[Lldb-commits] [lldb] [lldb] Change po fallback messaging (PR #175847)

[Dave Lee via lldb-commits]

https://github.com/kastiglione created https://github.com/llvm/llvm-project/pull/175847

When an object description expression fails, instead of emitting an error, mark it as a
warning instead. Additionally, send the more low level details of the failure to the
`expr` log, and show a more user friendly message:

> `po` was unsuccessful, running `p` instead

rdar://165190497


>From 0ce3b0e13a4f8d8d06c2dc04e7cfcbe38eabd2f6 Mon Sep 17 00:00:00 2001
From: Dave Lee <davelee.com at gmail.com>
Date: Tue, 13 Jan 2026 13:43:35 -0800
Subject: [PATCH] [lldb] Change po fallback messaging

When an object description expression fails, instead of emitting an error, mark it as a
warning instead. Additionally, send the more low level details of the failure to the
`expr` log, and show a more user friendly message:

> `po` was unsuccessful, running `p` instead

rdar://165190497
---
 lldb/source/DataFormatters/ValueObjectPrinter.cpp | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/lldb/source/DataFormatters/ValueObjectPrinter.cpp b/lldb/source/DataFormatters/ValueObjectPrinter.cpp
index e20051140806b..bdad8c0cc2343 100644
--- a/lldb/source/DataFormatters/ValueObjectPrinter.cpp
+++ b/lldb/source/DataFormatters/ValueObjectPrinter.cpp
@@ -12,6 +12,7 @@
 #include "lldb/Interpreter/CommandInterpreter.h"
 #include "lldb/Target/Language.h"
 #include "lldb/Target/Target.h"
+#include "lldb/Utility/Log.h"
 #include "lldb/Utility/Stream.h"
 #include "lldb/ValueObject/ValueObject.h"
 #include "llvm/Support/Error.h"
@@ -100,8 +101,10 @@ llvm::Error ValueObjectPrinter::PrintValueObject() {
     llvm::Expected<std::string> object_desc_or_err =
         GetMostSpecializedValue().GetObjectDescription();
     if (!object_desc_or_err) {
-      auto error_msg = toString(object_desc_or_err.takeError());
-      *m_stream << "error: " << error_msg << maybeNewline(error_msg);
+      *m_stream << "warning: `po` was unsuccessful, running `p` instead";
+      LLDB_LOG_ERROR(GetLog(LLDBLog::Expressions),
+                     object_desc_or_err.takeError(),
+                     "Object description fallback due to error: {0}");
 
       // Print the value object directly.
       m_options.DisableObjectDescription();