Extract visitor to utils

clippy_lints/src/loops.rs

@@ -1,36 +1,34 @@
-use crate::reexport::*;
-use if_chain::if_chain;
-use itertools::Itertools;
-use rustc::lint::in_external_macro;
-use rustc::middle::region;
-use rustc_hir::def::{DefKind, Res};
-use rustc_hir::def_id;
-use rustc_hir::intravisit::{walk_block, walk_expr, walk_pat, walk_stmt, NestedVisitorMap, Visitor};
-use rustc_hir::*;
-use rustc_lint::{LateContext, LateLintPass, LintContext};
-use rustc_session::{declare_lint_pass, declare_tool_lint};
-// use rustc::middle::region::CodeExtent;
 use crate::consts::{constant, Constant};
-use crate::utils::usage::mutated_variables;
-use crate::utils::{is_type_diagnostic_item, qpath_res, same_tys, sext, sugg};
-use rustc::hir::map::Map;
-use rustc::ty::{self, Ty};
-use rustc_data_structures::fx::{FxHashMap, FxHashSet};
-use rustc_errors::Applicability;
-use rustc_span::source_map::Span;
-use rustc_span::{BytePos, Symbol};
-use rustc_typeck::expr_use_visitor::*;
-use std::iter::{once, Iterator};
-use std::mem;
-use syntax::ast;
-
+use crate::reexport::*;
 use crate::utils::paths;
+use crate::utils::usage::{is_unused, mutated_variables};
 use crate::utils::{
     get_enclosing_block, get_parent_expr, get_trait_def_id, has_iter_method, higher, implements_trait,
     is_integer_const, is_refutable, last_path_segment, match_trait_method, match_type, match_var, multispan_sugg,
     snippet, snippet_opt, snippet_with_applicability, span_help_and_lint, span_lint, span_lint_and_sugg,
     span_lint_and_then, SpanlessEq,
 };
+use crate::utils::{is_type_diagnostic_item, qpath_res, same_tys, sext, sugg};
+use if_chain::if_chain;
+use itertools::Itertools;
+use rustc::hir::map::Map;
+use rustc::lint::in_external_macro;
+use rustc::middle::region;
+use rustc::ty::{self, Ty};
+use rustc_data_structures::fx::{FxHashMap, FxHashSet};
+use rustc_errors::Applicability;
+use rustc_hir::def::{DefKind, Res};
+use rustc_hir::def_id;
+use rustc_hir::intravisit::{walk_block, walk_expr, walk_pat, walk_stmt, NestedVisitorMap, Visitor};
+use rustc_hir::*;
+use rustc_lint::{LateContext, LateLintPass, LintContext};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_span::source_map::Span;
+use rustc_span::{BytePos, Symbol};
+use rustc_typeck::expr_use_visitor::*;
+use std::iter::{once, Iterator};
+use std::mem;
+use syntax::ast;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for for-loops that manually copy items between
@@ -1689,39 +1687,11 @@ fn check_for_mutation(
 fn pat_is_wild<'tcx>(pat: &'tcx PatKind<'_>, body: &'tcx Expr<'_>) -> bool {
     match *pat {
         PatKind::Wild => true,
-        PatKind::Binding(.., ident, None) if ident.as_str().starts_with('_') => {
-            let mut visitor = UsedVisitor {
-                var: ident.name,
-                used: false,
-            };
-            walk_expr(&mut visitor, body);
-            !visitor.used
-        },
+        PatKind::Binding(.., ident, None) if ident.as_str().starts_with('_') => is_unused(&ident, body),
         _ => false,
     }
 }
 
-struct UsedVisitor {
-    var: ast::Name, // var to look for
-    used: bool,     // has the var been used otherwise?
-}
-
-impl<'tcx> Visitor<'tcx> for UsedVisitor {
-    type Map = Map<'tcx>;
-
-    fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
-        if match_var(expr, self.var) {
-            self.used = true;
-        } else {
-            walk_expr(self, expr);
-        }
-    }
-
-    fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
-        NestedVisitorMap::None
-    }
-}
-
 struct LocalUsedVisitor<'a, 'tcx> {
     cx: &'a LateContext<'a, 'tcx>,
     local: HirId,

clippy_lints/src/matches.rs

@@ -1,26 +1,24 @@
 use crate::consts::{constant, miri_to_const, Constant};
 use crate::utils::paths;
 use crate::utils::sugg::Sugg;
+use crate::utils::usage::is_unused;
 use crate::utils::{
-    expr_block, is_allowed, is_expn_of, match_qpath, match_type, match_var, multispan_sugg, remove_blocks, snippet,
+    expr_block, is_allowed, is_expn_of, is_wild, match_qpath, match_type, multispan_sugg, remove_blocks, snippet,
     snippet_with_applicability, span_help_and_lint, span_lint_and_sugg, span_lint_and_then, span_note_and_lint,
     walk_ptrs_ty,
 };
 use if_chain::if_chain;
-use rustc::hir::map::Map;
-use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
+use rustc::lint::in_external_macro;
 use rustc::ty::{self, Ty};
 use rustc_errors::Applicability;
 use rustc_hir::def::CtorKind;
-use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
 use rustc_hir::*;
 use rustc_lint::{LateContext, LateLintPass, LintContext};
 use rustc_session::{declare_lint_pass, declare_tool_lint};
 use rustc_span::source_map::Span;
-use rustc_span::symbol::Ident;
 use std::cmp::Ordering;
 use std::collections::Bound;
-use syntax::ast::{self, LitKind};
+use syntax::ast::LitKind;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for matches with a single arm where an `if let`
@@ -464,43 +462,6 @@ fn check_overlapping_arms<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, ex: &'tcx Expr<'
     }
 }
 
-fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
-    match pat.kind {
-        PatKind::Wild => true,
-        _ => false,
-    }
-}
-
-fn is_unused<'tcx>(ident: &'tcx Ident, body: &'tcx Expr<'_>) -> bool {
-    let mut visitor = UsedVisitor {
-        var: ident.name,
-        used: false,
-    };
-    walk_expr(&mut visitor, body);
-    !visitor.used
-}
-
-struct UsedVisitor {
-    var: ast::Name, // var to look for
-    used: bool,     // has the var been used otherwise?
-}
-
-impl<'tcx> Visitor<'tcx> for UsedVisitor {
-    type Map = Map<'tcx>;
-
-    fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
-        if match_var(expr, self.var) {
-            self.used = true;
-        } else {
-            walk_expr(self, expr);
-        }
-    }
-
-    fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
-        NestedVisitorMap::None
-    }
-}
-
 fn check_wild_err_arm(cx: &LateContext<'_, '_>, ex: &Expr<'_>, arms: &[Arm<'_>]) {
     let ex_ty = walk_ptrs_ty(cx.tables.expr_ty(ex));
     if match_type(cx, ex_ty, &paths::RESULT) {

clippy_lints/src/utils/mod.rs

@@ -127,6 +127,14 @@ pub fn is_present_in_source<T: LintContext>(cx: &T, span: Span) -> bool {
     true
 }
 
+/// Checks if given pattern is a wildcard (`_`)
+pub fn is_wild<'tcx>(pat: &impl std::ops::Deref<Target = Pat<'tcx>>) -> bool {
+    match pat.kind {
+        PatKind::Wild => true,
+        _ => false,
+    }
+}
+
 /// Checks if type is struct, enum or union type with the given def path.
 pub fn match_type(cx: &LateContext<'_, '_>, ty: Ty<'_>, path: &[&str]) -> bool {
     match ty.kind {

clippy_lints/src/utils/usage.rs

@@ -1,9 +1,14 @@
+use crate::utils::match_var;
+use rustc::hir::map::Map;
 use rustc::ty;
 use rustc_data_structures::fx::FxHashSet;
 use rustc_hir::def::Res;
+use rustc_hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
 use rustc_hir::*;
 use rustc_lint::LateContext;
+use rustc_span::symbol::Ident;
 use rustc_typeck::expr_use_visitor::*;
+use syntax::ast;
 
 /// Returns a set of mutated local variable IDs, or `None` if mutations could not be determined.
 pub fn mutated_variables<'a, 'tcx>(expr: &'tcx Expr<'_>, cx: &'a LateContext<'a, 'tcx>) -> Option<FxHashSet<HirId>> {
@@ -70,3 +75,33 @@ impl<'tcx> Delegate<'tcx> for MutVarsDelegate {
         self.update(&cmt)
     }
 }
+
+pub struct UsedVisitor {
+    pub var: ast::Name, // var to look for
+    pub used: bool,     // has the var been used otherwise?
+}
+
+impl<'tcx> Visitor<'tcx> for UsedVisitor {
+    type Map = Map<'tcx>;
+
+    fn visit_expr(&mut self, expr: &'tcx Expr<'_>) {
+        if match_var(expr, self.var) {
+            self.used = true;
+        } else {
+            walk_expr(self, expr);
+        }
+    }
+
+    fn nested_visit_map(&mut self) -> NestedVisitorMap<'_, Self::Map> {
+        NestedVisitorMap::None
+    }
+}
+
+pub fn is_unused<'tcx>(ident: &'tcx Ident, body: &'tcx Expr<'_>) -> bool {
+    let mut visitor = UsedVisitor {
+        var: ident.name,
+        used: false,
+    };
+    walk_expr(&mut visitor, body);
+    !visitor.used
+}