Improve the CLI output when nothing changed (tailwindlabs#14351)

When we observe that no new candidates were found, then we can return
early because nothing really changed. There is also no need to
re-optimize (use Lightning CSS) in this case.

But this had a side effect that when no new candidates were detected,
that you didn't see any output either. This feels like nothing is
working from a DX perspective.

Typically you are changing things, so it's not really a problem. But the
moment you use a class that already existed (e.g.: in another file) you
also don't get any output because we have a shared cache.

This PR solves that by always showing the output. But it still doesn't
write to disk if nothing changed.

---------

Co-authored-by: Adam Wathan <adam.wathan@gmail.com>

Author: RobinMalfait

CHANGELOG.md

@@ -7,7 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- Nothing yet!
+### Fixed
+
+- Ensure there is always CLI feedback on save even when no new classes were found ([#14351](https://github.com/tailwindlabs/tailwindcss/pull/14351))
 
 ## [4.0.0-alpha.23] - 2024-09-05
 

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

@@ -236,9 +236,13 @@ export async function handle(args: Result<ReturnType<typeof options>>) {
           else if (rebuildStrategy === 'incremental') {
             let newCandidates = scanner.scanFiles(changedFiles)
 
-            // No candidates found which means we don't need to rebuild. This can
-            // happen if a file is detected but doesn't match any of the globs.
-            if (newCandidates.length <= 0) return
+            // No new candidates found which means we don't need to write to
+            // disk, and can return early.
+            if (newCandidates.length <= 0) {
+              let end = process.hrtime.bigint()
+              eprintln(`Done in ${formatDuration(end - start)}`)
+              return
+            }
 
             compiledCss = compiler.build(newCandidates)
           }