[lldb] Update dwim-print to show expanded objc instances

When printing an ObjC object, which is a pointer, lldb has handled it like it treats any
other pointer, printing only pointer address and class name. The object is not expanded,
and its children are not shown.

This change updates the dwim-print to print expanded objc pointers - it is assumed
that's what the user meant.

Note that this is currently possible using the `--ptr-depth`/`-P` flag, but the default
is 0. With this change, when dwim-print prints objc objects, the default is effectively
changed to 1.

Author: kastiglione

lldb/include/lldb/DataFormatters/DumpValueObjectOptions.h

@@ -125,6 +125,8 @@ class DumpValueObjectOptions {
 
   DumpValueObjectOptions &SetRevealEmptyAggregates(bool reveal = true);
 
+  DumpValueObjectOptions &SetExpandPointerTypeFlags(unsigned flags);
+
   DumpValueObjectOptions &SetElementCount(uint32_t element_count = 0);
 
   DumpValueObjectOptions &
@@ -142,6 +144,7 @@ class DumpValueObjectOptions {
   DeclPrintingHelper m_decl_printing_helper;
   ChildPrintingDecider m_child_printing_decider;
   PointerAsArraySettings m_pointer_as_array;
+  unsigned m_expand_ptr_type_flags = 0;
   bool m_use_synthetic : 1;
   bool m_scope_already_checked : 1;
   bool m_flat_output : 1;

lldb/source/Commands/CommandObjectDWIMPrint.cpp

@@ -87,7 +87,8 @@ void CommandObjectDWIMPrint::DoExecute(StringRef command,
 
   DumpValueObjectOptions dump_options = m_varobj_options.GetAsDumpOptions(
       m_expr_options.m_verbosity, m_format_options.GetFormat());
-  dump_options.SetHideRootName(suppress_result);
+  dump_options.SetHideRootName(suppress_result)
+      .SetExpandPointerTypeFlags(lldb::eTypeIsObjC);
 
   bool is_po = m_varobj_options.use_objc;
 

lldb/source/DataFormatters/DumpValueObjectOptions.cpp

@@ -201,6 +201,12 @@ DumpValueObjectOptions::SetRevealEmptyAggregates(bool reveal) {
   return *this;
 }
 
+DumpValueObjectOptions &
+DumpValueObjectOptions::SetExpandPointerTypeFlags(unsigned flags) {
+  m_expand_ptr_type_flags = flags;
+  return *this;
+}
+
 DumpValueObjectOptions &
 DumpValueObjectOptions::SetElementCount(uint32_t element_count) {
   m_pointer_as_array = PointerAsArraySettings(element_count);

lldb/source/DataFormatters/ValueObjectPrinter.cpp

@@ -554,12 +554,14 @@ bool ValueObjectPrinter::ShouldPrintChildren(
       return false;
 
     const bool is_root_level = m_curr_depth == 0;
-
-    if (is_ref && is_root_level && print_children) {
-      // If this is the root object (depth is zero) that we are showing and
-      // it is a reference, and no pointer depth has been supplied print out
-      // what it references. Don't do this at deeper depths otherwise we can
-      // end up with infinite recursion...
+    const bool is_expanded_ptr =
+        is_ptr && m_type_flags.Test(m_options.m_expand_ptr_type_flags);
+
+    if ((is_ref || is_expanded_ptr) && is_root_level && print_children) {
+      // If this is the root object (depth is zero) that we are showing and it
+      // is either a reference or a preferred type of pointer, then print it.
+      // Don't do this at deeper depths otherwise we can end up with infinite
+      // recursion...
       return true;
     }
 

lldb/test/API/commands/dwim-print/objc/Makefile

@@ -0,0 +1,3 @@
+OBJC_SOURCES := main.m
+
+include Makefile.rules

lldb/test/API/commands/dwim-print/objc/TestDWIMPrintObjC.py

@@ -0,0 +1,16 @@
+"""
+Test dwim-print with objc instances.
+"""
+
+import lldb
+from lldbsuite.test.lldbtest import *
+from lldbsuite.test.decorators import *
+import lldbsuite.test.lldbutil as lldbutil
+
+
+class TestCase(TestBase):
+
+    def test(self):
+        self.build()
+        lldbutil.run_to_source_breakpoint(self, "break here", lldb.SBFileSpec("main.m"))
+        self.expect("dwim-print obj", substrs=["_number = 15"])

lldb/test/API/commands/dwim-print/objc/main.m

@@ -0,0 +1,15 @@
+#import <Foundation/Foundation.h>
+
+@interface Object : NSObject
+@property(nonatomic) int number;
+@end
+
+@implementation Object
+@end
+
+int main(int argc, char **argv) {
+  Object *obj = [Object new];
+  obj.number = 15;
+  puts("break here");
+  return 0;
+}