libcxx @5.0.1 does not build on PPC

[barracuda156]

Trying to build with sudo port -v install libcxx configure.compiler=macports-gcc-7 supported_archs="ppc ppc64" fails with:

g++-mp-7: error: unrecognized command line option '-stdlib=libc++'
g++-mp-7: error: unrecognized command line option '-Wmismatched-tags'
g++-mp-7: error: unrecognized command line option '-Wshorten-64-to-32'
g++-mp-7: error: unrecognized command line option '-Wnewline-eof'

I need libcxx in order to build mrustc.

[kencu (Ken)]

you cannot (easily) build libcxx with the current Portfile on 10.5 for PPC using gcc. I have done it, last time in 2018. It's a big project.

Anyway, mrustc uses LLVM to build it's code, but LLVM does not work on PPC Darwin, so lost cause until someone like Iain fixes llvm to work on PPC darwin (five years and counting :> ).

[barracuda156]

Replying to kencu:

you cannot (easily) build libcxx with the current Portfile on 10.5 for PPC using gcc. I have done it, last time in 2018. It's a big project. Anyway, mrustc uses LLVM to build it's code, but LLVM does not work on PPC Darwin, so lost cause until someone like Iain fixes llvm to work on PPC darwin (five years and counting :> ).

Our friend @catap told me that Rust may allow using gcc soon. Probably sooner than llvm is fixed anyway )

Have you retained your custom port file for libcxx? I won’t request you to waste time on explaining that step by step to me, but if I have your old WIP, I can probably make it.

[evanmiller (Evan Miller)]

mrustc does not require LLVM directly. It only uses LLVM in order to bootstrap a real Rust, i.e. compile rustc.

I was able to build mrustc on Tiger/PPC without libcxx. However, the compiler hangs on any input due to the exception-handling bug described in ​https://github.com/iains/darwin-toolchains-start-here/discussions/17

[kencu (Ken)]

Hey, you're right. There is a gcc backend for rust. After that comment I went looking, never imagining such a thing might exist:

​https://github.com/rust-lang/rustc_codegen_gcc

Well now -- with mrustc not needing llvm, and a gcc backend for rust, having rust on other architectures, like PPC Darwin, suddenly seems not necessarily impossible someday.

[kencu (Ken)]

libcxx is not supported on PPC in MacPorts at present at least