nixpkgs manual: move stdenv chapters into one folder

2019-10-30 11:17:14 +01:00
parent ddbf4c1bac
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+<chapter xmlns="http://docbook.org/ns/docbook"
+         xmlns:xlink="http://www.w3.org/1999/xlink"
+         xml:id="chap-platform-notes">
+ <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>