Make sure GetObjectDescription falls back to the Objective-C runtime.

[aprantl]

Summary

This fixes an unintended regression introduced by https://reviews.llvm.org/D61451 by making sure the Objective-C runtime is also tried when the "correct" language runtime failed to return an object description.

rdar://problem/50791055

[aprantl]

lldb/source/Core/ValueObject.cpp

1112 ↗

(On Diff #199852)

This check was redundant, it is also performed by the ObjC runtime.

[jasonmolenda]

My one concern is how this will work in a swift-lldb where we have a swift ValueObject, the print description fails, and we fall back to the ObjC print description. That's a change in behavior, right? I imagine worst case is that the objc print description will fail to produce anything and we'll have the same behavior as we do today.

lldb/packages/Python/lldbsuite/test/lang/objcxx/cxx-bridged-po/TestObjCXXBridgedPO.py

16 ↗

(On Diff #199852)

@skipUnlessDarwin

[aprantl]

Address review feedback.

[aprantl]

Added test for raw pointer values.

packages/Python/lldbsuite/test/lang/objcxx/cxx-bridged-po/Makefile

+LEVEL = ../../../make
+
+OBJCXX_SOURCES := main.mm
+LDFLAGS = $(CFLAGS) -lobjc -framework CoreFoundation
+
+include $(LEVEL)/Makefile.rules

packages/Python/lldbsuite/test/lang/objcxx/cxx-bridged-po/TestObjCXXBridgedPO.py

+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+
+class TestObjCXXBridgedPO(TestBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    def setUp(self):
+        TestBase.setUp(self)
+
+    @skipUnlessDarwin
+    def test_bridged_type_po(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(
+            self, 'break here', lldb.SBFileSpec('main.mm'))
+        self.expect('po num',
+                    "did not get the Objective-C object description",
+                    substrs=['CFNumber', '0x', '42'])
+        pointer_val = str(self.frame().FindVariable('num').GetValue())
+        self.expect('po '+pointer_val,
+                    "did not get the Objective-C object description",
+                    substrs=['CFNumber', '0x', '42'])

packages/Python/lldbsuite/test/lang/objcxx/cxx-bridged-po/main.mm

+#include <CoreFoundation/CoreFoundation.h>
+
+void stop() {}
+
+int main(int argc, char **argv)
+{
+  int value = 42;
+  CFNumberRef num;
+  num = CFNumberCreate(kCFAllocatorDefault, kCFNumberIntType, &value);
+  stop(); // break here
+  return 0;
+}

source/Core/ValueObject.cpp

std::pair<TypeValidatorResult, std::string> ValueObject::GetValidationStatus() {
 
   auto outcome = m_type_validator_sp->FormatObject(this);
 
   return (m_validation_result = {outcome.m_result, outcome.m_message})
       .getValue();
 }
 
 const char *ValueObject::GetObjectDescription() {
-
   if (!UpdateValueIfNeeded(true))
-    return NULL;
+    return nullptr;
 
+  // Return cached value.
   if (!m_object_desc_str.empty())
     return m_object_desc_str.c_str();
 
   ExecutionContext exe_ctx(GetExecutionContextRef());
   Process *process = exe_ctx.GetProcessPtr();
-  if (process == NULL)
-    return NULL;
+  if (!process)
+    return nullptr;
 
+  // Returns the object description produced by one language runtime.
+  auto get_object_description = [&](LanguageType language) -> const char * {
+    if (LanguageRuntime *runtime = process->GetLanguageRuntime(language)) {
       StreamString s;
-
-  LanguageType language = GetObjectRuntimeLanguage();
-  LanguageRuntime *runtime = process->GetLanguageRuntime(language);
-
-  if (runtime == NULL) {
-    // Aw, hell, if the things a pointer, or even just an integer, let's try
-    // ObjC anyway...
-    CompilerType compiler_type = GetCompilerType();
-    if (compiler_type) {
-      bool is_signed;
-      if (compiler_type.IsIntegerType(is_signed) ||
-          compiler_type.IsPointerType()) {
-        runtime = process->GetLanguageRuntime(eLanguageTypeObjC);
-      }
+      if (runtime->GetObjectDescription(s, *this)) {
+        m_object_desc_str.append(s.GetString());
+        return m_object_desc_str.c_str();
       }
     }
+    return nullptr;
+  };
 
-  if (runtime && runtime->GetObjectDescription(s, *this)) {
-    m_object_desc_str.append(s.GetString());
+  // Try the native language runtime first.
+  LanguageType native_language = GetObjectRuntimeLanguage();
+  if (const char *desc = get_object_description(native_language))
+    return desc;
+
+  switch (native_language) {
+  case eLanguageTypeC:
+  case eLanguageTypeC_plus_plus:
+  case eLanguageTypeObjC:
+  case eLanguageTypeObjC_plus_plus:
+    // Try the Objective-C language runtime. This fallback is necessary
+    // for Objective-C++ and mixed Objective-C / C++ programs.
+    return get_object_description(eLanguageTypeObjC);
+  default:
+    return nullptr;
   }
-
-  if (m_object_desc_str.empty())
-    return NULL;
-  else
-    return m_object_desc_str.c_str();
 }
 
 bool ValueObject::GetValueAsCString(const lldb_private::TypeFormatImpl &format,
                                     std::string &destination) {
   if (UpdateValueIfNeeded(false))
     return format.FormatObject(this, destination);
   else
     return false;