Auto merge of #5191 - JohnTitor:clean-up, r=flip1995

Minor cleanup

- Use `Vec::with_capacity()` as possible
- Clean up imports

changelog: none

Author: bors

clippy_lints/src/booleans.rs

@@ -5,7 +5,6 @@ use crate::utils::{
 use if_chain::if_chain;
 use rustc::hir::map::Map;
 use rustc_errors::Applicability;
-use rustc_hir::intravisit;
 use rustc_hir::intravisit::*;
 use rustc_hir::*;
 use rustc_lint::{LateContext, LateLintPass};
@@ -60,7 +59,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for NonminimalBool {
     fn check_fn(
         &mut self,
         cx: &LateContext<'a, 'tcx>,
-        _: intravisit::FnKind<'tcx>,
+        _: FnKind<'tcx>,
         _: &'tcx FnDecl<'_>,
         body: &'tcx Body<'_>,
         _: Span,
@@ -359,7 +358,7 @@ impl<'a, 'tcx> NonminimalBoolVisitor<'a, 'tcx> {
                 }
                 simplified.push(simple_negated);
             }
-            let mut improvements = Vec::new();
+            let mut improvements = Vec::with_capacity(simplified.len());
             'simplified: for suggestion in &simplified {
                 let simplified_stats = terminal_stats(suggestion);
                 let mut improvement = false;

clippy_lints/src/consts.rs

@@ -11,7 +11,6 @@ use rustc_hir::*;
 use rustc_lint::LateContext;
 use rustc_span::symbol::Symbol;
 use std::cmp::Ordering::{self, Equal};
-use std::cmp::PartialOrd;
 use std::convert::TryInto;
 use std::hash::{Hash, Hasher};
 use syntax::ast::{FloatTy, LitKind};

clippy_lints/src/escape.rs

@@ -1,7 +1,6 @@
 use rustc::ty::layout::LayoutOf;
 use rustc::ty::{self, Ty};
-use rustc_hir::intravisit as visit;
-use rustc_hir::HirIdSet;
+use rustc_hir::intravisit;
 use rustc_hir::{self, *};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_lint::{LateContext, LateLintPass};
@@ -54,7 +53,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for BoxedLocal {
     fn check_fn(
         &mut self,
         cx: &LateContext<'a, 'tcx>,
-        _: visit::FnKind<'tcx>,
+        _: intravisit::FnKind<'tcx>,
         _: &'tcx FnDecl<'_>,
         body: &'tcx Body<'_>,
         _: Span,

clippy_lints/src/indexing_slicing.rs

@@ -1,9 +1,7 @@
 //! lint on indexing and slicing operations
 
 use crate::consts::{constant, Constant};
-use crate::utils;
-use crate::utils::higher;
-use crate::utils::higher::Range;
+use crate::utils::{higher, span_lint, span_lint_and_help};
 use rustc::ty;
 use rustc_hir::*;
 use rustc_lint::{LateContext, LateLintPass};
@@ -100,7 +98,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IndexingSlicing {
 
                     if let (Some(start), _) = const_range {
                         if start > size {
-                            utils::span_lint(
+                            span_lint(
                                 cx,
                                 OUT_OF_BOUNDS_INDEXING,
                                 range.start.map_or(expr.span, |start| start.span),
@@ -112,7 +110,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IndexingSlicing {
 
                     if let (_, Some(end)) = const_range {
                         if end > size {
-                            utils::span_lint(
+                            span_lint(
                                 cx,
                                 OUT_OF_BOUNDS_INDEXING,
                                 range.end.map_or(expr.span, |end| end.span),
@@ -136,7 +134,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IndexingSlicing {
                     (None, None) => return, // [..] is ok.
                 };
 
-                utils::span_lint_and_help(cx, INDEXING_SLICING, expr.span, "slicing may panic.", help_msg);
+                span_lint_and_help(cx, INDEXING_SLICING, expr.span, "slicing may panic.", help_msg);
             } else {
                 // Catchall non-range index, i.e., [n] or [n << m]
                 if let ty::Array(..) = ty.kind {
@@ -147,7 +145,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IndexingSlicing {
                     }
                 }
 
-                utils::span_lint_and_help(
+                span_lint_and_help(
                     cx,
                     INDEXING_SLICING,
                     expr.span,
@@ -163,7 +161,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for IndexingSlicing {
 /// the range. If the start or end is not constant, None is returned.
 fn to_const_range<'a, 'tcx>(
     cx: &LateContext<'a, 'tcx>,
-    range: Range<'_>,
+    range: higher::Range<'_>,
     array_size: u128,
 ) -> (Option<u128>, Option<u128>) {
     let s = range.start.map(|expr| constant(cx, cx.tables, expr).map(|(c, _)| c));

clippy_lints/src/loops.rs

@@ -18,7 +18,6 @@ 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_infer::infer::TyCtxtInferExt;

clippy_lints/src/matches.rs

@@ -724,7 +724,7 @@ fn is_panic_block(block: &Block<'_>) -> bool {
 
 fn check_match_ref_pats(cx: &LateContext<'_, '_>, ex: &Expr<'_>, arms: &[Arm<'_>], expr: &Expr<'_>) {
     if has_only_ref_pats(arms) {
-        let mut suggs = Vec::new();
+        let mut suggs = Vec::with_capacity(arms.len() + 1);
         let (title, msg) = if let ExprKind::AddrOf(BorrowKind::Ref, Mutability::Not, ref inner) = ex.kind {
             let span = ex.span.source_callsite();
             suggs.push((span, Sugg::hir_with_macro_callsite(cx, inner, "..").to_string()));

clippy_lints/src/ptr.rs

@@ -8,7 +8,6 @@ use crate::utils::{
 use if_chain::if_chain;
 use rustc::ty;
 use rustc_errors::Applicability;
-use rustc_hir::QPath;
 use rustc_hir::*;
 use rustc_lint::{LateContext, LateLintPass};
 use rustc_session::{declare_lint_pass, declare_tool_lint};

clippy_lints/src/ptr_offset_with_cast.rs

@@ -1,4 +1,4 @@
-use crate::utils;
+use crate::utils::{snippet_opt, span_lint, span_lint_and_sugg};
 use rustc_errors::Applicability;
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};
@@ -59,7 +59,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PtrOffsetWithCast {
 
         let msg = format!("use of `{}` with a `usize` casted to an `isize`", method);
         if let Some(sugg) = build_suggestion(cx, method, receiver_expr, cast_lhs_expr) {
-            utils::span_lint_and_sugg(
+            span_lint_and_sugg(
                 cx,
                 PTR_OFFSET_WITH_CAST,
                 expr.span,
@@ -69,7 +69,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for PtrOffsetWithCast {
                 Applicability::MachineApplicable,
             );
         } else {
-            utils::span_lint(cx, PTR_OFFSET_WITH_CAST, expr.span, &msg);
+            span_lint(cx, PTR_OFFSET_WITH_CAST, expr.span, &msg);
         }
     }
 }
@@ -119,8 +119,8 @@ fn build_suggestion<'a, 'tcx>(
     receiver_expr: &Expr<'_>,
     cast_lhs_expr: &Expr<'_>,
 ) -> Option<String> {
-    let receiver = utils::snippet_opt(cx, receiver_expr.span)?;
-    let cast_lhs = utils::snippet_opt(cx, cast_lhs_expr.span)?;
+    let receiver = snippet_opt(cx, receiver_expr.span)?;
+    let cast_lhs = snippet_opt(cx, cast_lhs_expr.span)?;
     Some(format!("{}.{}({})", receiver, method.suggestion(), cast_lhs))
 }
 

clippy_lints/src/shadow.rs

@@ -101,7 +101,7 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Shadow {
 }
 
 fn check_fn<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, decl: &'tcx FnDecl<'_>, body: &'tcx Body<'_>) {
-    let mut bindings = Vec::new();
+    let mut bindings = Vec::with_capacity(decl.inputs.len());
     for arg in iter_input_pats(decl, body) {
         if let PatKind::Binding(.., ident, _) = arg.pat.kind {
             bindings.push((ident.name, ident.span))

clippy_lints/src/temporary_assignment.rs

@@ -1,5 +1,4 @@
-use crate::utils::is_adjusted;
-use crate::utils::span_lint;
+use crate::utils::{is_adjusted, span_lint};
 use rustc_hir::def::{DefKind, Res};
 use rustc_hir::{Expr, ExprKind};
 use rustc_lint::{LateContext, LateLintPass};