<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> 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. </para> <para> 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> <refentrytitle>dyld</refentrytitle> <manvolnum>1</manvolnum></citerefentry> manpage. </para> <programlisting> dyld: Library not loaded: /nix/store/7hnmbscpayxzxrixrgxvvlifzlxdsdir-jq-1.5-lib/lib/libjq.1.dylib Referenced from: /private/tmp/nix-build-jq-1.5.drv-0/jq-1.5/tests/../jq Reason: image not found ./tests/jqtest: line 5: 75779 Abort trap: 6 </programlisting> <programlisting> stdenv.mkDerivation { name = "libfoo-1.2.3"; # ... doInstallCheck = true; installCheckTarget = "check"; } </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, this replacement is not 100% compatible with Xcode and can occasionally cause issues. </para> </listitem> </itemizedlist> </section> </chapter>