[libclang] Add API to query more information about base classes. #120300
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@llvm/pr-subscribers-clang Author: Eli Friedman (efriedma-quic) ChangesThe first API is clang_visitCXXBaseClasses: this allows visiting the base classes without going through the generic child visitor (which is awkward, and doesn't work for template instantiations). The second API is clang_getOffsetOfBase; this allows computing the offset of a base in the class layout, the same way clang_Cursor_getOffsetOfField computes the offset of a field. Also, add a Python binding for the existing function clang_isVirtualBase. Full diff: https://github.com/llvm/llvm-project/pull/120300.diff 6 Files Affected:
diff --git a/clang/bindings/python/clang/cindex.py b/clang/bindings/python/clang/cindex.py
index f8a20a1e224724..6e26eca9ce0a01 100644
--- a/clang/bindings/python/clang/cindex.py
+++ b/clang/bindings/python/clang/cindex.py
@@ -2123,6 +2123,14 @@ def get_field_offsetof(self):
"""Returns the offsetof the FIELD_DECL pointed by this Cursor."""
return conf.lib.clang_Cursor_getOffsetOfField(self) # type: ignore [no-any-return]
+ def get_base_offsetof(self, parent):
+ """Returns the offsetof the CXX_BASE_SPECIFIER pointed by this Cursor."""
+ return conf.lib.clang_getOffsetOfBase(parent, self) # type: ignore [no-any-return]
+
+ def is_virtual_base(self):
+ """Returns whether the CXX_BASE_SPECIFIER pointed by this Cursor is virtual."""
+ return conf.lib.clang_isVirtualBase(self) # type: ignore [no-any-return]
+
def is_anonymous(self):
"""
Check if the record is anonymous.
@@ -2663,6 +2671,21 @@ def visitor(field, children):
conf.lib.clang_Type_visitFields(self, fields_visit_callback(visitor), fields)
return iter(fields)
+ def get_bases(self):
+ """Return an iterator for accessing the base classes of this type."""
+
+ def visitor(field, children):
+ assert field != conf.lib.clang_getNullCursor()
+
+ # Create reference to TU so it isn't GC'd before Cursor.
+ field._tu = self._tu
+ fields.append(field)
+ return 1 # continue
+
+ fields: list[Cursor] = []
+ conf.lib.clang_visitCXXBaseClasses(self, fields_visit_callback(visitor), fields)
+ return iter(fields)
+
def get_exception_specification_kind(self):
"""
Return the kind of the exception specification; a value from
@@ -3844,6 +3867,7 @@ def write_main_file_to_stdout(self):
("clang_getNumDiagnosticsInSet", [c_object_p], c_uint),
("clang_getNumElements", [Type], c_longlong),
("clang_getNumOverloadedDecls", [Cursor], c_uint),
+ ("clang_getOffsetOfBase", [Cursor, Cursor], c_longlong),
("clang_getOverloadedDecl", [Cursor, c_uint], Cursor),
("clang_getPointeeType", [Type], Type),
("clang_getRange", [SourceLocation, SourceLocation], SourceRange),
@@ -3895,6 +3919,7 @@ def write_main_file_to_stdout(self):
[TranslationUnit, SourceRange, POINTER(POINTER(Token)), POINTER(c_uint)],
),
("clang_visitChildren", [Cursor, cursor_visit_callback, py_object], c_uint),
+ ("clang_visitCXXBaseClasses", [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 ce05fdb1a1ebc0..76497bdcf9f43f 100644
--- a/clang/bindings/python/tests/cindex/test_type.py
+++ b/clang/bindings/python/tests/cindex/test_type.py
@@ -1,4 +1,5 @@
import os
+import clang.cindex
from clang.cindex import Config, CursorKind, RefQualifierKind, TranslationUnit, TypeKind
@@ -514,3 +515,28 @@ class Template {
# Variable without a template argument.
cursor = get_cursor(tu, "bar")
self.assertEqual(cursor.get_num_template_arguments(), -1)
+
+ def test_base_classes(self):
+ source = """
+ class A { int a; };
+ class B { int b; };
+ class C { int c; };
+ template <typename T>
+ class Template : public A, public B, virtual C {
+ };
+ Template<int> instance;
+ int bar;
+ """
+ tu = get_tu(source, lang="cpp")
+ cursor = get_cursor(tu, "instance")
+ cursor_type = cursor.type
+ cursor_type_decl = cursor_type.get_declaration()
+ self.assertEqual(cursor.kind, CursorKind.VAR_DECL)
+ bases = list(cursor_type.get_bases())
+ self.assertEqual(len(bases), 3)
+ self.assertFalse(bases[0].is_virtual_base())
+ self.assertEqual(bases[0].get_base_offsetof(cursor_type_decl), 64)
+ self.assertFalse(bases[1].is_virtual_base())
+ 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)
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index 0c5ac80772e2b9..6ee4043efc9112 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -3731,6 +3731,12 @@ CINDEX_LINKAGE enum CXRefQualifierKind clang_Type_getCXXRefQualifier(CXType T);
*/
CINDEX_LINKAGE unsigned clang_isVirtualBase(CXCursor);
+/**
+ * Returns the offset in bits of a CX_CXXBaseSpecifier relative to the parent
+ * class.
+ */
+CINDEX_LINKAGE long long clang_getOffsetOfBase(CXCursor Parent, CXCursor Base);
+
/**
* Represents the C++ access control level to a base class for a
* cursor with kind CX_CXXBaseSpecifier.
@@ -6600,6 +6606,29 @@ typedef enum CXVisitorResult (*CXFieldVisitor)(CXCursor C,
CINDEX_LINKAGE unsigned clang_Type_visitFields(CXType T, CXFieldVisitor visitor,
CXClientData client_data);
+/**
+ * Visit the base classes of a type.
+ *
+ * This function visits all the direct base classes of a the given cursor,
+ * invoking the given \p visitor function with the cursors of each
+ * visited base. 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_visitCXXBaseClasses(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 ea6f97d39644e1..16f82c9bdb29a5 100644
--- a/clang/tools/libclang/CIndexCXX.cpp
+++ b/clang/tools/libclang/CIndexCXX.cpp
@@ -27,6 +27,33 @@ unsigned clang_isVirtualBase(CXCursor C) {
return B->isVirtual();
}
+unsigned clang_visitCXXBaseClasses(CXType PT, CXFieldVisitor visitor,
+ CXClientData client_data) {
+ CXCursor PC = clang_getTypeDeclaration(PT);
+ if (clang_isInvalid(PC.kind))
+ return false;
+ const CXXRecordDecl *RD =
+ dyn_cast_or_null<CXXRecordDecl>(cxcursor::getCursorDecl(PC));
+ if (!RD || RD->isInvalidDecl())
+ return false;
+ RD = RD->getDefinition();
+ if (!RD || RD->isInvalidDecl())
+ return false;
+
+ for (auto &Base : RD->bases()) {
+ // Callback to the client.
+ switch (
+ visitor(cxcursor::MakeCursorCXXBaseSpecifier(&Base, 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/CXType.cpp b/clang/tools/libclang/CXType.cpp
index b4df12405cf356..da04e041bee455 100644
--- a/clang/tools/libclang/CXType.cpp
+++ b/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/RecordLayout.h"
#include "clang/AST/Type.h"
#include "clang/Basic/AddressSpaces.h"
#include "clang/Frontend/ASTUnit.h"
@@ -1094,6 +1095,39 @@ long long clang_Cursor_getOffsetOfField(CXCursor C) {
return -1;
}
+long long clang_getOffsetOfBase(CXCursor Parent, CXCursor Base) {
+ if (Base.kind != CXCursor_CXXBaseSpecifier)
+ return -1;
+
+ if (!clang_isDeclaration(Parent.kind))
+ return -1;
+
+ // we need to validate the parent type
+ CXType PT = clang_getCursorType(Parent);
+ long long Error = validateFieldParentType(Parent, PT);
+ if (Error < 0)
+ return Error;
+
+ const CXXRecordDecl *ParentRD =
+ dyn_cast<CXXRecordDecl>(cxcursor::getCursorDecl(Parent));
+ if (!ParentRD)
+ return -1;
+
+ ASTContext &Ctx = cxcursor::getCursorContext(Base);
+ const CXXBaseSpecifier *B = cxcursor::getCursorCXXBaseSpecifier(Base);
+ if (ParentRD->bases_begin() > B || ParentRD->bases_end() <= B)
+ return -1;
+
+ const CXXRecordDecl *BaseRD = B->getType()->getAsCXXRecordDecl();
+ if (!BaseRD)
+ return -1;
+
+ const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(ParentRD);
+ if (B->isVirtual())
+ return Ctx.toBits(Layout.getVBaseClassOffset(BaseRD));
+ return Ctx.toBits(Layout.getBaseClassOffset(BaseRD));
+}
+
enum CXRefQualifierKind clang_Type_getCXXRefQualifier(CXType T) {
QualType QT = GetQualType(T);
if (QT.isNull())
diff --git a/clang/tools/libclang/libclang.map b/clang/tools/libclang/libclang.map
index 25d8ba57d32514..09e6a5f8d3a33b 100644
--- a/clang/tools/libclang/libclang.map
+++ b/clang/tools/libclang/libclang.map
@@ -437,6 +437,8 @@ LLVM_19 {
LLVM_20 {
global:
clang_isBeforeInTranslationUnit;
+ clang_getOffsetOfBase;
+ clang_visitCXXBaseClasses;
};
# Example of how to add a new symbol version entry. If you do add a new symbol
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efriedma-quic
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Just referencing #121502 since this PR seem somewhat related (making it easier to iterate over things and pointed out it doesn't work for template instantiations, which might be the underlying problem I encountered). I'd like to keep using libclang (and its Python bindings), so if there is a new API that could be added to libclang or a modification somewhere that is obvious, let me know and I'll see if I can make an attempt at it. |
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For what it's worth, to get around my issue in #121502 I followed your same pattern here and added a Looking at CXXRecordDecl, perhaps the following might all be useful to add to the libclang API (including Python):
For my purposes of parsing C++ headers and generating Python bindings via pybind11, this bases PR plus adding the Adding I'll open a PR for the |
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I think the relevant code that prevents visiting template instantiations is CursorVisitor::VisitClassTemplateSpecializationDecl. It intentionally skips implicit template instantiations, I guess because of the origin of the API, which was focused around code written by the user.
It might be a little weird to see uninstantiated methods in some cases... but this probably makes sense.
get_fields() already exists. |
erichkeane
approved these changes
Jan 10, 2025
clang/tools/libclang/CIndexCXX.cpp
Outdated
| if (clang_isInvalid(PC.kind)) | ||
| return false; | ||
| const CXXRecordDecl *RD = | ||
| dyn_cast_or_null<CXXRecordDecl>(cxcursor::getCursorDecl(PC)); |
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are we supposed to be using the if_present versions or not?
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Yup, the or_null variants are deprecated in favor of the is_present ones.
clang/tools/libclang/CIndexCXX.cpp
Outdated
| if (clang_isInvalid(PC.kind)) | ||
| return false; | ||
| const CXXRecordDecl *RD = | ||
| dyn_cast_or_null<CXXRecordDecl>(cxcursor::getCursorDecl(PC)); |
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Yup, the or_null variants are deprecated in favor of the is_present ones.
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The first API is clang_visitCXXBaseClasses: this allows visiting the base classes without going through the generic child visitor (which is awkward, and doesn't work for template instantiations). The second API is clang_getOffsetOfBase; this allows computing the offset of a base in the class layout, the same way clang_Cursor_getOffsetOfField compues the offset of a field. Also, add a Python binding for the existing function clang_isVirtualBase.
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Addressed review comments |
DeinAlptraum
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Re Python: LGTM!
On a sidenote just fyi, there's no need to amend & forcepush when you adress review comments. I know the contributor guide says something about how you should have only a single commit when submitting a patch, but that goes only for the initial thing (I got confused by this at the start). We squash on merge anyways.
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/154/builds/10273 Here is the relevant piece of the build log for the reference |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/73/builds/11714 Here is the relevant piece of the build log for the reference |
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The 32-bit Arm failures are fixed by 7aec7ca . The other failures appear to be unrelated. |
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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. --------- Co-authored-by: Vlad Serebrennikov <serebrennikov.vladislav@gmail.com> Co-authored-by: Aaron Ballman <aaron@aaronballman.com>
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…3539) Inspired by llvm/llvm-project#120300, add a new API `clang_visitCXXMethods` to libclang (and the Python bindings) which allows iterating over the class methods of a type. --------- Co-authored-by: Vlad Serebrennikov <serebrennikov.vladislav@gmail.com> Co-authored-by: Aaron Ballman <aaron@aaronballman.com>
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The first API is clang_visitCXXBaseClasses: this allows visiting the base classes without going through the generic child visitor (which is awkward, and doesn't work for template instantiations).
The second API is clang_getOffsetOfBase; this allows computing the offset of a base in the class layout, the same way clang_Cursor_getOffsetOfField computes the offset of a field.
Also, add a Python binding for the existing function clang_isVirtualBase.