Zig selects musl toolchain by default on riscv64

[hack3ric]

Zig Version

0.10.1

Steps to Reproduce and Observed Behavior

I am packaging Zig on Arch Linux riscv64. Since there's no LLVM 16 in Arch right now, we have to stick to v0.10.1.

On x86_64 the build script works just fine and produces x86_64-linux-gnu Zig. On riscv64 I switched CC and CXX to clang (since GCC segfaults/overflows, seems to relate to #3275), and it complains about redeclaration from musl:

[100%] Building stage3
error(compilation): clang failed with stderr: In file included from /build/zig/src/zig-0.10.1/lib/libcxx/src/strstream.cpp:15:
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/include/strstream:134:
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/include/istream:165:
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/include/ostream:169:
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/include/ios:221:
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/include/__locale:44:
/build/zig/src/zig-0.10.1/lib/libcxx/include/__support/musl/xlocale.h:27:8: error: cannot add 'abi_tag' attribute in a redeclaration
/build/zig/src/zig-0.10.1/lib/libcxx/include/__config:634:26: note: expanded from macro '_LIBCPP_HIDE_FROM_ABI'
/usr/include/stdlib.h:285:22: note: previous declaration is here
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/src/strstream.cpp:15:
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/include/strstream:134:
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/include/istream:165:
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/include/ostream:169:
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/include/ios:221:
In file included from /build/zig/src/zig-0.10.1/lib/libcxx/include/__locale:44:
/build/zig/src/zig-0.10.1/lib/libcxx/include/__support/musl/xlocale.h:32:8: error: cannot add 'abi_tag' attribute in a redeclaration
/build/zig/src/zig-0.10.1/lib/libcxx/include/__config:634:26: note: expanded from macro '_LIBCPP_HIDE_FROM_ABI'
/usr/include/stdlib.h:291:31: note: previous declaration is here
...

When I specified -DZIG_TARGET_TRIPLE=native-native-gnu, CMake complains about missing Clang:

-- Configuring zig version 0.10.1
-- Could NOT find clang (missing: CLANG_LIBRARIES) (Required is at least version "15")
-- Configuring done (0.5s)
CMake Error: The following variables are used in this project, but they are set to NOTFOUND.
Please set them or make sure they are set and tested correctly in the CMake files:
LLVM_LLVMAARCH64ASMPARSER_LIB
    linked by target "zigcpp" in directory /home/hacker/archrv/zig/repos/community-x86_64/src/zig-0.10.1
LLVM_LLVMAARCH64CODEGEN_LIB
    linked by target "zigcpp" in directory /home/hacker/archrv/zig/repos/community-x86_64/src/zig-0.10.1
LLVM_LLVMAARCH64DESC_LIB
    linked by target "zigcpp" in directory /home/hacker/archrv/zig/repos/community-x86_64/src/zig-0.10.1
LLVM_LLVMAARCH64DISASSEMBLER_LIB
    linked by target "zigcpp" in directory /home/hacker/archrv/zig/repos/community-x86_64/src/zig-0.10.1
...

Expected Behavior

Use riscv64-linux-gnu toolchain on riscv64 by default (?), or have a way to correctly specify it

[kassane]

Ref: ziglang/zig-bootstrap#115

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Edit

Zig 0.10.x use LLVM 15, not 16 (master only)