Comment by ​​ (JIRA)

A workaround is required to handle the optionality differences when building for iOS Simulator architectures (i.e. x86_64) vs. real iOS device architectures (i.e. arm64):

1. Building for iOS Simulator, the optionality for a `CVaListPointer` parameter is non-optional.
2. Building for real iOS device, the optionality for a `CVaListPointer` parameter is optional.

`va_list` is an array type for x86_64 and a pointer type for arm64, so the optionality differences between the archs appears correct.

Is this working as intended or should the Swift compiler try to handle the C to Swift bridging for arm64 so that the optionality is consistent with x86_64?

Other links:

1. `CVaListPointer` definition (

   swift/stdlib/public/core/CTypes.swift

   Line 227 in 28251a7

   /// A wrapper around a C `va_list` pointer.

   ).

2. MappedTypes note about special handling for platforms where `va_list` is an array (

   swift/lib/ClangImporter/MappedTypes.def

   Line 127 in f88be05

   // Note: this does not catch va_list on platforms where va_list is an array.

   ).

3. `VisitDecayedType(...)` workaround mentioned in MappedTypes (

   swift/lib/ClangImporter/ImportType.cpp

   Line 805 in 517f5d6

   ImportResult VisitDecayedType(const clang::DecayedType *type) {

   ).

4. `adjustTypeForConcreteImport(...)` code for handling null-unspecified `va_list` parameters (

   swift/lib/ClangImporter/ImportType.cpp

   Line 1441 in 517f5d6

   // Treat va_list specially: null-unspecified va_list parameters should be

   ).