[lldb][ObjC] Consult Objective-C runtime decl vendor when completing type

lldb/source/Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.cpp

@@ -423,6 +423,46 @@ Status ObjCLanguageRuntime::ObjCExceptionPrecondition::ConfigurePrecondition(
   return error;
 }
 
+CompilerType ObjCLanguageRuntime::LookupInModulesVendor(ConstString class_name,
+                                                        Target &target) {
+  assert(class_name);
+
+  auto *persistent_state = llvm::cast<ClangPersistentVariables>(
+      target.GetPersistentExpressionStateForLanguage(lldb::eLanguageTypeC));
+  if (!persistent_state)
+    return {};
+
+  auto clang_modules_decl_vendor_sp =
+      persistent_state->GetClangModulesDeclVendor();
+  if (!clang_modules_decl_vendor_sp)
+    return {};
+
+  auto types = clang_modules_decl_vendor_sp->FindTypes(
+      class_name, /*max_matches*/ UINT32_MAX);
+  if (types.empty())
+    return {};
+
+  return types.front();
+}
+
+CompilerType ObjCLanguageRuntime::LookupInRuntime(ConstString class_name) {
+  auto *runtime_vendor = GetDeclVendor();
+  if (!runtime_vendor)
+    return {};
+
+  std::vector<CompilerDecl> compiler_decls;
+  runtime_vendor->FindDecls(class_name, false, UINT32_MAX, compiler_decls);
+  if (compiler_decls.empty())
+    return {};
+
+  auto *ctx =
+      llvm::dyn_cast<TypeSystemClang>(compiler_decls[0].GetTypeSystem());
+  if (!ctx)
+    return {};
+
+  return ctx->GetTypeForDecl(compiler_decls[0].GetOpaqueDecl());
+}
+
 std::optional<CompilerType>
 ObjCLanguageRuntime::GetRuntimeType(CompilerType base_type) {
   CompilerType class_type;
@@ -442,18 +482,21 @@ ObjCLanguageRuntime::GetRuntimeType(CompilerType base_type) {
   if (!class_name)
     return std::nullopt;
 
-  TypeSP complete_objc_class_type_sp = LookupInCompleteClassCache(class_name);
-  if (!complete_objc_class_type_sp)
-    return std::nullopt;
-
-  CompilerType complete_class(
-      complete_objc_class_type_sp->GetFullCompilerType());
-  if (complete_class.GetCompleteType()) {
-    if (is_pointer_type)
-      return complete_class.GetPointerType();
-    else
-      return complete_class;
+  if (TypeSP complete_objc_class_type_sp =
+          LookupInCompleteClassCache(class_name)) {
+    if (CompilerType complete_class =
+            complete_objc_class_type_sp->GetFullCompilerType();
+        complete_class.GetCompleteType())
+      return is_pointer_type ? complete_class.GetPointerType() : complete_class;
   }
 
+  assert(m_process);
+  if (CompilerType found =
+          LookupInModulesVendor(class_name, m_process->GetTarget()))
+    return is_pointer_type ? found.GetPointerType() : found;
+
+  if (CompilerType found = LookupInRuntime(class_name))
+    return is_pointer_type ? found.GetPointerType() : found;
+
   return std::nullopt;
 }

lldb/source/Plugins/LanguageRuntime/ObjC/ObjCLanguageRuntime.h

@@ -465,6 +465,10 @@ class ObjCLanguageRuntime : public LanguageRuntime {
 
   ObjCLanguageRuntime(const ObjCLanguageRuntime &) = delete;
   const ObjCLanguageRuntime &operator=(const ObjCLanguageRuntime &) = delete;
+
+private:
+  CompilerType LookupInRuntime(ConstString class_name);
+  CompilerType LookupInModulesVendor(ConstString class_name, Target &process);
 };
 
 } // namespace lldb_private

lldb/test/API/lang/objc/ivar-in-framework-base/Makefile

@@ -0,0 +1,6 @@
+OBJC_SOURCES := main.m lib.m
+LD_EXTRAS = -framework Foundation
+
+include Makefile.rules
+
+lib.o: CFLAGS = $(CFLAGS_NO_DEBUG)

lldb/test/API/lang/objc/ivar-in-framework-base/TestIvarInFrameworkBase.py

@@ -0,0 +1,39 @@
+import lldb
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test import lldbutil
+
+
+class TestIvarInFrameworkBase(TestBase):
+    """
+    Tests whether LLDB's data inspection commands can correctly retrieve
+    information about ivars from the Objective-C runtime.
+    In this test-case we have a base class type for which we don't have access
+    to the debug-info of the implementation (mimicking the scenario of subclassing
+    a type from a system framework). LLDB won't be able to see the backing ivar for
+    'fooProp' from just debug-info, but it will fall back on the runtime to get the
+    necessary information.
+    """
+
+    def test_frame_var(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(self, "break here", lldb.SBFileSpec("main.m"))
+        self.expect("frame variable *bar", substrs=["_fooProp = 10", "_barProp = 15"])
+
+    def test_expr(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(self, "break here", lldb.SBFileSpec("main.m"))
+        self.expect_expr(
+            "*bar",
+            result_type="Bar",
+            result_children=[
+                ValueCheck(
+                    name="Foo",
+                    children=[
+                        ValueCheck(name="NSObject"),
+                        ValueCheck(name="_fooProp", value="10"),
+                    ],
+                ),
+                ValueCheck(name="_barProp", value="15"),
+            ],
+        )

lldb/test/API/lang/objc/ivar-in-framework-base/lib.h

@@ -0,0 +1,6 @@
+#import <Foundation/Foundation.h>
+
+@interface Foo : NSObject
+@property int fooProp;
+- (id)init;
+@end

lldb/test/API/lang/objc/ivar-in-framework-base/lib.m

@@ -0,0 +1,8 @@
+#import "lib.h"
+
+@implementation Foo
+- (id)init {
+  self.fooProp = 10;
+  return self;
+}
+@end

lldb/test/API/lang/objc/ivar-in-framework-base/main.m

@@ -0,0 +1,22 @@
+#import "lib.h"
+#include <stdio.h>
+
+@interface Bar : Foo
+@property int barProp;
+- (id)init;
+@end
+
+@implementation Bar
+
+- (id)init {
+  self = [super init];
+  self.barProp = 15;
+  return self;
+}
+@end
+
+int main() {
+  Bar *bar = [Bar new];
+  puts("break here");
+  return 0;
+}