Auto merge of #7333 - camsteffen:match-var, r=llogiq

Factor out match_var and get_pat_name utils ...because checking vars by name is bad, because of shadowing. changelog: none

Author: bors

clippy_lints/src/bytecount.rs

@@ -1,15 +1,15 @@
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_applicability;
 use clippy_utils::ty::match_type;
-use clippy_utils::{contains_name, get_pat_name, paths, single_segment_path};
+use clippy_utils::visitors::LocalUsedVisitor;
+use clippy_utils::{path_to_local_id, paths, peel_ref_operators, remove_blocks, strip_pat_refs};
 use if_chain::if_chain;
 use rustc_errors::Applicability;
-use rustc_hir::{BinOpKind, BorrowKind, Expr, ExprKind, UnOp};
+use rustc_hir::{BinOpKind, Expr, ExprKind, PatKind};
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_middle::ty::{self, UintTy};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::sym;
-use rustc_span::Symbol;
 
 declare_clippy_lint! {
  /// **What it does:** Checks for naive byte counts
@@ -38,42 +38,43 @@ declare_lint_pass!(ByteCount => [NAIVE_BYTECOUNT]);
 impl<'tcx> LateLintPass<'tcx> for ByteCount {
  fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
  if_chain! {
- if let ExprKind::MethodCall(count, _, count_args, _) = expr.kind;
+ if let ExprKind::MethodCall(count, _, [count_recv], _) = expr.kind;
  if count.ident.name == sym!(count);
- if count_args.len() == 1;
- if let ExprKind::MethodCall(filter, _, filter_args, _) = count_args[0].kind;
+ if let ExprKind::MethodCall(filter, _, [filter_recv, filter_arg], _) = count_recv.kind;
  if filter.ident.name == sym!(filter);
- if filter_args.len() == 2;
- if let ExprKind::Closure(_, _, body_id, _, _) = filter_args[1].kind;
+ if let ExprKind::Closure(_, _, body_id, _, _) = filter_arg.kind;
  let body = cx.tcx.hir().body(body_id);
- if body.params.len() == 1;
- if let Some(argname) = get_pat_name(body.params[0].pat);
+ if let [param] = body.params;
+ if let PatKind::Binding(_, arg_id, _, _) = strip_pat_refs(param.pat).kind;
  if let ExprKind::Binary(ref op, l, r) = body.value.kind;
  if op.node == BinOpKind::Eq;
  if match_type(cx,
- cx.typeck_results().expr_ty(&filter_args[0]).peel_refs(),
+ cx.typeck_results().expr_ty(filter_recv).peel_refs(),
  &paths::SLICE_ITER);
+ let operand_is_arg = |expr| {
+ let expr = peel_ref_operators(cx, remove_blocks(expr));
+ path_to_local_id(expr, arg_id)
+ };
+ let needle = if operand_is_arg(l) {
+ r
+ } else if operand_is_arg(r) {
+ l
+ } else {
+ return;
+ };
+ if ty::Uint(UintTy::U8) == *cx.typeck_results().expr_ty(needle).peel_refs().kind();
+ if !LocalUsedVisitor::new(cx, arg_id).check_expr(needle);
  then {
- let needle = match get_path_name(l) {
- Some(name) if check_arg(name, argname, r) => r,
- _ => match get_path_name(r) {
- Some(name) if check_arg(name, argname, l) => l,
- _ => { return; }
- }
- };
- if ty::Uint(UintTy::U8) != *cx.typeck_results().expr_ty(needle).peel_refs().kind() {
- return;
- }
  let haystack = if let ExprKind::MethodCall(path, _, args, _) =
- filter_args[0].kind {
+ filter_recv.kind {
  let p = path.ident.name;
  if (p == sym::iter || p == sym!(iter_mut)) && args.len() == 1 {
  &args[0]
  } else {
- &filter_args[0]
+ &filter_recv
  }
  } else {
- &filter_args[0]
+ &filter_recv
  };
  let mut applicability = Applicability::MaybeIncorrect;
  span_lint_and_sugg(
@@ -91,24 +92,3 @@ impl<'tcx> LateLintPass<'tcx> for ByteCount {
  };
  }
 }
-
-fn check_arg(name: Symbol, arg: Symbol, needle: &Expr<'_>) -> bool {
- name == arg && !contains_name(name, needle)
-}
-
-fn get_path_name(expr: &Expr<'_>) -> Option<Symbol> {
- match expr.kind {
- ExprKind::Box(e) | ExprKind::AddrOf(BorrowKind::Ref, _, e) | ExprKind::Unary(UnOp::Deref, e) => {
- get_path_name(e)
- },
- ExprKind::Block(b, _) => {
- if b.stmts.is_empty() {
- b.expr.as_ref().and_then(|p| get_path_name(p))
- } else {
- None
- }
- },
- ExprKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
- _ => None,
- }
-}

clippy_lints/src/collapsible_match.rs

@@ -1,11 +1,10 @@
 use clippy_utils::diagnostics::span_lint_and_then;
 use clippy_utils::visitors::LocalUsedVisitor;
-use clippy_utils::{is_lang_ctor, path_to_local, SpanlessEq};
+use clippy_utils::{is_lang_ctor, path_to_local, peel_ref_operators, SpanlessEq};
 use if_chain::if_chain;
 use rustc_hir::LangItem::OptionNone;
-use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind, StmtKind, UnOp};
+use rustc_hir::{Arm, Expr, ExprKind, Guard, HirId, Pat, PatKind, StmtKind};
 use rustc_lint::{LateContext, LateLintPass};
-use rustc_middle::ty::TypeckResults;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::{MultiSpan, Span};
 
@@ -73,7 +72,7 @@ fn check_arm<'tcx>(arm: &Arm<'tcx>, wild_outer_arm: &Arm<'tcx>, cx: &LateContext
  if arms_inner.iter().all(|arm| arm.guard.is_none());
  // match expression must be a local binding
  // match <local> { .. }
- if let Some(binding_id) = path_to_local(strip_ref_operators(expr_in, cx.typeck_results()));
+ if let Some(binding_id) = path_to_local(peel_ref_operators(cx, expr_in));
  // one of the branches must be "wild-like"
  if let Some(wild_inner_arm_idx) = arms_inner.iter().rposition(|arm_inner| arm_is_wild_like(cx, arm_inner));
  let (wild_inner_arm, non_wild_inner_arm) =
@@ -163,16 +162,3 @@ fn pat_contains_or(pat: &Pat<'_>) -> bool {
  });
  result
 }
-
-/// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
-/// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
-fn strip_ref_operators<'hir>(mut expr: &'hir Expr<'hir>, typeck_results: &TypeckResults<'_>) -> &'hir Expr<'hir> {
- loop {
- match expr.kind {
- ExprKind::AddrOf(_, _, e) => expr = e,
- ExprKind::Unary(UnOp::Deref, e) if typeck_results.expr_ty(e).is_ref() => expr = e,
- _ => break,
- }
- }
- expr
-}

clippy_lints/src/manual_map.rs

@@ -3,19 +3,17 @@ use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::{snippet_with_applicability, snippet_with_context};
 use clippy_utils::ty::{is_type_diagnostic_item, peel_mid_ty_refs_is_mutable};
 use clippy_utils::{
- can_move_expr_to_closure, in_constant, is_allowed, is_else_clause, is_lang_ctor, match_var, peel_hir_expr_refs,
+ can_move_expr_to_closure, in_constant, is_allowed, is_else_clause, is_lang_ctor, path_to_local_id,
+ peel_hir_expr_refs,
 };
 use rustc_ast::util::parser::PREC_POSTFIX;
 use rustc_errors::Applicability;
 use rustc_hir::LangItem::{OptionNone, OptionSome};
-use rustc_hir::{Arm, BindingAnnotation, Block, Expr, ExprKind, MatchSource, Mutability, Pat, PatKind};
+use rustc_hir::{Arm, BindingAnnotation, Block, Expr, ExprKind, HirId, MatchSource, Mutability, Pat, PatKind};
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_middle::lint::in_external_macro;
 use rustc_session::{declare_lint_pass, declare_tool_lint};
-use rustc_span::{
- symbol::{sym, Ident},
- SyntaxContext,
-};
+use rustc_span::{sym, SyntaxContext};
 
 declare_clippy_lint! {
  /// **What it does:** Checks for usages of `match` which could be implemented using `map`
@@ -141,13 +139,13 @@ impl LateLintPass<'_> for ManualMap {
  scrutinee_str.into()
  };
 
- let body_str = if let PatKind::Binding(annotation, _, some_binding, None) = some_pat.kind {
- match can_pass_as_func(cx, some_binding, some_expr) {
+ let body_str = if let PatKind::Binding(annotation, id, some_binding, None) = some_pat.kind {
+ match can_pass_as_func(cx, id, some_expr) {
  Some(func) if func.span.ctxt() == some_expr.span.ctxt() => {
  snippet_with_applicability(cx, func.span, "..", &mut app).into_owned()
  },
  _ => {
- if match_var(some_expr, some_binding.name)
+ if path_to_local_id(some_expr, id)
  && !is_allowed(cx, MATCH_AS_REF, expr.hir_id)
  && binding_ref.is_some()
  {
@@ -199,10 +197,10 @@ impl LateLintPass<'_> for ManualMap {
 
 // Checks whether the expression could be passed as a function, or whether a closure is needed.
 // Returns the function to be passed to `map` if it exists.
-fn can_pass_as_func(cx: &LateContext<'tcx>, binding: Ident, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
+fn can_pass_as_func(cx: &LateContext<'tcx>, binding: HirId, expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
  match expr.kind {
  ExprKind::Call(func, [arg])
- if match_var(arg, binding.name) && cx.typeck_results().expr_adjustments(arg).is_empty() =>
+ if path_to_local_id(arg, binding) && cx.typeck_results().expr_adjustments(arg).is_empty() =>
  {
  Some(func)
  },

clippy_utils/src/lib.rs

@@ -72,7 +72,7 @@ use rustc_hir::LangItem::{ResultErr, ResultOk};
 use rustc_hir::{
  def, Arm, BindingAnnotation, Block, Body, Constness, Destination, Expr, ExprKind, FnDecl, GenericArgs, HirId, Impl,
  ImplItem, ImplItemKind, IsAsync, Item, ItemKind, LangItem, Local, MatchSource, Node, Param, Pat, PatKind, Path,
- PathSegment, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind,
+ PathSegment, QPath, Stmt, StmtKind, TraitItem, TraitItemKind, TraitRef, TyKind, UnOp,
 };
 use rustc_lint::{LateContext, Level, Lint, LintContext};
 use rustc_middle::hir::exports::Export;
@@ -326,16 +326,6 @@ pub fn is_trait_method(cx: &LateContext<'_>, expr: &Expr<'_>, diag_item: Symbol)
  .map_or(false, |did| is_diag_trait_item(cx, did, diag_item))
 }
 
-/// Checks if an expression references a variable of the given name.
-pub fn match_var(expr: &Expr<'_>, var: Symbol) -> bool {
- if let ExprKind::Path(QPath::Resolved(None, path)) = expr.kind {
- if let [p] = path.segments {
- return p.ident.name == var;
- }
- }
- false
-}
-
 pub fn last_path_segment<'tcx>(path: &QPath<'tcx>) -> &'tcx PathSegment<'tcx> {
  match *path {
  QPath::Resolved(_, path) => path.segments.last().expect("A path must have at least one segment"),
@@ -707,16 +697,6 @@ pub fn get_item_name(cx: &LateContext<'_>, expr: &Expr<'_>) -> Option<Symbol> {
  }
 }
 
-/// Gets the name of a `Pat`, if any.
-pub fn get_pat_name(pat: &Pat<'_>) -> Option<Symbol> {
- match pat.kind {
- PatKind::Binding(.., ref spname, _) => Some(spname.name),
- PatKind::Path(ref qpath) => single_segment_path(qpath).map(|ps| ps.ident.name),
- PatKind::Box(p) | PatKind::Ref(p, _) => get_pat_name(&*p),
- _ => None,
- }
-}
-
 pub struct ContainsName {
  pub name: Symbol,
  pub result: bool,
@@ -1404,47 +1384,42 @@ pub fn is_must_use_func_call(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
 /// Checks if an expression represents the identity function
 /// Only examines closures and `std::convert::identity`
 pub fn is_expr_identity_function(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool {
- /// Returns true if the expression is a binding to the given pattern
- fn is_expr_pat_binding(cx: &LateContext<'_>, expr: &Expr<'_>, pat: &Pat<'_>) -> bool {
- if let PatKind::Binding(_, _, ident, _) = pat.kind {
- if match_var(expr, ident.name) {
- return !(cx.typeck_results().hir_owner == expr.hir_id.owner && is_adjusted(cx, expr));
- }
- }
-
- false
- }
-
  /// Checks if a function's body represents the identity function. Looks for bodies of the form:
  /// * `|x| x`
  /// * `|x| return x`
  /// * `|x| { return x }`
  /// * `|x| { return x; }`
  fn is_body_identity_function(cx: &LateContext<'_>, func: &Body<'_>) -> bool {
- let body = remove_blocks(&func.value);
-
- let value_pat = if let [value_param] = func.params {
- value_param.pat
- } else {
- return false;
+ let id = if_chain! {
+ if let [param] = func.params;
+ if let PatKind::Binding(_, id, _, _) = param.pat.kind;
+ then {
+ id
+ } else {
+ return false;
+ }
  };
 
- match body.kind {
- ExprKind::Path(QPath::Resolved(None, _)) => is_expr_pat_binding(cx, body, value_pat),
- ExprKind::Ret(Some(ret_val)) => is_expr_pat_binding(cx, ret_val, value_pat),
- ExprKind::Block(block, _) => {
- if_chain! {
- if let &[block_stmt] = &block.stmts;
- if let StmtKind::Semi(expr) | StmtKind::Expr(expr) = block_stmt.kind;
- if let ExprKind::Ret(Some(ret_val)) = expr.kind;
- then {
- is_expr_pat_binding(cx, ret_val, value_pat)
- } else {
- false
+ let mut expr = &func.value;
+ loop {
+ match expr.kind {
+ #[rustfmt::skip]
+ ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
+ | ExprKind::Ret(Some(e)) => expr = e,
+ #[rustfmt::skip]
+ ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
+ if_chain! {
+ if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
+ if let ExprKind::Ret(Some(ret_val)) = e.kind;
+ then {
+ expr = ret_val;
+ } else {
+ return false;
+ }
  }
- }
- },
- _ => false,
+ },
+  _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
+ }
  }
  }
 
@@ -1710,6 +1685,19 @@ pub fn peel_hir_expr_refs(expr: &'a Expr<'a>) -> (&'a Expr<'a>, usize) {
  (e, count)
 }
 
+/// Removes `AddrOf` operators (`&`) or deref operators (`*`), but only if a reference type is
+/// dereferenced. An overloaded deref such as `Vec` to slice would not be removed.
+pub fn peel_ref_operators<'hir>(cx: &LateContext<'_>, mut expr: &'hir Expr<'hir>) -> &'hir Expr<'hir> {
+ loop {
+ match expr.kind {
+ ExprKind::AddrOf(_, _, e) => expr = e,
+ ExprKind::Unary(UnOp::Deref, e) if cx.typeck_results().expr_ty(e).is_ref() => expr = e,
+ _ => break,
+ }
+ }
+ expr
+}
+
 #[macro_export]
 macro_rules! unwrap_cargo_metadata {
  ($cx: ident, $lint: ident, $deps: expr) => {{