[Webkit-unassigned] [Bug 237329] [XCBuild] Emit a discovered dependency file from offlineasm

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=237329

--- Comment #13 from Elliott Williams <emw at apple.com> ---
(In reply to Keith Miller from comment #10)
> What happens if someone adds that file later? e.g. someone adds the
> `Internal` directory after doing an OS build.

To answer this question more directly: We support making internal and OSS builds using the same build directory. At the very least, it's not a workflow I've seen tested.

There is a problem where, for instance, at build time an included file might come from the SDK ($(SDKROOT)/usr/local/WebKitAdditions/…), but later an Internal directory is updated so that now it is produced locally ($(BUILT_PRODUCTS_DIR)/usr/local/WebKitAdditions/…). Under this patch, offlineasm would not have put the relative-to-build-products path in its .d and thus would not re-run. 

This seems bad, but doesn't appear to cause problems in practice: clang has the same theoretical issue, since its header depfiles only recorded what it included, and not every header it searched for and did not find.

Fundamentally, I don't think discovered dependencies are a good fit for tracking "dependencies which *might* exist later but don't exist right now". And I'm not sure it's worth our time to make offlineasm better than clang at responding to filesystem changes from outside the project directory.

With that in mind, I've convinced myself not to try and emit dependencies for missing files -- wdyt?

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.webkit.org/pipermail/webkit-unassigned/attachments/20220303/b1ebd6a0/attachment-0001.htm>