zig: disable libcxx hardening flags

[DDoSolitary]

The libcxxhardeningfast and libcxxhardeingextensive hardening flags introduced by #442945 add _LIBCPP_HARDENING_MODE definitions to compiler invocations, but zig already sets it automatically. This causes macro redefinition warnings (or errors if -Werror is enabled) when compiling C++ projects with zigStdenv.

https://github.com/ziglang/zig/blob/4ea472808437c932f6240c0df5e4d5912d282052/src/libs/libcxx.zig#L542-L544

Repro:

nix build -L --impure --expr 'with builtins.getFlake "git+file:///home/ddosolitary/nixpkgs"; with legacyPackages.x86_64-linux; (hello-cpp.override { stdenv = zigStdenv; }).overrideAttrs { cmakeFlags = [ "-DCMAKE_CXX_LINKER_DEPFILE_SUPPORTED=OFF" ]; env.CXXFLAGS = "-Werror"; }'

hello-cpp> Running phase: unpackPhase
hello-cpp> unpacking source archive /nix/store/icxd577v8wc16sankg0di3wg5dpa6zdq-src
hello-cpp> source root is src
hello-cpp> Running phase: patchPhase
hello-cpp> Running phase: updateAutotoolsGnuConfigScriptsPhase
hello-cpp> Running phase: configurePhase
hello-cpp> cmake flags: -GNinja -DCMAKE_FIND_USE_SYSTEM_PACKAGE_REGISTRY=OFF -DCMAKE_FIND_USE_PACKAGE_REGISTRY=OFF -DCMAKE_EXPORT_NO_PACKAGE_REGISTRY=ON -DCMAKE_BUILD_TYPE=Release -DBUILD_TESTING=OFF -DCMAKE_INSTALL_LOCALEDIR=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp/share/locale -DCMAKE_INSTALL_LIBEXECDIR=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp/libexec -DCMAKE_INSTALL_LIBDIR=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp/lib -DCMAKE_INSTALL_DOCDIR=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp/share/doc/hello-cpp -DCMAKE_INSTALL_INFODIR=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp/share/info -DCMAKE_INSTALL_MANDIR=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp/share/man -DCMAKE_INSTALL_INCLUDEDIR=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp/include -DCMAKE_INSTALL_SBINDIR=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp/sbin -DCMAKE_INSTALL_BINDIR=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp/bin -DCMAKE_INSTALL_NAME_DIR=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp/lib -DCMAKE_STRIP= -DCMAKE_RANLIB=/nix/store/yyfy4mihm2nvb3in1zw5fvjrgnwhgwkf-zig-cc-wrapper-0.15.2/bin/ranlib -DCMAKE_AR=/nix/store/yyfy4mihm2nvb3in1zw5fvjrgnwhgwkf-zig-cc-wrapper-0.15.2/bin/ar -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_INSTALL_PREFIX=/nix/store/276rwjs6xcxr2xaz8agm4mldi2ni40fl-hello-cpp -DCMAKE_CXX_LINKER_DEPFILE_SUPPORTED=OFF
hello-cpp> -- The C compiler identification is Clang 20.1.8
hello-cpp> -- The CXX compiler identification is Clang 20.1.8
hello-cpp> -- Detecting C compiler ABI info
hello-cpp> -- Detecting C compiler ABI info - done
hello-cpp> -- Check for working C compiler: /nix/store/yyfy4mihm2nvb3in1zw5fvjrgnwhgwkf-zig-cc-wrapper-0.15.2/bin/clang - skipped
hello-cpp> -- Detecting C compile features
hello-cpp> -- Detecting C compile features - done
hello-cpp> -- Detecting CXX compiler ABI info
hello-cpp> -- Detecting CXX compiler ABI info - done
hello-cpp> -- Check for working CXX compiler: /nix/store/yyfy4mihm2nvb3in1zw5fvjrgnwhgwkf-zig-cc-wrapper-0.15.2/bin/clang++ - skipped
hello-cpp> -- Detecting CXX compile features
hello-cpp> -- Detecting CXX compile features - done
hello-cpp> -- Configuring done (9.7s)
hello-cpp> -- Generating done (0.0s)
hello-cpp> CMake Warning:
hello-cpp>   Manually-specified variables were not used by the project:
hello-cpp> 
hello-cpp>     BUILD_TESTING
hello-cpp>     CMAKE_EXPORT_NO_PACKAGE_REGISTRY
hello-cpp>     CMAKE_FIND_USE_PACKAGE_REGISTRY
hello-cpp>     CMAKE_FIND_USE_SYSTEM_PACKAGE_REGISTRY
hello-cpp>     CMAKE_INSTALL_DOCDIR
hello-cpp>     CMAKE_INSTALL_INCLUDEDIR
hello-cpp>     CMAKE_INSTALL_INFODIR
hello-cpp>     CMAKE_INSTALL_LIBDIR
hello-cpp>     CMAKE_INSTALL_LIBEXECDIR
hello-cpp>     CMAKE_INSTALL_LOCALEDIR
hello-cpp>     CMAKE_INSTALL_MANDIR
hello-cpp>     CMAKE_INSTALL_SBINDIR
hello-cpp> 
hello-cpp> 
hello-cpp> -- Build files have been written to: /build/src/build
hello-cpp> cmake: enabled parallel building
hello-cpp> cmake: enabled parallel installing
hello-cpp> Running phase: buildPhase
hello-cpp> build flags: -j24
hello-cpp> [1/2] Building CXX object CMakeFiles/hello-cpp.dir/main.cpp.o
hello-cpp> FAILED: [code=1] CMakeFiles/hello-cpp.dir/main.cpp.o
hello-cpp> /nix/store/yyfy4mihm2nvb3in1zw5fvjrgnwhgwkf-zig-cc-wrapper-0.15.2/bin/clang++   -Werror -O3 -DNDEBUG -MD -MT CMakeFiles/hello-cpp.dir/main.cpp.o -MF CMakeFiles/hello-cpp.dir/main.cpp.o.d -o CMakeFiles/hello-cpp.dir/main.cpp.o -c /build/src/main.cpp
hello-cpp> In file included from <built-in>:478:
hello-cpp> <command line>:23:9: error: '_LIBCPP_HARDENING_MODE' macro redefined [-Werror,-Wmacro-redefined]
hello-cpp>    23 | #define _LIBCPP_HARDENING_MODE _LIBCPP_HARDENING_MODE_EXTENSIVE
hello-cpp>       |         ^
hello-cpp> <command line>:20:9: note: previous definition is here
hello-cpp>    20 | #define _LIBCPP_HARDENING_MODE _LIBCPP_HARDENING_MODE_NONE
hello-cpp>       |         ^
hello-cpp> 1 error generated.
hello-cpp> ninja: build stopped: subcommand failed.
error: builder for '/nix/store/si1ag79a442k2vg0615jbvfkcw8ygz2m-hello-cpp.drv' failed with exit code 1;
       last 25 log lines:
       >     CMAKE_INSTALL_INFODIR
       >     CMAKE_INSTALL_LIBDIR
       >     CMAKE_INSTALL_LIBEXECDIR
       >     CMAKE_INSTALL_LOCALEDIR
       >     CMAKE_INSTALL_MANDIR
       >     CMAKE_INSTALL_SBINDIR
       >
       > 
       > -- Build files have been written to: /build/src/build
       > cmake: enabled parallel building
       > cmake: enabled parallel installing
       > Running phase: buildPhase
       > build flags: -j24
       > [1/2] Building CXX object CMakeFiles/hello-cpp.dir/main.cpp.o
       > FAILED: [code=1] CMakeFiles/hello-cpp.dir/main.cpp.o
       > /nix/store/yyfy4mihm2nvb3in1zw5fvjrgnwhgwkf-zig-cc-wrapper-0.15.2/bin/clang++   -Werror -O3 -DNDEBUG -MD -MT CMakeFiles/hello-cpp.dir/main.cpp.o -MF CMakeFiles/hello-cpp.dir/main.cpp.o.d -o CMakeFiles/hello-cpp.dir/main.cpp.o -c /build/src/main.cpp
       > In file included from <built-in>:478:
       > <command line>:23:9: error: '_LIBCPP_HARDENING_MODE' macro redefined [-Werror,-Wmacro-redefined]
       >    23 | #define _LIBCPP_HARDENING_MODE _LIBCPP_HARDENING_MODE_EXTENSIVE
       >       |         ^
       > <command line>:20:9: note: previous definition is here
       >    20 | #define _LIBCPP_HARDENING_MODE _LIBCPP_HARDENING_MODE_NONE
       >       |         ^
       > 1 error generated.
       > ninja: build stopped: subcommand failed.
       For full logs, run 'nix log /nix/store/si1ag79a442k2vg0615jbvfkcw8ygz2m-hello-cpp.drv'.

Things done

• Built on platform:
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• Tested, as applicable:
  • NixOS tests in nixos/tests.
  • Package tests at passthru.tests.
  • Tests in lib/tests or pkgs/test for functions and "core" functionality.
• Ran nixpkgs-review on this PR. See nixpkgs-review usage.
• Tested basic functionality of all binary files, usually in ./result/bin/.
• Nixpkgs Release Notes
  • Package update: when the change is major or breaking.
• NixOS Release Notes
  • Module addition: when adding a new NixOS module.
  • Module update: when the change is significant.
• Fits CONTRIBUTING.md, pkgs/README.md, maintainers/README.md and other READMEs.

---

Add a 👍 reaction to pull requests you find important.

[RossComputerGuy]

hello-cpp-aarch64-unknown-linux-gnu> [1/2] Building CXX object CMakeFiles/hello-cpp.dir/main.cpp.o
hello-cpp-aarch64-unknown-linux-gnu> [2/2] Linking CXX executable hello-cpp
hello-cpp-aarch64-unknown-linux-gnu> FAILED: [code=1] hello-cpp
hello-cpp-aarch64-unknown-linux-gnu> : && /nix/store/2j7nd7wmmssr2x95zdvi9qi0w6aq1rd8-aarch64-unknown-linux-gnu-zig-cc-wrapper-0.15.2/bin/aarch64-unknown-linux-gnu-clang++ -O3 -DNDEBUG -Xlinker --dependency-file=CMakeFiles/hello-cpp.dir/link.d CMakeFiles/hello-cpp.dir/main.cpp.o -o hello-cpp   && :
hello-cpp-aarch64-unknown-linux-gnu> error: unsupported linker arg: --dependency-file=CMakeFiles/hello-cpp.dir/link.d
hello-cpp-aarch64-unknown-linux-gnu> ninja: build stopped: subcommand failed.

I get this when building with your PR for pkgsZig.hello-cpp.

[DDoSolitary]

@RossComputerGuy The error is irrelevant to this PR. It occurs on current nixpkgs master without this PR, and is caused by incompatibility between Zig and CMake: ziglang/zig-bootstrap#206

You can work around it as shown in my repro command: hello-cpp.overrideAttrs { cmakeFlags = [ "-DCMAKE_CXX_LINKER_DEPFILE_SUPPORTED=OFF" ]; }

[GabrielDougherty]

nixpkgs-review result

Generated using nixpkgs-review.

Command: nixpkgs-review pr 463199
Commit: a55e7e1073f0275e5e6b7b58cc28a696790ccc9d

---

aarch64-darwin

✅ 2 packages built:

• nixpkgs-manual
• zigStdenv