62 lines
2.5 KiB
Markdown
62 lines
2.5 KiB
Markdown
# Platform Notes {#chap-platform-notes}
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## Darwin (macOS) {#sec-darwin}
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Some common issues when packaging software for Darwin:
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- The Darwin `stdenv` uses clang instead of gcc. When referring to the compiler `$CC` or `cc` will work in both cases. Some builds hardcode gcc/g++ in their build scripts, that can usually be fixed with using something like `makeFlags = [ "CC=cc" ];` or by patching the build scripts.
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```nix
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stdenv.mkDerivation {
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name = "libfoo-1.2.3";
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# ...
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buildPhase = ''
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$CC -o hello hello.c
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'';
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}
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```
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- On Darwin, libraries are linked using absolute paths, libraries are resolved by their `install_name` 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 `install_name_tool -id` during the `fixupPhase`.
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```nix
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stdenv.mkDerivation {
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name = "libfoo-1.2.3";
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# ...
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makeFlags = lib.optional stdenv.isDarwin "LDFLAGS=-Wl,-install_name,$(out)/lib/libfoo.dylib";
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}
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```
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- Even if the libraries are linked using absolute paths and resolved via their `install_name` correctly, tests can sometimes fail to run binaries. This happens because the `checkPhase` runs before the libraries are installed.
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This can usually be solved by running the tests after the `installPhase` or alternatively by using `DYLD_LIBRARY_PATH`. More information about this variable can be found in the *dyld(1)* manpage.
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```
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dyld: Library not loaded: /nix/store/7hnmbscpayxzxrixrgxvvlifzlxdsdir-jq-1.5-lib/lib/libjq.1.dylib
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Referenced from: /private/tmp/nix-build-jq-1.5.drv-0/jq-1.5/tests/../jq
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Reason: image not found
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./tests/jqtest: line 5: 75779 Abort trap: 6
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```
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```nix
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stdenv.mkDerivation {
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name = "libfoo-1.2.3";
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# ...
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doInstallCheck = true;
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installCheckTarget = "check";
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}
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```
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- Some packages assume xcode is available and use `xcrun` to resolve build tools like `clang`, etc. This causes errors like `xcode-select: error: no developer tools were found at '/Applications/Xcode.app'` while the build doesn’t actually depend on xcode.
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```nix
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stdenv.mkDerivation {
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name = "libfoo-1.2.3";
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# ...
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prePatch = ''
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substituteInPlace Makefile \
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--replace '/usr/bin/xcrun clang' clang
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'';
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}
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```
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The package `xcbuild` 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.
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