do minor cleanups

* ToString and AsRef are in prelude, no need to import them

clippy_lints/src/cargo_common_metadata.rs

@@ -8,8 +8,6 @@ use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
 use rustc_session::declare_tool_lint;
 use syntax::{ast::*, source_map::DUMMY_SP};
 
-use cargo_metadata;
-
 declare_clippy_lint! {
     /// **What it does:** Checks to see if all common metadata is defined in
     /// `Cargo.toml`. See: https://rust-lang-nursery.github.io/api-guidelines/documentation.html#cargotoml-includes-all-common-metadata-c-metadata
@@ -56,7 +54,7 @@ fn is_empty_path(value: &Option<PathBuf>) -> bool {
 
 fn is_empty_vec(value: &[String]) -> bool {
     // This works because empty iterators return true
-    value.iter().all(std::string::String::is_empty)
+    value.iter().all(String::is_empty)
 }
 
 declare_lint_pass!(CargoCommonMetadata => [CARGO_COMMON_METADATA]);

clippy_lints/src/consts.rs

@@ -253,7 +253,7 @@ impl<'c, 'cc> ConstEvalLateContext<'c, 'cc> {
                     let res = self.tables.qpath_res(qpath, callee.hir_id);
                     if let Some(def_id) = res.opt_def_id();
                     let def_path: Vec<_> = self.lcx.get_def_path(def_id).into_iter().map(Symbol::as_str).collect();
-                    let def_path: Vec<&str> = def_path.iter().map(|s| &**s).collect();
+                    let def_path: Vec<&str> = def_path.iter().take(4).map(|s| &**s).collect();
                     if let ["core", "num", int_impl, "max_value"] = *def_path;
                     then {
                        let value = match int_impl {

clippy_lints/src/doc.rs

@@ -1,6 +1,5 @@
 use crate::utils::{match_type, paths, return_ty, span_lint};
 use itertools::Itertools;
-use pulldown_cmark;
 use rustc::hir;
 use rustc::impl_lint_pass;
 use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};

clippy_lints/src/eta_reduction.rs

@@ -146,11 +146,7 @@ fn check_closure(cx: &LateContext<'_, '_>, expr: &Expr) {
 }
 
 /// Tries to determine the type for universal function call to be used instead of the closure
-fn get_ufcs_type_name(
-    cx: &LateContext<'_, '_>,
-    method_def_id: def_id::DefId,
-    self_arg: &Expr,
-) -> std::option::Option<String> {
+fn get_ufcs_type_name(cx: &LateContext<'_, '_>, method_def_id: def_id::DefId, self_arg: &Expr) -> Option<String> {
     let expected_type_of_self = &cx.tcx.fn_sig(method_def_id).inputs_and_output().skip_binder()[0];
     let actual_type_of_self = &cx.tables.node_type(self_arg.hir_id);
 

clippy_lints/src/lib.rs

@@ -47,7 +47,8 @@ extern crate syntax_pos;
 use rustc::lint::{self, LintId};
 use rustc::session::Session;
 use rustc_data_structures::fx::FxHashSet;
-use toml;
+
+use std::path::Path;
 
 /// Macro used to declare a Clippy lint.
 ///
@@ -349,16 +350,16 @@ pub fn read_conf(args: &[syntax::ast::NestedMetaItem], sess: &Session) -> Conf {
             let file_name = file_name.map(|file_name| {
                 if file_name.is_relative() {
                     sess.local_crate_source_file
-                        .as_ref()
-                        .and_then(|file| std::path::Path::new(&file).parent().map(std::path::Path::to_path_buf))
-                        .unwrap_or_default()
+                        .as_deref()
+                        .and_then(Path::parent)
+                        .unwrap_or_else(|| Path::new(""))
                         .join(file_name)
                 } else {
                     file_name
                 }
             });
 
-            let (conf, errors) = utils::conf::read(file_name.as_ref().map(std::convert::AsRef::as_ref));
+            let (conf, errors) = utils::conf::read(file_name.as_ref().map(AsRef::as_ref));
 
             // all conf errors are non-fatal, we just use the default conf in case of error
             for error in errors {

clippy_lints/src/literal_representation.rs

@@ -8,7 +8,6 @@ use rustc::{declare_lint_pass, impl_lint_pass};
 use rustc_errors::Applicability;
 use rustc_session::declare_tool_lint;
 use syntax::ast::*;
-use syntax_pos;
 
 declare_clippy_lint! {
     /// **What it does:** Warns if a long integral or floating-point constant does

clippy_lints/src/multiple_crate_versions.rs

@@ -6,7 +6,6 @@ use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
 use rustc_session::declare_tool_lint;
 use syntax::{ast::*, source_map::DUMMY_SP};
 
-use cargo_metadata;
 use itertools::Itertools;
 
 declare_clippy_lint! {

clippy_lints/src/regex.rs

@@ -1,7 +1,6 @@
 use crate::consts::{constant, Constant};
 use crate::utils::{is_expn_of, match_def_path, match_type, paths, span_help_and_lint, span_lint};
 use if_chain::if_chain;
-use regex_syntax;
 use rustc::hir::*;
 use rustc::impl_lint_pass;
 use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};

clippy_lints/src/utils/conf.rs

@@ -8,7 +8,6 @@ use std::io::Read;
 use std::sync::Mutex;
 use std::{env, fmt, fs, io, path};
 use syntax::{ast, source_map};
-use toml;
 
 /// Gets the configuration file from arguments.
 pub fn file_from_args(args: &[ast::NestedMetaItem]) -> Result<Option<path::PathBuf>, (&'static str, source_map::Span)> {
@@ -77,7 +76,6 @@ macro_rules! define_Conf {
             }
             $(
                 mod $rust_name {
-                    use serde;
                     use serde::Deserialize;
                     crate fn deserialize<'de, D: serde::Deserializer<'de>>(deserializer: D)
                     -> Result<define_Conf!(TY $($ty)+), D::Error> {

clippy_lints/src/utils/sugg.rs

@@ -5,9 +5,7 @@ use crate::utils::{higher, snippet, snippet_opt, snippet_with_macro_callsite};
 use matches::matches;
 use rustc::hir;
 use rustc::lint::{EarlyContext, LateContext, LintContext};
-use rustc_errors;
 use rustc_errors::Applicability;
-use std;
 use std::borrow::Cow;
 use std::convert::TryInto;
 use std::fmt::Display;

clippy_lints/src/wildcard_dependencies.rs

@@ -4,9 +4,7 @@ use rustc::lint::{EarlyContext, EarlyLintPass, LintArray, LintPass};
 use rustc_session::declare_tool_lint;
 use syntax::{ast::*, source_map::DUMMY_SP};
 
-use cargo_metadata;
 use if_chain::if_chain;
-use semver;
 
 declare_clippy_lint! {
     /// **What it does:** Checks for wildcard dependencies in the `Cargo.toml`.