         self.super_terminator(terminator, location);
+        // Do NOT early return in this function, it does some crucial fixup of the state at the end!
         match &mut terminator.kind {
             TerminatorKind::Assert { expected, ref mut cond, .. } => {
                 if let Some(ref value) = self.eval_operand(&cond) {
                     trace!("assertion on {:?} should be {:?}", value, expected);
                     let expected = Scalar::from_bool(*expected);
-                    let Ok(value_const) = self.ecx.read_scalar(&value) else {
-                        // FIXME should be used use_ecx rather than a local match... but we have
-                        // quite a few of these read_scalar/read_immediate that need fixing.
-                        return
-                    };
-                    if expected != value_const {
-                        // Poison all places this operand references so that further code
-                        // doesn't use the invalid value
-                        match cond {
-                            Operand::Move(ref place) | Operand::Copy(ref place) => {
-                                Self::remove_const(&mut self.ecx, place.local);
+                    // FIXME should be used use_ecx rather than a local match... but we have
+                    // quite a few of these read_scalar/read_immediate that need fixing.
+                    if let Ok(value_const) = self.ecx.read_scalar(&value) {
+                        if expected != value_const {
+                            // Poison all places this operand references so that further code
+                            // doesn't use the invalid value
+                            match cond {
+                                Operand::Move(ref place) | Operand::Copy(ref place) => {
+                                    Self::remove_const(&mut self.ecx, place.local);
+                                }
+                                Operand::Constant(_) => {}
+                            }
+                        } else {
+                            if self.should_const_prop(value) {
+                                *cond = self.operand_from_scalar(
+                                    value_const,
+                                    self.tcx.types.bool,
+                                    source_info.span,
+                                );
                             }
-                            Operand::Constant(_) => {}
-                        }
-                    } else {
-                        if self.should_const_prop(value) {
-                            *cond = self.operand_from_scalar(
-                                value_const,
-                                self.tcx.types.bool,
-                                source_info.span,
-                            );
                         }
                     }
                 }

compiler/rustc_mir_transform/src/const_prop.rs

@@ -69,6 +69,8 @@
     any(not(feature = "miri-test-libstd"), test, doctest),
     no_global_oom_handling,
     not(no_global_oom_handling),
+    not(no_rc),
+    not(no_sync),
     target_has_atomic = "ptr"
 ))]
 #![no_std]
@@ -225,16 +227,17 @@ mod boxed {
 }
 pub mod borrow;
 pub mod collections;
-#[cfg(not(no_global_oom_handling))]
+#[cfg(all(not(no_rc), not(no_sync), not(no_global_oom_handling)))]
 pub mod ffi;
 pub mod fmt;
+#[cfg(not(no_rc))]
 pub mod rc;
 pub mod slice;
 pub mod str;
 pub mod string;
-#[cfg(target_has_atomic = "ptr")]
+#[cfg(all(not(no_rc), not(no_sync), target_has_atomic = "ptr"))]
 pub mod sync;
-#[cfg(all(not(no_global_oom_handling), target_has_atomic = "ptr"))]
+#[cfg(all(not(no_global_oom_handling), not(no_rc), not(no_sync), target_has_atomic = "ptr"))]
 pub mod task;
 #[cfg(test)]
 mod tests;

library/alloc/src/lib.rs

@@ -113,6 +113,9 @@ macro_rules! widening_impl {
         /// This returns the low-order (wrapping) bits and the high-order (overflow) bits
         /// of the result as two separate values, in that order.
         ///
+        /// If you also need to add a carry to the wide result, then you want
+        /// [`Self::carrying_mul`] instead.
+        ///
         /// # Examples
         ///
         /// Basic usage:
@@ -148,6 +151,8 @@ macro_rules! widening_impl {
         /// additional amount of overflow. This allows for chaining together multiple
         /// multiplications to create "big integers" which represent larger values.
         ///
+        /// If you don't need the `carry`, then you can use [`Self::widening_mul`] instead.
+        ///
         /// # Examples
         ///
         /// Basic usage:
@@ -167,6 +172,31 @@ macro_rules! widening_impl {
         )]
         /// ```
         ///
+        /// This is the core operation needed for scalar multiplication when
+        /// implementing it for wider-than-native types.
+        ///
+        /// ```
+        /// #![feature(bigint_helper_methods)]
+        /// fn scalar_mul_eq(little_endian_digits: &mut Vec<u16>, multiplicand: u16) {
+        ///     let mut carry = 0;
+        ///     for d in little_endian_digits.iter_mut() {
+        ///         (*d, carry) = d.carrying_mul(multiplicand, carry);
+        ///     }
+        ///     if carry != 0 {
+        ///         little_endian_digits.push(carry);
+        ///     }
+        /// }
+        ///
+        /// let mut v = vec![10, 20];
+        /// scalar_mul_eq(&mut v, 3);
+        /// assert_eq!(v, [30, 60]);
+        ///
+        /// assert_eq!(0x87654321_u64 * 0xFEED, 0x86D3D159E38D);
+        /// let mut v = vec![0x4321, 0x8765];
+        /// scalar_mul_eq(&mut v, 0xFEED);
+        /// assert_eq!(v, [0xE38D, 0xD159, 0x86D3]);
+        /// ```
+        ///
         /// If `carry` is zero, this is similar to [`overflowing_mul`](Self::overflowing_mul),
         /// except that it gives the value of the overflow instead of just whether one happened:
         ///

library/core/src/num/mod.rs

@@ -2401,7 +2401,7 @@ impl Path {
         self.file_name().map(split_file_at_dot).and_then(|(before, _after)| Some(before))
     }
 
-    /// Extracts the extension of [`self.file_name`], if possible.
+    /// Extracts the extension (without the leading dot) of [`self.file_name`], if possible.
     ///
     /// The extension is:
     ///

library/std/src/path.rs

@@ -201,6 +201,8 @@ const EXTRA_CHECK_CFGS: &[(Option<Mode>, &'static str, Option<&[&'static str]>)]
     (Some(Mode::Std), "stdarch_intel_sde", None),
     (Some(Mode::Std), "no_fp_fmt_parse", None),
     (Some(Mode::Std), "no_global_oom_handling", None),
+    (Some(Mode::Std), "no_rc", None),
+    (Some(Mode::Std), "no_sync", None),
     (Some(Mode::Std), "freebsd12", None),
     (Some(Mode::Std), "backtrace_in_libstd", None),
     /* Extra values not defined in the built-in targets yet, but used in std */

src/bootstrap/lib.rs

@@ -0,0 +1,20 @@
+// compile-flags: -O -C debug-assertions=on
+// This needs inlining followed by ConstProp to reproduce, so we cannot use "unit-test".
+
+#[inline]
+pub fn imm8(x: u32) -> u32 {
+    let mut out = 0u32;
+    out |= (x >> 0) & 0xff;
+    out
+}
+
+// EMIT_MIR issue_101973.inner.ConstProp.diff
+#[inline(never)]
+pub fn inner(fields: u32) -> i64 {
+    imm8(fields).rotate_right(((fields >> 8) & 0xf) << 1) as i32 as i64
+}
+
+fn main() {
+    let val = inner(0xe32cf20f);
+    assert_eq!(val as u64, 0xfffffffff0000000);
+}

src/test/mir-opt/issue-101973.rs

@@ -0,0 +1,100 @@
+- // MIR for `inner` before ConstProp
++ // MIR for `inner` after ConstProp
+  
+  fn inner(_1: u32) -> i64 {
+      debug fields => _1;                  // in scope 0 at $DIR/issue-101973.rs:+0:14: +0:20
+      let mut _0: i64;                     // return place in scope 0 at $DIR/issue-101973.rs:+0:30: +0:33
+      let mut _2: i32;                     // in scope 0 at $DIR/issue-101973.rs:+1:5: +1:65
+      let mut _3: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:5: +1:58
+      let mut _4: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:5: +1:17
+      let mut _5: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:10: +1:16
+      let mut _6: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+      let mut _7: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:31: +1:52
+      let mut _8: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+      let mut _9: u32;                     // in scope 0 at $DIR/issue-101973.rs:+1:33: +1:39
+      let mut _10: (u32, bool);            // in scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+      let mut _11: (u32, bool);            // in scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+      scope 1 (inlined imm8) {             // at $DIR/issue-101973.rs:14:5: 14:17
+          debug x => _5;                   // in scope 1 at $DIR/issue-101973.rs:5:13: 5:14
+          let mut _12: u32;                // in scope 1 at $DIR/issue-101973.rs:7:12: 7:27
+          let mut _13: u32;                // in scope 1 at $DIR/issue-101973.rs:7:12: 7:20
+          let mut _14: u32;                // in scope 1 at $DIR/issue-101973.rs:7:13: 7:14
+          let mut _15: (u32, bool);        // in scope 1 at $DIR/issue-101973.rs:7:12: 7:20
+          scope 2 {
+              debug out => _4;             // in scope 2 at $DIR/issue-101973.rs:6:9: 6:16
+          }
+      }
+      scope 3 (inlined core::num::<impl u32>::rotate_right) { // at $DIR/issue-101973.rs:14:5: 14:58
+          debug self => _4;                // in scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          debug n => _6;                   // in scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          let mut _16: u32;                // in scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          let mut _17: u32;                // in scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+      }
+  
+      bb0: {
+          StorageLive(_2);                 // scope 0 at $DIR/issue-101973.rs:+1:5: +1:65
+          StorageLive(_3);                 // scope 0 at $DIR/issue-101973.rs:+1:5: +1:58
+          StorageLive(_4);                 // scope 0 at $DIR/issue-101973.rs:+1:5: +1:17
+          StorageLive(_5);                 // scope 0 at $DIR/issue-101973.rs:+1:10: +1:16
+          _5 = _1;                         // scope 0 at $DIR/issue-101973.rs:+1:10: +1:16
+          _4 = const 0_u32;                // scope 1 at $DIR/issue-101973.rs:6:19: 6:23
+          StorageLive(_12);                // scope 2 at $DIR/issue-101973.rs:7:12: 7:27
+          StorageLive(_13);                // scope 2 at $DIR/issue-101973.rs:7:12: 7:20
+          StorageLive(_14);                // scope 2 at $DIR/issue-101973.rs:7:13: 7:14
+          _14 = _5;                        // scope 2 at $DIR/issue-101973.rs:7:13: 7:14
+          _15 = CheckedShr(_14, const 0_i32); // scope 2 at $DIR/issue-101973.rs:7:12: 7:20
+          assert(!move (_15.1: bool), "attempt to shift right by `{}`, which would overflow", const 0_i32) -> bb3; // scope 2 at $DIR/issue-101973.rs:7:12: 7:20
+      }
+  
+      bb1: {
+          _8 = move (_10.0: u32);          // scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+          StorageDead(_9);                 // scope 0 at $DIR/issue-101973.rs:+1:44: +1:45
+          _7 = BitAnd(move _8, const 15_u32); // scope 0 at $DIR/issue-101973.rs:+1:31: +1:52
+          StorageDead(_8);                 // scope 0 at $DIR/issue-101973.rs:+1:51: +1:52
+          _11 = CheckedShl(_7, const 1_i32); // scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+          assert(!move (_11.1: bool), "attempt to shift left by `{}`, which would overflow", const 1_i32) -> bb2; // scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+      }
+  
+      bb2: {
+          _6 = move (_11.0: u32);          // scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+          StorageDead(_7);                 // scope 0 at $DIR/issue-101973.rs:+1:56: +1:57
+          StorageLive(_16);                // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          _16 = _4;                        // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          StorageLive(_17);                // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          _17 = _6;                        // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          _3 = rotate_right::<u32>(move _16, move _17) -> bb4; // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+                                           // mir::Constant
+                                           // + span: $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+                                           // + literal: Const { ty: extern "rust-intrinsic" fn(u32, u32) -> u32 {rotate_right::<u32>}, val: Value(<ZST>) }
+      }
+  
+      bb3: {
+          _13 = move (_15.0: u32);         // scope 2 at $DIR/issue-101973.rs:7:12: 7:20
+          StorageDead(_14);                // scope 2 at $DIR/issue-101973.rs:7:19: 7:20
+          _12 = BitAnd(move _13, const 255_u32); // scope 2 at $DIR/issue-101973.rs:7:12: 7:27
+          StorageDead(_13);                // scope 2 at $DIR/issue-101973.rs:7:26: 7:27
+          _4 = BitOr(_4, move _12);        // scope 2 at $DIR/issue-101973.rs:7:5: 7:27
+          StorageDead(_12);                // scope 2 at $DIR/issue-101973.rs:7:26: 7:27
+          StorageDead(_5);                 // scope 0 at $DIR/issue-101973.rs:+1:16: +1:17
+          StorageLive(_6);                 // scope 0 at $DIR/issue-101973.rs:+1:31: +1:57
+          StorageLive(_7);                 // scope 0 at $DIR/issue-101973.rs:+1:31: +1:52
+          StorageLive(_8);                 // scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+          StorageLive(_9);                 // scope 0 at $DIR/issue-101973.rs:+1:33: +1:39
+          _9 = _1;                         // scope 0 at $DIR/issue-101973.rs:+1:33: +1:39
+          _10 = CheckedShr(_9, const 8_i32); // scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+          assert(!move (_10.1: bool), "attempt to shift right by `{}`, which would overflow", const 8_i32) -> bb1; // scope 0 at $DIR/issue-101973.rs:+1:32: +1:45
+      }
+  
+      bb4: {
+          StorageDead(_17);                // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          StorageDead(_16);                // scope 3 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
+          StorageDead(_6);                 // scope 0 at $DIR/issue-101973.rs:+1:57: +1:58
+          StorageDead(_4);                 // scope 0 at $DIR/issue-101973.rs:+1:57: +1:58
+          _2 = move _3 as i32 (Misc);      // scope 0 at $DIR/issue-101973.rs:+1:5: +1:65
+          StorageDead(_3);                 // scope 0 at $DIR/issue-101973.rs:+1:64: +1:65
+          _0 = move _2 as i64 (Misc);      // scope 0 at $DIR/issue-101973.rs:+1:5: +1:72
+          StorageDead(_2);                 // scope 0 at $DIR/issue-101973.rs:+1:71: +1:72
+          return;                          // scope 0 at $DIR/issue-101973.rs:+2:2: +2:2
+      }
+  }
+  

src/test/mir-opt/issue_101973.inner.ConstProp.diff

@@ -0,0 +1,4 @@
+include ../tools.mk
+
+all:
+	$(RUSTC) --edition=2021 -Dwarnings --crate-type=rlib ../../../../library/alloc/src/lib.rs --cfg no_rc