1

Bizarre problem, wonder if anyone else has run into this.

I'm running macOS 12 which still has system Python 2.7. However my shell starts a conda environment by default with Python 3.9.12

A few weeks ago I installed Swift 5.10 using the package installer, to run from the command line.

In Xcode 13.4.1 I use the Toolchains dialog to select Swift 5.10 Release 2024-03-04

In the shell (zsh) I invoke

export TOOLCHAINS=swift

to select the 5.10 toolchain. Swift --version shows 5.10 as expected.

FOR WEEKS I have been running swift repl and swift test from the command line,
with no problems. I frequently run swift --version to make sure I really have 5.10. No changes to OS in those weeks.

TODAY, in swift repl , I was having trouble getting the compiler to parse an expression (it says it's too complicated!), and the compiler seemed stuck for a long time, so I killed the repl session (lldb) using the Activity Monitor.

From that point forward I cannot run swift repl or lldb from the command line. The start of the long error message :

dyld[33556]: Library not loaded: @rpath/Python3.framework/Versions/3.9/Python3
  Referenced from: /Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/System/Library/PrivateFrameworks/LLDB.framework/Versions/A/LLDB
  Reason: tried: '/usr/lib/swift/Python3.framework/Versions/3.9/Python3' (no such file)

(then follows a cavalcade o' folders, various permutations of Toolchains names...)

My interpretation of this is that the lldb framework is trying to use python from a directory under /usr/lib/swift. /usr/lib/swift exists , but has old content, couple files I have no clue about :

lrwxr-xr-x  1 root  wheel       71 Oct 17  2021 libswiftCreateML.dylib -> /System/Library/Frameworks/CreateML.framework/Versions/Current/CreateML
-rwxr-xr-x  1 root  wheel  1362544 Oct 17  2021 libswiftRemoteMirror.dylib

So what gives? I deleted the toolchain directory and reinstalled Swift 5.10, no change.

My sense is that Swift no longer relies on the macOS system python (good!), but now expects a separate distribution. My system python (2.7) and conda python (3.9) should be totally irrelevant.

This makes no sense: I was running Swift 5.10 in repl mode for weeks, if it was finding python , where did the python distro go? Why did killing lldb make this go permanently awry?

Thanks in advance,
Randy

P.S. It just occurred to me that /usr/lib/ is read-only in this OS. In fact all my files in /usr/lib are dated Oct 17 2021, that must be the date I upgraded to the current macOS 12.0 . So if the swift installer expects to put anything in /usr/lib/swift, not going to happen.

2

This is what I can provide for you.

For the downloaded Swift 5.10 release toolchain

export TOOLCHAINS=swift

otool -L $(xcrun -f lldb)
/Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/usr/bin/lldb (architecture x86_64):
	@rpath/LLDB.framework/Versions/A/LLDB (compatibility version 1.0.0, current version 15.0.0)
	...

otool -l $(xcrun -f lldb)
...
Load command 21
          cmd LC_RPATH
      cmdsize 56
         path @loader_path/../../../SharedFrameworks (offset 12)
Load command 22
          cmd LC_RPATH
      cmdsize 64
         path @loader_path/../../System/Library/PrivateFrameworks (offset 12)
Load command 23
          cmd LC_RPATH
      cmdsize 64
         path @loader_path/../../Library/PrivateFrameworks (offset 12)

So it will reference this file /Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/System/Library/PrivateFrameworks/LLDB.framework/Versions/A/LLDB.

otool -L /Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/System/Library/PrivateFrameworks/LLDB.framework/Versions/A/LLDB
/Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/System/Library/PrivateFrameworks/LLDB.framework/Versions/A/LLDB (architecture x86_64):
	@rpath/LLDB.framework/Versions/A/LLDB (compatibility version 1.0.0, current version 15.0.0)
	/usr/lib/libobjc.A.dylib (compatibility version 1.0.0, current version 228.0.0)
	@rpath/Python3.framework/Versions/3.9/Python3 (compatibility version 3.9.0, current version 3.9.0)
	...

otool -l /Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/System/Library/PrivateFrameworks/LLDB.framework/Versions/A/LLD
Load command 42
          cmd LC_RPATH
      cmdsize 72
         path @loader_path/../../../../../../../../Library/Frameworks/ (offset 12)
Load command 43
          cmd LC_RPATH
      cmdsize 72
         path @loader_path/../../../../../Developer/Library/Frameworks/ (offset 12)
Load command 44
          cmd LC_RPATH
      cmdsize 72
         path @loader_path/../../../../Developer/Library/Frameworks/ (offset 12)
Load command 45
          cmd LC_RPATH
      cmdsize 48
         path @loader_path/../../../../Frameworks (offset 12)
Load command 46
          cmd LC_RPATH
      cmdsize 40
         path @loader_path/../../../ (offset 12)
Load command 47
          cmd LC_RPATH
      cmdsize 72
         path /Library/Developer/CommandLineTools/Library/Frameworks (offset 12)
Load command 48
          cmd LC_RPATH
      cmdsize 80
         path /Applications/Xcode.app/Contents/Developer/Library/Frameworks/ (offset 12)
Load command 49
          cmd LC_RPATH
      cmdsize 64
         path @loader_path/../../../../../../usr/lib/swift/host (offset 12)

42 -> /Library/Frameworks (No Python3 here)
43 -> /Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/System/Developer/Library/Frameworks/ (Folder Not Exist)
44 -> /Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/System/Library/Developer/Library/Frameworks/ (Folder Not Exist)
45 -> /Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/System/Library/Frameworks (Folder Not Exist)
46 -> /Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/System/Library/PrivateFrameworks (No Python3 here)
47 -> /Library/Developer/CommandLineTools/Library/Frameworks (Found Python3 here)
48 -> ...
49 -> ...

You can run the above command and see why "Python3.framework" can not be found in your rpath.

In my case, it will locate and use python3.framework found in /Library/Developer/CommandLineTools/Library/Frameworks/

Make sure it can find one in the above rpath location. Or you can fix it by manually inserting a new rpath to the LLDB binary.

Help it can help solve your issue.

3

Kyle, thanks very much. That is correct, I did not have a Python3 framework anywhere in the paths listed. Interestingly. when I run otool I see no reference to /usr/lib/swift as you show, and yet the lldb error message implies that is the first alternate path tried.

I did fix the problem :

The path @rpath is clearly /Library/Developer/Toolchains/swift-5.10-RELEASE.xctoolchain/System/Library/PrivateFrameworks

So I just give it what it asks for :

Make directory @rpath/Python3.framework/Versions/3.9

Then make a link to my existing conda installation :

cd @rpath/Python3.framework/Versions/3.9
sudo ln -s /Users/zauhar/opt/miniconda3/lib/libpython3.9.dylib Python3

Now I can again run swift 5.10 repl and lldb from the command line .

So it's 'fixed', but I am still baffled as to how Swift 5.10 repl worked for several weeks without my having to do this? There is no system-supplied Python3 in MacOS 12.

To paraphrase Three Body Problem : 'Computer science doesn't exist. Computer science never existed'

Thanks,
Randy