LinkLibCpp failed for armv7a android target even after libc file is set

[hammerfunctor]

Zig Version

0.12.0-dev.1849+bb0f7d55e

Steps to Reproduce and Observed Behavior

build.zig:

const builtin = @import("builtin");
const std = @import("std");

pub fn build(b: *std.build.Builder) void {
    const target = b.standardTargetOptions(.{});
    const optimize = b.standardOptimizeOption(.{});

    const exe = b.addExecutable(.{
        .name = "cpp-hello",
        .root_source_file = .{ .path = "hello.cpp" },
        .target = target,
        .optimize = optimize,
    });

    exe.target = std.zig.CrossTarget{
        .cpu_arch = .arm,
        .os_tag = .linux,
        .abi = .android,
        .cpu_model = .baseline,
        .cpu_features_add = std.Target.arm.featureSet(&.{.v7a}),
    };

    exe.setLibCFile(.{ .path = "android-29-armeabi.conf" });
    exe.libc_file.?.addStepDependencies(&exe.step);

    exe.linkLibC();
    exe.linkLibCpp();

    // exe.linkSystemLibraryName("c");
    // exe.linkSystemLibraryName("c++");

    b.installArtifact(exe);
    const run_cmd = b.addRunArtifact(exe);
    run_cmd.step.dependOn(&exe.step);

    const run_step = b.step("run", "Run the app");
    run_step.dependOn(&run_cmd.step);
}

hello.cpp:

#include <iostream>

int main() {
    std::cout << "Hello World!\n";
    return 0;
}

android-29-armeabi.conf:

include_dir=/home/guest/AndroidSDK/ndk/25.1.8937393/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/include
sys_include_dir=/home/guest/AndroidSDK/ndk/25.1.8937393/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/include/arm-linux-androideabi
crt_dir=/home/guest/AndroidSDK/ndk/25.1.8937393/toolchains/llvm/prebuilt/linux-x86_64/sysroot/usr/lib/arm-linux-androideabi/29/
msvc_lib_dir=
kernel32_lib_dir=
gcc_dir=

Output:

zig build-exe cpp-hello Debug native: error: the following command failed with 3 compilation errors:
/home/guest/bin/share/zig-linux-x86_64-0.12.0-dev.1849+bb0f7d55e/zig build-exe /home/guest/arm32-libcxx/hello.cpp -lc++ -lc --libc /home/guest/arm32-libcxx/android-29-armeabi.conf --cache-dir /home/guest/arm32-libcxx/zig-cache --global-cache-dir /home/guest/.cache/zig --name cpp-hello -target arm-linux-android -mcpu baseline --listen=- 
Build Summary: 0/3 steps succeeded; 1 failed (disable with --summary none)
install transitive failure
└─ install cpp-hello transitive failure
   └─ zig build-exe cpp-hello Debug native 3 errors
error: unable to build libunwind: SubCompilationFailed
error: unable to build libcxx: SubCompilationFailed
error: unable to build libcxxabi: SubCompilationFailed

Output without setting libc file:

zig build-exe cpp-hello Debug native: error: the following command failed with 4 compilation errors:
/home/guest/bin/share/zig-linux-x86_64-0.12.0-dev.1849+bb0f7d55e/zig build-exe /home/guest/arm32-libcxx/hello.cpp -lc++ -lc --cache-dir /home/guest/arm32-libcxx/zig-cache --global-cache-dir /home/guest/.cache/zig --name cpp-hello -target arm-linux-android -mcpu baseline --listen=- 
Build Summary: 0/3 steps succeeded; 1 failed (disable with --summary none)
install transitive failure
└─ install cpp-hello transitive failure
   └─ zig build-exe cpp-hello Debug native 4 errors
/home/guest/bin/share/zig-linux-x86_64-0.12.0-dev.1849+bb0f7d55e/lib/libcxx/include/__config:430:14: error: 'features.h' file not found
#    include <features.h>
             ^~~~~~~~~~~~~
/home/guest/arm32-libcxx/hello.cpp:1:10: note: in file included from /home/guest/arm32-libcxx/hello.cpp:1:
#include <iostream>
         ^
/home/guest/bin/share/zig-linux-x86_64-0.12.0-dev.1849+bb0f7d55e/lib/libcxx/include/iostream:36:10: note: in file included from /home/guest/bin/share/zig-linux-x86_64-0.12.0-dev.1849+bb0f7d55e/lib/libcxx/include/iostream:36:
#include <__assert> // all public C++ headers provide the assertion handler
         ^
/home/guest/bin/share/zig-linux-x86_64-0.12.0-dev.1849+bb0f7d55e/lib/libcxx/include/__assert:13:10: note: in file included from /home/guest/bin/share/zig-linux-x86_64-0.12.0-dev.1849+bb0f7d55e/lib/libcxx/include/__assert:13:
#include <__config>
         ^
error: unable to build libunwind: SubCompilationFailed
error: unable to build libcxx: SubCompilationFailed
error: unable to build libcxxabi: SubCompilationFailed

Expected Behavior

Build

[badfishblues]

Also seeing SubCompilationFailed for a freestanding Armv7 cortex_r5f

[kassane]

Also seeing SubCompilationFailed for a freestanding Armv7 cortex_r5f

libcxx upstream - reference

• https://github.com/llvm/llvm-project/issues/78350