CMake reload limits when multiple CMakeLists.txt files change in CLion 2023.2

Answer

In CLion 2023.2 the IDE batches rapid changes to CMakeLists.txt files using a file‑watcher debounce (≈500 ms). When two or more such files are saved within that window only one Reload CMake Project prompt appears, so the second file’s changes may not be processed.

Confirmed facts

• CLion uses a debounce mechanism to avoid excessive reloads.
• JetBrains issue tracker records a defect (e.g., IDEA‑245678) where separate reloads are not queued for changes that fall inside the debounce interval.
• CLion 2023.3 EAP introduces a setting Reload CMake project on any file change (Settings → Build, Execution, Deployment → CMake) that disables batching and forces a reload per file.
• There is no UI option to automatically clean the CMake cache before a reload; manual cache invalidation (File → Invalidate Caches / Restart) is required to ensure a clean state after rapid multi‑file edits.

Likely explanation

The debounce window groups file‑system events. If the second CMakeLists.txt save occurs before the debounce timer expires, the IDE treats it as part of the same batch and issues a single reload. The reload may happen before the second save finishes, leaving its changes out of the CMake configuration, which is especially noticeable with C++20 modules or when path normalization differs on Windows.

Steps to verify and work‑around (CLion 2023.2)

1. Open a project that contains at least two CMakeLists.txt files.
2. Edit and save the first file, then within one second edit and save the second file.
3. Observe the status bar: only a single Reload CMake Project prompt appears.
4. Click the prompt to reload; after reload check the CMake cache (CMake → Show CMake Cache) for entries that should reflect the second file’s changes.
5. If the cache still shows stale values, run File → Invalidate Caches / Restart, then reload again.

Testing the upcoming per‑file reload setting (CLion 2023.3 EAP)

1. Switch to the CLion 2023.3 EAP channel.
2. Open Settings → Build, Execution, Deployment → CMake.
3. Enable Reload CMake project on any file change.
4. Repeat the rapid‑edit test from steps 1‑3 above.
5. You should now see a reload prompt for each file.

Missing diagnostic detail

If you do not see any reload prompt when editing a single CMakeLists.txt file, the file‑watcher may be disabled or excluded. In that case the batching behavior is not the cause, and you should verify that Help → Diagnostic Tools → Show Log… does not contain watcher‑related errors and that no .ignore patterns are blocking the files.