Auto merge of #73316 - Dylan-DPC:rollup-zgouwou, r=Dylan-DPC

Rollup of 8 pull requests

Successful merges:

 - #72932 (Clarify the behaviour of Pattern when used with methods like str::contains)
 - #73066 (Querify whether a type has structural equality (Take 2))
 - #73194 (Prefer the associated constants for pattern matching error)
 - #73241 (Add/update comments about MinGW late_link_args)
 - #73267 (Use the built cargo for cargotest.)
 - #73290 (Fix links when pinging notification groups)
 - #73302 (Adjusted some doctests in libcore to use `should_panic`.)
 - #73308 (pretty/asm.rs should only be tested for x86_64 and not AArch64)

Failed merges:

r? @ghost

Author: bors

src/bootstrap/test.rs

@@ -154,6 +154,7 @@ impl Step for Cargotest {
     fn run(self, builder: &Builder<'_>) {
         let compiler = builder.compiler(self.stage, self.host);
         builder.ensure(compile::Rustc { compiler, target: compiler.host });
+        let cargo = builder.ensure(tool::Cargo { compiler, target: compiler.host });
 
         // Note that this is a short, cryptic, and not scoped directory name. This
         // is currently to minimize the length of path on Windows where we otherwise
@@ -165,7 +166,7 @@ impl Step for Cargotest {
         let mut cmd = builder.tool_cmd(Tool::CargoTest);
         try_run(
             builder,
-            cmd.arg(&builder.initial_cargo)
+            cmd.arg(&cargo)
                 .arg(&out_dir)
                 .env("RUSTC", builder.rustc(compiler))
                 .env("RUSTDOC", builder.rustdoc(compiler)),

src/libcore/cell.rs

@@ -778,18 +778,13 @@ impl<T: ?Sized> RefCell<T> {
     ///
     /// An example of panic:
     ///
-    /// ```
+    /// ```should_panic
     /// use std::cell::RefCell;
-    /// use std::thread;
-    ///
-    /// let result = thread::spawn(move || {
-    ///    let c = RefCell::new(5);
-    ///    let m = c.borrow_mut();
     ///
-    ///    let b = c.borrow(); // this causes a panic
-    /// }).join();
+    /// let c = RefCell::new(5);
     ///
-    /// assert!(result.is_err());
+    /// let m = c.borrow_mut();
+    /// let b = c.borrow(); // this causes a panic
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -858,18 +853,13 @@ impl<T: ?Sized> RefCell<T> {
     ///
     /// An example of panic:
     ///
-    /// ```
+    /// ```should_panic
     /// use std::cell::RefCell;
-    /// use std::thread;
-    ///
-    /// let result = thread::spawn(move || {
-    ///    let c = RefCell::new(5);
-    ///    let m = c.borrow();
     ///
-    ///    let b = c.borrow_mut(); // this causes a panic
-    /// }).join();
+    /// let c = RefCell::new(5);
+    /// let m = c.borrow();
     ///
-    /// assert!(result.is_err());
+    /// let b = c.borrow_mut(); // this causes a panic
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]

src/libcore/char/convert.rs

@@ -278,16 +278,11 @@ impl fmt::Display for CharTryFromError {
 ///
 /// Passing a large radix, causing a panic:
 ///
-/// ```
-/// use std::thread;
+/// ```should_panic
 /// use std::char;
 ///
-/// let result = thread::spawn(|| {
-///     // this panics
-///     let c = char::from_digit(1, 37);
-/// }).join();
-///
-/// assert!(result.is_err());
+/// // this panics
+/// let c = char::from_digit(1, 37);
 /// ```
 #[inline]
 #[stable(feature = "rust1", since = "1.0.0")]

src/libcore/char/methods.rs

@@ -229,16 +229,11 @@ impl char {
     ///
     /// Passing a large radix, causing a panic:
     ///
-    /// ```
-    /// use std::thread;
+    /// ```should_panic
     /// use std::char;
     ///
-    /// let result = thread::spawn(|| {
-    ///     // this panics
-    ///     let c = char::from_digit(1, 37);
-    /// }).join();
-    ///
-    /// assert!(result.is_err());
+    /// // this panics
+    /// char::from_digit(1, 37);
     /// ```
     #[unstable(feature = "assoc_char_funcs", reason = "recently added", issue = "71763")]
     #[inline]
@@ -282,15 +277,9 @@ impl char {
     ///
     /// Passing a large radix, causing a panic:
     ///
-    /// ```
-    /// use std::thread;
-    ///
-    /// let result = thread::spawn(|| {
-    ///     // this panics
-    ///     '1'.is_digit(37);
-    /// }).join();
-    ///
-    /// assert!(result.is_err());
+    /// ```should_panic
+    /// // this panics
+    /// '1'.is_digit(37);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -337,14 +326,9 @@ impl char {
     ///
     /// Passing a large radix, causing a panic:
     ///
-    /// ```
-    /// use std::thread;
-    ///
-    /// let result = thread::spawn(|| {
-    ///     '1'.to_digit(37);
-    /// }).join();
-    ///
-    /// assert!(result.is_err());
+    /// ```should_panic
+    /// // this panics
+    /// '1'.to_digit(37);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -646,17 +630,11 @@ impl char {
     ///
     /// A buffer that's too small:
     ///
-    /// ```
-    /// use std::thread;
-    ///
-    /// let result = thread::spawn(|| {
-    ///     let mut b = [0; 1];
-    ///
-    ///     // this panics
-    ///    'ß'.encode_utf8(&mut b);
-    /// }).join();
+    /// ```should_panic
+    /// let mut b = [0; 1];
     ///
-    /// assert!(result.is_err());
+    /// // this panics
+    /// 'ß'.encode_utf8(&mut b);
     /// ```
     #[stable(feature = "unicode_encode_char", since = "1.15.0")]
     #[inline]
@@ -687,17 +665,11 @@ impl char {
     ///
     /// A buffer that's too small:
     ///
-    /// ```
-    /// use std::thread;
-    ///
-    /// let result = thread::spawn(|| {
-    ///     let mut b = [0; 1];
-    ///
-    ///     // this panics
-    ///     '𝕊'.encode_utf16(&mut b);
-    /// }).join();
+    /// ```should_panic
+    /// let mut b = [0; 1];
     ///
-    /// assert!(result.is_err());
+    /// // this panics
+    /// '𝕊'.encode_utf16(&mut b);
     /// ```
     #[stable(feature = "unicode_encode_char", since = "1.15.0")]
     #[inline]

src/libcore/str/pattern.rs

@@ -60,6 +60,43 @@ use crate::slice::memchr;
 /// The trait itself acts as a builder for an associated
 /// `Searcher` type, which does the actual work of finding
 /// occurrences of the pattern in a string.
+///
+/// Depending on the type of the pattern, the behaviour of methods like
+/// [`str::find`] and [`str::contains`] can change. The table below describes
+/// some of those behaviours.
+///
+/// | Pattern type             | Match condition                           |
+/// |--------------------------|-------------------------------------------|
+/// | `&str`                   | is substring                              |
+/// | `char`                   | is contained in string                    |
+/// | `&[char]                 | any char in slice is contained in string  |
+/// | `F: FnMut(char) -> bool` | `F` returns `true` for a char in string   |
+/// | `&&str`                  | is substring                              |
+/// | `&String`                | is substring                              |
+///
+/// # Examples
+/// ```
+/// // &str
+/// assert_eq!("abaaa".find("ba"), Some(1));
+/// assert_eq!("abaaa".find("bac"), None);
+///
+/// // char
+/// assert_eq!("abaaa".find('a'), Some(0));
+/// assert_eq!("abaaa".find('b'), Some(1));
+/// assert_eq!("abaaa".find('c'), None);
+///
+/// // &[char]
+/// assert_eq!("ab".find(&['b', 'a'][..]), Some(0));
+/// assert_eq!("abaaa".find(&['a', 'z'][..]), Some(0));
+/// assert_eq!("abaaa".find(&['c', 'd'][..]), None);
+///
+/// // FnMut(char) -> bool
+/// assert_eq!("abcdef_z".find(|ch| ch > 'd' && ch < 'y'), Some(4));
+/// assert_eq!("abcddd_z".find(|ch| ch > 'd' && ch < 'y'), None);
+/// ```
+///
+/// [`str::find`]: ../../../std/primitive.str.html#method.find
+/// [`str::contains`]: ../../../std/primitive.str.html#method.contains
 pub trait Pattern<'a>: Sized {
     /// Associated searcher for this pattern
     type Searcher: Searcher<'a>;

src/librustc_middle/query/mod.rs

@@ -789,6 +789,17 @@ rustc_queries! {
             desc { "computing whether `{}` needs drop", env.value }
         }
 
+        /// Query backing `TyS::is_structural_eq_shallow`.
+        ///
+        /// This is only correct for ADTs. Call `is_structural_eq_shallow` to handle all types
+        /// correctly.
+        query has_structural_eq_impls(ty: Ty<'tcx>) -> bool {
+            desc {
+                "computing whether `{:?}` implements `PartialStructuralEq` and `StructuralEq`",
+                ty
+            }
+        }
+
         /// A list of types where the ADT requires drop if and only if any of
         /// those types require drop. If the ADT is known to always need drop
         /// then `Err(AlwaysRequiresDrop)` is returned.

src/librustc_middle/ty/print/pretty.rs

@@ -986,7 +986,7 @@ pub trait PrettyPrinter<'tcx>:
 
                 let ui_str = ui.name_str();
                 if data == max {
-                    p!(write("std::{}::MAX", ui_str))
+                    p!(write("{}::MAX", ui_str))
                 } else {
                     if print_ty { p!(write("{}{}", data, ui_str)) } else { p!(write("{}", data)) }
                 };
@@ -999,8 +999,8 @@ pub trait PrettyPrinter<'tcx>:
 
                 let i_str = i.name_str();
                 match data {
-                    d if d == min => p!(write("std::{}::MIN", i_str)),
-                    d if d == max => p!(write("std::{}::MAX", i_str)),
+                    d if d == min => p!(write("{}::MIN", i_str)),
+                    d if d == max => p!(write("{}::MAX", i_str)),
                     _ => {
                         let data = sign_extend(data, size) as i128;
                         if print_ty {

src/librustc_middle/ty/util.rs

@@ -778,6 +778,57 @@ impl<'tcx> ty::TyS<'tcx> {
         }
     }
 
+    /// Returns `true` if equality for this type is both reflexive and structural.
+    ///
+    /// Reflexive equality for a type is indicated by an `Eq` impl for that type.
+    ///
+    /// Primitive types (`u32`, `str`) have structural equality by definition. For composite data
+    /// types, equality for the type as a whole is structural when it is the same as equality
+    /// between all components (fields, array elements, etc.) of that type. For ADTs, structural
+    /// equality is indicated by an implementation of `PartialStructuralEq` and `StructuralEq` for
+    /// that type.
+    ///
+    /// This function is "shallow" because it may return `true` for a composite type whose fields
+    /// are not `StructuralEq`. For example, `[T; 4]` has structural equality regardless of `T`
+    /// because equality for arrays is determined by the equality of each array element. If you
+    /// want to know whether a given call to `PartialEq::eq` will proceed structurally all the way
+    /// down, you will need to use a type visitor.
+    #[inline]
+    pub fn is_structural_eq_shallow(&'tcx self, tcx: TyCtxt<'tcx>) -> bool {
+        match self.kind {
+            // Look for an impl of both `PartialStructuralEq` and `StructuralEq`.
+            Adt(..) => tcx.has_structural_eq_impls(self),
+
+            // Primitive types that satisfy `Eq`.
+            Bool | Char | Int(_) | Uint(_) | Str | Never => true,
+
+            // Composite types that satisfy `Eq` when all of their fields do.
+            //
+            // Because this function is "shallow", we return `true` for these composites regardless
+            // of the type(s) contained within.
+            Ref(..) | Array(..) | Slice(_) | Tuple(..) => true,
+
+            // Raw pointers use bitwise comparison.
+            RawPtr(_) | FnPtr(_) => true,
+
+            // Floating point numbers are not `Eq`.
+            Float(_) => false,
+
+            // Conservatively return `false` for all others...
+
+            // Anonymous function types
+            FnDef(..) | Closure(..) | Dynamic(..) | Generator(..) => false,
+
+            // Generic or inferred types
+            //
+            // FIXME(ecstaticmorse): Maybe we should `bug` here? This should probably only be
+            // called for known, fully-monomorphized types.
+            Projection(_) | Opaque(..) | Param(_) | Bound(..) | Placeholder(_) | Infer(_) => false,
+
+            Foreign(_) | GeneratorWitness(..) | Error => false,
+        }
+    }
+
     pub fn same_type(a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
         match (&a.kind, &b.kind) {
             (&Adt(did_a, substs_a), &Adt(did_b, substs_b)) => {

src/librustc_mir/transform/check_consts/qualifs.rs

@@ -2,7 +2,6 @@
 //!
 //! See the `Qualif` trait for more info.
 
-use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::mir::*;
 use rustc_middle::ty::{self, subst::SubstsRef, AdtDef, Ty};
 use rustc_span::DUMMY_SP;
@@ -137,10 +136,7 @@ impl Qualif for CustomEq {
         substs: SubstsRef<'tcx>,
     ) -> bool {
         let ty = cx.tcx.mk_ty(ty::Adt(adt, substs));
-        let id = cx.tcx.hir().local_def_id_to_hir_id(cx.def_id.as_local().unwrap());
-        cx.tcx
-            .infer_ctxt()
-            .enter(|infcx| !traits::type_marked_structural(id, cx.body.span, &infcx, ty))
+        !ty.is_structural_eq_shallow(cx.tcx)
     }
 }
 

src/librustc_mir_build/hair/pattern/const_to_pat.rs

@@ -80,7 +80,7 @@ impl<'a, 'tcx> ConstToPat<'a, 'tcx> {
     }
 
     fn type_marked_structural(&self, ty: Ty<'tcx>) -> bool {
-        traits::type_marked_structural(self.id, self.span, &self.infcx, ty)
+        ty.is_structural_eq_shallow(self.infcx.tcx)
     }
 
     fn to_pat(

src/librustc_target/spec/windows_gnu_base.rs

@@ -17,6 +17,8 @@ pub fn opts() -> TargetOptions {
     let mut late_link_args = LinkArgs::new();
     let mut late_link_args_dynamic = LinkArgs::new();
     let mut late_link_args_static = LinkArgs::new();
+    // Order of `late_link_args*` was found through trial and error to work with various
+    // mingw-w64 versions (not tested on the CI). It's expected to change from time to time.
     late_link_args.insert(
         LinkerFlavor::Gcc,
         vec![
@@ -27,10 +29,9 @@ pub fn opts() -> TargetOptions {
             // And it seems that the linker fails to use import symbols from msvcrt
             // that are required from functions in msvcrt in certain cases. For example
             // `_fmode` that is used by an implementation of `__p__fmode` in x86_64.
-            // Listing the library twice seems to fix that, and seems to also be done
-            // by mingw's gcc (Though not sure if it's done on purpose, or by mistake).
+            // The library is purposely listed twice to fix that.
             //
-            // See https://github.com/rust-lang/rust/pull/47483
+            // See https://github.com/rust-lang/rust/pull/47483 for some more details.
             "-lmsvcrt".to_string(),
             "-luser32".to_string(),
             "-lkernel32".to_string(),

src/librustc_trait_selection/traits/mod.rs

@@ -60,7 +60,6 @@ pub use self::specialize::specialization_graph::FutureCompatOverlapError;
 pub use self::specialize::specialization_graph::FutureCompatOverlapErrorKind;
 pub use self::specialize::{specialization_graph, translate_substs, OverlapError};
 pub use self::structural_match::search_for_structural_match_violation;
-pub use self::structural_match::type_marked_structural;
 pub use self::structural_match::NonStructuralMatchTy;
 pub use self::util::{elaborate_predicates, elaborate_trait_ref, elaborate_trait_refs};
 pub use self::util::{expand_trait_aliases, TraitAliasExpander};
@@ -553,6 +552,7 @@ fn type_implements_trait<'tcx>(
 
 pub fn provide(providers: &mut ty::query::Providers<'_>) {
     object_safety::provide(providers);
+    structural_match::provide(providers);
     *providers = ty::query::Providers {
         specialization_graph_of: specialize::specialization_graph_provider,
         specializes: specialize::specializes,