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[cindex] Add API to query the class methods of a type #123539

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@trelau trelau commented Jan 20, 2025

Inspired by #120300, add a new API clang_visitCXXMethods to libclang (and the Python bindings) which allows iterating over the class methods of a type.

@trelau trelau requested a review from DeinAlptraum as a code owner January 20, 2025 00:28
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@llvmbot llvmbot added clang Clang issues not falling into any other category clang:as-a-library libclang and C++ API labels Jan 20, 2025
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llvmbot commented Jan 20, 2025

@llvm/pr-subscribers-clang

Author: Trevor Laughlin (trelau)

Changes

Inspired by #120300, add a new API clang_visitCXXMethods to libclang (and the Python bindings) which allows iterating over the class methods of a type.


Full diff: https://github.com/llvm/llvm-project/pull/123539.diff

6 Files Affected:

  • (modified) clang/bindings/python/clang/cindex.py (+16)
  • (modified) clang/bindings/python/tests/cindex/test_type.py (+18)
  • (modified) clang/docs/ReleaseNotes.rst (+4)
  • (modified) clang/include/clang-c/Index.h (+23)
  • (modified) clang/tools/libclang/CIndexCXX.cpp (+27)
  • (modified) clang/tools/libclang/libclang.map (+1)
diff --git a/clang/bindings/python/clang/cindex.py b/clang/bindings/python/clang/cindex.py
index 806e1b40f3c9e1..9e65ea2942d163 100644
--- a/clang/bindings/python/clang/cindex.py
+++ b/clang/bindings/python/clang/cindex.py
@@ -2710,6 +2710,21 @@ def visitor(base, children):
         conf.lib.clang_visitCXXBaseClasses(self, fields_visit_callback(visitor), bases)
         return iter(bases)
 
+    def get_methods(self):
+        """Return an iterator for accessing the methods of this type."""
+
+        def visitor(method, children):
+            assert method != conf.lib.clang_getNullCursor()
+
+            # Create reference to TU so it isn't GC'd before Cursor.
+            method._tu = self._tu
+            methods.append(method)
+            return 1  # continue
+
+        methods: list[Cursor] = []
+        conf.lib.clang_visitCXXMethods(self, fields_visit_callback(visitor), methods)
+        return iter(methods)
+
     def get_exception_specification_kind(self):
         """
         Return the kind of the exception specification; a value from
@@ -4017,6 +4032,7 @@ def set_property(self, property, value):
     ),
     ("clang_visitChildren", [Cursor, cursor_visit_callback, py_object], c_uint),
     ("clang_visitCXXBaseClasses", [Type, fields_visit_callback, py_object], c_uint),
+    ("clang_visitCXXMethods", [Type, fields_visit_callback, py_object], c_uint),
     ("clang_Cursor_getNumArguments", [Cursor], c_int),
     ("clang_Cursor_getArgument", [Cursor, c_uint], Cursor),
     ("clang_Cursor_getNumTemplateArguments", [Cursor], c_int),
diff --git a/clang/bindings/python/tests/cindex/test_type.py b/clang/bindings/python/tests/cindex/test_type.py
index 9bac33f3041f40..bc893d509524e0 100644
--- a/clang/bindings/python/tests/cindex/test_type.py
+++ b/clang/bindings/python/tests/cindex/test_type.py
@@ -559,3 +559,21 @@ class Template : public A, public B, virtual C {
         self.assertEqual(bases[1].get_base_offsetof(cursor_type_decl), 96)
         self.assertTrue(bases[2].is_virtual_base())
         self.assertEqual(bases[2].get_base_offsetof(cursor_type_decl), 128)
+
+    def test_class_methods(self):
+        source = """
+        template <typename T>
+        class Template { void Foo(); };
+        typedef Template<int> instance;
+        instance bar;
+        """
+        tu = get_tu(source, lang="cpp", flags=["--target=x86_64-linux-gnu"])
+        cursor = get_cursor(tu, "instance")
+        cursor_type = cursor.underlying_typedef_type
+        self.assertEqual(cursor.kind, CursorKind.TYPEDEF_DECL)
+        methods = list(cursor_type.get_methods())
+        self.assertEqual(len(methods), 4)
+        self.assertEqual(methods[0].kind, CursorKind.CXX_METHOD)
+        self.assertEqual(methods[1].kind, CursorKind.CONSTRUCTOR)
+        self.assertEqual(methods[2].kind, CursorKind.CONSTRUCTOR)
+        self.assertEqual(methods[3].kind, CursorKind.CONSTRUCTOR)
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index b02ac467cd3a22..dd9f722a6a08cb 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -1241,6 +1241,8 @@ libclang
   of a class.
 - Added ``clang_getOffsetOfBase``, which allows computing the offset of a base
   class in a class's layout.
+- Added ``clang_visitCXXMethods``, which allows visiting the methods
+  of a class.
 
 Static Analyzer
 ---------------
@@ -1394,6 +1396,8 @@ Python Binding Changes
   allows visiting the base classes of a class.
 - Added ``Cursor.get_base_offsetof``, a binding for ``clang_getOffsetOfBase``,
   which allows computing the offset of a base class in a class's layout.
+- Added ``Type.get_methods``, a binding for ``clang_visitCXXMethods``, which
+  allows visiting the methods of a class.
 
 OpenMP Support
 --------------
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index aac5d1fa8aa2e0..5d961ca0cdd7fc 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -6680,6 +6680,29 @@ CINDEX_LINKAGE unsigned clang_visitCXXBaseClasses(CXType T,
                                                   CXFieldVisitor visitor,
                                                   CXClientData client_data);
 
+/**
+ * Visit the class methods of a type.
+ *
+ * This function visits all the methods of the given cursor,
+ * invoking the given \p visitor function with the cursors of each
+ * visited method. The traversal may be ended prematurely, if
+ * the visitor returns \c CXFieldVisit_Break.
+ *
+ * \param T the record type whose field may be visited.
+ *
+ * \param visitor the visitor function that will be invoked for each
+ * field of \p T.
+ *
+ * \param client_data pointer data supplied by the client, which will
+ * be passed to the visitor each time it is invoked.
+ *
+ * \returns a non-zero value if the traversal was terminated
+ * prematurely by the visitor returning \c CXFieldVisit_Break.
+ */
+CINDEX_LINKAGE unsigned clang_visitCXXMethods(CXType T,
+                                              CXFieldVisitor visitor,
+                                              CXClientData client_data);
+
 /**
  * Describes the kind of binary operators.
  */
diff --git a/clang/tools/libclang/CIndexCXX.cpp b/clang/tools/libclang/CIndexCXX.cpp
index 8b84fdc22ecff1..4d8ff696950b34 100644
--- a/clang/tools/libclang/CIndexCXX.cpp
+++ b/clang/tools/libclang/CIndexCXX.cpp
@@ -54,6 +54,33 @@ unsigned clang_visitCXXBaseClasses(CXType PT, CXFieldVisitor visitor,
   return true;
 }
 
+unsigned clang_visitCXXMethods(CXType PT, CXFieldVisitor visitor,
+                               CXClientData client_data) {
+  CXCursor PC = clang_getTypeDeclaration(PT);
+  if (clang_isInvalid(PC.kind))
+    return false;
+  const CXXRecordDecl *RD =
+      dyn_cast_if_present<CXXRecordDecl>(cxcursor::getCursorDecl(PC));
+  if (!RD || RD->isInvalidDecl())
+    return false;
+  RD = RD->getDefinition();
+  if (!RD || RD->isInvalidDecl())
+    return false;
+
+  for (auto Method : RD->methods()) {
+    // Callback to the client.
+    switch (
+        visitor(cxcursor::MakeCXCursor(Method, getCursorTU(PC)),
+                client_data)) {
+    case CXVisit_Break:
+      return true;
+    case CXVisit_Continue:
+      break;
+    }
+  }
+  return true;
+}
+
 enum CX_CXXAccessSpecifier clang_getCXXAccessSpecifier(CXCursor C) {
   AccessSpecifier spec = AS_none;
 
diff --git a/clang/tools/libclang/libclang.map b/clang/tools/libclang/libclang.map
index 8ca8a58b76d9e0..a86c5a95303f8e 100644
--- a/clang/tools/libclang/libclang.map
+++ b/clang/tools/libclang/libclang.map
@@ -440,6 +440,7 @@ LLVM_20 {
     clang_getTypePrettyPrinted;
     clang_isBeforeInTranslationUnit;
     clang_visitCXXBaseClasses;
+    clang_visitCXXMethods;
 };
 
 # Example of how to add a new symbol version entry.  If you do add a new symbol

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⚠️ C/C++ code formatter, clang-format found issues in your code. ⚠️

You can test this locally with the following command:
git-clang-format --diff 293dbea8b0169525d93a4ee4b7d6c53aa9d4bee0 8aea4bc08a1f48819d8fa4e6608997b5f5c1d024 --extensions h,cpp -- clang/include/clang-c/Index.h clang/tools/libclang/CIndexCXX.cpp
View the diff from clang-format here.
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index 5d961ca0cd..d99fe3e48e 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -6699,8 +6699,7 @@ CINDEX_LINKAGE unsigned clang_visitCXXBaseClasses(CXType T,
  * \returns a non-zero value if the traversal was terminated
  * prematurely by the visitor returning \c CXFieldVisit_Break.
  */
-CINDEX_LINKAGE unsigned clang_visitCXXMethods(CXType T,
-                                              CXFieldVisitor visitor,
+CINDEX_LINKAGE unsigned clang_visitCXXMethods(CXType T, CXFieldVisitor visitor,
                                               CXClientData client_data);
 
 /**
diff --git a/clang/tools/libclang/CIndexCXX.cpp b/clang/tools/libclang/CIndexCXX.cpp
index 4d8ff69695..384be20c4f 100644
--- a/clang/tools/libclang/CIndexCXX.cpp
+++ b/clang/tools/libclang/CIndexCXX.cpp
@@ -70,8 +70,7 @@ unsigned clang_visitCXXMethods(CXType PT, CXFieldVisitor visitor,
   for (auto Method : RD->methods()) {
     // Callback to the client.
     switch (
-        visitor(cxcursor::MakeCXCursor(Method, getCursorTU(PC)),
-                client_data)) {
+        visitor(cxcursor::MakeCXCursor(Method, getCursorTU(PC)), client_data)) {
     case CXVisit_Break:
       return true;
     case CXVisit_Continue:

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The Python part looks mostly good to me. I'm not too familiar with the non-Python side of things though, so would like someone else to take a look as well.
@Endilll do you want to take a look?

Comment on lines 2055 to 2067
@property
def specialized(self):
"""
For a cursor that is instantiated from a template, returns a cursor
representing the template that it was instantiated from.
"""
if not hasattr(self, "_specialized"):
self._specialized = Cursor.from_result(
conf.lib.clang_getSpecializedCursorTemplate(self), self
)

return self._specialized

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This change seems unrelated to the rest of this PR, and should be in a separate one. It is also missing tests.

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removed this and will put into a different PR (with tests)

@trelau trelau force-pushed the class-methods-cindex branch from 8aea4bc to bb0542e Compare January 26, 2025 13:21
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Python part of this looks fine to me.
We need to rename fields_visit_callback to something else, but that's not in the scope of this PR.

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