Can't install on OS X

[Kapeli]

Xcode 5.1 seems to have updated clang, which turned a bunch of previous warnings into errors.

Other gems seem to have this problem, like rmagick/rmagick#96.

This is the error I get:

~ » sudo gem install redcarpet
Fetching: redcarpet-3.1.1.gem (100%)
Building native extensions.  This could take a while...
ERROR:  Error installing redcarpet:
    ERROR: Failed to build gem native extension.

    /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb
creating Makefile

make "DESTDIR=" clean

make "DESTDIR="
compiling autolink.c
compiling buffer.c
buffer.c:104:45: warning: passing 'const struct buf *' to parameter of type 'struct buf *' discards qualifiers [-Wincompatible-pointer-types-discards-qualifiers]
        if (buf->size + 1 <= buf->asize || bufgrow(buf, buf->size + 1) == 0) {
                                                   ^~~
buffer.c:53:21: note: passing argument to parameter 'buf' here
bufgrow(struct buf *buf, size_t neosz)
                    ^
1 warning generated.
compiling houdini_href_e.c
compiling houdini_html_e.c
compiling html.c
compiling html_smartypants.c
compiling markdown.c
compiling rc_markdown.c
compiling rc_render.c
compiling stack.c
linking shared-object redcarpet.bundle
clang: error: unknown argument: '-multiply_definedsuppress' [-Wunused-command-line-argument-hard-error-in-future]
clang: note: this will be a hard error (cannot be downgraded to a warning) in the future
make: *** [redcarpet.bundle] Error 1

make failed, exit code 2

[sharvilshah]

From Apple's Xcode/Clang release notes:

The Apple LLVM compiler in Xcode 5.1 treats unrecognized command-line options as errors. This issue has been seen when building both Python native extensions and Ruby Gems, where some invalid compiler options are currently specified.
Projects using invalid compiler options will need to be changed to remove those options. To help ?ease that transition, the compiler will temporarily accept an option to downgrade the error to a warning:

-Wno-error=unused-command-line-argument-hard-error-in-future

ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future gem install GemName

[mattr-]

Thanks for reporting. I haven't upgraded XCode to 5.1 yet because of these issues, but I'll upgrade it and give it a try and see if we can't ship a new version that somehow works around this.

[robin850]

@mattr- : Maybe we can simply set the ARCHFLAGS as pointed by @sharvilshah if the current platform is OS X in the extconf.rb file:

ENV['ARCHFLAGS']= "-Wno-error=unused-command-line-argument-hard-error-in-future"

But I'm not sure that this will work and that this is our responsibility. Maybe we should mention it in the README until RubyGems workaround this or a new Ruby version is released, what do you think ?

Anyway, the problem has already been reported to the ruby tracker.

[mattr-]

that's what i was thinking in the short term. I love how Apple adding this in the latest version of XCode actually broke their own software. 😉

I'm hoping I can find some time to work on this stuff by the end of the week. so busy.

[benzado]

I'm trying to install the gem and also encountering the error. I don't think unrecognized command line arguments are the problem. If you read the output @Kapeli posted, it is failing because of a type mismatch issue in buffer.c. If anything the warning to disable should be -Wno-incompatible-pointer-types-discards-qualifiers, however I think it would be better to simply fix the code by changing the type or inserting a cast.

[benzado]

Oops, nevermind, I see both of them now.

[robin850]

Ok, I guess we can close this one. At least this is not really our call ; according to this comment, you should rebuild Ruby or install another version (let's say through Rbenv or Chruby for instance).

I guess the problem has been reported enough to let people know the workaround.

@mattr- : Feel free to reopen if you disagree.

Thank you guys! :-)