tjh.dev
1<chapter xmlns="http://docbook.org/ns/docbook"
2 xmlns:xlink="http://www.w3.org/1999/xlink"
3 xml:id="chap-platform-notes">
4 <title>Platform Notes</title>
5 <section xml:id="sec-darwin">
6 <title>Darwin (macOS)</title>
7
8 <para>
9 Some common issues when packaging software for Darwin:
10 </para>
11
12 <itemizedlist>
13 <listitem>
14 <para>
15 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.
16 </para>
17<programlisting>
18stdenv.mkDerivation {
19 name = "libfoo-1.2.3";
20 # ...
21 buildPhase = ''
22 $CC -o hello hello.c
23 '';
24}
25</programlisting>
26 </listitem>
27 <listitem>
28 <para>
29 On Darwin, libraries are linked using absolute paths, libraries are resolved by their <literal>install_name</literal> at link time. Sometimes packages won't set this correctly causing the library lookups to fail at runtime. This can be fixed by adding extra linker flags or by running <command>install_name_tool -id</command> during the <function>fixupPhase</function>.
30 </para>
31<programlisting>
32stdenv.mkDerivation {
33 name = "libfoo-1.2.3";
34 # ...
35 makeFlags = stdenv.lib.optional stdenv.isDarwin "LDFLAGS=-Wl,-install_name,$(out)/lib/libfoo.dylib";
36}
37</programlisting>
38 </listitem>
39 <listitem>
40 <para>
41 Even if the libraries are linked using absolute paths and resolved via their <literal>install_name</literal> correctly, tests can sometimes fail to run binaries. This happens because the <varname>checkPhase</varname> runs before the libraries are installed.
42 </para>
43 <para>
44 This can usually be solved by running the tests after the <varname>installPhase</varname> or alternatively by using <varname>DYLD_LIBRARY_PATH</varname>. More information about this variable can be found in the <citerefentry>
45 <refentrytitle>dyld</refentrytitle>
46 <manvolnum>1</manvolnum></citerefentry> manpage.
47 </para>
48<programlisting>
49dyld: Library not loaded: /nix/store/7hnmbscpayxzxrixrgxvvlifzlxdsdir-jq-1.5-lib/lib/libjq.1.dylib
50Referenced from: /private/tmp/nix-build-jq-1.5.drv-0/jq-1.5/tests/../jq
51Reason: image not found
52./tests/jqtest: line 5: 75779 Abort trap: 6
53</programlisting>
54<programlisting>
55stdenv.mkDerivation {
56 name = "libfoo-1.2.3";
57 # ...
58 doInstallCheck = true;
59 installCheckTarget = "check";
60}
61</programlisting>
62 </listitem>
63 <listitem>
64 <para>
65 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.
66 </para>
67<programlisting>
68stdenv.mkDerivation {
69 name = "libfoo-1.2.3";
70 # ...
71 prePatch = ''
72 substituteInPlace Makefile \
73 --replace '/usr/bin/xcrun clang' clang
74 '';
75}
76</programlisting>
77 <para>
78 The package <literal>xcbuild</literal> can be used to build projects that really depend on Xcode. However, this replacement is not 100% compatible with Xcode and can occasionally cause issues.
79 </para>
80 </listitem>
81 </itemizedlist>
82 </section>
83</chapter>