Write to log file when using DEBUG=*

CHANGELOG.md

@@ -10,14 +10,16 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ### Added
 
 - Upgrade: Automatically convert candidates with arbitrary values to their utilities ([#17831](https://github.com/tailwindlabs/tailwindcss/pull/17831), [#17854](https://github.com/tailwindlabs/tailwindcss/pull/17854))
+- Write to log file when using `DEBUG=*` ([#17906](https://github.com/tailwindlabs/tailwindcss/pull/17906))
 
 ### Fixed
 
 - Ensure negative arbitrary `scale` values generate negative values ([#17831](https://github.com/tailwindlabs/tailwindcss/pull/17831))
 - Fix HAML extraction with embedded Ruby ([#17846](https://github.com/tailwindlabs/tailwindcss/pull/17846))
 - Don't scan files for utilities when using `@reference` ([#17836](https://github.com/tailwindlabs/tailwindcss/pull/17836))
 - Fix incorrectly replacing `_` with ` ` in arbitrary modifier shorthand `bg-red-500/(--my_opacity)` ([#17889](https://github.com/tailwindlabs/tailwindcss/pull/17889))
-- Upgrade: Bump dependendencies in parallel and make the upgrade faster ([#17898](https://github.com/tailwindlabs/tailwindcss/pull/17898))
+- Upgrade: Bump dependencies in parallel and make the upgrade faster ([#17898](https://github.com/tailwindlabs/tailwindcss/pull/17898))
+- Don't scan `.log` files for classes by default ([#17906](https://github.com/tailwindlabs/tailwindcss/pull/17906))
 
 ## [4.1.5] - 2025-04-30
 

crates/oxide/src/scanner/fixtures/ignored-extensions.txt

@@ -3,3 +3,4 @@ lock
 sass
 scss
 styl
+log

crates/oxide/src/scanner/mod.rs

@@ -16,10 +16,13 @@ use fxhash::{FxHashMap, FxHashSet};
 use ignore::{gitignore::GitignoreBuilder, WalkBuilder};
 use rayon::prelude::*;
 use std::collections::{BTreeMap, BTreeSet};
+use std::fs::OpenOptions;
+use std::io::{self, Write};
 use std::path::{Path, PathBuf};
 use std::sync::{self, Arc, Mutex};
 use std::time::SystemTime;
 use tracing::event;
+use tracing_subscriber::fmt::writer::BoxMakeWriter;
 
 // @source "some/folder";               // This is auto source detection
 // @source "some/folder/**/*";          // This is auto source detection
@@ -35,18 +38,67 @@ static SHOULD_TRACE: sync::LazyLock<bool> = sync::LazyLock::new(
     || matches!(std::env::var("DEBUG"), Ok(value) if value.eq("*") || (value.contains("tailwindcss:oxide") && !value.contains("-tailwindcss:oxide"))),
 );
 
+fn dim(input: &str) -> String {
+    format!("\u{001b}[2m{input}\u{001b}[22m")
+}
+
+fn blue(input: &str) -> String {
+    format!("\u{001b}[34m{input}\u{001b}[39m")
+}
+
+fn highlight(input: &str) -> String {
+    format!("{}{}{}", dim(&blue("`")), blue(input), dim(&blue("`")))
+}
+
 fn init_tracing() {
     if !*SHOULD_TRACE {
         return;
     }
 
+    let file_path = format!("tailwindcss-{}.log", std::process::id());
+    let file = OpenOptions::new()
+        .create(true)
+        .append(true)
+        .open(&file_path)
+        .unwrap_or_else(|_| panic!("Failed to open {file_path}"));
+
+    let file_path = Path::new(&file_path);
+    let absolute_file_path = dunce::canonicalize(file_path)
+        .unwrap_or_else(|_| panic!("Failed to canonicalize {file_path:?}"));
+    eprintln!(
+        "{} Writing debug info to: {}\n",
+        dim("[DEBUG]"),
+        highlight(absolute_file_path.as_path().to_str().unwrap())
+    );
+
+    let file = Arc::new(Mutex::new(file));
+
+    let writer: BoxMakeWriter = BoxMakeWriter::new({
+        let file = file.clone();
+        move || Box::new(MutexWriter(file.clone())) as Box<dyn Write + Send>
+    });
+
     _ = tracing_subscriber::fmt()
         .with_max_level(tracing::Level::INFO)
         .with_span_events(tracing_subscriber::fmt::format::FmtSpan::ACTIVE)
+        .with_writer(writer)
+        .with_ansi(false)
         .compact()
         .try_init();
 }
 
+struct MutexWriter(Arc<Mutex<std::fs::File>>);
+
+impl Write for MutexWriter {
+    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
+        self.0.lock().unwrap().write(buf)
+    }
+
+    fn flush(&mut self) -> io::Result<()> {
+        self.0.lock().unwrap().flush()
+    }
+}
+
 #[derive(Debug, Clone)]
 pub enum ChangedContent {
     File(PathBuf, String),
@@ -394,7 +446,10 @@ impl Scanner {
 fn read_changed_content(c: ChangedContent) -> Option<Vec<u8>> {
     let (content, extension) = match c {
         ChangedContent::File(file, extension) => match std::fs::read(&file) {
-            Ok(content) => (content, extension),
+            Ok(content) => {
+                event!(tracing::Level::INFO, "Reading {:?}", file);
+                (content, extension)
+            }
             Err(e) => {
                 event!(tracing::Level::ERROR, "Failed to read file: {:?}", e);
                 return None;
@@ -706,7 +761,11 @@ fn create_walker(sources: Sources) -> Option<WalkBuilder> {
 
             match (current_time, previous_time) {
                 (Some(current), Some(prev)) if prev == current => false,
-                _ => true,
+                _ => {
+                    event!(tracing::Level::INFO, "Discovering {:?}", path);
+
+                    true
+                }
             }
         }
     });

packages/@tailwindcss-cli/src/commands/build/index.ts

@@ -67,6 +67,9 @@ async function handleError<T>(fn: () => T): Promise<T> {
 }
 
 export async function handle(args: Result<ReturnType<typeof options>>) {
+  eprintln(header())
+  eprintln()
+
   using I = new Instrumentation()
   DEBUG && I.start('[@tailwindcss/cli] (initial build)')
 
@@ -87,8 +90,6 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
 
     // Ensure the provided `--input` exists.
     if (!existsSync(args['--input'])) {
-      eprintln(header())
-      eprintln()
       eprintln(`Specified input file ${highlight(relative(args['--input']))} does not exist.`)
       process.exit(1)
     }
@@ -97,8 +98,6 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
   // Check if the input and output file paths are identical, otherwise return an
   // error to the user.
   if (args['--input'] === args['--output'] && args['--input'] !== '-') {
-    eprintln(header())
-    eprintln()
     eprintln(
       `Specified input file ${highlight(relative(args['--input']))} and output file ${highlight(relative(args['--output']))} are identical.`,
     )
@@ -328,8 +327,6 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
   await write(output, args, I)
 
   let end = process.hrtime.bigint()
-  eprintln(header())
-  eprintln()
   eprintln(`Done in ${formatDuration(end - start)}`)
 }