darwin's stdenv bootstrap tools ship a broken libiconv.dylib

[veprbl]

Follow up on #158328

Steps to reproduce

nix-build pkgs/stdenv/darwin/make-bootstrap-tools.nix -A test

clang -idirafter /nix/store/widcf6mipqv5hazgwawj5hhj5xpykgmv-unpack/include-Libsystem --sysroot=/nix/store/widcf6mipqv5hazgwawj5hhj5xpykgmv-unpack -L/nix/store/widcf6mipqv5hazgwawj5hhj5xpykgmv-unpack/lib -L/private/tmp/nix-build-test.drv-0/libSystem-boot -Wl,-rpath,/nix/store/widcf6mipqv5hazgwawj5hhj5xpykgmv-unpack/lib -Wl,-v  -g -O2   -o hello src/hello.o  ./lib/libhello.a 
@(#)PROGRAM:ld  PROJECT:ld64-530
BUILD 03:37:00 Jan 17 2022
configured to support archs: armv6 armv7 armv7s arm64 arm64e arm64_32 i386 x86_64 x86_64h armv6m armv7k armv7m armv7em (tvOS)
Library search paths:
        /nix/store/widcf6mipqv5hazgwawj5hhj5xpykgmv-unpack/lib
        /private/tmp/nix-build-test.drv-0/libSystem-boot
Framework search paths:
Undefined symbols for architecture x86_64:
  "_iconv", referenced from:
      _mem_cd_iconv in libhello.a(striconv.o)
      _str_cd_iconv in libhello.a(striconv.o)
     (maybe you meant: _str_cd_iconv, _mem_cd_iconv , _xstr_cd_iconv , _xstr_iconv , _str_iconv , _xmem_cd_iconv )
  "_iconv_close", referenced from:
      _str_iconv in libhello.a(striconv.o)
  "_iconv_open", referenced from:
      _str_iconv in libhello.a(striconv.o)
ld: symbol(s) not found for architecture x86_64
clang-11: error: linker command failed with exit code 1 (use -v to see invocation)
make[2]: *** [Makefile:2173: hello] Error 1
make[2]: Leaving directory '/private/tmp/nix-build-test.drv-0/hello-2.12'
make[1]: *** [Makefile:2496: all-recursive] Error 1
make[1]: Leaving directory '/private/tmp/nix-build-test.drv-0/hello-2.12'
make: *** [Makefile:1899: all] Error 2

Problem

The library itself doesn't contain any symbols:

nm $(nix-build pkgs/stdenv/darwin/make-bootstrap-tools.nix -A build --no-out-link)/pack/lib/libiconv.dylib
0000000000000fb0 T _dont_use_this
                 U dyld_stub_binder

It seems to rely on LC_REEXPORT_DYLIB to link to the two other libraries:

otool -l $(nix-build pkgs/stdenv/darwin/make-bootstrap-tools.nix -A build --no-out-link)/pack/lib/libiconv.dylib | grep -A6 LC_REEXPORT_DYLIB
          cmd LC_REEXPORT_DYLIB
      cmdsize 56
         name @rpath/libiconv-nocharset.dylib (offset 24)
   time stamp 2 Wed Dec 31 19:00:02 1969
      current version 7.0.0
compatibility version 7.0.0
Load command 9
          cmd LC_REEXPORT_DYLIB
      cmdsize 56
         name @rpath/libcharset.1.dylib (offset 24)
   time stamp 2 Wed Dec 31 19:00:02 1969
      current version 2.0.0
compatibility version 2.0.0
Load command 10

However the RPATH is not set for the library (the store path can not be known in advance). But set during the test:

nixpkgs/pkgs/stdenv/darwin/make-bootstrap-tools.nix

Line 332 in 598c791

export CC="clang $flags -Wl,-rpath,${unpack}/lib -Wl,-v -Wl,-sdk_version,10.10"

Perhaps this should use @origin (but would that work for linking libhello?). And/or it could be that we can get rid of libiconv from the tools.

The normal version just uses full paths:

otool -l $(nix-build -A darwin.libiconv --no-out-link)/lib/libiconv.dylib | grep -A6 LC_REEXPORT_DYLIB
          cmd LC_REEXPORT_DYLIB
      cmdsize 112
         name /nix/store/cp7cr0c6q5cl4zxmpv21xzpaj131q9n8-libiconv-50/lib/libiconv-nocharset.dylib (offset 24)
   time stamp 2 Wed Dec 31 19:00:02 1969
      current version 7.0.0
compatibility version 7.0.0
Load command 9
          cmd LC_REEXPORT_DYLIB
      cmdsize 104
         name /nix/store/cp7cr0c6q5cl4zxmpv21xzpaj131q9n8-libiconv-50/lib/libcharset.1.dylib (offset 24)
   time stamp 2 Wed Dec 31 19:00:02 1969
      current version 2.0.0
compatibility version 2.0.0
Load command 10

[zowoq]

Opened a PR with a workaround in the bootstrap tools build for now so this doesn't happen the next time someone bumps hello: #158517

[reckenrode]

Is this resolved by #302387?

[ghost]

yes. i'd close the issue but do not have the necessary permissions.