nixpkgs/doc/platform-notes.xml
2017-11-01 18:08:19 +01:00

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<chapter xmlns="http://docbook.org/ns/docbook"
xmlns:xlink="http://www.w3.org/1999/xlink"
xml:id="chap-platform-nodes">
<title>Platform Notes</title>
<section xml:id="sec-darwin">
<title>Darwin (macOS)</title>
<para>Some common issues when packaging software for darwin:</para>
<itemizedlist>
<listitem>
<para>
The darwin <literal>stdenv</literal> uses clang instead of gcc.
When referring to the compiler <varname>$CC</varname> or <command>cc</command>
will work in both cases. Some builds hardcode gcc/g++ in their
build scripts, that can usually be fixed with using something
like <literal>makeFlags = [ "CC=cc" ];</literal> or by patching
the build scripts.
</para>
<programlisting>
stdenv.mkDerivation {
name = "libfoo-1.2.3";
# ...
buildPhase = ''
$CC -o hello hello.c
'';
}
</programlisting>
</listitem>
<listitem>
<para>
On darwin libraries are linked using absolute paths, libraries
are resolved by their <literal>install_name</literal> at link
time. Sometimes packages won't set this correctly causing the
library lookups to fail at runtime. This can be fixed by adding
extra linker flags or by running <command>install_name_tool -id</command>
during the <function>fixupPhase</function>.
</para>
<programlisting>
stdenv.mkDerivation {
name = "libfoo-1.2.3";
# ...
makeFlags = stdenv.lib.optional stdenv.isDarwin "LDFLAGS=-Wl,-install_name,$(out)/lib/libfoo.dylib";
}
</programlisting>
</listitem>
<listitem>
<para>
Some packages assume xcode is available and use <command>xcrun</command>
to resolve build tools like <command>clang</command>, etc.
This causes errors like <code>xcode-select: error: no developer tools were found at '/Applications/Xcode.app'</code>
while the build doesn't actually depend on xcode.
</para>
<programlisting>
stdenv.mkDerivation {
name = "libfoo-1.2.3";
# ...
prePatch = ''
substituteInPlace Makefile \
--replace '/usr/bin/xcrun clang' clang
'';
}
</programlisting>
<para>
The package <literal>xcbuild</literal> can be used to build projects
that really depend on Xcode, however projects that build some kind of
graphical interface won't work without using Xcode in an impure way.
</para>
</listitem>
</itemizedlist>
</section>
</chapter>