From 4f74037f4122f2eab6786106c8abda7540ee7a36 Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Sun, 5 May 2024 10:11:21 -0400
Subject: [PATCH] pipe debug output through rustfmt

is there a nicer way to do this?!
---
 components/salsa-2022-macros/src/debug.rs | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

diff --git a/components/salsa-2022-macros/src/debug.rs b/components/salsa-2022-macros/src/debug.rs
index ed9e2a8b..22ba8561 100644
--- a/components/salsa-2022-macros/src/debug.rs
+++ b/components/salsa-2022-macros/src/debug.rs
@@ -1,3 +1,5 @@
+use std::io::Write;
+use std::process::{Command, Stdio};
 use std::sync::OnceLock;
 
 use proc_macro2::TokenStream;
@@ -16,7 +18,22 @@ pub(crate) fn debug_enabled(input_name: impl ToString) -> bool {
 
 pub(crate) fn dump_tokens(input_name: impl ToString, tokens: TokenStream) -> TokenStream {
     if debug_enabled(input_name) {
-        eprintln!("{}", tokens);
+        let token_string = tokens.to_string();
+
+        let _: Result<(), ()> = Command::new("rustfmt")
+            .arg("--emit=stdout")
+            .stdin(Stdio::piped())
+            .spawn()
+            .and_then(|mut rustfmt| {
+                rustfmt
+                    .stdin
+                    .take()
+                    .unwrap()
+                    .write_all(token_string.as_bytes())?;
+                rustfmt.wait_with_output()
+            })
+            .and_then(|output| Ok(eprintln!("{}", String::from_utf8_lossy(&output.stdout))))
+            .or_else(|_| Ok(eprintln!("{token_string}")));
     }
 
     tokens