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1<chapter xmlns="http://docbook.org/ns/docbook"
2 xmlns:xlink="http://www.w3.org/1999/xlink"
3 xml:id="chap-platform-nodes">
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
16 referring to the compiler <varname>$CC</varname> or <command>cc</command>
17 will work in both cases. Some builds hardcode gcc/g++ in their build
18 scripts, that can usually be fixed with using something like
19 <literal>makeFlags = [ "CC=cc" ];</literal> or by patching the build
20 scripts.
21 </para>
22<programlisting>
23 stdenv.mkDerivation {
24 name = "libfoo-1.2.3";
25 # ...
26 buildPhase = ''
27 $CC -o hello hello.c
28 '';
29 }
30 </programlisting>
31 </listitem>
32 <listitem>
33 <para>
34 On darwin libraries are linked using absolute paths, libraries are
35 resolved by their <literal>install_name</literal> at link time. Sometimes
36 packages won't set this correctly causing the library lookups to fail at
37 runtime. This can be fixed by adding extra linker flags or by running
38 <command>install_name_tool -id</command> during the
39 <function>fixupPhase</function>.
40 </para>
41<programlisting>
42 stdenv.mkDerivation {
43 name = "libfoo-1.2.3";
44 # ...
45 makeFlags = stdenv.lib.optional stdenv.isDarwin "LDFLAGS=-Wl,-install_name,$(out)/lib/libfoo.dylib";
46 }
47 </programlisting>
48 </listitem>
49 <listitem>
50 <para>
51 Even if the libraries are linked using absolute paths and resolved via
52 their <literal>install_name</literal> correctly, tests can sometimes fail
53 to run binaries. This happens because the <varname>checkPhase</varname>
54 runs before the libraries are installed.
55 </para>
56 <para>
57 This can usually be solved by running the tests after the
58 <varname>installPhase</varname> or alternatively by using
59 <varname>DYLD_LIBRARY_PATH</varname>. More information about this variable
60 can be found in the <citerefentry>
61 <refentrytitle>dyld</refentrytitle>
62 <manvolnum>1</manvolnum></citerefentry> manpage.
63 </para>
64<programlisting>
65 dyld: Library not loaded: /nix/store/7hnmbscpayxzxrixrgxvvlifzlxdsdir-jq-1.5-lib/lib/libjq.1.dylib
66 Referenced from: /private/tmp/nix-build-jq-1.5.drv-0/jq-1.5/tests/../jq
67 Reason: image not found
68 ./tests/jqtest: line 5: 75779 Abort trap: 6
69 </programlisting>
70<programlisting>
71 stdenv.mkDerivation {
72 name = "libfoo-1.2.3";
73 # ...
74 doInstallCheck = true;
75 installCheckTarget = "check";
76 }
77 </programlisting>
78 </listitem>
79 <listitem>
80 <para>
81 Some packages assume xcode is available and use <command>xcrun</command>
82 to resolve build tools like <command>clang</command>, etc. This causes
83 errors like <code>xcode-select: error: no developer tools were found at
84 '/Applications/Xcode.app'</code> while the build doesn't actually depend
85 on xcode.
86 </para>
87<programlisting>
88 stdenv.mkDerivation {
89 name = "libfoo-1.2.3";
90 # ...
91 prePatch = ''
92 substituteInPlace Makefile \
93 --replace '/usr/bin/xcrun clang' clang
94 '';
95 }
96 </programlisting>
97 <para>
98 The package <literal>xcbuild</literal> can be used to build projects that
99 really depend on Xcode, however projects that build some kind of graphical
100 interface won't work without using Xcode in an impure way.
101 </para>
102 </listitem>
103 </itemizedlist>
104 </section>
105</chapter>