Rollup of 7 pull requests

compiler/rustc_lint/src/array_into_iter.rs

@@ -3,8 +3,8 @@ use rustc_errors::Applicability;
 use rustc_hir as hir;
 use rustc_middle::ty;
 use rustc_middle::ty::adjustment::{Adjust, Adjustment};
-use rustc_session::lint::FutureBreakage;
 use rustc_span::symbol::sym;
+use rustc_span::Span;
 
 declare_lint! {
     /// The `array_into_iter` lint detects calling `into_iter` on arrays.
@@ -20,37 +20,40 @@ declare_lint! {
     ///
     /// ### Explanation
     ///
-    /// In the future, it is planned to add an `IntoIter` implementation for
-    /// arrays such that it will iterate over *values* of the array instead of
-    /// references. Due to how method resolution works, this will change
-    /// existing code that uses `into_iter` on arrays. The solution to avoid
-    /// this warning is to use `iter()` instead of `into_iter()`.
-    ///
-    /// This is a [future-incompatible] lint to transition this to a hard error
-    /// in the future. See [issue #66145] for more details and a more thorough
-    /// description of the lint.
-    ///
-    /// [issue #66145]: https://github.com/rust-lang/rust/issues/66145
-    /// [future-incompatible]: ../index.md#future-incompatible-lints
+    /// Since Rust 1.53, arrays implement `IntoIterator`. However, to avoid
+    /// breakage, `array.into_iter()` in Rust 2015 and 2018 code will still
+    /// behave as `(&array).into_iter()`, returning an iterator over
+    /// references, just like in Rust 1.52 and earlier.
+    /// This only applies to the method call syntax `array.into_iter()`, not to
+    /// any other syntax such as `for _ in array` or `IntoIterator::into_iter(array)`.
     pub ARRAY_INTO_ITER,
     Warn,
-    "detects calling `into_iter` on arrays",
-    @future_incompatible = FutureIncompatibleInfo {
-        reference: "issue #66145 <https://github.com/rust-lang/rust/issues/66145>",
-        edition: None,
-        future_breakage: Some(FutureBreakage {
-            date: None
-        })
-    };
+    "detects calling `into_iter` on arrays in Rust 2015 and 2018",
+}
+
+#[derive(Copy, Clone, Default)]
+pub struct ArrayIntoIter {
+    for_expr_span: Span,
 }
 
-declare_lint_pass!(
-    /// Checks for instances of calling `into_iter` on arrays.
-    ArrayIntoIter => [ARRAY_INTO_ITER]
-);
+impl_lint_pass!(ArrayIntoIter => [ARRAY_INTO_ITER]);
 
 impl<'tcx> LateLintPass<'tcx> for ArrayIntoIter {
     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'tcx>) {
+        // Save the span of expressions in `for _ in expr` syntax,
+        // so we can give a better suggestion for those later.
+        if let hir::ExprKind::Match(arg, [_], hir::MatchSource::ForLoopDesugar) = &expr.kind {
+            if let hir::ExprKind::Call(path, [arg]) = &arg.kind {
+                if let hir::ExprKind::Path(hir::QPath::LangItem(
+                    hir::LangItem::IntoIterIntoIter,
+                    _,
+                )) = &path.kind
+                {
+                    self.for_expr_span = arg.span;
+                }
+            }
+        }
+
         // We only care about method call expressions.
         if let hir::ExprKind::MethodCall(call, span, args, _) = &expr.kind {
             if call.ident.name != sym::into_iter {
@@ -106,19 +109,37 @@ impl<'tcx> LateLintPass<'tcx> for ArrayIntoIter {
                 _ => bug!("array type coerced to something other than array or slice"),
             };
             cx.struct_span_lint(ARRAY_INTO_ITER, *span, |lint| {
-                lint.build(&format!(
-                "this method call currently resolves to `<&{} as IntoIterator>::into_iter` (due \
-                    to autoref coercions), but that might change in the future when \
-                    `IntoIterator` impls for arrays are added.",
-                target,
-                ))
-                .span_suggestion(
+                let mut diag = lint.build(&format!(
+                    "this method call resolves to `<&{} as IntoIterator>::into_iter` \
+                    (due to backwards compatibility), \
+                    but will resolve to <{} as IntoIterator>::into_iter in Rust 2021.",
+                    target, target,
+                ));
+                diag.span_suggestion(
                     call.ident.span,
                     "use `.iter()` instead of `.into_iter()` to avoid ambiguity",
                     "iter".into(),
                     Applicability::MachineApplicable,
-                )
-                .emit();
+                );
+                if self.for_expr_span == expr.span {
+                    let expr_span = expr.span.ctxt().outer_expn_data().call_site;
+                    diag.span_suggestion(
+                        receiver_arg.span.shrink_to_hi().to(expr_span.shrink_to_hi()),
+                        "or remove `.into_iter()` to iterate by value",
+                        String::new(),
+                        Applicability::MaybeIncorrect,
+                    );
+                } else {
+                    diag.multipart_suggestion(
+                        "or use `IntoIterator::into_iter(..)` instead of `.into_iter()` to explicitly iterate by value",
+                        vec![
+                            (expr.span.shrink_to_lo(), "IntoIterator::into_iter(".into()),
+                            (receiver_arg.span.shrink_to_hi().to(expr.span.shrink_to_hi()), ")".into()),
+                        ],
+                        Applicability::MaybeIncorrect,
+                    );
+                }
+                diag.emit();
             })
         }
     }

compiler/rustc_lint/src/lib.rs

@@ -163,7 +163,7 @@ macro_rules! late_lint_passes {
                 // FIXME: Turn the computation of types which implement Debug into a query
                 // and change this to a module lint pass
                 MissingDebugImplementations: MissingDebugImplementations::default(),
-                ArrayIntoIter: ArrayIntoIter,
+                ArrayIntoIter: ArrayIntoIter::default(),
                 ClashingExternDeclarations: ClashingExternDeclarations::new(),
                 DropTraitConstraints: DropTraitConstraints,
                 TemporaryCStringAsPtr: TemporaryCStringAsPtr,

compiler/rustc_middle/src/mir/mod.rs

@@ -494,6 +494,8 @@ impl<'tcx> Body<'tcx> {
 #[derive(Copy, Clone, PartialEq, Eq, Debug, TyEncodable, TyDecodable, HashStable)]
 pub enum Safety {
     Safe,
+    /// Unsafe because of compiler-generated unsafe code, like `await` desugaring
+    BuiltinUnsafe,
     /// Unsafe because of an unsafe fn
     FnUnsafe,
     /// Unsafe because of an `unsafe` block

compiler/rustc_middle/src/thir.rs

@@ -114,6 +114,7 @@ pub struct Adt<'tcx> {
 #[derive(Copy, Clone, Debug, HashStable)]
 pub enum BlockSafety {
     Safe,
+    BuiltinUnsafe,
     ExplicitUnsafe(hir::HirId),
 }
 

compiler/rustc_mir/src/transform/check_unsafety.rs

@@ -321,6 +321,7 @@ impl<'a, 'tcx> UnsafetyChecker<'a, 'tcx> {
                 }
                 false
             }
+            Safety::BuiltinUnsafe => true,
             Safety::ExplicitUnsafe(hir_id) => {
                 // mark unsafe block as used if there are any unsafe operations inside
                 if !violations.is_empty() {

compiler/rustc_mir_build/src/build/block.rs

@@ -214,6 +214,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         debug!("update_source_scope_for({:?}, {:?})", span, safety_mode);
         let new_unsafety = match safety_mode {
             BlockSafety::Safe => None,
+            BlockSafety::BuiltinUnsafe => Some(Safety::BuiltinUnsafe),
             BlockSafety::ExplicitUnsafe(hir_id) => {
                 match self.in_scope_unsafe {
                     Safety::Safe => {}

compiler/rustc_mir_build/src/check_unsafety.rs

@@ -29,11 +29,7 @@ struct UnsafetyVisitor<'a, 'tcx> {
 }
 
 impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
-    fn in_safety_context<R>(
-        &mut self,
-        safety_context: SafetyContext,
-        f: impl FnOnce(&mut Self) -> R,
-    ) {
+    fn in_safety_context(&mut self, safety_context: SafetyContext, f: impl FnOnce(&mut Self)) {
         if let (
             SafetyContext::UnsafeBlock { span: enclosing_span, .. },
             SafetyContext::UnsafeBlock { span: block_span, hir_id, .. },
@@ -63,14 +59,14 @@ impl<'tcx> UnsafetyVisitor<'_, 'tcx> {
                 );
             }
             self.safety_context = prev_context;
-            return;
         }
     }
 
     fn requires_unsafe(&mut self, span: Span, kind: UnsafeOpKind) {
         let (description, note) = kind.description_and_note();
         let unsafe_op_in_unsafe_fn_allowed = self.unsafe_op_in_unsafe_fn_allowed();
         match self.safety_context {
+            SafetyContext::BuiltinUnsafeBlock => {}
             SafetyContext::UnsafeBlock { ref mut used, .. } => {
                 if !self.body_unsafety.is_unsafe() || !unsafe_op_in_unsafe_fn_allowed {
                     // Mark this block as useful
@@ -142,13 +138,23 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
     }
 
     fn visit_block(&mut self, block: &Block) {
-        if let BlockSafety::ExplicitUnsafe(hir_id) = block.safety_mode {
-            self.in_safety_context(
-                SafetyContext::UnsafeBlock { span: block.span, hir_id, used: false },
-                |this| visit::walk_block(this, block),
-            );
-        } else {
-            visit::walk_block(self, block);
+        match block.safety_mode {
+            // compiler-generated unsafe code should not count towards the usefulness of
+            // an outer unsafe block
+            BlockSafety::BuiltinUnsafe => {
+                self.in_safety_context(SafetyContext::BuiltinUnsafeBlock, |this| {
+                    visit::walk_block(this, block)
+                });
+            }
+            BlockSafety::ExplicitUnsafe(hir_id) => {
+                self.in_safety_context(
+                    SafetyContext::UnsafeBlock { span: block.span, hir_id, used: false },
+                    |this| visit::walk_block(this, block),
+                );
+            }
+            BlockSafety::Safe => {
+                visit::walk_block(self, block);
+            }
         }
     }
 
@@ -250,6 +256,7 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
 #[derive(Clone, Copy)]
 enum SafetyContext {
     Safe,
+    BuiltinUnsafeBlock,
     UnsafeFn,
     UnsafeBlock { span: Span, hir_id: hir::HirId, used: bool },
 }

compiler/rustc_mir_build/src/thir/cx/block.rs

@@ -26,7 +26,12 @@ impl<'tcx> Cx<'tcx> {
             expr: block.expr.map(|expr| self.mirror_expr(expr)),
             safety_mode: match block.rules {
                 hir::BlockCheckMode::DefaultBlock => BlockSafety::Safe,
-                hir::BlockCheckMode::UnsafeBlock(..) => BlockSafety::ExplicitUnsafe(block.hir_id),
+                hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::CompilerGenerated) => {
+                    BlockSafety::BuiltinUnsafe
+                }
+                hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::UserProvided) => {
+                    BlockSafety::ExplicitUnsafe(block.hir_id)
+                }
             },
         }
     }

src/librustdoc/clean/types.rs

@@ -523,6 +523,33 @@ impl Item {
             .collect()
     }
 
+    /// Find a list of all link names, without finding their href.
+    ///
+    /// This is used for generating summary text, which does not include
+    /// the link text, but does need to know which `[]`-bracketed names
+    /// are actually links.
+    crate fn link_names(&self, cache: &Cache) -> Vec<RenderedLink> {
+        cache
+            .intra_doc_links
+            .get(&self.def_id)
+            .map_or(&[][..], |v| v.as_slice())
+            .iter()
+            .filter_map(|ItemLink { link: s, link_text, did, fragment }| {
+                // FIXME(83083): using fragments as a side-channel for
+                // primitive names is very unfortunate
+                if did.is_some() || fragment.is_some() {
+                    Some(RenderedLink {
+                        original_text: s.clone(),
+                        new_text: link_text.clone(),
+                        href: String::new(),
+                    })
+                } else {
+                    None
+                }
+            })
+            .collect()
+    }
+
     crate fn is_crate(&self) -> bool {
         self.is_mod() && self.def_id.as_real().map_or(false, |did| did.index == CRATE_DEF_INDEX)
     }