Ungoogled-chromium: Hardcoded GCC version in macOS

[scottydelta]

The build fails due to hard coded GCC versions in the code. eg:
brew install gcc49 installs binary x86_64-apple-darwin16.0.0-c++-4.9 on MacOS Sierra but the code has x86_64-apple-darwin15.4.0-c++-4.9 and is hard coded in resources/macos/patches/ungoogled-macos/fix-libcxx-archive-build-script.patch and buildlib/macos.py

The versions can be put into a config file and can be parsed using ConfigParser but not sure how to include that version in the patch file(resources/macos/patches/ungoogled-macos/fix-libcxx-archive-build-script.patch)

[Eloston]

Yeah someone reported that earlier and they closed it themselves for reasons I'm not sure...

Instead of hardcoding the path in a config file, I want to implemenet a function in MacOSBuilder that can auto-detect the path to Homebrew's GCC. However, I don't know enough about Homebrew to figure out the best way to detect the GCC path.

I am planning on using #69 to solve the problem of a version-dependent path to the compiler in the patch file.

[Eloston]

Adding help wanted label so someone can help out with Homebrew.

[dangom]

I'm no expert, but this does the trick under Python 3.5 on MacOS Sierra:

@static_method
def get_homebrew_gcc_bin():
    brew_list_gcc = subprocess.Popen(['brew', 'list', 'gcc'],
                                     stdout=subprocess.PIPE)
    grep_gcc_path = subprocess.Popen(['grep', 'bin/x86_64'],
                                stdin=brew_list_gcc.stdout,
                                stdout=subprocess.PIPE,
                                stderr=subprocess.PIPE)
    out, err = grep_gcc_path.communicate()
    result = out.split(b'\n')[0]
    if not result:
        raise OSError("Is gcc properly installed? Please check the output of \"brew list gcc\"")
    return result

In [34]: get_homebrew_gcc_bin()
Out[34]: 
b'/usr/local/Cellar/gcc/6.2.0/bin/x86_64-apple-darwin15.6.0-c++-6'

[Eloston]

I did some research, and this gist gives us some helpful hints.
@dangom: Is gcc-4.9 or something similar already in your PATH?

• If it does, does it point to Homebrew's GCC for that version?
• If not, is there one in $(brew --prefix)/bin?

[dangom]

@Eloston
_Is gcc-4.9 or something similar already in your PATH?_
No, it isn't.
_If not, is there one in $(brew --prefix)/bin?_
No, I only have 6.2 on brew, and it isn't symlinked to /usr/local/bin/. My PATH still points to /usr/bin/gcc.
I haven't built Chromium myself yet.

The dummy function above will always return the oldest available brew install - since the folders are listed in alphabetical order. Should the oldest be 4.9.0, then that's what we get.

We can force search for gcc-4.9:
grep_gcc_path = subprocess.Popen(['grep', 'bin/x86_64.*c++-4.9'],

Massaging the output of the function gives us the directory name we need:

import functools as ftools
tmp = get_homebrew_gcc_bin()
gcc_path = b'/' + ftools.reduce(lambda a,b: a + b'/' + b, tmp.split(b'/')[1:-1])

In [128]: gcc_path
Out[128]: 
b'/usr/local/Cellar/gcc/6.2.0/bin'

Prepending this to the PATH, as you suggested in #69, should do the trick without having to symlink all gcc binaries or overwrite user defaults.

Again, I'm not an expert. Would a fix for the include and lib directories also be necessary for the build?

[Eloston]

No, it isn't.

So that means gcc-6.2 is not in your PATH? That's interesting.

No, I only have 6.2 on brew, and it isn't symlinked to /usr/local/bin/. My PATH still points to /usr/bin/gcc.

So brew --prefix returns /usr/local? Well I guess that makes sense.

Prepending this to the PATH, as you suggested in #69, should do the trick without having to symlink all gcc binaries or overwrite user defaults.

I'm confused. Are you saying that there's a gcc-6.2 in /usr/local/Cellar/gcc/6.2.0/bin? If not, then it doesn't help to append that to the PATH. Also, #69 isn't suggesting prepending system directories to PATH, unless I'm misinterpreting what you're saying.

Do you know if there's a way to get a list of installed GCC versions? Is there a function to get information about a specific GCC version that's installed?

[dangom]

_Are you saying that there's a gcc-6.2 in /usr/local/Cellar/gcc/6.2.0/bin?_

Yes. These are the files in said directory:

/usr/local/Cellar/gcc/6.2.0/bin/x86_64-apple-darwin15.6.0-c++-6
/usr/local/Cellar/gcc/6.2.0/bin/x86_64-apple-darwin15.6.0-g++-6
/usr/local/Cellar/gcc/6.2.0/bin/x86_64-apple-darwin15.6.0-gcc-6
/usr/local/Cellar/gcc/6.2.0/bin/x86_64-apple-darwin15.6.0-gcc-6.2.0
/usr/local/Cellar/gcc/6.2.0/bin/x86_64-apple-darwin15.6.0-gcc-ar-6
/usr/local/Cellar/gcc/6.2.0/bin/x86_64-apple-darwin15.6.0-gcc-nm-6
/usr/local/Cellar/gcc/6.2.0/bin/x86_64-apple-darwin15.6.0-gcc-ranlib-6
/usr/local/Cellar/gcc/6.2.0/bin/x86_64-apple-darwin15.6.0-gfortran-6

$ /usr/local/Cellar/gcc/6.2.0/bin/x86_64-apple-darwin15.6.0-gcc-6 --version
x86_64-apple-darwin15.6.0-gcc-6 (Homebrew gcc 6.2.0) 6.2.0
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

I guess I must have misunderstood #69 then. My bad.

Create a directory build/path_overrides that contains files to override PATH commands. ...
For Python, /usr/bin/python will have to be changed to point to the Python command in path_overrides.

Your idea is to have a directory with symlinks to the correct binaries? And prepend this build/path_overrides to the PATH?

I don't know how to get a list of installed GCC versions apart from brew list | grep gcc. Or looping through the $PATH and seeing what's in there.
What information about GCC versions are you interested in?

[Eloston]

Yes. These are the files in said directory:

But there's no file called gcc-6.2 in that directory. The problem is that those file names contain other values that are more likely to change depending on the version being built. gcc-6.2 is supposed to match against the latest GCC in the 6.2.x series. That's why I was hoping that there was a file named gcc-6.2 in /usr/local/bin so we wouldn't have to assume certain patterns in the actual GCC path.

The reason I want a command like that is so I don't have to use #69 to solve this problem.

Well I did some very quick research and came across this bug report. It looks like there is a way to list gcc versions, and a way to create symlinks in /usr/local/bin. Could you try running brew link gcc and seeing if that adds a command called gcc-6.2 to your PATH?

[dangom]

Not quite gcc-6.2, but brew link gcc adds gcc-6 to my path.

$ which gcc-6
/usr/local/bin/gcc-6

$ gcc-6 --version
gcc-6 (Homebrew gcc 6.2.0) 6.2.0
Copyright (C) 2016 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[Eloston]

Oh cool. I think that will work instead of using #69.

Would you mind testing to see if GCC 4.9 from Homebrew is available as gcc-4.9 or something similar?

[dangom]

It is. Takes an awful long time to build though.

brew install homebrew/versions/gcc49
🍺 /usr/local/Cellar/gcc49/4.9.3: 1,181 files, 196.4M, built in 62 minutes 48 seconds

$ which gcc-4.9 && gcc-4.9 --version
/usr/local/bin/gcc-4.9
gcc-4.9 (Homebrew gcc49 4.9.3) 4.9.3
Copyright (C) 2015 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[Eloston]

It is. Takes an awful long time to build though.

Oh cool. Glad to hear it works. I didn't know that Homebrew actually builds the compiler each time; that's interesting.

[takinbo]

Hey, I had this problem the first time I was building the project for MacOS. I had to modify the patch file in order to get it to build. I made a pull request based on the conversation here to properly detect the existence of gcc-4.9 and then use the c++-4.9 binary that gcc-4.9 provides when it's installed.