Use IsTerminal in rustc_errors

Cargo.lock

@@ -3452,7 +3452,6 @@ name = "rustc_errors"
 version = "0.0.0"
 dependencies = [
  "annotate-snippets",
- "atty",
  "rustc_ast",
  "rustc_ast_pretty",
  "rustc_data_structures",

compiler/rustc_errors/Cargo.toml

@@ -18,7 +18,6 @@ rustc_target = { path = "../rustc_target" }
 rustc_hir = { path = "../rustc_hir" }
 rustc_lint_defs = { path = "../rustc_lint_defs" }
 unicode-width = "0.1.4"
-atty = "0.2"
 termcolor = "1.0"
 annotate-snippets = "0.9"
 termize = "0.1.1"

compiler/rustc_errors/src/emitter.rs

@@ -28,8 +28,8 @@
 use rustc_span::hygiene::{ExpnKind, MacroKind};
 use std::borrow::Cow;
 use std::cmp::{max, min, Reverse};
-use std::io;
 use std::io::prelude::*;
+use std::io::{self, IsTerminal};
 use std::iter;
 use std::path::Path;
 use termcolor::{Ansi, BufferWriter, ColorChoice, ColorSpec, StandardStream};
@@ -619,14 +619,14 @@ impl ColorConfig {
     fn to_color_choice(self) -> ColorChoice {
         match self {
             ColorConfig::Always => {
-                if atty::is(atty::Stream::Stderr) {
+                if io::stderr().is_terminal() {
                     ColorChoice::Always
                 } else {
                     ColorChoice::AlwaysAnsi
                 }
             }
             ColorConfig::Never => ColorChoice::Never,
-            ColorConfig::Auto if atty::is(atty::Stream::Stderr) => ColorChoice::Auto,
+            ColorConfig::Auto if io::stderr().is_terminal() => ColorChoice::Auto,
             ColorConfig::Auto => ColorChoice::Never,
         }
     }

compiler/rustc_errors/src/lib.rs

@@ -5,6 +5,7 @@
 #![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
 #![feature(drain_filter)]
 #![feature(if_let_guard)]
+#![feature(is_terminal)]
 #![feature(adt_const_params)]
 #![feature(let_chains)]
 #![feature(never_type)]