1 files changed, 77 insertions, 11 deletions

diff --git a/lldb/source/Commands/CommandObjectDWIMPrint.cpp b/lldb/source/Commands/CommandObjectDWIMPrint.cpp
index b2b7f201a5ad..695f3d7931cd 100644
--- a/lldb/source/Commands/CommandObjectDWIMPrint.cpp
+++ b/lldb/source/Commands/CommandObjectDWIMPrint.cpp
@@ -25,6 +25,8 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Support/FormatVariadic.h"
 
+#include <regex>
+
 using namespace llvm;
 using namespace lldb;
 using namespace lldb_private;
@@ -56,7 +58,7 @@ void CommandObjectDWIMPrint::HandleArgumentCompletion(
       GetCommandInterpreter(), lldb::eVariablePathCompletion, request, nullptr);
 }
 
-bool CommandObjectDWIMPrint::DoExecute(StringRef command,
+void CommandObjectDWIMPrint::DoExecute(StringRef command,
                                        CommandReturnObject &result) {
   m_option_group.NotifyOptionParsingStarting(&m_exe_ctx);
   OptionsWithRaw args{command};
@@ -65,13 +67,13 @@ bool CommandObjectDWIMPrint::DoExecute(StringRef command,
   if (expr.empty()) {
     result.AppendErrorWithFormatv("'{0}' takes a variable or expression",
                                   m_cmd_name);
-    return false;
+    return;
   }
 
   if (args.HasArgs()) {
     if (!ParseOptionsAndNotify(args.GetArgs(), result, m_option_group,
                                m_exe_ctx))
-      return false;
+      return;
   }
 
   // If the user has not specified, default to disabling persistent results.
@@ -95,8 +97,46 @@ bool CommandObjectDWIMPrint::DoExecute(StringRef command,
       m_expr_options.m_verbosity, m_format_options.GetFormat());
   dump_options.SetHideRootName(suppress_result);
 
+  bool is_po = m_varobj_options.use_objc;
+
   StackFrame *frame = m_exe_ctx.GetFramePtr();
 
+  // Either Swift was explicitly specified, or the frame is Swift.
+  lldb::LanguageType language = m_expr_options.language;
+  if (language == lldb::eLanguageTypeUnknown && frame)
+    language = frame->GuessLanguage();
+
+  // Add a hint if object description was requested, but no description
+  // function was implemented.
+  auto maybe_add_hint = [&](llvm::StringRef output) {
+    // Identify the default output of object description for Swift and
+    // Objective-C
+    // "<Name: 0x...>. The regex is:
+    // - Start with "<".
+    // - Followed by 1 or more non-whitespace characters.
+    // - Followed by ": 0x".
+    // - Followed by 5 or more hex digits.
+    // - Followed by ">".
+    // - End with zero or more whitespace characters.
+    const std::regex swift_class_regex("^<\\S+: 0x[[:xdigit:]]{5,}>\\s*$");
+
+    if (GetDebugger().GetShowDontUsePoHint() && target_ptr &&
+        (language == lldb::eLanguageTypeSwift ||
+         language == lldb::eLanguageTypeObjC) &&
+        std::regex_match(output.data(), swift_class_regex)) {
+
+      static bool note_shown = false;
+      if (note_shown)
+        return;
+
+      result.GetOutputStream()
+          << "note: object description requested, but type doesn't implement "
+             "a custom object description. Consider using \"p\" instead of "
+             "\"po\" (this note will only be shown once per debug session).\n";
+      note_shown = true;
+    }
+  };
+
   // First, try `expr` as the name of a frame variable.
   if (frame) {
     auto valobj_sp = frame->FindVariable(ConstString(expr));
@@ -114,9 +154,17 @@ bool CommandObjectDWIMPrint::DoExecute(StringRef command,
                                         flags, expr);
       }
 
-      valobj_sp->Dump(result.GetOutputStream(), dump_options);
+      if (is_po) {
+        StreamString temp_result_stream;
+        valobj_sp->Dump(temp_result_stream, dump_options);
+        llvm::StringRef output = temp_result_stream.GetString();
+        maybe_add_hint(output);
+        result.GetOutputStream() << output;
+      } else {
+        valobj_sp->Dump(result.GetOutputStream(), dump_options);
+      }
       result.SetStatus(eReturnStatusSuccessFinishResult);
-      return true;
+      return;
     }
   }
 
@@ -124,8 +172,19 @@ bool CommandObjectDWIMPrint::DoExecute(StringRef command,
   {
     auto *exe_scope = m_exe_ctx.GetBestExecutionContextScope();
     ValueObjectSP valobj_sp;
-    ExpressionResults expr_result =
-        target.EvaluateExpression(expr, exe_scope, valobj_sp, eval_options);
+    std::string fixed_expression;
+
+    ExpressionResults expr_result = target.EvaluateExpression(
+        expr, exe_scope, valobj_sp, eval_options, &fixed_expression);
+
+    // Only mention Fix-Its if the expression evaluator applied them.
+    // Compiler errors refer to the final expression after applying Fix-It(s).
+    if (!fixed_expression.empty() && target.GetEnableNotifyAboutFixIts()) {
+      Stream &error_stream = result.GetErrorStream();
+      error_stream << "  Evaluated this expression after applying Fix-It(s):\n";
+      error_stream << "    " << fixed_expression << "\n";
+    }
+
     if (expr_result == eExpressionCompleted) {
       if (verbosity != eDWIMPrintVerbosityNone) {
         StringRef flags;
@@ -135,8 +194,17 @@ bool CommandObjectDWIMPrint::DoExecute(StringRef command,
                                         expr);
       }
 
-      if (valobj_sp->GetError().GetError() != UserExpression::kNoResult)
-        valobj_sp->Dump(result.GetOutputStream(), dump_options);
+      if (valobj_sp->GetError().GetError() != UserExpression::kNoResult) {
+        if (is_po) {
+          StreamString temp_result_stream;
+          valobj_sp->Dump(temp_result_stream, dump_options);
+          llvm::StringRef output = temp_result_stream.GetString();
+          maybe_add_hint(output);
+          result.GetOutputStream() << output;
+        } else {
+          valobj_sp->Dump(result.GetOutputStream(), dump_options);
+        }
+      }
 
       if (suppress_result)
         if (auto result_var_sp =
@@ -148,14 +216,12 @@ bool CommandObjectDWIMPrint::DoExecute(StringRef command,
         }
 
       result.SetStatus(eReturnStatusSuccessFinishResult);
-      return true;
     } else {
       if (valobj_sp)
         result.SetError(valobj_sp->GetError());
       else
         result.AppendErrorWithFormatv(
             "unknown error evaluating expression `{0}`", expr);
-      return false;
     }
   }
 }