Auto merge of #67271 - Centril:rollup-i71iqkv, r=Centril

Rollup of 6 pull requests

Successful merges:

 - #66341 (Match `VecDeque::extend` to `Vec::extend_desugared`)
 - #67243 (LinkedList: drop remaining items when drop panics)
 - #67247 (Don't suggest wrong snippet in closure)
 - #67250 (Remove the `DelimSpan` from `NamedMatch::MatchedSeq`.)
 - #67251 (Require `allow_internal_unstable` for stable min_const_fn using unsta…)
 - #67269 (parser: recover on `&'lifetime mut? $pat`.)

Failed merges:

r? @ghost

src/liballoc/collections/linked_list.rs

@@ -808,7 +808,21 @@ impl<T> LinkedList<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 unsafe impl<#[may_dangle] T> Drop for LinkedList<T> {
     fn drop(&mut self) {
-        while let Some(_) = self.pop_front_node() {}
+        struct DropGuard<'a, T>(&'a mut LinkedList<T>);
+
+        impl<'a, T> Drop for DropGuard<'a, T> {
+            fn drop(&mut self) {
+                // Continue the same loop we do below. This only runs when a destructor has
+                // panicked. If another one panics this will abort.
+                while let Some(_) = self.0.pop_front_node() {}
+            }
+        }
+
+        while let Some(node) = self.pop_front_node() {
+            let guard = DropGuard(self);
+            drop(node);
+            mem::forget(guard);
+        }
     }
 }
 

src/liballoc/collections/vec_deque.rs

@@ -2809,7 +2809,22 @@ impl<'a, T> IntoIterator for &'a mut VecDeque<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<A> Extend<A> for VecDeque<A> {
     fn extend<T: IntoIterator<Item = A>>(&mut self, iter: T) {
-        iter.into_iter().for_each(move |elt| self.push_back(elt));
+        // This function should be the moral equivalent of:
+        //
+        //      for item in iter.into_iter() {
+        //          self.push_back(item);
+        //      }
+        let mut iter = iter.into_iter();
+        while let Some(element) = iter.next() {
+            if self.len() == self.capacity() {
+                let (lower, _) = iter.size_hint();
+                self.reserve(lower.saturating_add(1));
+            }
+
+            let head = self.head;
+            self.head = self.wrap_add(self.head, 1);
+            unsafe { self.buffer_write(head, element); }
+        }
     }
 }
 

src/liballoc/tests/linked_list.rs

@@ -1,4 +1,5 @@
 use std::collections::LinkedList;
+use std::panic::catch_unwind;
 
 #[test]
 fn test_basic() {
@@ -529,3 +530,109 @@ fn drain_filter_complex() {
         assert_eq!(list.into_iter().collect::<Vec<_>>(), vec![1, 3, 5, 7, 9, 11, 13, 15, 17, 19]);
     }
 }
+
+
+#[test]
+fn test_drop() {
+    static mut DROPS: i32 = 0;
+    struct Elem;
+    impl Drop for Elem {
+        fn drop(&mut self) {
+            unsafe {
+                DROPS += 1;
+            }
+        }
+    }
+
+    let mut ring = LinkedList::new();
+    ring.push_back(Elem);
+    ring.push_front(Elem);
+    ring.push_back(Elem);
+    ring.push_front(Elem);
+    drop(ring);
+
+    assert_eq!(unsafe { DROPS }, 4);
+}
+
+#[test]
+fn test_drop_with_pop() {
+    static mut DROPS: i32 = 0;
+    struct Elem;
+    impl Drop for Elem {
+        fn drop(&mut self) {
+            unsafe {
+                DROPS += 1;
+            }
+        }
+    }
+
+    let mut ring = LinkedList::new();
+    ring.push_back(Elem);
+    ring.push_front(Elem);
+    ring.push_back(Elem);
+    ring.push_front(Elem);
+
+    drop(ring.pop_back());
+    drop(ring.pop_front());
+    assert_eq!(unsafe { DROPS }, 2);
+
+    drop(ring);
+    assert_eq!(unsafe { DROPS }, 4);
+}
+
+#[test]
+fn test_drop_clear() {
+    static mut DROPS: i32 = 0;
+    struct Elem;
+    impl Drop for Elem {
+        fn drop(&mut self) {
+            unsafe {
+                DROPS += 1;
+            }
+        }
+    }
+
+    let mut ring = LinkedList::new();
+    ring.push_back(Elem);
+    ring.push_front(Elem);
+    ring.push_back(Elem);
+    ring.push_front(Elem);
+    ring.clear();
+    assert_eq!(unsafe { DROPS }, 4);
+
+    drop(ring);
+    assert_eq!(unsafe { DROPS }, 4);
+}
+
+#[test]
+fn test_drop_panic() {
+    static mut DROPS: i32 = 0;
+
+    struct D(bool);
+
+    impl Drop for D {
+        fn drop(&mut self) {
+            unsafe {
+                DROPS += 1;
+            }
+
+            if self.0 {
+                panic!("panic in `drop`");
+            }
+        }
+    }
+
+    let mut q = LinkedList::new();
+    q.push_back(D(false));
+    q.push_back(D(false));
+    q.push_back(D(false));
+    q.push_back(D(false));
+    q.push_back(D(false));
+    q.push_front(D(false));
+    q.push_front(D(false));
+    q.push_front(D(true));
+
+    catch_unwind(move || drop(q)).ok();
+
+    assert_eq!(unsafe { DROPS }, 8);
+}

src/librustc_mir/borrow_check/diagnostics/move_errors.rs

@@ -223,18 +223,24 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
 
     fn report(&mut self, error: GroupedMoveError<'tcx>) {
         let (mut err, err_span) = {
-            let (span, original_path, kind): (Span, &Place<'tcx>, &IllegalMoveOriginKind<'_>) =
+            let (span, use_spans, original_path, kind,):
+            (
+                Span,
+                Option<UseSpans>,
+                &Place<'tcx>,
+                &IllegalMoveOriginKind<'_>,
+            ) =
                 match error {
                     GroupedMoveError::MovesFromPlace { span, ref original_path, ref kind, .. } |
                     GroupedMoveError::MovesFromValue { span, ref original_path, ref kind, .. } => {
-                        (span, original_path, kind)
+                        (span, None, original_path, kind)
                     }
                     GroupedMoveError::OtherIllegalMove {
                         use_spans,
                         ref original_path,
                         ref kind
                     } => {
-                        (use_spans.args_or_use(), original_path, kind)
+                        (use_spans.args_or_use(), Some(use_spans), original_path, kind)
                     },
                 };
             debug!("report: original_path={:?} span={:?}, kind={:?} \
@@ -250,6 +256,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
                             original_path,
                             target_place,
                             span,
+                            use_spans,
                         )
                     }
                     IllegalMoveOriginKind::InteriorOfTypeWithDestructor { container_ty: ty } => {
@@ -296,6 +303,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         move_place: &Place<'tcx>,
         deref_target_place: &Place<'tcx>,
         span: Span,
+        use_spans: Option<UseSpans>,
     ) -> DiagnosticBuilder<'a> {
         // Inspect the type of the content behind the
         // borrow to provide feedback about why this
@@ -416,7 +424,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> {
         if let Ok(snippet) = self.infcx.tcx.sess.source_map().span_to_snippet(span) {
             let is_option = move_ty.starts_with("std::option::Option");
             let is_result = move_ty.starts_with("std::result::Result");
-            if is_option || is_result {
+            if (is_option || is_result) && use_spans.map_or(true, |v| !v.for_closure()) {
                 err.span_suggestion(
                     span,
                     &format!("consider borrowing the `{}`'s content", if is_option {

src/librustc_mir/transform/qualify_min_const_fn.rs

@@ -80,7 +80,7 @@ fn check_ty(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, span: Span, fn_def_id: DefId) -> Mc
     for ty in ty.walk() {
         match ty.kind {
             ty::Ref(_, _, hir::Mutability::Mutable) => {
-                if !tcx.features().const_mut_refs {
+                if !feature_allowed(tcx, fn_def_id, sym::const_mut_refs) {
                     return Err((
                         span,
                         "mutable references in const fn are unstable".into(),
@@ -220,7 +220,7 @@ fn check_statement(
         }
 
         | StatementKind::FakeRead(FakeReadCause::ForMatchedPlace, _)
-        if !tcx.features().const_if_match
+        if !feature_allowed(tcx, def_id, sym::const_if_match)
         => {
             Err((span, "loops and conditional expressions are not stable in const fn".into()))
         }
@@ -272,7 +272,7 @@ fn check_place(
     while let &[ref proj_base @ .., elem] = cursor {
         cursor = proj_base;
         match elem {
-            ProjectionElem::Downcast(..) if !tcx.features().const_if_match
+            ProjectionElem::Downcast(..) if !feature_allowed(tcx, def_id, sym::const_if_match)
                 => return Err((span, "`match` or `if let` in `const fn` is unstable".into())),
             ProjectionElem::Downcast(_symbol, _variant_index) => {}
 
@@ -329,7 +329,7 @@ fn check_terminator(
 
         | TerminatorKind::FalseEdges { .. }
         | TerminatorKind::SwitchInt { .. }
-        if !tcx.features().const_if_match
+        if !feature_allowed(tcx, def_id, sym::const_if_match)
         => Err((
             span,
             "loops and conditional expressions are not stable in const fn".into(),
@@ -341,7 +341,7 @@ fn check_terminator(
         }
 
         // FIXME(ecstaticmorse): We probably want to allow `Unreachable` unconditionally.
-        TerminatorKind::Unreachable if tcx.features().const_if_match => Ok(()),
+        TerminatorKind::Unreachable if feature_allowed(tcx, def_id, sym::const_if_match) => Ok(()),
 
         | TerminatorKind::Abort | TerminatorKind::Unreachable => {
             Err((span, "const fn with unreachable code is not stable".into()))

src/librustc_parse/parser/pat.rs

@@ -459,16 +459,26 @@ impl<'a> Parser<'a> {
     /// Parse `&pat` / `&mut pat`.
     fn parse_pat_deref(&mut self, expected: Expected) -> PResult<'a, PatKind> {
         self.expect_and()?;
+        self.recover_lifetime_in_deref_pat();
         let mutbl = self.parse_mutability();
+        let subpat = self.parse_pat_with_range_pat(false, expected)?;
+        Ok(PatKind::Ref(subpat, mutbl))
+    }
 
+    fn recover_lifetime_in_deref_pat(&mut self) {
         if let token::Lifetime(name) = self.token.kind {
-            let mut err = self.fatal(&format!("unexpected lifetime `{}` in pattern", name));
-            err.span_label(self.token.span, "unexpected lifetime");
-            return Err(err);
-        }
+            self.bump(); // `'a`
 
-        let subpat = self.parse_pat_with_range_pat(false, expected)?;
-        Ok(PatKind::Ref(subpat, mutbl))
+            let span = self.prev_span;
+            self.struct_span_err(span, &format!("unexpected lifetime `{}` in pattern", name))
+                .span_suggestion(
+                    span,
+                    "remove the lifetime",
+                    String::new(),
+                    Applicability::MachineApplicable,
+                )
+                .emit();
+        }
     }
 
     /// Parse a tuple or parenthesis pattern.

src/libsyntax_expand/mbe/macro_parser.rs

@@ -83,7 +83,7 @@ use syntax::print::pprust;
 use syntax::sess::ParseSess;
 use syntax::symbol::{kw, sym, Symbol};
 use syntax::token::{self, DocComment, Nonterminal, Token};
-use syntax::tokenstream::{DelimSpan, TokenStream};
+use syntax::tokenstream::TokenStream;
 
 use errors::{PResult, FatalError};
 use smallvec::{smallvec, SmallVec};
@@ -164,11 +164,6 @@ struct MatcherPos<'root, 'tt> {
     /// The position of the "dot" in this matcher
     idx: usize,
 
-    /// The first span of source that the beginning of this matcher corresponds to. In other
-    /// words, the token in the source whose span is `sp_open` is matched against the first token of
-    /// the matcher.
-    sp_open: Span,
-
     /// For each named metavar in the matcher, we keep track of token trees matched against the
     /// metavar by the black box parser. In particular, there may be more than one match per
     /// metavar if we are in a repetition (each repetition matches each of the variables).
@@ -307,17 +302,15 @@ fn create_matches(len: usize) -> Box<[Lrc<NamedMatchVec>]> {
 }
 
 /// Generates the top-level matcher position in which the "dot" is before the first token of the
-/// matcher `ms` and we are going to start matching at the span `open` in the source.
-fn initial_matcher_pos<'root, 'tt>(ms: &'tt [TokenTree], open: Span) -> MatcherPos<'root, 'tt> {
+/// matcher `ms`.
+fn initial_matcher_pos<'root, 'tt>(ms: &'tt [TokenTree]) -> MatcherPos<'root, 'tt> {
     let match_idx_hi = count_names(ms);
     let matches = create_matches(match_idx_hi);
     MatcherPos {
         // Start with the top level matcher given to us
         top_elts: TtSeq(ms), // "elts" is an abbr. for "elements"
         // The "dot" is before the first token of the matcher
         idx: 0,
-        // We start matching at the span `open` in the source code
-        sp_open: open,
 
         // Initialize `matches` to a bunch of empty `Vec`s -- one for each metavar in `top_elts`.
         // `match_lo` for `top_elts` is 0 and `match_hi` is `matches.len()`. `match_cur` is 0 since
@@ -355,7 +348,7 @@ fn initial_matcher_pos<'root, 'tt>(ms: &'tt [TokenTree], open: Span) -> MatcherP
 /// token tree it was derived from.
 #[derive(Debug, Clone)]
 crate enum NamedMatch {
-    MatchedSeq(Lrc<NamedMatchVec>, DelimSpan),
+    MatchedSeq(Lrc<NamedMatchVec>),
     MatchedNonterminal(Lrc<Nonterminal>),
 }
 
@@ -497,8 +490,7 @@ fn inner_parse_loop<'root, 'tt>(
                     // Add matches from this repetition to the `matches` of `up`
                     for idx in item.match_lo..item.match_hi {
                         let sub = item.matches[idx].clone();
-                        let span = DelimSpan::from_pair(item.sp_open, token.span);
-                        new_pos.push_match(idx, MatchedSeq(sub, span));
+                        new_pos.push_match(idx, MatchedSeq(sub));
                     }
 
                     // Move the "dot" past the repetition in `up`
@@ -552,7 +544,7 @@ fn inner_parse_loop<'root, 'tt>(
                         new_item.match_cur += seq.num_captures;
                         new_item.idx += 1;
                         for idx in item.match_cur..item.match_cur + seq.num_captures {
-                            new_item.push_match(idx, MatchedSeq(Lrc::new(smallvec![]), sp));
+                            new_item.push_match(idx, MatchedSeq(Lrc::new(smallvec![])));
                         }
                         cur_items.push(new_item);
                     }
@@ -568,7 +560,6 @@ fn inner_parse_loop<'root, 'tt>(
                         match_cur: item.match_cur,
                         match_hi: item.match_cur + seq.num_captures,
                         up: Some(item),
-                        sp_open: sp.open,
                         top_elts: Tt(TokenTree::Sequence(sp, seq)),
                     })));
                 }
@@ -663,7 +654,7 @@ pub(super) fn parse(
     //
     // This MatcherPos instance is allocated on the stack. All others -- and
     // there are frequently *no* others! -- are allocated on the heap.
-    let mut initial = initial_matcher_pos(ms, parser.token.span);
+    let mut initial = initial_matcher_pos(ms);
     let mut cur_items = smallvec![MatcherPosHandle::Ref(&mut initial)];
     let mut next_items = Vec::new();
 

src/libsyntax_expand/mbe/macro_rules.rs

@@ -379,7 +379,7 @@ pub fn compile_declarative_macro(
 
     // Extract the arguments:
     let lhses = match argument_map[&lhs_nm] {
-        MatchedSeq(ref s, _) => s
+        MatchedSeq(ref s) => s
             .iter()
             .map(|m| {
                 if let MatchedNonterminal(ref nt) = *m {
@@ -402,7 +402,7 @@ pub fn compile_declarative_macro(
     };
 
     let rhses = match argument_map[&rhs_nm] {
-        MatchedSeq(ref s, _) => s
+        MatchedSeq(ref s) => s
             .iter()
             .map(|m| {
                 if let MatchedNonterminal(ref nt) = *m {