macOS: Library not loaded: @rpath/libwatcher-c.0.dylib, Reason: no LC_RPATH's found

[dunglas]

After installing the library on macOS following these instructions, I get the following error:

dyld[10323]: Library not loaded: @rpath/libwatcher-c.0.dylib
  Referenced from: <8785CF2B-926F-3E20-D16E-76B30E23CA2D> /private/var/folders/nf/_zwcfbtx7m9d5g8jgympqy5r0000gn/T/go-build49046516/b237/frankenphp.test
  Reason: no LC_RPATH's found
signal: abort trap
FAIL	github.com/dunglas/frankenphp/internal/watcher	0.189s

It looks like it can be fixed in the cmake definition: https://discourse.cmake.org/t/how-to-get-an-lc-rpath-and-rpath-prefix-on-a-dylib-on-macos/5540/4

[dunglas]

I'm loading the library from Go using cgo.

I fixed this by passing an explicit rpath to the linker by using the env var CGO_LDFLAGS with the following value: -lwatcher-c -lstdc++ -Wl,-rpath /usr/local/lib

[e-dant]

I think we can fix this -- I'll try to get on it today

[e-dant]

Does the next branch work ok now?

[e-dant]

Looking at this more closely, I think the issue might also involve cgo itself not adding the appropriate rpath.

libwatcher-c also probably might need an rpath on Apple to properly load libc++, but I think cgo needs to add an rpath to find libwatcher-c

[e-dant]

I ran otool on the libcwatcher on the next branch.

There's no LC_RPATH in there...

I don't know much about the linker, or linking shenanigans.

I'm not sure

• if our CMake file's rpath handling is broken or
• if libraries aren't candidates for having an LC_RPATH
• if the rpath is being replaced with /what/we/set instead of an LC_RPATH being written (/usr/local/lib is used where I think I would expect an rpath?)

$ cmake -S . -B out/tmp -G 'Unix Makefiles' -DBUILD_LIB=ON -DBUILD_BIN=ON -DBUILD_HDR=ON -DBUILD_TESTING=OFF -DBUILD_SAN=OFF && cmake --build out/tmp
$ otool -l out/tmp/libwatcher-c.0.13.1.dylib
out/tmp/libwatcher-c.0.13.1.dylib:
Load command 0
      cmd LC_SEGMENT_64
  cmdsize 472
  segname __TEXT
   vmaddr 0x0000000000000000
   vmsize 0x0000000000008000
  fileoff 0
 filesize 32768
  maxprot 0x00000005
 initprot 0x00000005
   nsects 5
    flags 0x0
Section
  sectname __text
   segname __TEXT
      addr 0x000000000000498c
      size 0x000000000000331c
    offset 18828
     align 2^2 (4)
    reloff 0
    nreloc 0
     flags 0x80000400
 reserved1 0
 reserved2 0
Section
  sectname __stubs
   segname __TEXT
      addr 0x0000000000007ca8
      size 0x0000000000000288
    offset 31912
     align 2^2 (4)
    reloff 0
    nreloc 0
     flags 0x80000408
 reserved1 0 (index into indirect symbol table)
 reserved2 12 (size of stubs)
Section
  sectname __const
   segname __TEXT
      addr 0x0000000000007f30
      size 0x0000000000000020
    offset 32560
     align 2^4 (16)
    reloff 0
    nreloc 0
     flags 0x00000000
 reserved1 0
 reserved2 0
Section
  sectname __cstring
   segname __TEXT
      addr 0x0000000000007f50
      size 0x000000000000004c
    offset 32592
     align 2^0 (1)
    reloff 0
    nreloc 0
     flags 0x00000002
 reserved1 0
 reserved2 0
Section
  sectname __unwind_info
   segname __TEXT
      addr 0x0000000000007f9c
      size 0x0000000000000058
    offset 32668
     align 2^2 (4)
    reloff 0
    nreloc 0
     flags 0x00000000
 reserved1 0
 reserved2 0
Load command 1
      cmd LC_SEGMENT_64
  cmdsize 232
  segname __DATA_CONST
   vmaddr 0x0000000000008000
   vmsize 0x0000000000004000
  fileoff 32768
 filesize 16384
  maxprot 0x00000003
 initprot 0x00000003
   nsects 2
    flags 0x10
Section
  sectname __got
   segname __DATA_CONST
      addr 0x0000000000008000
      size 0x00000000000001c8
    offset 32768
     align 2^3 (8)
    reloff 0
    nreloc 0
     flags 0x00000006
 reserved1 54 (index into indirect symbol table)
 reserved2 0
Section
  sectname __const
   segname __DATA_CONST
      addr 0x00000000000081c8
      size 0x00000000000000a8
    offset 33224
     align 2^3 (8)
    reloff 0
    nreloc 0
     flags 0x00000000
 reserved1 0
 reserved2 0
Load command 2
      cmd LC_SEGMENT_64
  cmdsize 152
  segname __DATA
   vmaddr 0x000000000000c000
   vmsize 0x0000000000004000
  fileoff 0
 filesize 0
  maxprot 0x00000003
 initprot 0x00000003
   nsects 1
    flags 0x0
Section
  sectname __bss
   segname __DATA
      addr 0x000000000000c000
      size 0x0000000000000040
    offset 0
     align 2^3 (8)
    reloff 0
    nreloc 0
     flags 0x00000001
 reserved1 0
 reserved2 0
Load command 3
      cmd LC_SEGMENT_64
  cmdsize 72
  segname __LINKEDIT
   vmaddr 0x0000000000010000
   vmsize 0x0000000000004000
  fileoff 49152
 filesize 11800
  maxprot 0x00000001
 initprot 0x00000001
   nsects 0
    flags 0x0
Load command 4
          cmd LC_ID_DYLIB
      cmdsize 56
         name @rpath/libwatcher-c.0.dylib (offset 24)
   time stamp 1 Wed Dec 31 19:00:01 1969
      current version 0.13.1
compatibility version 0.0.0
Load command 5
      cmd LC_DYLD_CHAINED_FIXUPS
  cmdsize 16
  dataoff 49152
 datasize 2032
Load command 6
      cmd LC_DYLD_EXPORTS_TRIE
  cmdsize 16
  dataoff 51184
 datasize 48
Load command 7
     cmd LC_SYMTAB
 cmdsize 24
  symoff 51304
   nsyms 99
  stroff 53336
 strsize 6992
Load command 8
            cmd LC_DYSYMTAB
        cmdsize 80
      ilocalsym 0
      nlocalsym 40
     iextdefsym 40
     nextdefsym 2
      iundefsym 42
      nundefsym 57
         tocoff 0
           ntoc 0
      modtaboff 0
        nmodtab 0
   extrefsymoff 0
    nextrefsyms 0
 indirectsymoff 52888
  nindirectsyms 111
      extreloff 0
        nextrel 0
      locreloff 0
        nlocrel 0
Load command 9
     cmd LC_UUID
 cmdsize 24
    uuid 6A0D237A-B2E2-3831-9210-54291330E6A9
Load command 10
      cmd LC_BUILD_VERSION
  cmdsize 32
 platform 1
    minos 15.0
      sdk 15.0
   ntools 1
     tool 3
  version 1115.7.3
Load command 11
      cmd LC_SOURCE_VERSION
  cmdsize 16
  version 0.0
Load command 12
          cmd LC_LOAD_DYLIB
      cmdsize 104
         name /System/Library/Frameworks/CoreFoundation.framework/Versions/A/CoreFoundation (offset 24)
   time stamp 2 Wed Dec 31 19:00:02 1969
      current version 3038.1.255
compatibility version 150.0.0
Load command 13
          cmd LC_LOAD_DYLIB
      cmdsize 104
         name /System/Library/Frameworks/CoreServices.framework/Versions/A/CoreServices (offset 24)
   time stamp 2 Wed Dec 31 19:00:02 1969
      current version 1226.0.0
compatibility version 1.0.0
Load command 14
          cmd LC_LOAD_DYLIB
      cmdsize 48
         name /usr/lib/libc++.1.dylib (offset 24)
   time stamp 2 Wed Dec 31 19:00:02 1969
      current version 1800.101.0
compatibility version 1.0.0
Load command 15
          cmd LC_LOAD_DYLIB
      cmdsize 56
         name /usr/lib/libSystem.B.dylib (offset 24)
   time stamp 2 Wed Dec 31 19:00:02 1969
      current version 1351.0.0
compatibility version 1.0.0
Load command 16
      cmd LC_FUNCTION_STARTS
  cmdsize 16
  dataoff 51232
 datasize 72
Load command 17
      cmd LC_DATA_IN_CODE
  cmdsize 16
  dataoff 51304
 datasize 0
Load command 18
      cmd LC_CODE_SIGNATURE
  cmdsize 16
  dataoff 60336
 datasize 616

[dunglas]

Maybe this SO answer can help: https://stackoverflow.com/a/71321163/1352334

[e-dant]

I think the current state of the next branch might be ok. AFAICT:

• The libc++ that libwatcher-c wants doesn't load with an RPATH. I don't know if this is undesirable or not.
• Any (Apple) binaries that link to libwatcher-c need an rpath (to where libwatcher-c lives: /usr/local/lib on macOS)

[e-dant]

• The libc++ that libwatcher-c wants doesn't load with an RPATH. I don't know if this is undesirable or not.

(IOW, I don't know if we need an LC_RPATH in the library, since it seems unused)