Tim Kientzle fac8c972a5 Tailored error reporting when dynamic casts have nonsensical type args ...

This inserts a suitably named function into the stack trace whenever
a dynamic cast failure involves a NULL source or target type.
Very often, crash logs include backtraces with function names but
no log output; with this change, such a backtrace might look like
the following -- note `TARGET_TYPE_NULL` in the function name
here to mark the missing type information:

```
 frame #0: __pthread_kill + 8
 frame #1: pthread_kill + 288
 frame #2: abort + 128
 frame #3: swift::fatalErrorv()
 frame #4: swift::fatalError()
 frame #5: swift_dynamicCastFailure_TARGET_TYPE_NULL()
 frame #6: swift::swift_dynamicCastFailure()
 frame #7: ::swift_dynamicCast()
```

Resolves rdar://130630157

2024-07-10 15:57:36 -07:00

60 KiB

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