Make tidy errors red

This makes it easier to see them (and makes people go owo).

Cargo.lock

@@ -2675,9 +2675,9 @@ dependencies = [
 
 [[package]]
 name = "owo-colors"
-version = "3.4.0"
+version = "3.5.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "decf7381921fea4dcb2549c5667eda59b3ec297ab7e2b5fc33eac69d2e7da87b"
+checksum = "c1b04fb49957986fdce4d6ee7a65027d55d4b6d2265e5848bbb507b58ccfdb6f"
 
 [[package]]
 name = "packed_simd_2"
@@ -5203,9 +5203,9 @@ dependencies = [
 
 [[package]]
 name = "termcolor"
-version = "1.1.2"
+version = "1.1.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "2dfed899f0eb03f32ee8c6a0aabdb8a7949659e3466561fc0adf54e26d88c5f4"
+checksum = "bab24d30b911b2376f3a13cc2cd443142f0c81dda04c118693e35b3835757755"
 dependencies = [
  "winapi-util",
 ]
@@ -5309,6 +5309,7 @@ dependencies = [
  "lazy_static",
  "miropt-test-tools",
  "regex",
+ "termcolor",
  "walkdir",
 ]
 

src/tools/tidy/Cargo.toml

@@ -11,6 +11,7 @@ miropt-test-tools = { path = "../miropt-test-tools" }
 lazy_static = "1"
 walkdir = "2"
 ignore = "0.4.18"
+termcolor = "1.1.3"
 
 [[bin]]
 name = "rust-tidy"

src/tools/tidy/src/lib.rs

@@ -3,6 +3,10 @@
 //! This library contains the tidy lints and exposes it
 //! to be used by tools.
 
+use std::fmt::Display;
+
+use termcolor::WriteColor;
+
 /// A helper macro to `unwrap` a result except also print out details like:
 ///
 /// * The expression that failed
@@ -26,18 +30,27 @@ macro_rules! t {
 }
 
 macro_rules! tidy_error {
-    ($bad:expr, $fmt:expr) => ({
-        *$bad = true;
-        eprint!("tidy error: ");
-        eprintln!($fmt);
-    });
-    ($bad:expr, $fmt:expr, $($arg:tt)*) => ({
-        *$bad = true;
-        eprint!("tidy error: ");
-        eprintln!($fmt, $($arg)*);
+    ($bad:expr, $($fmt:tt)*) => ({
+        $crate::tidy_error($bad, format_args!($($fmt)*)).expect("failed to output error");
     });
 }
 
+fn tidy_error(bad: &mut bool, args: impl Display) -> std::io::Result<()> {
+    use std::io::Write;
+    use termcolor::{Color, ColorChoice, ColorSpec, StandardStream};
+
+    *bad = true;
+
+    let mut stderr = StandardStream::stdout(ColorChoice::Auto);
+    stderr.set_color(ColorSpec::new().set_fg(Some(Color::Red)))?;
+
+    write!(&mut stderr, "tidy error")?;
+    stderr.set_color(&ColorSpec::new())?;
+
+    writeln!(&mut stderr, ": {args}")?;
+    Ok(())
+}
+
 pub mod alphabetical;
 pub mod bins;
 pub mod debug_artifacts;