…at least in the specific case of initializers.
Normally, clang validates that a SwiftNameAttr’s specified name seems to have the right number of argument labels for the declaration it’s applied to; if it doesn’t, it diagnoses and drops the attribute. However, this checking isn’t perfect because clang doesn’t know all of Clang Importer’s throwing rules. The upshot is that it’s possible to get a mismatched SwiftNameAttr into Clang Importer if the last parameter looks like an out parameter. This trips an assertion in asserts compilers, but release compilers get past that and don’t seem to notice the mismatch at all.
Add code to the compiler to tolerate this condition, at least in initializers, by modifying the Swift name to have the correct number of argument labels and deprecating the declaration with a message explaining the problem.
Fixes rdar://141124373.
Initializers should always have Swift names that have the special `DeclBaseName::createConstructor()` base name. Although there is an assertion to this effect in the constructor for ConstructorDecl, ClangImporter did not actually reject custom Swift names for initializers that violated this rule. This meant that asserts compilers would crash if they encountered code with an invalid `swift_name` attribute, while release compilers would silently accept them (while excluding these decls from certain checks since lookups that were supposed to find all initializers didn’t find them).
Modify ClangImporter to diagnose this condition and ignore the custom Swift name.
Previously this (1) did not work (the constant just disappeared), and
(2) would actually crash if the destination context was a class.
rdar://problem/32208235
These new Clang attributes identify whether an enum is intended to
represent an option set or not, and whether the set of cases listed in
the enum declaration is exhaustive. (Swift doesn't currently have a
closed/open distinction for enums, so treat any C enum with
enum_extensibility as a proper closed Swift enum, like we do with
NS_ENUM.)
Enums with neither attribute will continue to be imported as unique
types.
rdar://problem/28476618
