[cindex] Add support for calling getFullyQualifiedName to the Python binding. (#135420)

We're coming from llvm 11. There was a change made back in 15f3cd6 that
changed how type spelling works. Previous we were given namespaces of
the types within the spelling, and this was necessary in our use-case.
There is a more appropriate function available but it was not being
exposed over the Python bindings. This PR is intended to make make this
already-existing functionality accessible.

---------

Co-authored-by: Jannick Kremer <jannick.kremer@mailbox.org>

clang/bindings/python/clang/cindex.py

@@ -2593,6 +2593,19 @@ class Type(Structure):
         """
         return Type.from_result(conf.lib.clang_getCanonicalType(self), (self,))
 
+    def get_fully_qualified_name(self, policy, with_global_ns_prefix=False):
+        """
+        Get the fully qualified name for a type.
+
+        This includes full qualification of all template parameters.
+
+        policy - This PrintingPolicy can further refine the type formatting
+        with_global_ns_prefix - If true, prepend '::' to qualified names
+        """
+        return _CXString.from_result(
+            conf.lib.clang_getFullyQualifiedName(self, policy, with_global_ns_prefix)
+        )
+
     def is_const_qualified(self):
         """Determine whether a Type has the "const" qualifier set.
 
@@ -4022,6 +4035,7 @@ FUNCTION_LIST: list[LibFunc] = [
     ("clang_getTypeSpelling", [Type], _CXString),
     ("clang_hashCursor", [Cursor], c_uint),
     ("clang_isAttribute", [CursorKind], bool),
+    ("clang_getFullyQualifiedName", [Type, PrintingPolicy, c_uint], _CXString),
     ("clang_isConstQualifiedType", [Type], bool),
     ("clang_isCursorDefinition", [Cursor], bool),
     ("clang_isDeclaration", [CursorKind], bool),

clang/bindings/python/tests/cindex/test_type.py

@@ -535,6 +535,25 @@ class A
         pp.set_property(PrintingPolicyProperty.SuppressTagKeyword, False)
         self.assertEqual(f.type.get_canonical().pretty_printed(pp), "struct X")
 
+    def test_fully_qualified_name(self):
+        source = """
+        namespace home {
+          class Bar {
+          };
+          class Foo {
+            public:
+              void setIt(Bar*);
+          };
+        }
+        class A : public home::Foo {
+        };
+        """
+        tu = get_tu(source, lang="cpp")
+        arg = next(get_cursor(tu, "setIt").get_arguments())
+        pp = PrintingPolicy.create(arg)
+        self.assertEqual(arg.type.get_fully_qualified_name(pp), "home::Bar *")
+        self.assertEqual(arg.type.get_fully_qualified_name(pp, True), "::home::Bar *")
+
     def test_base_classes(self):
         source = """
         class A { int a; };

clang/docs/ReleaseNotes.rst

@@ -607,6 +607,8 @@ libclang
 --------
 - Added ``clang_visitCXXMethods``, which allows visiting the methods
   of a class.
+- Added ``clang_getFullyQualifiedName``, which provides fully qualified type names as
+  instructed by a PrintingPolicy.
 
 - Fixed a buffer overflow in ``CXString`` implementation. The fix may result in
   increased memory allocation.
@@ -661,6 +663,8 @@ Python Binding Changes
   the cursor is a specialization of.
 - Added ``Type.get_methods``, a binding for ``clang_visitCXXMethods``, which
   allows visiting the methods of a class.
+- Added ``Type.get_fully_qualified_name``, which provides fully qualified type names as
+  instructed by a PrintingPolicy.
 
 OpenMP Support
 --------------

clang/include/clang-c/Index.h

@@ -4223,6 +4223,18 @@ CINDEX_LINKAGE CXString clang_getCursorPrettyPrinted(CXCursor Cursor,
 CINDEX_LINKAGE CXString clang_getTypePrettyPrinted(CXType CT,
                                                    CXPrintingPolicy cxPolicy);
 
+/**
+ * Get the fully qualified name for a type.
+ *
+ * This includes full qualification of all template parameters.
+ *
+ * Policy - Further refine the type formatting
+ * WithGlobalNsPrefix - If non-zero, function will prepend a '::' to qualified
+ * names
+ */
+CINDEX_LINKAGE CXString clang_getFullyQualifiedName(
+    CXType CT, CXPrintingPolicy Policy, unsigned WithGlobalNsPrefix);
+
 /**
  * Retrieve the display name for the entity referenced by this cursor.
  *

clang/tools/libclang/CXType.cpp

@@ -19,6 +19,7 @@
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/DeclTemplate.h"
 #include "clang/AST/Expr.h"
+#include "clang/AST/QualTypeNames.h"
 #include "clang/AST/RecordLayout.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/AddressSpaces.h"
@@ -328,6 +329,22 @@ CXString clang_getTypePrettyPrinted(CXType CT, CXPrintingPolicy cxPolicy) {
   return cxstring::createDup(OS.str());
 }
 
+CXString clang_getFullyQualifiedName(CXType CT, CXPrintingPolicy cxPolicy,
+                                     unsigned int WithGlobalNsPrefix) {
+  const QualType T = GetQualType(CT);
+  if (T.isNull())
+    return cxstring::createEmpty();
+  const CXTranslationUnit TU = GetTU(CT);
+  const ASTContext &Ctx = cxtu::getASTUnit(TU)->getASTContext();
+  const PrintingPolicy *UserPolicy = static_cast<PrintingPolicy *>(cxPolicy);
+  const bool WithGlobalNs = (WithGlobalNsPrefix != 0);
+
+  const std::string Str =
+      TypeName::getFullyQualifiedName(T, Ctx, *UserPolicy, WithGlobalNs);
+
+  return cxstring::createDup(Str);
+}
+
 CXType clang_getTypedefDeclUnderlyingType(CXCursor C) {
   using namespace cxcursor;
   CXTranslationUnit TU = cxcursor::getCursorTU(C);

clang/tools/libclang/libclang.map

@@ -438,6 +438,11 @@ LLVM_20 {
     clang_visitCXXMethods;
 };
 
+LLVM_21 {
+  global:
+    clang_getFullyQualifiedName;
+};
+
 # Example of how to add a new symbol version entry.  If you do add a new symbol
 # version, please update the example to depend on the version you added.
 # LLVM_X {