Auto merge of rust-lang#93376 - flip1995:clippyup, r=Manishearth

Update Clippy r? `@Manishearth`

Author: bors

src/tools/clippy/CHANGELOG.md

@@ -981,7 +981,7 @@ Released 2021-03-25
  [#6532](https://github.com/rust-lang/rust-clippy/pull/6532)
 * [`single_match`] Suggest `if` over `if let` when possible
  [#6574](https://github.com/rust-lang/rust-clippy/pull/6574)
-* [`ref_in_deref`] Use parentheses correctly in suggestion
+* `ref_in_deref` Use parentheses correctly in suggestion
  [#6609](https://github.com/rust-lang/rust-clippy/pull/6609)
 * [`stable_sort_primitive`] Clarify error message
  [#6611](https://github.com/rust-lang/rust-clippy/pull/6611)
@@ -3227,7 +3227,6 @@ Released 2018-09-13
 [`redundant_slicing`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_slicing
 [`redundant_static_lifetimes`]: https://rust-lang.github.io/rust-clippy/master/index.html#redundant_static_lifetimes
 [`ref_binding_to_reference`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_binding_to_reference
-[`ref_in_deref`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_in_deref
 [`ref_option_ref`]: https://rust-lang.github.io/rust-clippy/master/index.html#ref_option_ref
 [`regex_macro`]: https://rust-lang.github.io/rust-clippy/master/index.html#regex_macro
 [`repeat_once`]: https://rust-lang.github.io/rust-clippy/master/index.html#repeat_once

src/tools/clippy/clippy_dev/src/bless.rs

@@ -9,9 +9,14 @@ use walkdir::WalkDir;
 
 use crate::clippy_project_root;
 
+#[cfg(not(windows))]
+static CARGO_CLIPPY_EXE: &str = "cargo-clippy";
+#[cfg(windows)]
+static CARGO_CLIPPY_EXE: &str = "cargo-clippy.exe";
+
 static CLIPPY_BUILD_TIME: SyncLazy<Option<std::time::SystemTime>> = SyncLazy::new(|| {
  let mut path = std::env::current_exe().unwrap();
- path.set_file_name("cargo-clippy");
+ path.set_file_name(CARGO_CLIPPY_EXE);
  fs::metadata(path).ok()?.modified().ok()
 });
 

src/tools/clippy/clippy_dev/src/lint.rs

@@ -7,7 +7,6 @@ pub fn run(filename: &str) {
  .args(["-Z", "no-codegen"])
  .args(["--edition", "2021"])
  .arg(filename)
- .env("__CLIPPY_INTERNAL_TESTS", "true")
  .status()
  .expect("failed to run cargo")
  .code();

src/tools/clippy/clippy_lints/src/borrow_as_ptr.rs

@@ -94,4 +94,6 @@ impl<'tcx> LateLintPass<'tcx> for BorrowAsPtr {
  }
  }
  }
+
+ extract_msrv_attr!(LateContext);
 }

src/tools/clippy/clippy_lints/src/casts/unnecessary_cast.rs

@@ -23,15 +23,14 @@ pub(super) fn check(
 
  if_chain! {
  if let LitKind::Int(n, _) = lit.node;
- if let Some(src) = snippet_opt(cx, lit.span);
+ if let Some(src) = snippet_opt(cx, cast_expr.span);
  if cast_to.is_floating_point();
  if let Some(num_lit) = NumericLiteral::from_lit_kind(&src, &lit.node);
  let from_nbits = 128 - n.leading_zeros();
  let to_nbits = fp_ty_mantissa_nbits(cast_to);
  if from_nbits != 0 && to_nbits != 0 && from_nbits <= to_nbits && num_lit.is_decimal();
  then {
- let literal_str = if is_unary_neg(cast_expr) { format!("-{}", num_lit.integer) } else { num_lit.integer.into() };
- lint_unnecessary_cast(cx, expr, &literal_str, cast_from, cast_to);
+ lint_unnecessary_cast(cx, expr, num_lit.integer, cast_from, cast_to);
  return true
  }
  }
@@ -48,7 +47,7 @@ pub(super) fn check(
  | LitKind::Float(_, LitFloatType::Suffixed(_))
  if cast_from.kind() == cast_to.kind() =>
  {
- if let Some(src) = snippet_opt(cx, lit.span) {
+ if let Some(src) = snippet_opt(cx, cast_expr.span) {
  if let Some(num_lit) = NumericLiteral::from_lit_kind(&src, &lit.node) {
  lint_unnecessary_cast(cx, expr, num_lit.integer, cast_from, cast_to);
  }
@@ -113,7 +112,3 @@ fn fp_ty_mantissa_nbits(typ: Ty<'_>) -> u32 {
  _ => 0,
  }
 }
-
-fn is_unary_neg(expr: &Expr<'_>) -> bool {
- matches!(expr.kind, ExprKind::Unary(UnOp::Neg, _))
-}

src/tools/clippy/clippy_lints/src/dereference.rs

@@ -1,5 +1,6 @@
 use clippy_utils::diagnostics::{span_lint_and_sugg, span_lint_and_then};
 use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
+use clippy_utils::sugg::has_enclosing_paren;
 use clippy_utils::ty::peel_mid_ty_refs;
 use clippy_utils::{get_parent_expr, get_parent_node, is_lint_allowed, path_to_local};
 use rustc_ast::util::parser::{PREC_POSTFIX, PREC_PREFIX};
@@ -10,11 +11,10 @@ use rustc_hir::{
  Pat, PatKind, UnOp,
 };
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow};
+use rustc_middle::ty::adjustment::{Adjust, Adjustment, AutoBorrow, AutoBorrowMutability};
 use rustc_middle::ty::{self, Ty, TyCtxt, TyS, TypeckResults};
 use rustc_session::{declare_tool_lint, impl_lint_pass};
 use rustc_span::{symbol::sym, Span};
-use std::iter;
 
 declare_clippy_lint! {
  /// ### What it does
@@ -131,8 +131,6 @@ pub struct Dereferencing {
 struct StateData {
  /// Span of the top level expression
  span: Span,
- /// The required mutability
- target_mut: Mutability,
 }
 
 enum State {
@@ -141,9 +139,13 @@ enum State {
  // The number of calls in a sequence which changed the referenced type
  ty_changed_count: usize,
  is_final_ufcs: bool,
+ /// The required mutability
+ target_mut: Mutability,
  },
  DerefedBorrow {
- count: u32,
+ count: usize,
+ required_precedence: i8,
+ msg: &'static str,
  },
 }
 
@@ -214,59 +216,98 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
  1
  },
  is_final_ufcs: matches!(expr.kind, ExprKind::Call(..)),
- },
- StateData {
- span: expr.span,
  target_mut,
  },
+ StateData { span: expr.span },
  ));
  },
  RefOp::AddrOf => {
  // Find the number of times the borrow is auto-derefed.
  let mut iter = find_adjustments(cx.tcx, typeck, expr).iter();
- if let Some((i, adjust)) = iter.by_ref().enumerate().find_map(|(i, adjust)| {
- if !matches!(adjust.kind, Adjust::Deref(_)) {
- Some((i, adjust))
- } else if !adjust.target.is_ref() {
- // Add one to the number of references found.
- Some((i + 1, adjust))
+ let mut deref_count = 0usize;
+ let next_adjust = loop {
+ match iter.next() {
+ Some(adjust) => {
+ if !matches!(adjust.kind, Adjust::Deref(_)) {
+ break Some(adjust);
+ } else if !adjust.target.is_ref() {
+ deref_count += 1;
+ break iter.next();
+ }
+ deref_count += 1;
+ },
+ None => break None,
+ };
+ };
+
+ // Determine the required number of references before any can be removed. In all cases the
+ // reference made by the current expression will be removed. After that there are four cases to
+ // handle.
+ //
+ // 1. Auto-borrow will trigger in the current position, so no further references are required.
+ // 2. Auto-deref ends at a reference, or the underlying type, so one extra needs to be left to
+ // handle the automatically inserted re-borrow.
+ // 3. Auto-deref hits a user-defined `Deref` impl, so at least one reference needs to exist to
+ // start auto-deref.
+ // 4. If the chain of non-user-defined derefs ends with a mutable re-borrow, and re-borrow
+ // adjustments will not be inserted automatically, then leave one further reference to avoid
+ // moving a mutable borrow.
+ // e.g.
+ // fn foo<T>(x: &mut Option<&mut T>, y: &mut T) {
+ // let x = match x {
+ // // Removing the borrow will cause `x` to be moved
+ // Some(x) => &mut *x,
+ // None => y
+ // };
+ // }
+ let deref_msg =
+ "this expression creates a reference which is immediately dereferenced by the compiler";
+ let borrow_msg = "this expression borrows a value the compiler would automatically borrow";
+
+ let (required_refs, required_precedence, msg) = if is_auto_borrow_position(parent, expr.hir_id)
+ {
+ (1, PREC_POSTFIX, if deref_count == 1 { borrow_msg } else { deref_msg })
+ } else if let Some(&Adjust::Borrow(AutoBorrow::Ref(_, mutability))) =
+ next_adjust.map(|a| &a.kind)
+ {
+ if matches!(mutability, AutoBorrowMutability::Mut { .. })
+ && !is_auto_reborrow_position(parent)
+ {
+ (3, 0, deref_msg)
  } else {
- None
- }
- }) {
- // Found two consecutive derefs. At least one can be removed.
- if i > 1 {
- let target_mut = iter::once(adjust)
- .chain(iter)
- .find_map(|adjust| match adjust.kind {
- Adjust::Borrow(AutoBorrow::Ref(_, m)) => Some(m.into()),
- _ => None,
- })
- // This default should never happen. Auto-deref always reborrows.
- .unwrap_or(Mutability::Not);
- self.state = Some((
- // Subtract one for the current borrow expression, and one to cover the last
- // reference which can't be removed (it's either reborrowed, or needed for
- // auto-deref to happen).
- State::DerefedBorrow {
- count:
- // Truncation here would require more than a `u32::MAX` level reference. The compiler
- // does not support this.
- #[allow(clippy::cast_possible_truncation)]
- { i as u32 - 2 }
- },
- StateData {
- span: expr.span,
- target_mut,
- },
- ));
+ (2, 0, deref_msg)
  }
+ } else {
+ (2, 0, deref_msg)
+ };
+
+ if deref_count >= required_refs {
+ self.state = Some((
+ State::DerefedBorrow {
+ // One of the required refs is for the current borrow expression, the remaining ones
+ // can't be removed without breaking the code. See earlier comment.
+ count: deref_count - required_refs,
+ required_precedence,
+ msg,
+ },
+ StateData { span: expr.span },
+ ));
  }
  },
  _ => (),
  }
  },
- (Some((State::DerefMethod { ty_changed_count, .. }, data)), RefOp::Method(_)) => {
+ (
+ Some((
+ State::DerefMethod {
+ target_mut,
+ ty_changed_count,
+ ..
+ },
+ data,
+ )),
+ RefOp::Method(_),
+ ) => {
  self.state = Some((
  State::DerefMethod {
  ty_changed_count: if deref_method_same_type(typeck.expr_ty(expr), typeck.expr_ty(sub_expr)) {
@@ -275,12 +316,30 @@ impl<'tcx> LateLintPass<'tcx> for Dereferencing {
  ty_changed_count + 1
  },
  is_final_ufcs: matches!(expr.kind, ExprKind::Call(..)),
+ target_mut,
  },
  data,
  ));
  },
- (Some((State::DerefedBorrow { count }, data)), RefOp::AddrOf) if count != 0 => {
- self.state = Some((State::DerefedBorrow { count: count - 1 }, data));
+ (
+ Some((
+ State::DerefedBorrow {
+ count,
+ required_precedence,
+ msg,
+ },
+ data,
+ )),
+ RefOp::AddrOf,
+ ) if count != 0 => {
+ self.state = Some((
+ State::DerefedBorrow {
+ count: count - 1,
+ required_precedence,
+ msg,
+ },
+ data,
+ ));
  },
 
  (Some((state, data)), _) => report(cx, expr, state, data),
@@ -455,6 +514,30 @@ fn is_linted_explicit_deref_position(parent: Option<Node<'_>>, child_id: HirId,
  }
 }
 
+/// Checks if the given expression is in a position which can be auto-reborrowed.
+/// Note: This is only correct assuming auto-deref is already occurring.
+fn is_auto_reborrow_position(parent: Option<Node<'_>>) -> bool {
+ match parent {
+ Some(Node::Expr(parent)) => matches!(parent.kind, ExprKind::MethodCall(..) | ExprKind::Call(..)),
+ Some(Node::Local(_)) => true,
+ _ => false,
+ }
+}
+
+/// Checks if the given expression is a position which can auto-borrow.
+fn is_auto_borrow_position(parent: Option<Node<'_>>, child_id: HirId) -> bool {
+ if let Some(Node::Expr(parent)) = parent {
+ match parent.kind {
+ ExprKind::MethodCall(_, [self_arg, ..], _) => self_arg.hir_id == child_id,
+ ExprKind::Field(..) => true,
+ ExprKind::Call(f, _) => f.hir_id == child_id,
+ _ => false,
+ }
+ } else {
+ false
+ }
+}
+
 /// Adjustments are sometimes made in the parent block rather than the expression itself.
 fn find_adjustments<'tcx>(
  tcx: TyCtxt<'tcx>,
@@ -503,6 +586,7 @@ fn report(cx: &LateContext<'_>, expr: &Expr<'_>, state: State, data: StateData)
  State::DerefMethod {
  ty_changed_count,
  is_final_ufcs,
+ target_mut,
  } => {
  let mut app = Applicability::MachineApplicable;
  let (expr_str, expr_is_macro_call) = snippet_with_context(cx, expr.span, data.span.ctxt(), "..", &mut app);
@@ -517,12 +601,12 @@ fn report(cx: &LateContext<'_>, expr: &Expr<'_>, state: State, data: StateData)
  };
  let addr_of_str = if ty_changed_count < ref_count {
  // Check if a reborrow from &mut T -> &T is required.
- if data.target_mut == Mutability::Not && matches!(ty.kind(), ty::Ref(_, _, Mutability::Mut)) {
+ if target_mut == Mutability::Not && matches!(ty.kind(), ty::Ref(_, _, Mutability::Mut)) {
  "&*"
  } else {
  ""
  }
- } else if data.target_mut == Mutability::Mut {
+ } else if target_mut == Mutability::Mut {
  "&mut "
  } else {
  "&"
@@ -538,7 +622,7 @@ fn report(cx: &LateContext<'_>, expr: &Expr<'_>, state: State, data: StateData)
  cx,
  EXPLICIT_DEREF_METHODS,
  data.span,
- match data.target_mut {
+ match target_mut {
  Mutability::Not => "explicit `deref` method call",
  Mutability::Mut => "explicit `deref_mut` method call",
  },
@@ -547,19 +631,24 @@ fn report(cx: &LateContext<'_>, expr: &Expr<'_>, state: State, data: StateData)
  app,
  );
  },
- State::DerefedBorrow { .. } => {
+ State::DerefedBorrow {
+ required_precedence,
+ msg,
+ ..
+ } => {
  let mut app = Applicability::MachineApplicable;
  let snip = snippet_with_context(cx, expr.span, data.span.ctxt(), "..", &mut app).0;
  span_lint_and_sugg(
  cx,
  NEEDLESS_BORROW,
  data.span,
- &format!(
- "this expression borrows a reference (`{}`) that is immediately dereferenced by the compiler",
- cx.typeck_results().expr_ty(expr),
- ),
+ msg,
  "change this to",
- snip.into(),
+ if required_precedence > expr.precedence().order() && !has_enclosing_paren(&snip) {
+ format!("({})", snip)
+ } else {
+ snip.into()
+ },
  app,
  );
  },