Qt v5.11.0–5.11.2 Fail to Build From Source and Install `--with-docs` Under OS X v10.11.6 'El Capitan'

[RandomDSdevel]

     For prior discussion and the initial issue report, see here and here upstream. I'm using this downstream issue to track any further developments with respect to forward progress on resolving this that I might possibly make, as I was never able to get it fixed despite the corresponding issue being closed upstream. (Note also that I've been keeping a personal branch containing some stale fix attempts rebased against upstream's 'master' branch, though I haven't able to do much anything else with it yet than that.)

[RandomDSdevel]

     I'm tentatively CCing Qt documentation developer Paul '@DocWicking' Wicking to this issue but should later follow up with a proper upstream issue report, as he noted one would be desired if this came up again here in Qt's upstream bug tracker.

[RandomDSdevel]

     I should also note that it's entirely possible that I just never pulled all the patches needed against the Qt v5.11.x series to get this to work there… I'm not sure which additional changes, if any, might help, though.

[RandomDSdevel]

     Additionally, this is preventing me from upgrading my local copies of:

• LLVM (to v7.0.0) (This is complicated by my:

  • building LLVM with documentation, thus:
    • pulling in Doxygen, which:
      • I installed using a Homebrew formula option that pulls in Qt,

  thus possibly introducing a circular dependency loop here. I can probably massage Homebrew into first upgrading Qt by building it using my current Homebrew LLVM installation, then rebuilding LLVM against the new Qt, then finally rebuilding Qt against this new LLVM, however, though that's likely going to be a bit painful given how long Qt builds take on the antiquated jalopy of a machine I'm still stuck with…)

  (Edit: The option to build LLVM with documentation has since been removed from the package's formula in Homebrew's 'Homebrew Core' tap. I may restore it in the future, but that can wait. In the meantime, I now have a working, up-to-date copy of the LLVM tool suite! I was even able to get LLDB to build, which I've never managed before! Woo-hoo!)

• clingo (to v5.3.0)

Hi Bryce,

first of all, thanks for taking an active interest in QDoc. As you've discovered, there are unfortunately some issues with QDoc in Qt 5.11, and we're well aware of them. This is related to the switch to clang as C++ parser, as that requires us to link to libclang. On macOS, we need libclang in addition to what is there from the SDK, as we require the header clang-c/Index.h which isn't included with XCode. With the upcoming (and near) release of Qt 5.12, we use llvm-config to auto-discover the location of libclang. Note, however, that our assumption in that case is that libclang is installed with homebrew.

If you've compiled your own libclang or installed it in some other way that evades our assumptions when we look for it, you can specify the location to libclang by setting the environment variable LLVM_INSTALL_DIR=/path/to/libclang before you configure and build Qt. See the online documentation for Qt 5.12 for further details.

If you experience other issues or have suggestions to improve QDoc, please report them on the Qt bugtracker.

[RandomDSdevel]

@DocWicking:

     The 'libclang' I've been attempting to use is the one provided by Homebrew's LLVM, but Qt couldn't seem to find it while building itself from within Homebrew even after I attempted to backport what I thought were all of the relevant changes needed to make this work from Qt v5.12 to v5.11.x (v5.11.2 at present.) (As I recall, attempting to run a build with 'LLVM_INSTALL_DIR' set also failed.)

[RandomDSdevel]

     I've now edited a comment I made earlier on this thread concerning what dependents my not being able to upgrade Qt was preventing me from updating to mention that LLVM no longer has the option to be built with documentation as distributed by Homebrew, so that package's dependency on Qt was severed. (See that post for more details.)

[RandomDSdevel]

     The release of Qt v5.12.0 has allowed me to remove the patches I'd been pulling in as part of the changes I'd staged on a personal branch, as they're now merged upstream into that stable release. (I haven't tested the new release yet to see if it really fixes this issue, though.)

[RandomDSdevel]

     This now blocks upgrading Doxygen from v1.8.14 to v1.8.15 as well (via its Homebrew formula's '--with-qt' option.)

[RandomDSdevel]

     Homebrew Core has now removed Doxygen's formula's '--with-qt' option, among others (in Homebrew#36069.) Though this adds another thing to fix to what I know of @portage-brew's prospective task list, it unblocked my installing Doxygen and, thus, also 'clingo,' so I'll take what I can get for now in that respect. I still want Qt's documentation locally, though.