Auto merge of #71539 - Dylan-DPC:rollup-a2vbfh9, r=Dylan-DPC

Rollup of 8 pull requests

Successful merges:

 - #69456 (fix misleading type annotation diagonstics)
 - #71330 (Only run dataflow for const qualification if type-based check would fail)
 - #71480 (Improve PanicInfo examples readability)
 - #71485 (Add BinaryHeap::retain as suggested in #42849)
 - #71512 (Remove useless "" args)
 - #71527 (Miscellaneous cleanup in `check_consts`)
 - #71534 (Avoid unused Option::map results)
 - #71535 (Fix typos in docs for keyword "in")

Failed merges:

r? @ghost

Author: bors

src/bootstrap/toolstate.rs

@@ -93,12 +93,12 @@ static NIGHTLY_TOOLS: &[(&str, &str)] = &[
 ];
 
 fn print_error(tool: &str, submodule: &str) {
-    eprintln!("");
+    eprintln!();
     eprintln!("We detected that this PR updated '{}', but its tests failed.", tool);
-    eprintln!("");
+    eprintln!();
     eprintln!("If you do intend to update '{}', please check the error messages above and", tool);
     eprintln!("commit another update.");
-    eprintln!("");
+    eprintln!();
     eprintln!("If you do NOT intend to update '{}', please ensure you did not accidentally", tool);
     eprintln!("change the submodule at '{}'. You may ask your reviewer for the", submodule);
     eprintln!("proper steps.");

src/liballoc/collections/binary_heap.rs

@@ -665,6 +665,34 @@ impl<T: Ord> BinaryHeap<T> {
     pub fn drain_sorted(&mut self) -> DrainSorted<'_, T> {
         DrainSorted { inner: self }
     }
+
+    /// Retains only the elements specified by the predicate.
+    ///
+    /// In other words, remove all elements `e` such that `f(&e)` returns
+    /// `false`. The elements are visited in unsorted (and unspecified) order.
+    ///
+    /// # Examples
+    ///
+    /// Basic usage:
+    ///
+    /// ```
+    /// #![feature(binary_heap_retain)]
+    /// use std::collections::BinaryHeap;
+    ///
+    /// let mut heap = BinaryHeap::from(vec![-10, -5, 1, 2, 4, 13]);
+    ///
+    /// heap.retain(|x| x % 2 == 0); // only keep even numbers
+    ///
+    /// assert_eq!(heap.into_sorted_vec(), [-10, 2, 4])
+    /// ```
+    #[unstable(feature = "binary_heap_retain", issue = "71503")]
+    pub fn retain<F>(&mut self, f: F)
+    where
+        F: FnMut(&T) -> bool,
+    {
+        self.data.retain(f);
+        self.rebuild();
+    }
 }
 
 impl<T> BinaryHeap<T> {

src/liballoc/tests/binary_heap.rs

@@ -372,6 +372,14 @@ fn assert_covariance() {
     }
 }
 
+#[test]
+fn test_retain() {
+    let mut a = BinaryHeap::from(vec![-10, -5, 1, 2, 4, 13]);
+    a.retain(|x| x % 2 == 0);
+
+    assert_eq!(a.into_sorted_vec(), [-10, 2, 4])
+}
+
 // old binaryheap failed this test
 //
 // Integrity means that all elements are present after a comparison panics,

src/liballoc/tests/lib.rs

@@ -14,6 +14,7 @@
 #![feature(binary_heap_drain_sorted)]
 #![feature(vec_remove_item)]
 #![feature(split_inclusive)]
+#![feature(binary_heap_retain)]
 
 use std::collections::hash_map::DefaultHasher;
 use std::hash::{Hash, Hasher};

src/libcore/panic.rs

@@ -77,7 +77,11 @@ impl<'a> PanicInfo<'a> {
     /// use std::panic;
     ///
     /// panic::set_hook(Box::new(|panic_info| {
-    ///     println!("panic occurred: {:?}", panic_info.payload().downcast_ref::<&str>().unwrap());
+    ///     if let Some(s) = panic_info.payload().downcast_ref::<&str>() {
+    ///         println!("panic occurred: {:?}", s);
+    ///     } else {
+    ///         println!("panic occurred");
+    ///     }
     /// }));
     ///
     /// panic!("Normal panic");
@@ -112,8 +116,10 @@ impl<'a> PanicInfo<'a> {
     ///
     /// panic::set_hook(Box::new(|panic_info| {
     ///     if let Some(location) = panic_info.location() {
-    ///         println!("panic occurred in file '{}' at line {}", location.file(),
-    ///             location.line());
+    ///         println!("panic occurred in file '{}' at line {}",
+    ///             location.file(),
+    ///             location.line(),
+    ///         );
     ///     } else {
     ///         println!("panic occurred but can't get location information...");
     ///     }

src/librustc_attr/builtin.rs

@@ -98,7 +98,7 @@ pub fn find_unwind_attr(diagnostic: Option<&Handler>, attrs: &[Attribute]) -> Op
                         }
                     }
 
-                    diagnostic.map(|d| {
+                    if let Some(d) = diagnostic {
                         struct_span_err!(d, attr.span, E0633, "malformed `unwind` attribute input")
                             .span_label(attr.span, "invalid argument")
                             .span_suggestions(
@@ -110,7 +110,7 @@ pub fn find_unwind_attr(diagnostic: Option<&Handler>, attrs: &[Attribute]) -> Op
                                 Applicability::MachineApplicable,
                             )
                             .emit();
-                    });
+                    };
                 }
             }
         }

src/librustc_expand/expand.rs

@@ -1172,10 +1172,10 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
             // ignore derives so they remain unused
             let (attr, after_derive) = self.classify_nonitem(&mut expr);
 
-            if attr.is_some() {
+            if let Some(ref attr_value) = attr {
                 // Collect the invoc regardless of whether or not attributes are permitted here
                 // expansion will eat the attribute so it won't error later.
-                attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
+                self.cfg.maybe_emit_expr_attr_err(attr_value);
 
                 // AstFragmentKind::Expr requires the macro to emit an expression.
                 return self
@@ -1322,8 +1322,8 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
             // Ignore derives so they remain unused.
             let (attr, after_derive) = self.classify_nonitem(&mut expr);
 
-            if attr.is_some() {
-                attr.as_ref().map(|a| self.cfg.maybe_emit_expr_attr_err(a));
+            if let Some(ref attr_value) = attr {
+                self.cfg.maybe_emit_expr_attr_err(attr_value);
 
                 return self
                     .collect_attr(

src/librustc_hir/definitions.rs

@@ -246,7 +246,7 @@ impl DefPath {
 
         let mut opt_delimiter = None;
         for component in &self.data {
-            opt_delimiter.map(|d| s.push(d));
+            s.extend(opt_delimiter);
             opt_delimiter = Some('-');
             if component.disambiguator == 0 {
                 write!(s, "{}", component.data.as_symbol()).unwrap();

src/librustc_infer/infer/error_reporting/mod.rs

@@ -755,7 +755,9 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             },
             ObligationCauseCode::IfExpression(box IfExpressionCause { then, outer, semicolon }) => {
                 err.span_label(then, "expected because of this");
-                outer.map(|sp| err.span_label(sp, "`if` and `else` have incompatible types"));
+                if let Some(sp) = outer {
+                    err.span_label(sp, "`if` and `else` have incompatible types");
+                }
                 if let Some(sp) = semicolon {
                     err.span_suggestion_short(
                         sp,

src/librustc_infer/infer/error_reporting/need_type_info.rs

@@ -17,23 +17,27 @@ use std::borrow::Cow;
 struct FindHirNodeVisitor<'a, 'tcx> {
     infcx: &'a InferCtxt<'a, 'tcx>,
     target: GenericArg<'tcx>,
+    target_span: Span,
     found_node_ty: Option<Ty<'tcx>>,
     found_local_pattern: Option<&'tcx Pat<'tcx>>,
     found_arg_pattern: Option<&'tcx Pat<'tcx>>,
     found_closure: Option<&'tcx Expr<'tcx>>,
     found_method_call: Option<&'tcx Expr<'tcx>>,
+    found_exact_method_call: Option<&'tcx Expr<'tcx>>,
 }
 
 impl<'a, 'tcx> FindHirNodeVisitor<'a, 'tcx> {
-    fn new(infcx: &'a InferCtxt<'a, 'tcx>, target: GenericArg<'tcx>) -> Self {
+    fn new(infcx: &'a InferCtxt<'a, 'tcx>, target: GenericArg<'tcx>, target_span: Span) -> Self {
         Self {
             infcx,
             target,
+            target_span,
             found_node_ty: None,
             found_local_pattern: None,
             found_arg_pattern: None,
             found_closure: None,
             found_method_call: None,
+            found_exact_method_call: None,
         }
     }
 
@@ -103,6 +107,17 @@ impl<'a, 'tcx> Visitor<'tcx> for FindHirNodeVisitor<'a, 'tcx> {
     }
 
     fn visit_expr(&mut self, expr: &'tcx Expr<'tcx>) {
+        if let ExprKind::MethodCall(_, call_span, exprs) = expr.kind {
+            if call_span == self.target_span
+                && Some(self.target)
+                    == self.infcx.in_progress_tables.and_then(|tables| {
+                        tables.borrow().node_type_opt(exprs.first().unwrap().hir_id).map(Into::into)
+                    })
+            {
+                self.found_exact_method_call = Some(&expr);
+                return;
+            }
+        }
         if self.node_ty_contains_target(expr.hir_id).is_some() {
             match expr.kind {
                 ExprKind::Closure(..) => self.found_closure = Some(&expr),
@@ -234,7 +249,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         let ty = self.resolve_vars_if_possible(&ty);
         let (name, name_sp, descr, parent_name, parent_descr) = self.extract_type_name(&ty, None);
 
-        let mut local_visitor = FindHirNodeVisitor::new(&self, ty.into());
+        let mut local_visitor = FindHirNodeVisitor::new(&self, ty.into(), span);
         let ty_to_string = |ty: Ty<'tcx>| -> String {
             let mut s = String::new();
             let mut printer = ty::print::FmtPrinter::new(self.tcx, &mut s, Namespace::TypeNS);
@@ -287,14 +302,15 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
                 (!ty.is_impl_trait() || self.tcx.features().impl_trait_in_bindings)
         };
 
-        let ty_msg = match local_visitor.found_node_ty {
-            Some(ty::TyS { kind: ty::Closure(_, substs), .. }) => {
+        let ty_msg = match (local_visitor.found_node_ty, local_visitor.found_exact_method_call) {
+            (_, Some(_)) => String::new(),
+            (Some(ty::TyS { kind: ty::Closure(_, substs), .. }), _) => {
                 let fn_sig = substs.as_closure().sig();
                 let args = closure_args(&fn_sig);
                 let ret = fn_sig.output().skip_binder().to_string();
                 format!(" for the closure `fn({}) -> {}`", args, ret)
             }
-            Some(ty) if is_named_and_not_impl_trait(ty) => {
+            (Some(ty), _) if is_named_and_not_impl_trait(ty) => {
                 let ty = ty_to_string(ty);
                 format!(" for `{}`", ty)
             }
@@ -370,7 +386,37 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
             _ => "a type".to_string(),
         };
 
-        if let Some(pattern) = local_visitor.found_arg_pattern {
+        if let Some(e) = local_visitor.found_exact_method_call {
+            if let ExprKind::MethodCall(segment, ..) = &e.kind {
+                // Suggest specifying type params or point out the return type of the call:
+                //
+                // error[E0282]: type annotations needed
+                //   --> $DIR/type-annotations-needed-expr.rs:2:39
+                //    |
+                // LL |     let _ = x.into_iter().sum() as f64;
+                //    |                           ^^^
+                //    |                           |
+                //    |                           cannot infer type for `S`
+                //    |                           help: consider specifying the type argument in
+                //    |                           the method call: `sum::<S>`
+                //    |
+                //    = note: type must be known at this point
+                //
+                // or
+                //
+                // error[E0282]: type annotations needed
+                //   --> $DIR/issue-65611.rs:59:20
+                //    |
+                // LL |     let x = buffer.last().unwrap().0.clone();
+                //    |             -------^^^^--
+                //    |             |      |
+                //    |             |      cannot infer type for `T`
+                //    |             this method call resolves to `std::option::Option<&T>`
+                //    |
+                //    = note: type must be known at this point
+                self.annotate_method_call(segment, e, &mut err);
+            }
+        } else if let Some(pattern) = local_visitor.found_arg_pattern {
             // We don't want to show the default label for closures.
             //
             // So, before clearing, the output would look something like this: