[LLDB] Fix GetIndexOfChildMemberWithName to handle anonymous structs. (#138487)

When handling anonymous structs, GetIndexOfChildMemberWithName needs to
add the number of non-empty base classes to the child index, to get the
actual correct index. It was not doing so. This fixes that.

Author: cmtice

lldb/source/Plugins/TypeSystem/Clang/TypeSystemClang.cpp

@@ -6743,7 +6743,9 @@ size_t TypeSystemClang::GetIndexOfChildMemberWithName(
           if (field_name.empty()) {
             CompilerType field_type = GetType(field->getType());
             std::vector<uint32_t> save_indices = child_indexes;
-            child_indexes.push_back(child_idx);
+            child_indexes.push_back(
+                child_idx + TypeSystemClang::GetNumBaseClasses(
+                                cxx_record_decl, omit_empty_base_classes));
             if (field_type.GetIndexOfChildMemberWithName(
                     name, omit_empty_base_classes, child_indexes))
               return child_indexes.size();

lldb/test/API/lang/cpp/type_lookup_anon_struct/Makefile

@@ -0,0 +1,3 @@
+CXX_SOURCES := main.cpp
+
+include Makefile.rules

lldb/test/API/lang/cpp/type_lookup_anon_struct/TestCppTypeLookupAnonStruct.py

@@ -0,0 +1,43 @@
+"""
+Test that we properly print multiple types.
+"""
+
+import lldb
+import lldbsuite.test.lldbutil as lldbutil
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import decorators
+
+
+class TestTypeLookupAnonStruct(TestBase):
+    def test_lookup_anon_struct(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, "// Set breakpoint here", lldb.SBFileSpec("main.cpp")
+        )
+
+        self.expect_var_path("unnamed_derived.y", value="2")
+        self.expect_var_path("unnamed_derived.z", value="13")
+        self.expect(
+            'frame variable "derb.x"',
+            error=True,
+            substrs=['"x" is not a member of "(DerivedB) derb"']
+        )
+        self.expect(
+            'frame variable "derb.y"',
+            error=True,
+            substrs=['"y" is not a member of "(DerivedB) derb"']
+        )
+        self.expect_var_path("derb.w", value="14")
+        self.expect_var_path("derb.k", value="15")
+        self.expect_var_path("derb.a.x", value="1")
+        self.expect_var_path("derb.a.y", value="2")
+
+        self.expect_var_path("multi1.m", value="16")
+        self.expect_var_path("multi1.y", value="30")
+
+        self.expect_var_path("multi2.i", value="42")
+        self.expect_var_path("multi2.w", value="23")
+        self.expect_var_path("multi2.a.x", value="1")
+        self.expect_var_path("multi2.a.y", value="2")
+        self.expect_var_path("multi2.y", value="2")
+        self.expect_var_path("multi2.n", value="7")

lldb/test/API/lang/cpp/type_lookup_anon_struct/main.cpp

@@ -0,0 +1,52 @@
+int main(int argc, char **argv) {
+  struct A {
+    struct {
+      int x = 1;
+    };
+    int y = 2;
+  } a;
+
+  struct B {
+    // Anonymous struct inherits another struct.
+    struct : public A {
+      int z = 3;
+    };
+    int w = 4;
+    A a;
+  } b;
+
+
+  struct EmptyBase {
+  };
+
+  struct : public A {
+    struct {
+      int z = 13;
+    };
+  } unnamed_derived;
+
+  struct DerivedB : public B {
+    struct {
+      // `w` in anonymous struct shadows `w` from `B`.
+      int w = 14;
+      int k = 15;
+    };
+  } derb;
+
+  struct MultiBase : public EmptyBase, public A {
+    struct {
+      int m = 16;
+      int y = 30;
+    };
+  } multi1;
+
+  struct MB2 : public B, EmptyBase, public A {
+    int i = 42;
+    struct {
+      int w = 23;
+      int n = 7;
+    };
+  } multi2;
+
+  return 0; // Set breakpoint here
+}