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

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_recv, filter_arg], _) = count_recv.kind;
-            if let ExprKind::MethodCall(filter, _, filter_args, _) = count_args[0].kind;
             if filter.ident.name == sym!(filter);
-            if filter_args.len() == 2;
+            if let ExprKind::Closure(_, _, body_id, _, _) = filter_arg.kind;
-            if let ExprKind::Closure(_, _, body_id, _, _) = filter_args[1].kind;
             let body = cx.tcx.hir().body(body_id);
-            if body.params.len() == 1;
+            if let [param] = body.params;
-            if let Some(argname) = get_pat_name(body.params[0].pat);
+            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::{
+use rustc_span::{sym, SyntaxContext};
-    symbol::{sym, Ident},
-    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 {
+            let body_str = if let PatKind::Binding(annotation, id, some_binding, None) = some_pat.kind {
-                match can_pass_as_func(cx, some_binding, some_expr) {
+                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 id = if_chain! {
-
+            if let [param] = func.params;
-        let value_pat = if let [value_param] = func.params {
+            if let PatKind::Binding(_, id, _, _) = param.pat.kind;
-            value_param.pat
+            then {
-        } else {
+                id
-            return false;
+            } else {
+                return false;
+            }
         };
 
-        match body.kind {
+        let mut expr = &func.value;
-            ExprKind::Path(QPath::Resolved(None, _)) => is_expr_pat_binding(cx, body, value_pat),
+        loop {
-            ExprKind::Ret(Some(ret_val)) => is_expr_pat_binding(cx, ret_val, value_pat),
+            match expr.kind {
-            ExprKind::Block(block, _) => {
+                #[rustfmt::skip]
-                if_chain! {
+                ExprKind::Block(&Block { stmts: [], expr: Some(e), .. }, _, )
-                    if let &[block_stmt] = &block.stmts;
+                | ExprKind::Ret(Some(e)) => expr = e,
-                    if let StmtKind::Semi(expr) | StmtKind::Expr(expr) = block_stmt.kind;
+                #[rustfmt::skip]
-                    if let ExprKind::Ret(Some(ret_val)) = expr.kind;
+                ExprKind::Block(&Block { stmts: [stmt], expr: None, .. }, _) => {
-                    then {
+                    if_chain! {
-                        is_expr_pat_binding(cx, ret_val, value_pat)
+                        if let StmtKind::Semi(e) | StmtKind::Expr(e) = stmt.kind;
-                    } else {
+                        if let ExprKind::Ret(Some(ret_val)) = e.kind;
-                        false
+                        then {
+                            expr = ret_val;
+                        } else {
+                            return false;
+                        }
                     }
-                }
+                },
-            },
+                _ => return path_to_local_id(expr, id) && cx.typeck_results().expr_adjustments(expr).is_empty(),
-            _ => false,
+            }
         }
     }
 
@@ -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) => {{

clippy_utils/src/ptr.rs

@@ -1,10 +1,10 @@
 use crate::source::snippet;
-use crate::{get_pat_name, match_var};
+use crate::{path_to_local_id, strip_pat_refs};
 use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
-use rustc_hir::{Body, BodyId, Expr, ExprKind, Param};
+use rustc_hir::{Body, BodyId, Expr, ExprKind, HirId, PatKind};
 use rustc_lint::LateContext;
 use rustc_middle::hir::map::Map;
-use rustc_span::{Span, Symbol};
+use rustc_span::Span;
 use std::borrow::Cow;
 
 pub fn get_spans(
@@ -14,10 +14,11 @@ pub fn get_spans(
     replacements: &[(&'static str, &'static str)],
 ) -> Option<Vec<(Span, Cow<'static, str>)>> {
     if let Some(body) = opt_body_id.map(|id| cx.tcx.hir().body(id)) {
-        get_binding_name(&body.params[idx]).map_or_else(
+        if let PatKind::Binding(_, binding_id, _, _) = strip_pat_refs(body.params[idx].pat).kind {
-            || Some(vec![]),
+            extract_clone_suggestions(cx, binding_id, replacements, body)
-            |name| extract_clone_suggestions(cx, name, replacements, body),
+        } else {
-        )
+            Some(vec![])
+        }
     } else {
         Some(vec![])
     }
@@ -25,13 +26,13 @@ pub fn get_spans(
 
 fn extract_clone_suggestions<'tcx>(
     cx: &LateContext<'tcx>,
-    name: Symbol,
+    id: HirId,
     replace: &[(&'static str, &'static str)],
     body: &'tcx Body<'_>,
 ) -> Option<Vec<(Span, Cow<'static, str>)>> {
     let mut visitor = PtrCloneVisitor {
         cx,
-        name,
+        id,
         replace,
         spans: vec![],
         abort: false,
@@ -42,7 +43,7 @@ fn extract_clone_suggestions<'tcx>(
 
 struct PtrCloneVisitor<'a, 'tcx> {
     cx: &'a LateContext<'tcx>,
-    name: Symbol,
+    id: HirId,
     replace: &'a [(&'static str, &'static str)],
     spans: Vec<(Span, Cow<'static, str>)>,
     abort: bool,
@@ -55,16 +56,15 @@ impl<'a, 'tcx> Visitor<'tcx> for PtrCloneVisitor<'a, 'tcx> {
         if self.abort {
             return;
         }
-        if let ExprKind::MethodCall(seg, _, args, _) = expr.kind {
+        if let ExprKind::MethodCall(seg, _, [recv], _) = expr.kind {
-            if args.len() == 1 && match_var(&args[0], self.name) {
+            if path_to_local_id(recv, self.id) {
                 if seg.ident.name.as_str() == "capacity" {
                     self.abort = true;
                     return;
                 }
                 for &(fn_name, suffix) in self.replace {
                     if seg.ident.name.as_str() == fn_name {
-                        self.spans
+                        self.spans.push((expr.span, snippet(self.cx, recv.span, "_") + suffix));
-                            .push((expr.span, snippet(self.cx, args[0].span, "_") + suffix));
                         return;
                     }
                 }
@@ -77,7 +77,3 @@ impl<'a, 'tcx> Visitor<'tcx> for PtrCloneVisitor<'a, 'tcx> {
         NestedVisitorMap::None
     }
 }
-
-fn get_binding_name(arg: &Param<'_>) -> Option<Symbol> {
-    get_pat_name(arg.pat)
-}