I have verified that this is only an issue with the PNG code provided as part of pTk. I was able to manually run tests on all the rest of the pTk code, which was almost 100% successful, but have not yet had the time to nail down the specific cause of this PNG issue.

Here is where I'm currently at:

The offending line, causing the segfault, in the basic.t test file is:

my $image = $mw->Photo('-format' => "png", -file => $file);

Where:

file="~/.cpan/build/Tk-804.036-0/PNG/t/../pngtest.png"

When a segmentation fault occurs on a Mac, a *.ips file is created in ~/Library/Logs/DiagnosticReports providing more details on the fault. Stack frame analysis from this data yields:

"frames":[
{"imageOffset":9468,"symbol":"_longjmp","symbolLocation":72,"imageIndex":0}, {"imageOffset":18446639227543793010,"imageIndex":1}, {"imageOffset":166568,"symbol":"png_error","symbolLocation":420,"imageIndex":2}, {"imageOffset":91072,"symbol":"png_create_read_struct_2","symbolLocation":636,"imageIndex":2}, {"imageOffset":90424,"symbol":"png_create_read_struct","symbolLocation":60,"imageIndex":2}, {"imageOffset":10552,"symbol":"ChnReadPNG","symbolLocation":112,"imageIndex":2}, {"imageOffset":419820,"symbol":"ImgPhotoConfigureMaster","symbolLocation":1176,"imageIndex":3}, {"imageOffset":398084,"symbol":"ImgPhotoCreate","symbolLocation":204,"imageIndex":3}, {"imageOffset":366856,"symbol":"Tk_ImageObjCmd","symbolLocation":1664,"imageIndex":3}, {"imageOffset":88836,"symbol":"Call_Tk","symbolLocation":624,"imageIndex":3}, {"imageOffset":133540,"symbol":"XStoImage","symbolLocation":608,"imageIndex":3}, {"imageOffset":752088,"symbol":"Perl_pp_entersub","symbolLocation":1696,"imageIndex":4}, {"imageOffset":712144,"symbol":"Perl_runops_standard","symbolLocation":32,"imageIndex":4}, {"imageOffset":157920,"symbol":"S_run_body","symbolLocation":116,"imageIndex":4}, {"imageOffset":157800,"symbol":"perl_run","symbolLocation":648,"imageIndex":4}, {"imageOffset":15952,"symbol":"main","symbolLocation":180,"imageIndex":5}, {"imageOffset":20620,"symbol":"start","symbolLocation":520,"imageIndex":6}

As you can see we did hit png_error() before heading to imagIndex(), then to _longjmp, which I'm guessing is the cause of the segfault.

Since I'm not currently using PNG images for anything in my code, I just stubbed out the two test files and installed pTk via CPAN as you normally would. Everything else seems to be working fine.

I would like to eventually figure out why this code segfaults on macOS Monterey (12.6) with Apple M1 chip, and feedback to the PNG group on what needs to be fixed.

Any suggestions on what to try next would be welcome!

Thanks

-Craig