After a formula is built, scan all mach-o files for dynamic links
to see if any of them point to a C++ stdlib (libc++ or libstdc++).
If one of them is linked, record that information in the formula's tab.
This replaces the old behaviour where all files were assumed to be C++
code, and stdlibs were always tracked regardless of whether they were
actually linked against.
This also modifies the way that tabs are written - now tabs are written
with the stdlib field null, and values are only written if an stdlib
is detected.
Comparing two objects should not raise an exception, even if they have
different types.
The semantics of #== are now the same as #eql?, so make one an alias.
* When a versioned keg_only formula installs the same set of executables
or libraries as a unversioned formula that links to $HOMEBREW_PREFIX,
install_name_tool will prefer to use the linked paths for files in
keg_only formula. This breaks software that should link to the
keg_only formula but links to the unversioned one instead.
* Add an additional "options" parameter with keg_only field to specify
the correct install path for keg_only formulae.
When subformulae are initialized without a name parameter, Homebrew
assigns the name "__UNKNOWN__". This may cause collisions in the cache.
Currently CurlDownloadStrategy and its descendants handles this by
extracting the basename form the URL and using that as the cached
filename. However, other strategies simply raise an exception.
We can improve the other strategies by URL-encoding the URL string and
using that as the cached directory name.
Note that this happens very rarely, especially now that resources (which
always have a name) are preferred to subformulae. The most common case
is a subformula that specifies a head download.
ClosesHomebrew/homebrew#22949.
