Cannot run helloworld on macOS after 0.4.3 release

[rmartin16]

Describe the bug

The helloworld app fails to run on macOS.

Briefcase CI is also failing: https://github.com/beeware/briefcase/actions/runs/8973799632/job/24646416726?pr=1778

Traceback:

[15:08:51] Application quit abnormally (Exit code -6)!                                                                                                             subprocess.py:195
           Traceback (most recent call last):                                                                                                                      subprocess.py:195
             File "/Users/user/tmp/beeware/helloworld/build/helloworld/macos/xcode/build/Release/Hello World.app/Contents/Resources/app_packages/toga/icons.py",   subprocess.py:195
           line 35, in __get__                                                                                                                                                      
               value = getattr(cls, f"__{self.f.__name__}")                                                                                                        subprocess.py:195
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^                                                                                                        subprocess.py:195
           AttributeError: type object 'Icon' has no attribute '__APP_ICON'. Did you mean: 'APP_ICON'?                                                             subprocess.py:195
                                                                                                                                                                   subprocess.py:195
           During handling of the above exception, another exception occurred:                                                                                     subprocess.py:195
                                                                                                                                                                   subprocess.py:195
           Traceback (most recent call last):                                                                                                                      subprocess.py:195
             File "/Users/user/tmp/beeware/helloworld/build/helloworld/macos/xcode/build/Release/Hello World.app/Contents/Resources/app_packages/toga/icons.py",   subprocess.py:195
           line 126, in __init__                                                                                                                                                    
               full_path = self._full_path(                                                                                                                        subprocess.py:195
                           ^^^^^^^^^^^^^^^^                                                                                                                        subprocess.py:195
[15:08:52]   File "/Users/user/tmp/beeware/helloworld/build/helloworld/macos/xcode/build/Release/Hello World.app/Contents/Resources/app_packages/toga/icons.py",   subprocess.py:195
           line 182, in _full_path                                                                                                                                                  
               raise FileNotFoundError(f"Can't find icon {self.path}")                                                                                             subprocess.py:195
           FileNotFoundError: Can't find icon resources/helloworld                                                                                                 subprocess.py:195
                                                                                                                                                                   subprocess.py:195
           During handling of the above exception, another exception occurred:                                                                                     subprocess.py:195
                                                                                                                                                                   subprocess.py:195
           Traceback (most recent call last):                                                                                                                      subprocess.py:195
             File "<frozen runpy>", line 198, in _run_module_as_main                                                                                               subprocess.py:195
             File "<frozen runpy>", line 88, in _run_code                                                                                                          subprocess.py:195
             File "/Users/user/tmp/beeware/helloworld/build/helloworld/macos/xcode/build/Release/Hello World.app/Contents/Resources/app/helloworld/__main__.py",   subprocess.py:195
           line 4, in <module>                                                                                                                                                      
               main().main_loop()                                                                                                                                  subprocess.py:195
               ^^^^^^                                                                                                                                              subprocess.py:195
             File "/Users/user/tmp/beeware/helloworld/build/helloworld/macos/xcode/build/Release/Hello World.app/Contents/Resources/app/helloworld/app.py", line   subprocess.py:195
           26, in main                                                                                                                                                              
               return HelloWorld()                                                                                                                                 subprocess.py:195
                      ^^^^^^^^^^^^                                                                                                                                 subprocess.py:195
             File "/Users/user/tmp/beeware/helloworld/build/helloworld/macos/xcode/build/Release/Hello World.app/Contents/Resources/app_packages/toga/app.py",     subprocess.py:195
           line 474, in __init__                                                                                                                                                    
               self.icon = Icon.APP_ICON                                                                                                                           subprocess.py:195
                           ^^^^^^^^^^^^^                                                                                                                           subprocess.py:195
             File "/Users/user/tmp/beeware/helloworld/build/helloworld/macos/xcode/build/Release/Hello World.app/Contents/Resources/app_packages/toga/icons.py",   subprocess.py:195
           line 37, in __get__                                                                                                                                                      
               value = self.f(owner)                                                                                                                               subprocess.py:195
                       ^^^^^^^^^^^^^                                                                                                                               subprocess.py:195
             File "/Users/user/tmp/beeware/helloworld/build/helloworld/macos/xcode/build/Release/Hello World.app/Contents/Resources/app_packages/toga/icons.py",   subprocess.py:195
           line 70, in APP_ICON                                                                                                                                                     
               return Icon(_APP_ICON)                                                                                                                              subprocess.py:195
                      ^^^^^^^^^^^^^^^                                                                                                                              subprocess.py:195
             File "/Users/user/tmp/beeware/helloworld/build/helloworld/macos/xcode/build/Release/Hello World.app/Contents/Resources/app_packages/toga/icons.py",   subprocess.py:195
           line 145, in __init__                                                                                                                                                    
               self._impl = self.factory.Icon(interface=self, path=None)                                                                                           subprocess.py:195
                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^                                                                                           subprocess.py:195
             File "/Users/user/tmp/beeware/helloworld/build/helloworld/macos/xcode/build/Release/Hello                                                             subprocess.py:195
           World.app/Contents/Resources/app_packages/toga_cocoa/icons.py", line 43, in __init__                                                                                     
               raise ValueError(f"Unable to load icon from {path}")                                                                                                subprocess.py:195
           ValueError: Unable to load icon from None                                                                                                               subprocess.py:195
           Traceback (most recent call last):                                                                                                                      subprocess.py:195
             File "Hello World.app/Contents/Resources/app_packages/toga/icons.py", line 35, in __get__                                                             subprocess.py:195
               value = getattr(cls, f"__{self.f.__name__}")                                                                                                        subprocess.py:195
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^                                                                                                        subprocess.py:195
           AttributeError: type object 'Icon' has no attribute '__APP_ICON'. Did you mean: 'APP_ICON'?                                                             subprocess.py:195

Steps to reproduce

briefcase new --no-input && cd helloworld && briefcase run macos xcode

Expected behavior

Tutorial helloworld app builds and runs on macOS.

Screenshots

No response

Environment

• Operating System: Sonoma
• Python version: 3.12.1
• Software versions:
  • Briefcase: 0.3.18
  • Toga: 0.4.3

Logs

briefcase.2024_05_06-15_08_56.run.log

Additional context

No response

[freakboy3742]

This only appears to affect the macOS Xcode target; AFAICT, the briefcase run macOS target works fine. @rmartin16 can you confirm this is the case for you?

[rmartin16]

Indeed; I had to target Xcode to trigger the error in my VM.

[freakboy3742]

The issue appears to be in the Info.plist for the generated template; it's not adding the .icns extension to the CFBundleIconFile attribute.

[freakboy3742]

There's a secondary problem in that the ValueError being raised when an icon can't be loaded isn't being caught by the base Icon class.

I'll push a fix for both of these shortly. The Info.plist can be fixed by backporting the template change; that will be enough to avoid immediate problems. The base Icon class fix will need a new Toga release.

EDIT: To clarify - we would need to cut a new release to get the fix for this bug into the wild. I think we can live with just the template fix for the short term.

[freakboy3742]

Hrm... I take that back - it might not be that simple. I thought it was just a fix to the input metadata, but it looks like Xcode transforms that value on its way to the final build product. We might need to do a 0.4.5 release to correct this.