Should poppler include QT by default?

[lukaso]

In looking at poppler and the projects that depend on it there are some anomalies.

There are 3 categories of packages:

• ones that use Gtk3 and therefore would not benefit from QT
• ones that are command line only or use a different widget library
• ones that should depend on poppler-qt5 if they require QT at all

In fact, of all the projects that depends_on "poppler", I couldn't find any that clearly require QT.

Therefore my questions are:

• Would it make sense to rename poppler to poppler-qt6 and create a new formula poppler that comes without QT as a dependency?
• Alternatively, would it make sense to create a poppler-noqt formula?
• And finally, would it make sense to move all these projects onto the new "no QT" formula (however named)?

I'm happy to take on the task of creating the new formula and moving the formulas over (though might take a bit of time).

Here's my analysis:

These formulas depend on gtk3:

• evince
• pdfpc
• pqiv
• pympress

These formulas don't have any need for QT that I can see (command line; different widget library; all had no reference to QT in source code):

• diff-pdf
• elf
• exiftran
• mat2
• pdf2djvu
• pdf2svg
• pdfgrep
• pdfsandwich
• vips

These formulas appear to have a QT connection:

• pdftoipe - However, the code refers to QT_SELECT=5 in a number of places and best case it is therefore pulling in the wrong version of QT. https://github.com/otfried/ipe-tools/blob/eca6ecc5e8ed3ca87ba7797db5a4d643fd016fde/obs/debian/rules#L10
• nuxeo - appears to require QT5 if anything.

Is see this as a bit of continuing cleanup from the removal of options: Remove options:
Homebrew/homebrew-core@2264def

My selfish reasons are that I want to build Gimp from homebrew and don't want to include QT unnecessarily in the package.

[danielnachun]

I have wondered this myself as qt is an unwieldy dependency and has only gotten worse since we've added QtWebEngine support to all platforms on Qt5 and all platforms except macOS Catalina on Qt6. It's especially problematic for Linux HPC users like myself who don't use any packages that depend on the Poppler QT bindings. It may be possible for us to split the package as you've suggested into something along the lines of:

poppler
poppler-qt5 which would depend on poppler
poppler-qt6 which would depend on poppler

I will add to your list that there are two other packages dspdfviewer and gdal that use poppler-qt5. gdal is also just a library that doesn't use Qt, while dspdfviewer does actually use Qt. I also looked more carefully at pdftoipe and it does not itself actually use Qt at all. So in total we have 2 formulae which actually use the Qt5 Poppler bindings, 0 packages using the Qt6 bindings, and 19 packages not using the Qt bindings at all.

@Homebrew/core what do we think about splitting poppler along these lines? It does seem kind of unreasonable to foist Qt and its massive dependency tree as a dependency upon so many users for just 2 packages which are not terribly popular (dspdfviewer has 56 installs in 30 days while nuxeo has just 30). By contrast, poppler has ~25,000 installs/month and poppler-qt5 has ~14,000 installs/month.

[carlocab]

Just get rid of the qt dependency in poppler. If users need it with qt support, they can use poppler-qt5.

If they need Poppler with Qt6, they can help migrate poppler-qt5 and its dependency tree to Qt6. Or host their own poppler-qt6 in their own tap. If their poppler-qt6 formula is sufficiently popular, it'll show up in our analytics and we can migrate it to homebrew-core.

[danielnachun]

That seems reasonable. poppler-qt5 will still need to be used by dspdfviewer - I double checked the nuxeo code and I can't find any references to QT there. gdal also needs to be switched from poppler-qt5 to poppler. Overall this seems to require a pretty minimal set of changes.

If we eventually pick up more formulae that actually need Poppler with Qt 6 support, we'll have to re-evaluate adding it as a formula. The only two packages Arch Linux has that currently depend on their poppler-qt6 package are texstudio and gimagereader-qt, neither of which currently have formulae. There are quite a few others that use their poppler-qt5 package, but we don't have formulae for any of those either.

[danielnachun]

I've opened Homebrew/homebrew-core#105996 to remove the qt dependency in poppler.

[sunderme]

texstudio needs poppler-qt6 and I specifically provided pull-requests to make it happen here.
Killing sane functionality without providing a future path is not nice.

[danielnachun]

Also regarding what is built by the taps, a big_sur bottle will also work on monterey, so the only platforms missing are Catalina (whose support will end soon) and native support for ARM64 macOS. I'm hoping GitHub gets ARM64 macOS support soon as Apple isn't making any new Intel Macs so the need for supporting that as a target is growing more urgent.

[muzimuzhi]

Homebrew is not a library manager so we probably wouldn't accept poppler-qt6 as a formula on its own given that no Homebrew formulae use it.

There's always some formulae which are not used by any other formulae. Why a not-used-by-any poppler-qt6 is less acceptable than a such texstudio? Maybe because poppler is considered more low-level and closer to CLI users/developers (thus more likely to be depended on by other formulae), but texstudio closer to GUI users. OK, popularity seems to be a stronger (rejection) reason.

To the texstudio case, it's currently provided as a cask and I think that's the right place for a multi-platform GUI (La)TeX editor.

[fxcoudert]

As was said already:

Homebrew is not a library manager

texstudio is an app. poppler-qt6 is a library.

[carlocab]

Sorry for breaking your usage of the formula.

However, poppler has many users, and qt is a gigantic dependency. It doesn't seem correct to me to require qt for every user who uses poppler to benefit the very small number of users who need Poppler built with Qt6.

If it turns out that our assessment that only a very small fraction of poppler users want it built with Qt6 is incorrect, then we can revisit this decision.

[sunderme]

Homebrew is preinstalled on the github osx runners which allows package buiding on osx which provides the binaries homebrew uses for its casks. One could be proud of that but that is apparently not the case.

The sad part is that there is barely any effort involved to remedy the situation by copying the old poppler formula to poppler-qt6.

And finally I am curious how porting to qt6 should happen when the dependencies are not provided for qt6, especially since qt6 is nominally the main qt version in homebrew.