Failed to build on Macbook M1

[trangnv]

Hi there, I'm trying to cargo build with cxx as dependencies

[dependencies]
cxx = "1.0.94"

But facing error: error: failed to run custom build command for cxx v1.0.94`

error occurred: Command "c++" "-O3" "-ffunction-sections" "-fdata-sections" "-fPIC" "-arch" "arm64" "-Wall" "-Wextra" "-o" "/Users/nvtrang/code/starknet/cxx/target/release/build/cxx-090a4ae2985bda90/out/src/cxx.o" "-c" "src/cxx.cc" with args "c++" did not execute successfully (status code exit status: 1).

I have these Homebrew Fomulae:

==> Formulae
autoconf        freetype        glib            libpng          libxdmcp        lzo             openssl@3       [email protected]     tcl-tk          zstd
ca-certificates gdbm            gmp             libtiff         libxext         m4              pcre2           [email protected]      tree
cmake           gettext         graphite2       libx11          libxrender      make            pixman          readline        xorgproto
coreutils       giflib          icu4c           libxau          little-cms2     mpdecimal       pkg-config      six             xz
fontconfig      git-lfs         jpeg-turbo      libxcb          lz4             [email protected]     protobuf        sqlite          z3

==> Casks
raycast temurin

I appreciate any help. Thank you

[schreter]

There must be more error output somewhere. This just tells you it failed.

Anyway, I use Xcode command line tools, which provide clang, and it works just fine on M1 Mac.

[Vany]

running: "c++" "-O0" "-ffunction-sections" "-fdata-sections" "-fPIC" "-gdwarf-2" "-fno-omit-frame-pointer" "-arch" "arm64" "-Wall" "-Wextra" "-o" "/Users/vany/b/unpack/target/debug/build/cxx-e088f39d86964a61/out/src/cxx.o" "-c" "src/cxx.cc"
  cargo:warning=In file included from src/cxx.cc:1:
  cargo:warning=src/../include/cxx.h:24:1: warning: inline namespaces are a C++11 feature [-Wc++11-inline-namespace]
  cargo:warning=inline namespace cxxbridge1 {
  cargo:warning=^
  cargo:warning=src/../include/cxx.h:36:14: warning: 'final' keyword is a C++11 extension [-Wc++11-extensions]
  cargo:warning=class String final {
  cargo:warning=             ^
  cargo:warning=src/../include/cxx.h:38:11: error: expected ';' at end of declaration list
  cargo:warning=  String() noexcept;
  cargo:warning=          ^
  cargo:warning=          ;

unpack$c++ --version
Apple clang version 14.0.3 (clang-1403.0.22.14.1)
Target: arm64-apple-darwin22.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

!!! export CXXFLAGS="c++11" helps ... but why?

[Vany]

may be this will help https://developer.apple.com/documentation/xcode-release-notes/xcode-14-release-notes

[cschwan]

We experience the same problem (see the link above this comment). It seems that c++ is called without the -std=c++11 flag, although it should be.

[mbrobbel]

You can add: https://github.com/dtolnay/cxx/blob/c96397721c2fd61b0809ca4c38d9c5ef9008b25a/gen/build/src/lib.rs#L134

[cschwan]

This flag is already present in all crates that I control. Also notice that the compiler error appears when compiling src/cxx.cc, which is coming from one of the cxx crates. Where is this file compiled? I believe - I might be wrong though - there's a problem.

Another observation: I've only encountered this for

 $ c++ --version
Apple clang version 14.0.3 (clang-1403.0.22.14.1)
Target: arm64-apple-darwin22.5.0
Thread model: posix
InstalledDir: /Library/Developer/CommandLineTools/usr/bin

which is the same platform reported in https://github.com/dtolnay/cxx/issues/1217#issuecomment-1607779334. On my desktop PC with a GCC compiler the -std=c++11 switch is present when compiling src/cxx.cc.

[cschwan]

I now believe this to be a problem in cc, specifically this one: https://github.com/rust-lang/cc-rs/issues/730. This Issue is then probably a duplicate of https://github.com/dtolnay/cxx/issues/952.

Since both Issues have been marked 'fixed', but the newest release of cc, in which the fixes are included, has been yanked I see two possibilities:

1. wait for cc to release a newer version. In that case I would appreciate keeping this Issue open to let users know this is a problem and to avoid duplicate Issues
2. set the C++ standard using the newly introduced cc::Build::std() method instead of using cc::Build::is_flag_supported() here: https://github.com/dtolnay/cxx/blob/dbd370482772df3bc5de18de4fd949c3a78bf279/build.rs#L9-L15 However, I haven't had a look a the std method implementation. It's possible it uses is_flag_supported internally at some point and therefore suffers from the same problem. On the other hand, in the long run it's probably best to avoid duplicating the set-the-C++-standard logic in this crate (although technically it was duplicated in cc, I guess). If this is the desired solution, I can volunteer to write a pull request.

[cschwan]

With https://github.com/rust-lang/cc-rs/issues/730 being merged I believe this no longer to be a problem. Moreover #1321 and #1322 being merged implements what I suggested in my last comment.

I think this Issue can be closed.

[dtolnay]

Thank you!