[libclang] Expose warn_unused and warn_unused_result attributes.

[emilio]

Summary

This is helpful to properly detect them, and fixing issues like
https://github.com/rust-lang/rust-bindgen/issues/1518.

[Anastasia]

LGTM! Although for consistency we could add this into python bindings too.

[emilio]

Landed with that change, thanks for the review @Anastasia!

bindings/python/clang/cindex.py

 CursorKind.CUDAHOST_ATTR = CursorKind(415)
 CursorKind.CUDASHARED_ATTR = CursorKind(416)
 
 CursorKind.VISIBILITY_ATTR = CursorKind(417)
 
 CursorKind.DLLEXPORT_ATTR = CursorKind(418)
 CursorKind.DLLIMPORT_ATTR = CursorKind(419)
 CursorKind.CONVERGENT_ATTR = CursorKind(438)
+CursorKind.WARN_UNUSED_ATTR = CursorKind(439)
+CursorKind.WARN_UNUSED_RESULT_ATTR = CursorKind(440)
 
 ###
 # Preprocessing
 CursorKind.PREPROCESSING_DIRECTIVE = CursorKind(500)
 CursorKind.MACRO_DEFINITION = CursorKind(501)
 CursorKind.MACRO_INSTANTIATION = CursorKind(502)
 CursorKind.INCLUSION_DIRECTIVE = CursorKind(503)
 

include/clang-c/Index.h

  * The version constants for the libclang API.
  * CINDEX_VERSION_MINOR should increase when there are API additions.
  * CINDEX_VERSION_MAJOR is intended for "major" source/ABI breaking changes.
  *
  * The policy about the libclang API was always to keep it source and ABI
  * compatible, thus CINDEX_VERSION_MAJOR is expected to remain stable.
  */
 #define CINDEX_VERSION_MAJOR 0
-#define CINDEX_VERSION_MINOR 51
+#define CINDEX_VERSION_MINOR 52
 
 #define CINDEX_VERSION_ENCODE(major, minor) ( \
       ((major) * 10000)                       \
     + ((minor) *     1))
 
 #define CINDEX_VERSION CINDEX_VERSION_ENCODE( \
     CINDEX_VERSION_MAJOR,                     \
     CINDEX_VERSION_MINOR )
enum CXCursorKind {
   CXCursor_ObjCRootClass                 = 431,
   CXCursor_ObjCSubclassingRestricted     = 432,
   CXCursor_ObjCExplicitProtocolImpl      = 433,
   CXCursor_ObjCDesignatedInitializer     = 434,
   CXCursor_ObjCRuntimeVisible            = 435,
   CXCursor_ObjCBoxable                   = 436,
   CXCursor_FlagEnum                      = 437,
   CXCursor_ConvergentAttr                = 438,
-  CXCursor_LastAttr                      = CXCursor_ConvergentAttr,
+  CXCursor_WarnUnusedAttr                = 439,
+  CXCursor_WarnUnusedResultAttr          = 440,
+  CXCursor_LastAttr                      = CXCursor_WarnUnusedResultAttr,
 
   /* Preprocessing */
   CXCursor_PreprocessingDirective        = 500,
   CXCursor_MacroDefinition               = 501,
   CXCursor_MacroExpansion                = 502,
   CXCursor_MacroInstantiation            = CXCursor_MacroExpansion,
   CXCursor_InclusionDirective            = 503,
   CXCursor_FirstPreprocessing            = CXCursor_PreprocessingDirective,

test/Index/attributes.c

 // RUN: c-index-test -test-load-source all %s | FileCheck %s
 
 struct __attribute__((packed)) Test2 {
   char a;
 };
 
 void pure_fn() __attribute__((pure));
 void const_fn() __attribute__((const));
 void noduplicate_fn() __attribute__((noduplicate));
 
 enum __attribute((flag_enum)) FlagEnum {
   Foo
 };
 
 void convergent_fn() __attribute__((convergent));
 
+int warn_unused_result_fn() __attribute__((warn_unused_result));
+
+struct __attribute__((warn_unused)) WarnUnused {
+  int b;
+};
+
 // CHECK: attributes.c:3:32: StructDecl=Test2:3:32 (Definition) Extent=[3:1 - 5:2]
 // CHECK: attributes.c:3:23: attribute(packed)=packed Extent=[3:23 - 3:29]
 // CHECK: attributes.c:4:8: FieldDecl=a:4:8 (Definition) Extent=[4:3 - 4:9] [access=public]
 
 // CHECK: attributes.c:7:6: FunctionDecl=pure_fn:7:6 Extent=[7:1 - 7:37]
 // CHECK: attributes.c:7:31: attribute(pure)= Extent=[7:31 - 7:35]
 // CHECK: attributes.c:8:6: FunctionDecl=const_fn:8:6 Extent=[8:1 - 8:39]
 // CHECK: attributes.c:8:32: attribute(const)= Extent=[8:32 - 8:37]
 // CHECK: attributes.c:9:6: FunctionDecl=noduplicate_fn:9:6 Extent=[9:1 - 9:51]
 // CHECK: attributes.c:9:38: attribute(noduplicate)= Extent=[9:38 - 9:49]
 // CHECK: attributes.c:11:31: EnumDecl=FlagEnum:11:31 (Definition) Extent=[11:1 - 13:2]
 // CHECK: attributes.c:11:19: attribute(flag_enum)= Extent=[11:19 - 11:28]
 // CHECK: attributes.c:12:3: EnumConstantDecl=Foo:12:3 (Definition) Extent=[12:3 - 12:6]
 // CHECK: attributes.c:15:6: FunctionDecl=convergent_fn:15:6 Extent=[15:1 - 15:49]
 // CHECK: attributes.c:15:37: attribute(convergent)= Extent=[15:37 - 15:47]
+// CHECK: attributes.c:17:5: FunctionDecl=warn_unused_result_fn:17:5 Extent=[17:1 - 17:64]
+// CHECK: attributes.c:17:44: attribute(warn_unused_result)= Extent=[17:44 - 17:62]
+// CHECK: attributes.c:19:37: StructDecl=WarnUnused:19:37 (Definition) Extent=[19:1 - 21:2]
+// CHECK: attributes.c:19:23: attribute(warn_unused)= Extent=[19:23 - 19:34]

tools/libclang/CIndex.cpp

CXString clang_getCursorKindSpelling(enum CXCursorKind Kind) {
   case CXCursor_TypeAliasTemplateDecl:
       return cxstring::createRef("TypeAliasTemplateDecl");
   case CXCursor_StaticAssert:
       return cxstring::createRef("StaticAssert");
   case CXCursor_FriendDecl:
       return cxstring::createRef("FriendDecl");
   case CXCursor_ConvergentAttr:
       return cxstring::createRef("attribute(convergent)");
+  case CXCursor_WarnUnusedAttr:
+      return cxstring::createRef("attribute(warn_unused)");
+  case CXCursor_WarnUnusedResultAttr:
+      return cxstring::createRef("attribute(warn_unused_result)");
   }
 
   llvm_unreachable("Unhandled CXCursorKind");
 }
 
 struct GetCursorData {
   SourceLocation TokenBeginLoc;
   bool PointsAtMacroArgExpansion;

tools/libclang/CXCursor.cpp

switch (A->getKind()) {
     case attr::ObjCRootClass: return CXCursor_ObjCRootClass;
     case attr::ObjCSubclassingRestricted: return CXCursor_ObjCSubclassingRestricted;
     case attr::ObjCExplicitProtocolImpl: return CXCursor_ObjCExplicitProtocolImpl;
     case attr::ObjCDesignatedInitializer: return CXCursor_ObjCDesignatedInitializer;
     case attr::ObjCRuntimeVisible: return CXCursor_ObjCRuntimeVisible;
     case attr::ObjCBoxable: return CXCursor_ObjCBoxable;
     case attr::FlagEnum: return CXCursor_FlagEnum;
     case attr::Convergent: return CXCursor_ConvergentAttr;
+    case attr::WarnUnused: return CXCursor_WarnUnusedAttr;
+    case attr::WarnUnusedResult: return CXCursor_WarnUnusedResultAttr;
   }
 
   return CXCursor_UnexposedAttr;
 }
 
 CXCursor cxcursor::MakeCXCursor(const Attr *A, const Decl *Parent,
                                 CXTranslationUnit TU) {
   assert(A && Parent && TU && "Invalid arguments!");