do minor cleanups

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

Author: tesuji

clippy_dev/src/lib.rs

@@ -50,7 +50,7 @@ impl Lint {
             name: name.to_lowercase(),
             group: group.to_string(),
             desc: NL_ESCAPE_RE.replace(&desc.replace("\\\"", "\""), "").to_string(),
-            deprecation: deprecation.map(std::string::ToString::to_string),
+            deprecation: deprecation.map(ToString::to_string),
             module: module.to_string(),
         }
     }

clippy_lints/src/cargo_common_metadata.rs

@@ -56,7 +56,7 @@ 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/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

@@ -358,7 +358,7 @@ pub fn read_conf(args: &[syntax::ast::NestedMetaItem], sess: &Session) -> Conf {
                 }
             });
 
-            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 {

src/driver.rs

@@ -1,5 +1,6 @@
 #![cfg_attr(feature = "deny-warnings", deny(warnings))]
 #![feature(rustc_private)]
+#![feature(str_strip)]
 
 // FIXME: switch to something more ergonomic here, once available.
 // (Currently there is no way to opt into sysroot crates without `extern crate`.)
@@ -18,6 +19,8 @@ use rustc_tools_util::*;
 
 use lazy_static::lazy_static;
 use std::borrow::Cow;
+use std::env;
+use std::ops::Deref;
 use std::panic;
 use std::path::{Path, PathBuf};
 use std::process::{exit, Command};
@@ -26,42 +29,38 @@ mod lintlist;
 
 /// If a command-line option matches `find_arg`, then apply the predicate `pred` on its value. If
 /// true, then return it. The parameter is assumed to be either `--arg=value` or `--arg value`.
-fn arg_value<'a>(
-    args: impl IntoIterator<Item = &'a String>,
+fn arg_value<'a, T: Deref<Target = str>>(
+    args: &'a [T],
     find_arg: &str,
     pred: impl Fn(&str) -> bool,
 ) -> Option<&'a str> {
-    let mut args = args.into_iter().map(String::as_str);
-
+    let mut args = args.iter().map(Deref::deref);
     while let Some(arg) = args.next() {
-        let arg: Vec<_> = arg.splitn(2, '=').collect();
-        if arg.get(0) != Some(&find_arg) {
+        let mut arg = arg.splitn(2, '=');
+        if arg.next() != Some(find_arg) {
             continue;
         }
 
-        let value = arg.get(1).cloned().or_else(|| args.next());
-        if value.as_ref().map_or(false, |p| pred(p)) {
-            return value;
+        match arg.next().or_else(|| args.next()) {
+            Some(v) if pred(v) => return Some(v),
+            _ => {},
         }
     }
     None
 }
 
 #[test]
 fn test_arg_value() {
-    let args: Vec<_> = ["--bar=bar", "--foobar", "123", "--foo"]
-        .iter()
-        .map(std::string::ToString::to_string)
-        .collect();
-
-    assert_eq!(arg_value(None, "--foobar", |_| true), None);
-    assert_eq!(arg_value(&args, "--bar", |_| false), None);
-    assert_eq!(arg_value(&args, "--bar", |_| true), Some("bar"));
-    assert_eq!(arg_value(&args, "--bar", |p| p == "bar"), Some("bar"));
-    assert_eq!(arg_value(&args, "--bar", |p| p == "foo"), None);
-    assert_eq!(arg_value(&args, "--foobar", |p| p == "foo"), None);
-    assert_eq!(arg_value(&args, "--foobar", |p| p == "123"), Some("123"));
-    assert_eq!(arg_value(&args, "--foo", |_| true), None);
+    let args = &["--bar=bar", "--foobar", "123", "--foo"];
+
+    assert_eq!(arg_value(&[] as &[&str], "--foobar", |_| true), None);
+    assert_eq!(arg_value(args, "--bar", |_| false), None);
+    assert_eq!(arg_value(args, "--bar", |_| true), Some("bar"));
+    assert_eq!(arg_value(args, "--bar", |p| p == "bar"), Some("bar"));
+    assert_eq!(arg_value(args, "--bar", |p| p == "foo"), None);
+    assert_eq!(arg_value(args, "--foobar", |p| p == "foo"), None);
+    assert_eq!(arg_value(args, "--foobar", |p| p == "123"), Some("123"));
+    assert_eq!(arg_value(args, "--foo", |_| true), None);
 }
 
 #[allow(clippy::too_many_lines)]
@@ -276,7 +275,7 @@ fn report_clippy_ice(info: &panic::PanicInfo<'_>, bug_report_url: &str) {
     }
 
     // If backtraces are enabled, also print the query stack
-    let backtrace = std::env::var_os("RUST_BACKTRACE").map_or(false, |x| &x != "0");
+    let backtrace = env::var_os("RUST_BACKTRACE").map_or(false, |x| &x != "0");
 
     if backtrace {
         TyCtxt::try_print_query_stack(&handler);
@@ -288,16 +287,14 @@ pub fn main() {
     lazy_static::initialize(&ICE_HOOK);
     exit(
         rustc_driver::catch_fatal_errors(move || {
-            use std::env;
+            let mut orig_args: Vec<String> = env::args().collect();
 
-            if std::env::args().any(|a| a == "--version" || a == "-V") {
+            if orig_args.iter().any(|a| a == "--version" || a == "-V") {
                 let version_info = rustc_tools_util::get_version_info!();
                 println!("{}", version_info);
                 exit(0);
             }
 
-            let mut orig_args: Vec<String> = env::args().collect();
-
             // Get the sysroot, looking from most specific to this invocation to the least:
             // - command line
             // - runtime environment
@@ -350,7 +347,7 @@ pub fn main() {
             }
 
             let should_describe_lints = || {
-                let args: Vec<_> = std::env::args().collect();
+                let args: Vec<_> = env::args().collect();
                 args.windows(2).any(|args| {
                     args[1] == "help"
                         && match args[0].as_str() {
@@ -368,15 +365,9 @@ pub fn main() {
             // this conditional check for the --sysroot flag is there so users can call
             // `clippy_driver` directly
             // without having to pass --sysroot or anything
-            let mut args: Vec<String> = if have_sys_root_arg {
-                orig_args.clone()
-            } else {
-                orig_args
-                    .clone()
-                    .into_iter()
-                    .chain(Some("--sysroot".to_owned()))
-                    .chain(Some(sys_root))
-                    .collect()
+            let mut args: Vec<String> = orig_args.clone();
+            if !have_sys_root_arg {
+                args.extend(vec!["--sysroot".into(), sys_root]);
             };
 
             // this check ensures that dependencies are built but not linted and the final
@@ -385,7 +376,7 @@ pub fn main() {
                 || arg_value(&orig_args, "--cap-lints", |val| val == "allow").is_none();
 
             if clippy_enabled {
-                args.extend_from_slice(&["--cfg".to_owned(), r#"feature="cargo-clippy""#.to_owned()]);
+                args.extend(vec!["--cfg".into(), r#"feature="cargo-clippy""#.into()]);
                 if let Ok(extra_args) = env::var("CLIPPY_ARGS") {
                     args.extend(extra_args.split("__CLIPPY_HACKERY__").filter_map(|s| {
                         if s.is_empty() {
@@ -396,12 +387,10 @@ pub fn main() {
                     }));
                 }
             }
-
             let mut clippy = ClippyCallbacks;
             let mut default = rustc_driver::DefaultCallbacks;
             let callbacks: &mut (dyn rustc_driver::Callbacks + Send) =
                 if clippy_enabled { &mut clippy } else { &mut default };
-            let args = args;
             rustc_driver::run_compiler(&args, callbacks, None, None)
         })
         .and_then(|result| result)

tests/ui/inefficient_to_string.fixed

@@ -2,7 +2,6 @@
 #![deny(clippy::inefficient_to_string)]
 
 use std::borrow::Cow;
-use std::string::ToString;
 
 fn main() {
     let rstr: &str = "hello";

tests/ui/inefficient_to_string.rs

@@ -2,7 +2,6 @@
 #![deny(clippy::inefficient_to_string)]
 
 use std::borrow::Cow;
-use std::string::ToString;
 
 fn main() {
     let rstr: &str = "hello";

tests/ui/inefficient_to_string.stderr

@@ -1,5 +1,5 @@
 error: calling `to_string` on `&&str`
-  --> $DIR/inefficient_to_string.rs:12:21
+  --> $DIR/inefficient_to_string.rs:11:21
    |
 LL |     let _: String = rrstr.to_string();
    |                     ^^^^^^^^^^^^^^^^^ help: try dereferencing the receiver: `(*rrstr).to_string()`
@@ -12,39 +12,39 @@ LL | #![deny(clippy::inefficient_to_string)]
    = help: `&str` implements `ToString` through a slower blanket impl, but `str` has a fast specialization of `ToString`
 
 error: calling `to_string` on `&&&str`
-  --> $DIR/inefficient_to_string.rs:13:21
+  --> $DIR/inefficient_to_string.rs:12:21
    |
 LL |     let _: String = rrrstr.to_string();
    |                     ^^^^^^^^^^^^^^^^^^ help: try dereferencing the receiver: `(**rrrstr).to_string()`
    |
    = help: `&&str` implements `ToString` through a slower blanket impl, but `str` has a fast specialization of `ToString`
 
 error: calling `to_string` on `&&std::string::String`
-  --> $DIR/inefficient_to_string.rs:21:21
+  --> $DIR/inefficient_to_string.rs:20:21
    |
 LL |     let _: String = rrstring.to_string();
    |                     ^^^^^^^^^^^^^^^^^^^^ help: try dereferencing the receiver: `(*rrstring).to_string()`
    |
    = help: `&std::string::String` implements `ToString` through a slower blanket impl, but `std::string::String` has a fast specialization of `ToString`
 
 error: calling `to_string` on `&&&std::string::String`
-  --> $DIR/inefficient_to_string.rs:22:21
+  --> $DIR/inefficient_to_string.rs:21:21
    |
 LL |     let _: String = rrrstring.to_string();
    |                     ^^^^^^^^^^^^^^^^^^^^^ help: try dereferencing the receiver: `(**rrrstring).to_string()`
    |
    = help: `&&std::string::String` implements `ToString` through a slower blanket impl, but `std::string::String` has a fast specialization of `ToString`
 
 error: calling `to_string` on `&&std::borrow::Cow<'_, str>`
-  --> $DIR/inefficient_to_string.rs:30:21
+  --> $DIR/inefficient_to_string.rs:29:21
    |
 LL |     let _: String = rrcow.to_string();
    |                     ^^^^^^^^^^^^^^^^^ help: try dereferencing the receiver: `(*rrcow).to_string()`
    |
    = help: `&std::borrow::Cow<'_, str>` implements `ToString` through a slower blanket impl, but `std::borrow::Cow<'_, str>` has a fast specialization of `ToString`
 
 error: calling `to_string` on `&&&std::borrow::Cow<'_, str>`
-  --> $DIR/inefficient_to_string.rs:31:21
+  --> $DIR/inefficient_to_string.rs:30:21
    |
 LL |     let _: String = rrrcow.to_string();
    |                     ^^^^^^^^^^^^^^^^^^ help: try dereferencing the receiver: `(**rrrcow).to_string()`