[clang] Add Obj-C bridging-related attributes to C-Index API

[jevinskie]

Yowza, I haven't tried to upstream anything to LLVM in a long time. It was so long ago I just had my coworker submit it for me with their SVN access...

Anyways, this adds ObjCBridgeAttr, ObjCBridgeMutableAttr, and ObjCBridgeRelatedAttr attributes to C-Index (c-index? C-index?). Truth be told, I just wanted a way to figure out that a SecKeyRef parameter in a header was usable as an Obj-C object.

Now c-index-test -test-print-type -Xclang -triple -Xclang arm64-apple-ios17.0.0 -x objective-c ./objc-bridge-attr-test.h prints:

<pre-defined macro definition spam>
...
ObjCClassRef=Protocol:0:0 [type=Protocol] [typekind=ObjCInterface] [isPOD=0] [isAnonRecDecl=0]
StructDecl=__SecKey:3:60 [type=struct __SecKey] [typekind=Record] [isPOD=0] [isAnonRecDecl=0]
attribute(packed)=packed [type=] [typekind=Invalid] [isPOD=0] [isAnonRecDecl=0]
ObjCBridgeAttr= [type=] [typekind=Invalid] [isPOD=0] [isAnonRecDecl=0]
TypedefDecl=SecKeyRef:3:70 (Definition) [type=SecKeyRef] [typekind=Typedef] [canonicaltype=struct __SecKey *] [canonicaltypekind=Pointer] [isPOD=1] [isAnonRecDecl=0]
TypeRef=struct __SecKey:3:60 [type=struct __SecKey] [typekind=Record] [isPOD=0] [isAnonRecDecl=0]
FunctionDecl=i_take_a_key:5:12 [type=int (SecKeyRef)] [typekind=FunctionProto] [canonicaltype=int (struct __SecKey *)] [canonicaltypekind=FunctionProto] [resulttype=int] [resulttypekind=Int] [args= [SecKeyRef] [Elaborated]] [isPOD=0] [isAnonRecDecl=0]
ParmDecl=my_key:5:35 (Definition) [type=SecKeyRef] [typekind=Elaborated] [canonicaltype=struct __SecKey *] [canonicaltypekind=Pointer] [isPOD=1] [isAnonRecDecl=0]
TypeRef=SecKeyRef:3:70 [type=SecKeyRef] [typekind=Typedef] [canonicaltype=struct __SecKey *] [canonicaltypekind=Pointer] [isPOD=1] [isAnonRecDecl=0]

with objc-bridge-attr-test.h:

#define CF_BRIDGED_TYPE(T) __attribute__((objc_bridge(T)))

typedef struct __attribute__((packed)) CF_BRIDGED_TYPE(id) __SecKey *SecKeyRef;

extern int i_take_a_key(SecKeyRef my_key);

(That is not the true typedef of SecKeyRef, I just threw another, already supported, __attribute__((packed)) in there for testing.)

Speaking of testing, do all new CXCursorKind enums need unit tests written for them?

Thanks and long live the Dragon.