From fec4dc9418842bced4a0eea6b48b0601840210f6 Mon Sep 17 00:00:00 2001
From: Douglas Gregor <dgregor@apple.com>
Date: Fri, 19 Nov 2010 23:44:15 +0000
Subject: [PATCH] Implement clang_getCanonicalCursor() in libclang, which does
 the obvious thing.

llvm-svn: 119874
---
 clang/include/clang-c/Index.h                | 26 ++++++++++++++++++++
 clang/tools/libclang/CIndex.cpp              | 10 ++++++++
 clang/tools/libclang/libclang.darwin.exports |  1 +
 clang/tools/libclang/libclang.exports        |  1 +
 4 files changed, 38 insertions(+)

diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index 2fc408973542..ebe74e2d2fc5 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -2074,6 +2074,32 @@ CINDEX_LINKAGE CXCursor clang_getCursorDefinition(CXCursor);
  */
 CINDEX_LINKAGE unsigned clang_isCursorDefinition(CXCursor);
 
+/**
+ * \brief Retrieve the canonical cursor corresponding to the given cursor.
+ *
+ * In the C family of languages, many kinds of entities can be declared several
+ * times within a single translation unit. For example, a structure type can
+ * be forward-declared (possibly multiple times) and later defined:
+ *
+ * \code
+ * struct X;
+ * struct X;
+ * struct X {
+ *   int member;
+ * };
+ * \endcode
+ *
+ * The declarations and the definition of \c X are represented by three 
+ * different cursors, all of which are declarations of the same underlying 
+ * entity. One of these cursor is considered the "canonical" cursor, which
+ * is effectively the representative for the underlying entity. One can 
+ * determine if two cursors are declarations of the same underlying entity by
+ * comparing their canonical cursors.
+ *
+ * \returns The canonical cursor for the entity referred to by the given cursor.
+ */
+CINDEX_LINKAGE CXCursor clang_getCanonicalCursor(CXCursor);
+
 /**
  * @}
  */
diff --git a/clang/tools/libclang/CIndex.cpp b/clang/tools/libclang/CIndex.cpp
index 9137172daf88..9116667ec74a 100644
--- a/clang/tools/libclang/CIndex.cpp
+++ b/clang/tools/libclang/CIndex.cpp
@@ -3717,6 +3717,16 @@ unsigned clang_isCursorDefinition(CXCursor C) {
   return clang_getCursorDefinition(C) == C;
 }
 
+CXCursor clang_getCanonicalCursor(CXCursor C) {
+  if (!clang_isDeclaration(C.kind))
+    return C;
+  
+  if (Decl *D = getCursorDecl(C))
+    return MakeCXCursor(D->getCanonicalDecl(), getCursorTU(C));
+  
+  return C;
+}
+  
 unsigned clang_getNumOverloadedDecls(CXCursor C) {
   if (C.kind != CXCursor_OverloadedDeclRef)
     return 0;
diff --git a/clang/tools/libclang/libclang.darwin.exports b/clang/tools/libclang/libclang.darwin.exports
index 5e8abf25333b..e132f7f9aab1 100644
--- a/clang/tools/libclang/libclang.darwin.exports
+++ b/clang/tools/libclang/libclang.darwin.exports
@@ -32,6 +32,7 @@ _clang_equalTypes
 _clang_formatDiagnostic
 _clang_getCString
 _clang_getCXXAccessSpecifier
+_clang_getCanonicalCursor
 _clang_getCanonicalType
 _clang_getClangVersion
 _clang_getCompletionAvailability
diff --git a/clang/tools/libclang/libclang.exports b/clang/tools/libclang/libclang.exports
index ca9a9d1016dd..fce89ca87bc0 100644
--- a/clang/tools/libclang/libclang.exports
+++ b/clang/tools/libclang/libclang.exports
@@ -32,6 +32,7 @@ clang_equalTypes
 clang_formatDiagnostic
 clang_getCString
 clang_getCXXAccessSpecifier
+clang_getCanonicalCursor
 clang_getCanonicalType
 clang_getClangVersion
 clang_getCompletionAvailability