Use std::io::IsTerminal instead of atty (#1129)

This is a new feature of Rust 1.71.0 and enables dropping a small
dependency in favor of built-in functionality.

Cargo.toml

@@ -62,7 +62,6 @@ wit-smith = { version = "0.1.6", path = "crates/wit-smith" }
 [dependencies]
 anyhow = { workspace = true }
 env_logger = { workspace = true }
-atty = "0.2"
 log = { workspace = true }
 clap = { workspace = true }
 tempfile = "3.2.0"

src/bin/wasm-tools/main.rs

@@ -1,6 +1,6 @@
 use anyhow::Result;
 use clap::Parser;
-use std::io::{self, Write};
+use std::io::{self, IsTerminal, Write};
 use std::process::ExitCode;
 use termcolor::{Color, ColorChoice, ColorSpec, StandardStream, WriteColor};
 
@@ -100,7 +100,7 @@ fn main() -> ExitCode {
 }
 
 fn print_error(color: ColorChoice, err: anyhow::Error) -> Result<()> {
-    let color = if color == ColorChoice::Auto && !atty::is(atty::Stream::Stderr) {
+    let color = if color == ColorChoice::Auto && !io::stderr().is_terminal() {
         ColorChoice::Never
     } else {
         color

src/lib.rs

@@ -2,6 +2,7 @@
 
 use anyhow::{bail, Context, Result};
 use std::fs::File;
+use std::io::IsTerminal;
 use std::io::{BufWriter, Read, Write};
 use std::path::{Path, PathBuf};
 use termcolor::{Ansi, ColorChoice, NoColor, StandardStream, WriteColor};
@@ -135,10 +136,11 @@ impl OutputArg {
                             .context(format!("failed to write `{}`", path.display()))?;
                     }
                     None => {
-                        if atty::is(atty::Stream::Stdout) {
+                        let mut stdout = std::io::stdout();
+                        if stdout.is_terminal() {
                             bail!("cannot print binary wasm output to a terminal, pass the `-t` flag to print the text format");
                         }
-                        std::io::stdout()
+                        stdout
                             .write_all(bytes)
                             .context("failed to write to stdout")?;
                     }
@@ -176,7 +178,8 @@ impl OutputArg {
                 }
             }
             None => {
-                if color == ColorChoice::Auto && !atty::is(atty::Stream::Stdout) {
+                let stdout = std::io::stdout();
+                if color == ColorChoice::Auto && !stdout.is_terminal() {
                     Ok(Box::new(StandardStream::stdout(ColorChoice::Never)))
                 } else {
                     Ok(Box::new(StandardStream::stdout(color)))