Auto merge of rust-lang#94761 - Dylan-DPC:rollup-v4emqsy, r=Dylan-DPC

Rollup of 6 pull requests

Successful merges:

 - rust-lang#94312 (Edit `rustc_trait_selection::infer::lattice` docs)
 - rust-lang#94583 (Add a team for '`@rustbot` ping fuchsia')
 - rust-lang#94686 (Do not allow `#[rustc_legacy_const_generics]` on methods)
 - rust-lang#94699 (BTree: remove dead data needlessly complicating insert)
 - rust-lang#94756 (Use `unreachable!` for an unreachable code path)
 - rust-lang#94759 (Update cargo)

Failed merges:

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

Cargo.lock

@@ -345,7 +345,6 @@ dependencies = [
  "libgit2-sys",
  "log",
  "memchr",
- "num_cpus",
  "opener",
  "openssl",
  "os_info",
@@ -1503,9 +1502,9 @@ dependencies = [
 
 [[package]]
 name = "git2"
-version = "0.13.23"
+version = "0.14.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2a8057932925d3a9d9e4434ea016570d37420ddb1ceed45a174d577f24ed6700"
+checksum = "6e7d3b96ec1fcaa8431cf04a4f1ef5caafe58d5cf7bcc31f09c1626adddb0ffe"
 dependencies = [
  "bitflags",
  "libc",
@@ -1518,9 +1517,9 @@ dependencies = [
 
 [[package]]
 name = "git2-curl"
-version = "0.14.1"
+version = "0.15.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "883539cb0ea94bab3f8371a98cd8e937bbe9ee7c044499184aa4c17deb643a50"
+checksum = "1ee51709364c341fbb6fe2a385a290fb9196753bdde2fc45447d27cd31b11b13"
 dependencies = [
  "curl",
  "git2",
@@ -1975,9 +1974,9 @@ dependencies = [
 
 [[package]]
 name = "libgit2-sys"
-version = "0.12.24+1.3.0"
+version = "0.13.1+1.4.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ddbd6021eef06fb289a8f54b3c2acfdd85ff2a585dfbb24b8576325373d2152c"
+checksum = "43e598aa7a4faedf1ea1b4608f582b06f0f40211eec551b7ef36019ae3f62def"
 dependencies = [
  "cc",
  "libc",

compiler/rustc_infer/src/infer/glb.rs

@@ -1,3 +1,5 @@
+//! Greatest lower bound. See [`lattice`].
+
 use super::combine::CombineFields;
 use super::lattice::{self, LatticeDir};
 use super::InferCtxt;

compiler/rustc_infer/src/infer/lattice.rs

@@ -1,23 +1,21 @@
-//! # Lattice Variables
+//! # Lattice variables
 //!
-//! This file contains generic code for operating on inference variables
-//! that are characterized by an upper- and lower-bound. The logic and
-//! reasoning is explained in detail in the large comment in `infer.rs`.
+//! Generic code for operating on [lattices] of inference variables
+//! that are characterized by an upper- and lower-bound.
 //!
-//! The code in here is defined quite generically so that it can be
+//! The code is defined quite generically so that it can be
 //! applied both to type variables, which represent types being inferred,
 //! and fn variables, which represent function types being inferred.
-//! It may eventually be applied to their types as well, who knows.
+//! (It may eventually be applied to their types as well.)
 //! In some cases, the functions are also generic with respect to the
 //! operation on the lattice (GLB vs LUB).
 //!
-//! Although all the functions are generic, we generally write the
-//! comments in a way that is specific to type variables and the LUB
-//! operation. It's just easier that way.
+//! ## Note
 //!
-//! In general all of the functions are defined parametrically
-//! over a `LatticeValue`, which is a value defined with respect to
-//! a lattice.
+//! Although all the functions are generic, for simplicity, comments in the source code
+//! generally refer to type variables and the LUB operation.
+//!
+//! [lattices]: https://en.wikipedia.org/wiki/Lattice_(order)
 
 use super::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
 use super::InferCtxt;
@@ -27,6 +25,11 @@ use rustc_middle::ty::relate::{RelateResult, TypeRelation};
 use rustc_middle::ty::TyVar;
 use rustc_middle::ty::{self, Ty};
 
+/// Trait for returning data about a lattice, and for abstracting
+/// over the "direction" of the lattice operation (LUB/GLB).
+///
+/// GLB moves "down" the lattice (to smaller values); LUB moves
+/// "up" the lattice (to bigger values).
 pub trait LatticeDir<'f, 'tcx>: TypeRelation<'tcx> {
     fn infcx(&self) -> &'f InferCtxt<'f, 'tcx>;
 
@@ -41,6 +44,7 @@ pub trait LatticeDir<'f, 'tcx>: TypeRelation<'tcx> {
     fn relate_bound(&mut self, v: Ty<'tcx>, a: Ty<'tcx>, b: Ty<'tcx>) -> RelateResult<'tcx, ()>;
 }
 
+/// Relates two types using a given lattice.
 pub fn super_lattice_tys<'a, 'tcx: 'a, L>(
     this: &mut L,
     a: Ty<'tcx>,

compiler/rustc_infer/src/infer/lub.rs

@@ -1,3 +1,5 @@
+//! Least upper bound. See [`lattice`].
+
 use super::combine::CombineFields;
 use super::lattice::{self, LatticeDir};
 use super::InferCtxt;

compiler/rustc_passes/src/check_attr.rs

@@ -1345,7 +1345,7 @@ impl CheckAttrVisitor<'_> {
         target: Target,
         item: Option<ItemLike<'_>>,
     ) -> bool {
-        let is_function = matches!(target, Target::Fn | Target::Method(..));
+        let is_function = matches!(target, Target::Fn);
         if !is_function {
             self.tcx
                 .sess

library/alloc/src/collections/btree/map/entry.rs

@@ -3,7 +3,7 @@ use core::marker::PhantomData;
 use core::mem;
 
 use super::super::borrow::DormantMutRef;
-use super::super::node::{marker, Handle, InsertResult::*, NodeRef};
+use super::super::node::{marker, Handle, NodeRef};
 use super::BTreeMap;
 
 use Entry::*;
@@ -313,13 +313,13 @@ impl<'a, K: Ord, V> VacantEntry<'a, K, V> {
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn insert(self, value: V) -> &'a mut V {
         let out_ptr = match self.handle.insert_recursing(self.key, value) {
-            (Fit(_), val_ptr) => {
+            (None, val_ptr) => {
                 // SAFETY: We have consumed self.handle and the handle returned.
                 let map = unsafe { self.dormant_map.awaken() };
                 map.length += 1;
                 val_ptr
             }
-            (Split(ins), val_ptr) => {
+            (Some(ins), val_ptr) => {
                 drop(ins.left);
                 // SAFETY: We have consumed self.handle and the reference returned.
                 let map = unsafe { self.dormant_map.awaken() };

library/alloc/src/collections/btree/node.rs

@@ -861,11 +861,10 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, mark
     /// this edge. This method splits the node if there isn't enough room.
     ///
     /// The returned pointer points to the inserted value.
-    fn insert(mut self, key: K, val: V) -> (InsertResult<'a, K, V, marker::Leaf>, *mut V) {
+    fn insert(mut self, key: K, val: V) -> (Option<SplitResult<'a, K, V, marker::Leaf>>, *mut V) {
         if self.node.len() < CAPACITY {
             let val_ptr = self.insert_fit(key, val);
-            let kv = unsafe { Handle::new_kv(self.node, self.idx) };
-            (InsertResult::Fit(kv), val_ptr)
+            (None, val_ptr)
         } else {
             let (middle_kv_idx, insertion) = splitpoint(self.idx);
             let middle = unsafe { Handle::new_kv(self.node, middle_kv_idx) };
@@ -879,7 +878,7 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, mark
                 },
             };
             let val_ptr = insertion_edge.insert_fit(key, val);
-            (InsertResult::Split(result), val_ptr)
+            (Some(result), val_ptr)
         }
     }
 }
@@ -923,13 +922,12 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>,
         key: K,
         val: V,
         edge: Root<K, V>,
-    ) -> InsertResult<'a, K, V, marker::Internal> {
+    ) -> Option<SplitResult<'a, K, V, marker::Internal>> {
         assert!(edge.height == self.node.height - 1);
 
         if self.node.len() < CAPACITY {
             self.insert_fit(key, val, edge);
-            let kv = unsafe { Handle::new_kv(self.node, self.idx) };
-            InsertResult::Fit(kv)
+            None
         } else {
             let (middle_kv_idx, insertion) = splitpoint(self.idx);
             let middle = unsafe { Handle::new_kv(self.node, middle_kv_idx) };
@@ -943,7 +941,7 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Internal>,
                 },
             };
             insertion_edge.insert_fit(key, val, edge);
-            InsertResult::Split(result)
+            Some(result)
         }
     }
 }
@@ -953,32 +951,26 @@ impl<'a, K: 'a, V: 'a> Handle<NodeRef<marker::Mut<'a>, K, V, marker::Leaf>, mark
     /// this edge. This method splits the node if there isn't enough room, and tries to
     /// insert the split off portion into the parent node recursively, until the root is reached.
     ///
-    /// If the returned result is a `Fit`, its handle's node can be this edge's node or an ancestor.
-    /// If the returned result is a `Split`, the `left` field will be the root node.
-    /// The returned pointer points to the inserted value.
+    /// If the returned result is some `SplitResult`, the `left` field will be the root node.
+    /// The returned pointer points to the inserted value, which in the case of `SplitResult`
+    /// is in the `left` or `right` tree.
     pub fn insert_recursing(
         self,
         key: K,
         value: V,
-    ) -> (InsertResult<'a, K, V, marker::LeafOrInternal>, *mut V) {
+    ) -> (Option<SplitResult<'a, K, V, marker::LeafOrInternal>>, *mut V) {
         let (mut split, val_ptr) = match self.insert(key, value) {
-            (InsertResult::Fit(handle), ptr) => {
-                return (InsertResult::Fit(handle.forget_node_type()), ptr);
-            }
-            (InsertResult::Split(split), val_ptr) => (split.forget_node_type(), val_ptr),
+            (None, val_ptr) => return (None, val_ptr),
+            (Some(split), val_ptr) => (split.forget_node_type(), val_ptr),
         };
 
         loop {
             split = match split.left.ascend() {
                 Ok(parent) => match parent.insert(split.kv.0, split.kv.1, split.right) {
-                    InsertResult::Fit(handle) => {
-                        return (InsertResult::Fit(handle.forget_node_type()), val_ptr);
-                    }
-                    InsertResult::Split(split) => split.forget_node_type(),
+                    None => return (None, val_ptr),
+                    Some(split) => split.forget_node_type(),
                 },
-                Err(root) => {
-                    return (InsertResult::Split(SplitResult { left: root, ..split }), val_ptr);
-                }
+                Err(root) => return (Some(SplitResult { left: root, ..split }), val_ptr),
             };
         }
     }
@@ -1529,14 +1521,6 @@ impl<BorrowType, K, V> Handle<NodeRef<BorrowType, K, V, marker::Leaf>, marker::K
     }
 }
 
-impl<BorrowType, K, V> Handle<NodeRef<BorrowType, K, V, marker::Internal>, marker::KV> {
-    pub fn forget_node_type(
-        self,
-    ) -> Handle<NodeRef<BorrowType, K, V, marker::LeafOrInternal>, marker::KV> {
-        unsafe { Handle::new_kv(self.node.forget_type(), self.idx) }
-    }
-}
-
 impl<BorrowType, K, V, Type> Handle<NodeRef<BorrowType, K, V, marker::LeafOrInternal>, Type> {
     /// Checks whether the underlying node is an `Internal` node or a `Leaf` node.
     pub fn force(
@@ -1621,7 +1605,7 @@ pub enum ForceResult<Leaf, Internal> {
 pub struct SplitResult<'a, K, V, NodeType> {
     // Altered node in existing tree with elements and edges that belong to the left of `kv`.
     pub left: NodeRef<marker::Mut<'a>, K, V, NodeType>,
-    // Some key and value split off, to be inserted elsewhere.
+    // Some key and value that existed before and were split off, to be inserted elsewhere.
     pub kv: (K, V),
     // Owned, unattached, new node with elements and edges that belong to the right of `kv`.
     pub right: NodeRef<marker::Owned, K, V, NodeType>,
@@ -1639,11 +1623,6 @@ impl<'a, K, V> SplitResult<'a, K, V, marker::Internal> {
     }
 }
 
-pub enum InsertResult<'a, K, V, NodeType> {
-    Fit(Handle<NodeRef<marker::Mut<'a>, K, V, NodeType>, marker::KV>),
-    Split(SplitResult<'a, K, V, NodeType>),
-}
-
 pub mod marker {
     use core::marker::PhantomData;
 

library/std/src/sys/windows/mod.rs

@@ -224,8 +224,14 @@ where
             } as usize;
             if k == n && c::GetLastError() == c::ERROR_INSUFFICIENT_BUFFER {
                 n *= 2;
-            } else if k >= n {
+            } else if k > n {
                 n = k;
+            } else if k == n {
+                // It is impossible to reach this point.
+                // On success, k is the returned string length excluding the null.
+                // On failure, k is the required buffer length including the null.
+                // Therefore k never equals n.
+                unreachable!();
             } else {
                 return Ok(f2(&buf[..k]));
             }

src/test/ui/invalid/invalid-rustc_legacy_const_generics-arguments.rs

@@ -29,6 +29,11 @@ extern {
 #[rustc_legacy_const_generics(0)] //~ ERROR #[rustc_legacy_const_generics] functions must only have
 fn foo8<X>() {}
 
+impl S {
+    #[rustc_legacy_const_generics(0)] //~ ERROR attribute should be applied to a function
+    fn foo9<const X: usize>() {}
+}
+
 #[rustc_legacy_const_generics] //~ ERROR malformed `rustc_legacy_const_generics` attribute
 fn bar1() {}
 

src/test/ui/invalid/invalid-rustc_legacy_const_generics-arguments.stderr

@@ -7,13 +7,13 @@ LL | #[rustc_legacy_const_generics(0usize)]
    = help: instead of using a suffixed literal (`1u8`, `1.0f32`, etc.), use an unsuffixed version (`1`, `1.0`, etc.)
 
 error: malformed `rustc_legacy_const_generics` attribute input
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:32:1
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:37:1
    |
 LL | #[rustc_legacy_const_generics]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[rustc_legacy_const_generics(N)]`
 
 error: malformed `rustc_legacy_const_generics` attribute input
-  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:35:1
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:40:1
    |
 LL | #[rustc_legacy_const_generics = 1]
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: must be of the form: `#[rustc_legacy_const_generics(N)]`
@@ -66,6 +66,14 @@ LL | #[rustc_legacy_const_generics(0)]
 LL | fn foo8<X>() {}
    |         - non-const generic parameter
 
+error: attribute should be applied to a function
+  --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:33:5
+   |
+LL |     #[rustc_legacy_const_generics(0)]
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+LL |     fn foo9<const X: usize>() {}
+   |     ---------------------------- not a function
+
 error: attribute should be applied to a function
   --> $DIR/invalid-rustc_legacy_const_generics-arguments.rs:25:5
    |
@@ -82,6 +90,6 @@ LL |     fn foo7<const X: usize>();
    |
    = help: replace the const parameters with concrete consts
 
-error: aborting due to 12 previous errors
+error: aborting due to 13 previous errors
 
 For more information about this error, try `rustc --explain E0044`.

triagebot.toml

@@ -73,6 +73,13 @@ Thanks! <3
 """
 label = "O-riscv"
 
+[ping.fuchsia]
+message = """\
+Hey friends of Fuchsia! This issue could use some guidance on how this should be
+resolved/implemented on Fuchsia. Could one of you weigh in?
+"""
+label = "O-fuchsia"
+
 [prioritize]
 label = "I-prioritize"