Auto merge of rust-lang#105512 - matthiaskrgr:rollup-i74avrf, r=matthiaskrgr

Rollup of 9 pull requests

Successful merges:

 - rust-lang#102406 (Make `missing_copy_implementations` more cautious)
 - rust-lang#105265 (Add `rustc_on_unimplemented` to `Sum` and `Product` trait.)
 - rust-lang#105385 (Skip test on s390x as LLD does not support the platform)
 - rust-lang#105453 (Make `VecDeque::from_iter` O(1) from `vec(_deque)::IntoIter`)
 - rust-lang#105468 (Mangle "main" as "__main_void" on wasm32-wasi)
 - rust-lang#105480 (rustdoc: remove no-op mobile CSS `#sidebar-toggle { text-align }`)
 - rust-lang#105489 (Fix typo in apple_base.rs)
 - rust-lang#105504 (rustdoc: make stability badge CSS more consistent)
 - rust-lang#105506 (Tweak `rustc_must_implement_one_of` diagnostic output)

Failed merges:

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

Author: bors

compiler/rustc_hir_analysis/src/collect.rs

@@ -955,7 +955,7 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
                     .struct_span_err(
                         attr.span,
                         "the `#[rustc_must_implement_one_of]` attribute must be \
-                        used with at least 2 args",
+                         used with at least 2 args",
                     )
                     .emit();
 
@@ -987,7 +987,7 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
                             tcx.sess
                                 .struct_span_err(
                                     item.span,
-                                    "This function doesn't have a default implementation",
+                                    "function doesn't have a default implementation",
                                 )
                                 .span_note(attr_span, "required by this annotation")
                                 .emit();
@@ -999,17 +999,17 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
                     }
                     Some(item) => {
                         tcx.sess
-                            .struct_span_err(item.span, "Not a function")
+                            .struct_span_err(item.span, "not a function")
                             .span_note(attr_span, "required by this annotation")
                             .note(
-                                "All `#[rustc_must_implement_one_of]` arguments \
-                            must be associated function names",
+                                "all `#[rustc_must_implement_one_of]` arguments must be associated \
+                                 function names",
                             )
                             .emit();
                     }
                     None => {
                         tcx.sess
-                            .struct_span_err(ident.span, "Function not found in this trait")
+                            .struct_span_err(ident.span, "function not found in this trait")
                             .emit();
                     }
                 }
@@ -1027,11 +1027,8 @@ fn trait_def(tcx: TyCtxt<'_>, def_id: DefId) -> ty::TraitDef {
             for ident in &*list {
                 if let Some(dup) = set.insert(ident.name, ident.span) {
                     tcx.sess
-                        .struct_span_err(vec![dup, ident.span], "Functions names are duplicated")
-                        .note(
-                            "All `#[rustc_must_implement_one_of]` arguments \
-                            must be unique",
-                        )
+                        .struct_span_err(vec![dup, ident.span], "functions names are duplicated")
+                        .note("all `#[rustc_must_implement_one_of]` arguments must be unique")
                         .emit();
 
                     no_dups = false;

compiler/rustc_lint/src/builtin.rs

@@ -53,7 +53,8 @@ use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{BytePos, InnerSpan, Span};
 use rustc_target::abi::{Abi, VariantIdx};
-use rustc_trait_selection::traits::{self, misc::can_type_implement_copy};
+use rustc_trait_selection::infer::{InferCtxtExt, TyCtxtInferExt};
+use rustc_trait_selection::traits::{self, misc::can_type_implement_copy, EvaluationResult};
 
 use crate::nonstandard_style::{method_context, MethodLateContext};
 
@@ -750,10 +751,39 @@ impl<'tcx> LateLintPass<'tcx> for MissingCopyImplementations {
         if def.has_dtor(cx.tcx) {
             return;
         }
+
+        // If the type contains a raw pointer, it may represent something like a handle,
+        // and recommending Copy might be a bad idea.
+        for field in def.all_fields() {
+            let did = field.did;
+            if cx.tcx.type_of(did).is_unsafe_ptr() {
+                return;
+            }
+        }
         let param_env = ty::ParamEnv::empty();
         if ty.is_copy_modulo_regions(cx.tcx, param_env) {
             return;
         }
+
+        // We shouldn't recommend implementing `Copy` on stateful things,
+        // such as iterators.
+        if let Some(iter_trait) = cx.tcx.get_diagnostic_item(sym::Iterator) {
+            if cx.tcx.infer_ctxt().build().type_implements_trait(iter_trait, [ty], param_env)
+                == EvaluationResult::EvaluatedToOk
+            {
+                return;
+            }
+        }
+
+        // Default value of clippy::trivially_copy_pass_by_ref
+        const MAX_SIZE: u64 = 256;
+
+        if let Some(size) = cx.layout_of(ty).ok().map(|l| l.size.bytes()) {
+            if size > MAX_SIZE {
+                return;
+            }
+        }
+
         if can_type_implement_copy(
             cx.tcx,
             param_env,

compiler/rustc_target/src/spec/apple_base.rs

@@ -204,7 +204,7 @@ pub fn macos_llvm_target(arch: Arch) -> String {
 fn link_env_remove(arch: Arch, os: &'static str) -> StaticCow<[StaticCow<str>]> {
     // Apple platforms only officially support macOS as a host for any compilation.
     //
-    // If building for macOS, we go ahead and remove any erronous environment state
+    // If building for macOS, we go ahead and remove any erroneous environment state
     // that's only applicable to cross-OS compilation. Always leave anything for the
     // host OS alone though.
     if os == "macos" {

compiler/rustc_target/src/spec/wasm32_wasi.rs

@@ -104,6 +104,10 @@ pub fn target() -> Target {
     // `args::args()` makes the WASI API calls itself.
     options.main_needs_argc_argv = false;
 
+    // And, WASI mangles the name of "main" to distinguish between different
+    // signatures.
+    options.entry_name = "__main_void".into();
+
     Target {
         llvm_target: "wasm32-wasi".into(),
         pointer_width: 32,

library/alloc/src/collections/vec_deque/into_iter.rs

@@ -25,6 +25,10 @@ impl<T, A: Allocator> IntoIter<T, A> {
     pub(super) fn new(inner: VecDeque<T, A>) -> Self {
         IntoIter { inner }
     }
+
+    pub(super) fn into_vecdeque(self) -> VecDeque<T, A> {
+        self.inner
+    }
 }
 
 #[stable(feature = "collection_debug", since = "1.17.0")]

library/alloc/src/collections/vec_deque/mod.rs

@@ -55,6 +55,10 @@ use self::spec_extend::SpecExtend;
 
 mod spec_extend;
 
+use self::spec_from_iter::SpecFromIter;
+
+mod spec_from_iter;
+
 #[cfg(test)]
 mod tests;
 
@@ -586,6 +590,38 @@ impl<T, A: Allocator> VecDeque<T, A> {
         VecDeque { head: 0, len: 0, buf: RawVec::with_capacity_in(capacity, alloc) }
     }
 
+    /// Creates a `VecDeque` from a raw allocation, when the initialized
+    /// part of that allocation forms a *contiguous* subslice thereof.
+    ///
+    /// For use by `vec::IntoIter::into_vecdeque`
+    ///
+    /// # Safety
+    ///
+    /// All the usual requirements on the allocated memory like in
+    /// `Vec::from_raw_parts_in`, but takes a *range* of elements that are
+    /// initialized rather than only supporting `0..len`.  Requires that
+    /// `initialized.start` ≤ `initialized.end` ≤ `capacity`.
+    #[inline]
+    pub(crate) unsafe fn from_contiguous_raw_parts_in(
+        ptr: *mut T,
+        initialized: Range<usize>,
+        capacity: usize,
+        alloc: A,
+    ) -> Self {
+        debug_assert!(initialized.start <= initialized.end);
+        debug_assert!(initialized.end <= capacity);
+
+        // SAFETY: Our safety precondition guarantees the range length won't wrap,
+        // and that the allocation is valid for use in `RawVec`.
+        unsafe {
+            VecDeque {
+                head: initialized.start,
+                len: initialized.end.unchecked_sub(initialized.start),
+                buf: RawVec::from_raw_parts_in(ptr, capacity, alloc),
+            }
+        }
+    }
+
     /// Provides a reference to the element at the given index.
     ///
     /// Element at index 0 is the front of the queue.
@@ -2699,18 +2735,8 @@ impl<T, A: Allocator> IndexMut<usize> for VecDeque<T, A> {
 
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T> FromIterator<T> for VecDeque<T> {
-    #[inline]
     fn from_iter<I: IntoIterator<Item = T>>(iter: I) -> VecDeque<T> {
-        // Since converting is O(1) now, might as well re-use that logic
-        // (including things like the `vec::IntoIter`→`Vec` specialization)
-        // especially as that could save us some monomorphiziation work
-        // if one uses the same iterators (like slice ones) with both.
-        return from_iter_via_vec(iter.into_iter());
-
-        #[inline]
-        fn from_iter_via_vec<U>(iter: impl Iterator<Item = U>) -> VecDeque<U> {
-            Vec::from_iter(iter).into()
-        }
+        SpecFromIter::spec_from_iter(iter.into_iter())
     }
 }
 

library/alloc/src/collections/vec_deque/spec_from_iter.rs

@@ -0,0 +1,33 @@
+use super::{IntoIter, VecDeque};
+
+/// Specialization trait used for `VecDeque::from_iter`
+pub(super) trait SpecFromIter<T, I> {
+    fn spec_from_iter(iter: I) -> Self;
+}
+
+impl<T, I> SpecFromIter<T, I> for VecDeque<T>
+where
+    I: Iterator<Item = T>,
+{
+    default fn spec_from_iter(iterator: I) -> Self {
+        // Since converting is O(1) now, just re-use the `Vec` logic for
+        // anything where we can't do something extra-special for `VecDeque`,
+        // especially as that could save us some monomorphiziation work
+        // if one uses the same iterators (like slice ones) with both.
+        crate::vec::Vec::from_iter(iterator).into()
+    }
+}
+
+impl<T> SpecFromIter<T, crate::vec::IntoIter<T>> for VecDeque<T> {
+    #[inline]
+    fn spec_from_iter(iterator: crate::vec::IntoIter<T>) -> Self {
+        iterator.into_vecdeque()
+    }
+}
+
+impl<T> SpecFromIter<T, IntoIter<T>> for VecDeque<T> {
+    #[inline]
+    fn spec_from_iter(iterator: IntoIter<T>) -> Self {
+        iterator.into_vecdeque()
+    }
+}

library/alloc/src/vec/into_iter.rs

@@ -1,6 +1,8 @@
 #[cfg(not(no_global_oom_handling))]
 use super::AsVecIntoIter;
 use crate::alloc::{Allocator, Global};
+#[cfg(not(no_global_oom_handling))]
+use crate::collections::VecDeque;
 use crate::raw_vec::RawVec;
 use core::array;
 use core::fmt;
@@ -132,6 +134,33 @@ impl<T, A: Allocator> IntoIter<T, A> {
     pub(crate) fn forget_remaining_elements(&mut self) {
         self.ptr = self.end;
     }
+
+    #[cfg(not(no_global_oom_handling))]
+    #[inline]
+    pub(crate) fn into_vecdeque(self) -> VecDeque<T, A> {
+        // Keep our `Drop` impl from dropping the elements and the allocator
+        let mut this = ManuallyDrop::new(self);
+
+        // SAFETY: This allocation originally came from a `Vec`, so it passes
+        // all those checks.  We have `this.buf` ≤ `this.ptr` ≤ `this.end`,
+        // so the `sub_ptr`s below cannot wrap, and will produce a well-formed
+        // range.  `end` ≤ `buf + cap`, so the range will be in-bounds.
+        // Taking `alloc` is ok because nothing else is going to look at it,
+        // since our `Drop` impl isn't going to run so there's no more code.
+        unsafe {
+            let buf = this.buf.as_ptr();
+            let initialized = if T::IS_ZST {
+                // All the pointers are the same for ZSTs, so it's fine to
+                // say that they're all at the beginning of the "allocation".
+                0..this.len()
+            } else {
+                this.ptr.sub_ptr(buf)..this.end.sub_ptr(buf)
+            };
+            let cap = this.cap;
+            let alloc = ManuallyDrop::take(&mut this.alloc);
+            VecDeque::from_contiguous_raw_parts_in(buf, initialized, cap, alloc)
+        }
+    }
 }
 
 #[stable(feature = "vec_intoiter_as_ref", since = "1.46.0")]

library/alloc/tests/vec_deque.rs

@@ -1736,3 +1736,39 @@ fn test_resize_keeps_reserved_space_from_item() {
     d.resize(1, v);
     assert_eq!(d[0].capacity(), 1234);
 }
+
+#[test]
+fn test_collect_from_into_iter_keeps_allocation() {
+    let mut v = Vec::with_capacity(13);
+    v.extend(0..7);
+    check(v.as_ptr(), v.last().unwrap(), v.into_iter());
+
+    let mut v = VecDeque::with_capacity(13);
+    v.extend(0..7);
+    check(&v[0], &v[v.len() - 1], v.into_iter());
+
+    fn check(buf: *const i32, last: *const i32, mut it: impl Iterator<Item = i32>) {
+        assert_eq!(it.next(), Some(0));
+        assert_eq!(it.next(), Some(1));
+
+        let mut v: VecDeque<i32> = it.collect();
+        assert_eq!(v.capacity(), 13);
+        assert_eq!(v.as_slices().0.as_ptr(), buf.wrapping_add(2));
+        assert_eq!(&v[v.len() - 1] as *const _, last);
+
+        assert_eq!(v.as_slices(), ([2, 3, 4, 5, 6].as_slice(), [].as_slice()));
+        v.push_front(7);
+        assert_eq!(v.as_slices(), ([7, 2, 3, 4, 5, 6].as_slice(), [].as_slice()));
+        v.push_front(8);
+        assert_eq!(v.as_slices(), ([8, 7, 2, 3, 4, 5, 6].as_slice(), [].as_slice()));
+
+        // Now that we've adding thing in place of the two that we removed from
+        // the front of the iterator, we're back to matching the buffer pointer.
+        assert_eq!(v.as_slices().0.as_ptr(), buf);
+        assert_eq!(&v[v.len() - 1] as *const _, last);
+
+        v.push_front(9);
+        assert_eq!(v.as_slices(), ([9].as_slice(), [8, 7, 2, 3, 4, 5, 6].as_slice()));
+        assert_eq!(v.capacity(), 13);
+    }
+}

library/core/src/iter/traits/accum.rs

@@ -10,6 +10,10 @@ use crate::num::Wrapping;
 /// [`sum()`]: Iterator::sum
 /// [`FromIterator`]: iter::FromIterator
 #[stable(feature = "iter_arith_traits", since = "1.12.0")]
+#[rustc_on_unimplemented(
+    message = "a value of type `{Self}` cannot be made by summing an iterator over elements of type `{A}`",
+    label = "value of type `{Self}` cannot be made by summing a `std::iter::Iterator<Item={A}>`"
+)]
 pub trait Sum<A = Self>: Sized {
     /// Method which takes an iterator and generates `Self` from the elements by
     /// "summing up" the items.
@@ -27,6 +31,10 @@ pub trait Sum<A = Self>: Sized {
 /// [`product()`]: Iterator::product
 /// [`FromIterator`]: iter::FromIterator
 #[stable(feature = "iter_arith_traits", since = "1.12.0")]
+#[rustc_on_unimplemented(
+    message = "a value of type `{Self}` cannot be made by multiplying all elements of type `{A}` from an iterator",
+    label = "value of type `{Self}` cannot be made by multiplying all elements from a `std::iter::Iterator<Item={A}>`"
+)]
 pub trait Product<A = Self>: Sized {
     /// Method which takes an iterator and generates `Self` from the elements by
     /// multiplying the items.