Rollup merge of #103117 - joshtriplett:use-is-terminal, r=eholk

Use `IsTerminal` in place of `atty`

In any crate that can use nightly features, use `IsTerminal` rather than
`atty`:

- Use `IsTerminal` in `rustc_errors`
- Use `IsTerminal` in `rustc_driver`
- Use `IsTerminal` in `rustc_log`
- Use `IsTerminal` in `librustdoc`

src/librustdoc/lib.rs

@@ -8,6 +8,7 @@
 #![feature(box_patterns)]
 #![feature(control_flow_enum)]
 #![feature(drain_filter)]
+#![feature(is_terminal)]
 #![feature(let_chains)]
 #![feature(test)]
 #![feature(never_type)]
@@ -69,7 +70,7 @@ extern crate jemalloc_sys;
 
 use std::default::Default;
 use std::env::{self, VarError};
-use std::io;
+use std::io::{self, IsTerminal};
 use std::process;
 
 use rustc_driver::abort_on_err;
@@ -179,7 +180,7 @@ fn init_logging() {
     let color_logs = match std::env::var("RUSTDOC_LOG_COLOR").as_deref() {
         Ok("always") => true,
         Ok("never") => false,
-        Ok("auto") | Err(VarError::NotPresent) => atty::is(atty::Stream::Stdout),
+        Ok("auto") | Err(VarError::NotPresent) => io::stdout().is_terminal(),
         Ok(value) => early_error(
             ErrorOutputType::default(),
             &format!("invalid log color value '{}': expected one of always, never, or auto", value),