[Lldb-commits] [lldb] [lldb] Inline expression evaluator error visualization (PR #106470)

Adrian Prantl via lldb-commits lldb-commits at lists.llvm.org
Thu Sep 19 13:53:22 PDT 2024


https://github.com/adrian-prantl updated https://github.com/llvm/llvm-project/pull/106470

>From 8c682fc70bff5c6dff43c4601c14e5e61d11a08f Mon Sep 17 00:00:00 2001
From: Adrian Prantl <aprantl at apple.com>
Date: Wed, 28 Aug 2024 10:04:33 -0700
Subject: [PATCH 1/2] [lldb] Store expression evaluator diagnostics in an
 llvm::Error (NFC)

This patch is a reworking of Pete Lawrence's (@PortalPete) proposal
for better expression evaluator error messages:
https://github.com/llvm/llvm-project/pull/80938

This patch is preparatory patch for improving the rendering of
expression evaluator diagnostics. Currently diagnostics are rendered
into a string and the command interpreter layer then textually parses
words like "error:" to (sometimes) color the output accordingly. In
order to enable user interfaces to do better with diagnostics, we need
to store them in a machine-readable fromat. This patch does this by
adding a new llvm::Error kind wrapping a DiagnosticDetail struct that
is used when the error type is eErrorTypeExpression. Multiple
diagnostics are modeled using llvm::ErrorList.

Right now the extra information is not used by the CommandInterpreter,
this will be added in a follow-up patch!
---
 .../lldb/Expression/DiagnosticManager.h       | 91 +++++++++++++-----
 lldb/include/lldb/Utility/Status.h            |  5 +-
 lldb/source/Breakpoint/BreakpointLocation.cpp | 10 +-
 lldb/source/Expression/DiagnosticManager.cpp  | 94 +++++++++++++++----
 lldb/source/Expression/ExpressionParser.cpp   |  5 +-
 lldb/source/Expression/UserExpression.cpp     | 32 ++++---
 lldb/source/Expression/UtilityFunction.cpp    | 16 ++--
 .../ExpressionParser/Clang/ClangDiagnostic.h  |  5 +-
 .../Clang/ClangExpressionParser.cpp           | 69 ++++++++++----
 .../Clang/ClangUserExpression.h               |  2 +
 .../Plugins/Platform/POSIX/PlatformPOSIX.cpp  | 10 +-
 .../Platform/Windows/PlatformWindows.cpp      | 10 +-
 lldb/source/Target/Target.cpp                 |  2 +-
 lldb/source/Utility/Status.cpp                |  8 ++
 .../TestModulesCompileError.py                |  2 +-
 .../Expression/DiagnosticManagerTest.cpp      | 22 +++--
 lldb/unittests/Utility/StatusTest.cpp         |  2 +-
 17 files changed, 267 insertions(+), 118 deletions(-)

diff --git a/lldb/include/lldb/Expression/DiagnosticManager.h b/lldb/include/lldb/Expression/DiagnosticManager.h
index d49b7c99b114fb..1c0763eea92f05 100644
--- a/lldb/include/lldb/Expression/DiagnosticManager.h
+++ b/lldb/include/lldb/Expression/DiagnosticManager.h
@@ -12,6 +12,9 @@
 #include "lldb/lldb-defines.h"
 #include "lldb/lldb-types.h"
 
+#include "lldb/Utility/FileSpec.h"
+#include "lldb/Utility/Status.h"
+
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 
@@ -20,6 +23,52 @@
 
 namespace lldb_private {
 
+/// A compiler-independent representation of a Diagnostic. Expression
+/// evaluation failures often have more than one diagnostic that a UI
+/// layer might want to render differently, for example to colorize
+/// it.
+///
+/// Running example:
+///   (lldb) expr 1+foo
+///   error: <user expression 0>:1:3: use of undeclared identifier 'foo'
+///   1+foo
+///     ^
+struct DiagnosticDetail {
+  struct SourceLocation {
+    FileSpec file;
+    unsigned line = 0;
+    uint16_t column = 0;
+    uint16_t length = 0;
+    bool in_user_input = false;
+  };
+  /// Contains {{}, 1, 3, 3, true} in the example above.
+  std::optional<SourceLocation> source_location;
+  /// Contains eSeverityError in the example above.
+  lldb::Severity severity = lldb::eSeverityInfo;
+  /// Contains "use of undeclared identifier 'x'" in the example above.
+  std::string message;
+  /// Contains the fully rendered error message.
+  std::string rendered;
+};
+
+/// An llvm::Error used to communicate diagnostics in Status. Multiple
+/// diagnostics may be chained in an llvm::ErrorList.
+class DetailedExpressionError
+    : public llvm::ErrorInfo<DetailedExpressionError, CloneableError> {
+  DiagnosticDetail m_detail;
+
+public:
+  using llvm::ErrorInfo<DetailedExpressionError, CloneableError>::ErrorInfo;
+  DetailedExpressionError(DiagnosticDetail detail) : m_detail(detail) {}
+  std::string message() const override;
+  DiagnosticDetail GetDetail() const { return m_detail; }
+  std::error_code convertToErrorCode() const override;
+  void log(llvm::raw_ostream &OS) const override;
+  std::unique_ptr<CloneableError> Clone() const override;
+
+  static char ID;
+};
+
 enum DiagnosticOrigin {
   eDiagnosticOriginUnknown = 0,
   eDiagnosticOriginLLDB,
@@ -49,37 +98,28 @@ class Diagnostic {
     }
   }
 
-  Diagnostic(llvm::StringRef message, lldb::Severity severity,
-             DiagnosticOrigin origin, uint32_t compiler_id)
-      : m_message(message), m_severity(severity), m_origin(origin),
-        m_compiler_id(compiler_id) {}
-
-  Diagnostic(const Diagnostic &rhs)
-      : m_message(rhs.m_message), m_severity(rhs.m_severity),
-        m_origin(rhs.m_origin), m_compiler_id(rhs.m_compiler_id) {}
+  Diagnostic(DiagnosticOrigin origin, uint32_t compiler_id,
+             DiagnosticDetail detail)
+      : m_origin(origin), m_compiler_id(compiler_id), m_detail(detail) {}
 
   virtual ~Diagnostic() = default;
 
   virtual bool HasFixIts() const { return false; }
 
-  lldb::Severity GetSeverity() const { return m_severity; }
+  lldb::Severity GetSeverity() const { return m_detail.severity; }
 
   uint32_t GetCompilerID() const { return m_compiler_id; }
 
-  llvm::StringRef GetMessage() const { return m_message; }
+  llvm::StringRef GetMessage() const { return m_detail.message; }
+  llvm::Error GetAsError() const;
 
-  void AppendMessage(llvm::StringRef message,
-                     bool precede_with_newline = true) {
-    if (precede_with_newline)
-      m_message.push_back('\n');
-    m_message += message;
-  }
+  void AppendMessage(llvm::StringRef message, bool precede_with_newline = true);
 
 protected:
-  std::string m_message;
-  lldb::Severity m_severity;
   DiagnosticOrigin m_origin;
-  uint32_t m_compiler_id; // Compiler-specific diagnostic ID
+  /// Compiler-specific diagnostic ID.
+  uint32_t m_compiler_id;
+  DiagnosticDetail m_detail;
 };
 
 typedef std::vector<std::unique_ptr<Diagnostic>> DiagnosticList;
@@ -102,10 +142,7 @@ class DiagnosticManager {
 
   void AddDiagnostic(llvm::StringRef message, lldb::Severity severity,
                      DiagnosticOrigin origin,
-                     uint32_t compiler_id = LLDB_INVALID_COMPILER_ID) {
-    m_diagnostics.emplace_back(
-        std::make_unique<Diagnostic>(message, severity, origin, compiler_id));
-  }
+                     uint32_t compiler_id = LLDB_INVALID_COMPILER_ID);
 
   void AddDiagnostic(std::unique_ptr<Diagnostic> diagnostic) {
     if (diagnostic)
@@ -130,6 +167,14 @@ class DiagnosticManager {
       m_diagnostics.back()->AppendMessage(str);
   }
 
+  /// Copies the diagnostics into an llvm::Error{List}.
+  /// The first diagnostic wraps \c result.
+  llvm::Error GetAsError(lldb::ExpressionResults result) const;
+
+  /// Copies the diagnostics into an llvm::Error, the first diagnostic
+  /// being an llvm::StringError.
+  llvm::Error GetAsError(llvm::Twine msg) const;
+
   // Returns a string containing errors in this format:
   //
   // "error: error text\n
diff --git a/lldb/include/lldb/Utility/Status.h b/lldb/include/lldb/Utility/Status.h
index 084ce4afb8cefd..cac0fad4c3b309 100644
--- a/lldb/include/lldb/Utility/Status.h
+++ b/lldb/include/lldb/Utility/Status.h
@@ -175,8 +175,11 @@ class Status {
   /// Avoid using this in new code. Migrate APIs to llvm::Expected instead.
   static Status FromError(llvm::Error error);
 
-  /// FIXME: Replace this with a takeError() method.
+  /// FIXME: Replace all uses with takeError() instead.
   llvm::Error ToError() const;
+
+  llvm::Error takeError() { return std::move(m_error); }
+
   /// Don't call this function in new code. Instead, redesign the API
   /// to use llvm::Expected instead of Status.
   Status Clone() const { return Status(ToError()); }
diff --git a/lldb/source/Breakpoint/BreakpointLocation.cpp b/lldb/source/Breakpoint/BreakpointLocation.cpp
index 8d7364052a006a..fd9248eb0677c5 100644
--- a/lldb/source/Breakpoint/BreakpointLocation.cpp
+++ b/lldb/source/Breakpoint/BreakpointLocation.cpp
@@ -264,9 +264,9 @@ bool BreakpointLocation::ConditionSaysStop(ExecutionContext &exe_ctx,
     if (!m_user_expression_sp->Parse(diagnostics, exe_ctx,
                                      eExecutionPolicyOnlyWhenNeeded, true,
                                      false)) {
-      error = Status::FromErrorStringWithFormat(
-          "Couldn't parse conditional expression:\n%s",
-          diagnostics.GetString().c_str());
+      error = Status::FromError(
+          diagnostics.GetAsError("Couldn't parse conditional expression:"));
+
       m_user_expression_sp.reset();
       return true;
     }
@@ -324,8 +324,8 @@ bool BreakpointLocation::ConditionSaysStop(ExecutionContext &exe_ctx,
     }
   } else {
     ret = false;
-    error = Status::FromErrorStringWithFormat(
-        "Couldn't execute expression:\n%s", diagnostics.GetString().c_str());
+    error = Status::FromError(
+        diagnostics.GetAsError("Couldn't execute expression:"));
   }
 
   return ret;
diff --git a/lldb/source/Expression/DiagnosticManager.cpp b/lldb/source/Expression/DiagnosticManager.cpp
index a8330138f3d53b..99533aefb685b1 100644
--- a/lldb/source/Expression/DiagnosticManager.cpp
+++ b/lldb/source/Expression/DiagnosticManager.cpp
@@ -14,22 +14,7 @@
 #include "lldb/Utility/StreamString.h"
 
 using namespace lldb_private;
-
-void DiagnosticManager::Dump(Log *log) {
-  if (!log)
-    return;
-
-  std::string str = GetString();
-
-  // GetString() puts a separator after each diagnostic. We want to remove the
-  // last '\n' because log->PutCString will add one for us.
-
-  if (str.size() && str.back() == '\n') {
-    str.pop_back();
-  }
-
-  log->PutCString(str.c_str());
-}
+char DetailedExpressionError::ID;
 
 static const char *StringForSeverity(lldb::Severity severity) {
   switch (severity) {
@@ -44,9 +29,28 @@ static const char *StringForSeverity(lldb::Severity severity) {
   llvm_unreachable("switch needs another case for lldb::Severity enum");
 }
 
+std::string DetailedExpressionError::message() const {
+  std::string str;
+  llvm::raw_string_ostream(str)
+      << StringForSeverity(m_detail.severity) << m_detail.rendered;
+  return str;
+}
+
+std::error_code DetailedExpressionError::convertToErrorCode() const {
+  return llvm::inconvertibleErrorCode();
+}
+
+void DetailedExpressionError::log(llvm::raw_ostream &OS) const {
+  OS << message();
+}
+
+std::unique_ptr<CloneableError> DetailedExpressionError::Clone() const {
+  return std::make_unique<DetailedExpressionError>(m_detail);
+}
+
 std::string DiagnosticManager::GetString(char separator) {
-  std::string ret;
-  llvm::raw_string_ostream stream(ret);
+  std::string str;
+  llvm::raw_string_ostream stream(str);
 
   for (const auto &diagnostic : Diagnostics()) {
     llvm::StringRef severity = StringForSeverity(diagnostic->GetSeverity());
@@ -61,8 +65,50 @@ std::string DiagnosticManager::GetString(char separator) {
       stream << message.drop_front(severity_pos + severity.size());
     stream << separator;
   }
+  return str;
+}
 
-  return ret;
+void DiagnosticManager::Dump(Log *log) {
+  if (!log)
+    return;
+
+  std::string str = GetString();
+
+  // We want to remove the last '\n' because log->PutCString will add
+  // one for us.
+
+  if (str.size() && str.back() == '\n')
+    str.pop_back();
+
+  log->PutString(str);
+}
+
+llvm::Error Diagnostic::GetAsError() const {
+  return llvm::make_error<DetailedExpressionError>(m_detail);
+}
+
+llvm::Error
+DiagnosticManager::GetAsError(lldb::ExpressionResults result) const {
+  llvm::Error diags = Status::FromExpressionError(result, "").takeError();
+  for (const auto &diagnostic : m_diagnostics)
+    diags = llvm::joinErrors(std::move(diags), diagnostic->GetAsError());
+  return diags;
+}
+
+llvm::Error DiagnosticManager::GetAsError(llvm::Twine msg) const {
+  llvm::Error diags = llvm::createStringError(msg);
+  for (const auto &diagnostic : m_diagnostics)
+    diags = llvm::joinErrors(std::move(diags), diagnostic->GetAsError());
+  return diags;
+}
+
+void DiagnosticManager::AddDiagnostic(llvm::StringRef message,
+                                      lldb::Severity severity,
+                                      DiagnosticOrigin origin,
+                                      uint32_t compiler_id) {
+  m_diagnostics.emplace_back(std::make_unique<Diagnostic>(
+      origin, compiler_id,
+      DiagnosticDetail{{}, severity, message.str(), message.str()}));
 }
 
 size_t DiagnosticManager::Printf(lldb::Severity severity, const char *format,
@@ -85,3 +131,13 @@ void DiagnosticManager::PutString(lldb::Severity severity,
     return;
   AddDiagnostic(str, severity, eDiagnosticOriginLLDB);
 }
+
+void Diagnostic::AppendMessage(llvm::StringRef message,
+                               bool precede_with_newline) {
+  if (precede_with_newline) {
+    m_detail.message.push_back('\n');
+    m_detail.rendered.push_back('\n');
+  }
+  m_detail.message += message;
+  m_detail.rendered += message;
+}
diff --git a/lldb/source/Expression/ExpressionParser.cpp b/lldb/source/Expression/ExpressionParser.cpp
index 868556c1c58a57..26bc19874c53cc 100644
--- a/lldb/source/Expression/ExpressionParser.cpp
+++ b/lldb/source/Expression/ExpressionParser.cpp
@@ -63,9 +63,8 @@ ExpressionParser::RunStaticInitializers(IRExecutionUnitSP &execution_unit_sp,
             exe_ctx, call_static_initializer, options, execution_errors);
 
     if (results != eExpressionCompleted) {
-      err = Status::FromErrorStringWithFormat(
-          "couldn't run static initializer: %s",
-          execution_errors.GetString().c_str());
+      err = Status::FromError(
+          execution_errors.GetAsError("couldn't run static initializer:"));
       return err;
     }
   }
diff --git a/lldb/source/Expression/UserExpression.cpp b/lldb/source/Expression/UserExpression.cpp
index 872f6304f91baa..55ba857db88db6 100644
--- a/lldb/source/Expression/UserExpression.cpp
+++ b/lldb/source/Expression/UserExpression.cpp
@@ -328,18 +328,20 @@ UserExpression::Evaluate(ExecutionContext &exe_ctx,
     }
 
     if (!parse_success) {
-      std::string msg;
-      {
-        llvm::raw_string_ostream os(msg);
-        if (!diagnostic_manager.Diagnostics().empty())
-          os << diagnostic_manager.GetString();
-        else
-          os << "expression failed to parse (no further compiler diagnostics)";
-        if (target->GetEnableNotifyAboutFixIts() && fixed_expression &&
-            !fixed_expression->empty())
-          os << "\nfixed expression suggested:\n  " << *fixed_expression;
+      if (target->GetEnableNotifyAboutFixIts() && fixed_expression &&
+          !fixed_expression->empty()) {
+        std::string fixit =
+            "fixed expression suggested:\n  " + *fixed_expression;
+        diagnostic_manager.AddDiagnostic(fixit, lldb::eSeverityInfo,
+                                         eDiagnosticOriginLLDB);
       }
-      error = Status::FromExpressionError(execution_results, msg);
+      if (diagnostic_manager.Diagnostics().empty())
+        error = Status::FromExpressionError(
+            execution_results,
+            "expression failed to parse (no further compiler diagnostics)");
+      else
+        error =
+            Status::FromError(diagnostic_manager.GetAsError(execution_results));
     }
   }
 
@@ -351,7 +353,7 @@ UserExpression::Evaluate(ExecutionContext &exe_ctx,
       LLDB_LOG(log, "== [UserExpression::Evaluate] Expression may not run, but "
                     "is not constant ==");
 
-      if (!diagnostic_manager.Diagnostics().size())
+      if (diagnostic_manager.Diagnostics().empty())
         error = Status::FromExpressionError(
             lldb::eExpressionSetupError,
             "expression needed to run but couldn't");
@@ -380,12 +382,12 @@ UserExpression::Evaluate(ExecutionContext &exe_ctx,
         LLDB_LOG(log, "== [UserExpression::Evaluate] Execution completed "
                       "abnormally ==");
 
-        if (!diagnostic_manager.Diagnostics().size())
+        if (diagnostic_manager.Diagnostics().empty())
           error = Status::FromExpressionError(
               execution_results, "expression failed to execute, unknown error");
         else
-          error = Status::FromExpressionError(execution_results,
-                                              diagnostic_manager.GetString());
+          error = Status::FromError(
+              diagnostic_manager.GetAsError(execution_results));
       } else {
         if (expr_result) {
           result_valobj_sp = expr_result->GetValueObject();
diff --git a/lldb/source/Expression/UtilityFunction.cpp b/lldb/source/Expression/UtilityFunction.cpp
index 55ebfb8ef342e8..e35c0774815298 100644
--- a/lldb/source/Expression/UtilityFunction.cpp
+++ b/lldb/source/Expression/UtilityFunction.cpp
@@ -83,19 +83,18 @@ FunctionCaller *UtilityFunction::MakeFunctionCaller(
   m_caller_up.reset(process_sp->GetTarget().GetFunctionCallerForLanguage(
       Language().AsLanguageType(), return_type, impl_code_address,
       arg_value_list, name.c_str(), error));
-  if (error.Fail()) {
-
+  if (error.Fail())
     return nullptr;
-  }
+
   if (m_caller_up) {
     DiagnosticManager diagnostics;
 
     unsigned num_errors =
         m_caller_up->CompileFunction(thread_to_use_sp, diagnostics);
     if (num_errors) {
-      error = Status::FromErrorStringWithFormat(
-          "Error compiling %s caller function: \"%s\".",
-          m_function_name.c_str(), diagnostics.GetString().c_str());
+      error = Status::FromError(diagnostics.GetAsError(
+          "Error compiling " + m_function_name + " caller function:"));
+
       m_caller_up.reset();
       return nullptr;
     }
@@ -104,9 +103,8 @@ FunctionCaller *UtilityFunction::MakeFunctionCaller(
     ExecutionContext exe_ctx(process_sp);
 
     if (!m_caller_up->WriteFunctionWrapper(exe_ctx, diagnostics)) {
-      error = Status::FromErrorStringWithFormat(
-          "Error inserting caller function for %s: \"%s\".",
-          m_function_name.c_str(), diagnostics.GetString().c_str());
+      error = Status::FromError(diagnostics.GetAsError(
+          "Error inserting " + m_function_name + " caller function:"));
       m_caller_up.reset();
       return nullptr;
     }
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangDiagnostic.h b/lldb/source/Plugins/ExpressionParser/Clang/ClangDiagnostic.h
index 21abd71cc34eeb..c473df808ee8d0 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangDiagnostic.h
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangDiagnostic.h
@@ -29,9 +29,8 @@ class ClangDiagnostic : public Diagnostic {
     return diag->getKind() == eDiagnosticOriginClang;
   }
 
-  ClangDiagnostic(llvm::StringRef message, lldb::Severity severity,
-                  uint32_t compiler_id)
-      : Diagnostic(message, severity, eDiagnosticOriginClang, compiler_id) {}
+  ClangDiagnostic(DiagnosticDetail detail, uint32_t compiler_id)
+      : Diagnostic(eDiagnosticOriginClang, compiler_id, detail) {}
 
   ~ClangDiagnostic() override = default;
 
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
index 2fe3c0460aa7f8..92bd554767dae2 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -26,6 +26,7 @@
 #include "clang/Frontend/FrontendActions.h"
 #include "clang/Frontend/FrontendDiagnostic.h"
 #include "clang/Frontend/FrontendPluginRegistry.h"
+#include "clang/Frontend/TextDiagnostic.h"
 #include "clang/Frontend/TextDiagnosticBuffer.h"
 #include "clang/Frontend/TextDiagnosticPrinter.h"
 #include "clang/Lex/Preprocessor.h"
@@ -161,7 +162,8 @@ static void AddAllFixIts(ClangDiagnostic *diag, const clang::Diagnostic &Info) {
 
 class ClangDiagnosticManagerAdapter : public clang::DiagnosticConsumer {
 public:
-  ClangDiagnosticManagerAdapter(DiagnosticOptions &opts) {
+  ClangDiagnosticManagerAdapter(DiagnosticOptions &opts, StringRef filename)
+      : m_filename(filename) {
     DiagnosticOptions *options = new DiagnosticOptions(opts);
     options->ShowPresumedLoc = true;
     options->ShowLevel = false;
@@ -212,20 +214,20 @@ class ClangDiagnosticManagerAdapter : public clang::DiagnosticConsumer {
     m_passthrough->HandleDiagnostic(DiagLevel, Info);
     m_os->flush();
 
-    lldb::Severity severity;
+    DiagnosticDetail detail;
     bool make_new_diagnostic = true;
 
     switch (DiagLevel) {
     case DiagnosticsEngine::Level::Fatal:
     case DiagnosticsEngine::Level::Error:
-      severity = lldb::eSeverityError;
+      detail.severity = lldb::eSeverityError;
       break;
     case DiagnosticsEngine::Level::Warning:
-      severity = lldb::eSeverityWarning;
+      detail.severity = lldb::eSeverityWarning;
       break;
     case DiagnosticsEngine::Level::Remark:
     case DiagnosticsEngine::Level::Ignored:
-      severity = lldb::eSeverityInfo;
+      detail.severity = lldb::eSeverityInfo;
       break;
     case DiagnosticsEngine::Level::Note:
       m_manager->AppendMessageToDiagnostic(m_output);
@@ -254,14 +256,46 @@ class ClangDiagnosticManagerAdapter : public clang::DiagnosticConsumer {
       std::string stripped_output =
           std::string(llvm::StringRef(m_output).trim());
 
-      auto new_diagnostic = std::make_unique<ClangDiagnostic>(
-          stripped_output, severity, Info.getID());
+      // Translate the source location.
+      if (Info.hasSourceManager()) {
+        DiagnosticDetail::SourceLocation loc;
+        clang::SourceManager &sm = Info.getSourceManager();
+        const clang::SourceLocation sloc = Info.getLocation();
+        if (sloc.isValid()) {
+          const clang::FullSourceLoc fsloc(sloc, sm);
+          clang::PresumedLoc PLoc = fsloc.getPresumedLoc(true);
+          StringRef filename =
+              PLoc.isValid() ? PLoc.getFilename() : StringRef{};
+          loc.file = FileSpec(filename);
+          loc.line = fsloc.getSpellingLineNumber();
+          loc.column = fsloc.getSpellingColumnNumber();
+          loc.in_user_input = filename == m_filename;
+
+          // Find the range of the primary location.
+          for (const auto &range : Info.getRanges()) {
+            if (range.getBegin() == sloc) {
+              // FIXME: This is probably not handling wide characters correctly.
+              unsigned end_col = sm.getSpellingColumnNumber(range.getEnd());
+              if (end_col > loc.column)
+                loc.length = end_col - loc.column;
+              break;
+            }
+          }
+          detail.source_location = loc;
+        }
+      }
+      llvm::SmallString<0> msg;
+      Info.FormatDiagnostic(msg);
+      detail.message = msg.str();
+      detail.rendered = stripped_output;
+      auto new_diagnostic =
+          std::make_unique<ClangDiagnostic>(detail, Info.getID());
 
       // Don't store away warning fixits, since the compiler doesn't have
       // enough context in an expression for the warning to be useful.
       // FIXME: Should we try to filter out FixIts that apply to our generated
       // code, and not the user's expression?
-      if (severity == lldb::eSeverityError)
+      if (detail.severity == lldb::eSeverityError)
         AddAllFixIts(new_diagnostic.get(), Info);
 
       m_manager->AddDiagnostic(std::move(new_diagnostic));
@@ -281,6 +315,7 @@ class ClangDiagnosticManagerAdapter : public clang::DiagnosticConsumer {
   std::shared_ptr<llvm::raw_string_ostream> m_os;
   /// Output string filled by m_os.
   std::string m_output;
+  StringRef m_filename;
 };
 
 /// Returns true if the SDK for the specified triple supports
@@ -711,8 +746,8 @@ ClangExpressionParser::ClangExpressionParser(
 
   // 4. Set language options.
   SetupLangOpts(*m_compiler, *exe_scope, expr);
-  if (auto *clang_expr = dyn_cast<ClangUserExpression>(&m_expr);
-      clang_expr && clang_expr->DidImportCxxModules()) {
+  auto *clang_expr = dyn_cast<ClangUserExpression>(&m_expr);
+  if (clang_expr && clang_expr->DidImportCxxModules()) {
     LLDB_LOG(log, "Adding lang options for importing C++ modules");
     SetupImportStdModuleLangOpts(*m_compiler, *target_sp);
     SetupModuleHeaderPaths(m_compiler.get(), m_include_directories, target_sp);
@@ -739,9 +774,9 @@ ClangExpressionParser::ClangExpressionParser(
 		                 m_compiler->getLangOpts());
 
   // 5. Set up the diagnostic buffer for reporting errors
-
   auto diag_mgr = new ClangDiagnosticManagerAdapter(
-      m_compiler->getDiagnostics().getDiagnosticOptions());
+      m_compiler->getDiagnostics().getDiagnosticOptions(),
+      clang_expr ? clang_expr->GetFilename() : StringRef());
   m_compiler->getDiagnostics().setClient(diag_mgr);
 
   // 6. Set up the source management objects inside the compiler
@@ -1503,13 +1538,9 @@ lldb_private::Status ClangExpressionParser::DoPrepareForExecution(
               new ClangDynamicCheckerFunctions();
 
           DiagnosticManager install_diags;
-          if (Error Err = dynamic_checkers->Install(install_diags, exe_ctx)) {
-            std::string ErrMsg = "couldn't install checkers: " + toString(std::move(Err));
-            if (install_diags.Diagnostics().size())
-              ErrMsg = ErrMsg + "\n" + install_diags.GetString().c_str();
-            err = Status(ErrMsg);
-            return err;
-          }
+          if (Error Err = dynamic_checkers->Install(install_diags, exe_ctx))
+            return Status::FromError(
+                install_diags.GetAsError("couldn't install checkers:"));
 
           process->SetDynamicCheckers(dynamic_checkers);
 
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.h b/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.h
index 09604feea5dec4..7c0c6a0147e2a0 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.h
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangUserExpression.h
@@ -177,6 +177,8 @@ class ClangUserExpression : public LLVMUserExpression {
   /// Returns true iff this expression is using any imported C++ modules.
   bool DidImportCxxModules() const { return !m_imported_cpp_modules.empty(); }
 
+  llvm::StringRef GetFilename() const { return m_filename; }
+
 private:
   /// Populate m_in_cplusplus_method and m_in_objectivec_method based on the
   /// environment.
diff --git a/lldb/source/Plugins/Platform/POSIX/PlatformPOSIX.cpp b/lldb/source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
index 31315e46ca168d..5d873bf73da260 100644
--- a/lldb/source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
+++ b/lldb/source/Plugins/Platform/POSIX/PlatformPOSIX.cpp
@@ -863,9 +863,8 @@ uint32_t PlatformPOSIX::DoLoadImage(lldb_private::Process *process,
                                                  func_args_addr,
                                                  arguments,
                                                  diagnostics)) {
-    error = Status::FromErrorStringWithFormat(
-        "dlopen error: could not write function arguments: %s",
-        diagnostics.GetString().c_str());
+    error = Status::FromError(diagnostics.GetAsError(
+        "dlopen error: could not write function arguments:"));
     return LLDB_INVALID_IMAGE_TOKEN;
   }
   
@@ -906,9 +905,8 @@ uint32_t PlatformPOSIX::DoLoadImage(lldb_private::Process *process,
   ExpressionResults results = do_dlopen_function->ExecuteFunction(
       exe_ctx, &func_args_addr, options, diagnostics, return_value);
   if (results != eExpressionCompleted) {
-    error = Status::FromErrorStringWithFormat(
-        "dlopen error: failed executing dlopen wrapper function: %s",
-        diagnostics.GetString().c_str());
+    error = Status::FromError(diagnostics.GetAsError(
+        "dlopen error: failed executing dlopen wrapper function:"));
     return LLDB_INVALID_IMAGE_TOKEN;
   }
   
diff --git a/lldb/source/Plugins/Platform/Windows/PlatformWindows.cpp b/lldb/source/Plugins/Platform/Windows/PlatformWindows.cpp
index 7352d6f33f2174..fa39d93a91297c 100644
--- a/lldb/source/Plugins/Platform/Windows/PlatformWindows.cpp
+++ b/lldb/source/Plugins/Platform/Windows/PlatformWindows.cpp
@@ -341,9 +341,8 @@ uint32_t PlatformWindows::DoLoadImage(Process *process,
   diagnostics.Clear();
   if (!invocation->WriteFunctionArguments(context, injected_parameters,
                                           parameters, diagnostics)) {
-    error = Status::FromErrorStringWithFormat(
-        "LoadLibrary error: unable to write function parameters: %s",
-        diagnostics.GetString().c_str());
+    error = Status::FromError(diagnostics.GetAsError(
+        "LoadLibrary error: unable to write function parameters:"));
     return LLDB_INVALID_IMAGE_TOKEN;
   }
 
@@ -384,9 +383,8 @@ uint32_t PlatformWindows::DoLoadImage(Process *process,
       invocation->ExecuteFunction(context, &injected_parameters, options,
                                   diagnostics, value);
   if (result != eExpressionCompleted) {
-    error = Status::FromErrorStringWithFormat(
-        "LoadLibrary error: failed to execute LoadLibrary helper: %s",
-        diagnostics.GetString().c_str());
+    error = Status::FromError(diagnostics.GetAsError(
+        "LoadLibrary error: failed to execute LoadLibrary helper:"));
     return LLDB_INVALID_IMAGE_TOKEN;
   }
 
diff --git a/lldb/source/Target/Target.cpp b/lldb/source/Target/Target.cpp
index f1659aae0800db..57061ecd5bd445 100644
--- a/lldb/source/Target/Target.cpp
+++ b/lldb/source/Target/Target.cpp
@@ -2605,7 +2605,7 @@ Target::CreateUtilityFunction(std::string expression, std::string name,
 
   DiagnosticManager diagnostics;
   if (!utility_fn->Install(diagnostics, exe_ctx))
-    return llvm::createStringError(diagnostics.GetString());
+    return diagnostics.GetAsError("Could not install utility function:");
 
   return std::move(utility_fn);
 }
diff --git a/lldb/source/Utility/Status.cpp b/lldb/source/Utility/Status.cpp
index ba08353c7b24d2..3099e54af483ff 100644
--- a/lldb/source/Utility/Status.cpp
+++ b/lldb/source/Utility/Status.cpp
@@ -224,6 +224,14 @@ const char *Status::AsCString(const char *default_error_str) const {
     if (!m_string.empty() && m_string[m_string.size() - 1] == '\n')
       m_string.pop_back();
 
+  // FIXME: Workaround for ErrorList[ExpressionError, ...].
+  if (m_error.isA<llvm::ErrorList>()) {
+    while (!m_string.empty() && m_string[0] == '\n')
+      m_string = std::string(m_string.data() + 1, m_string.size() - 1);
+    if (!m_string.empty() && m_string[m_string.size() - 1] != '\n')
+      m_string += '\n';
+  }
+
   if (m_string.empty()) {
     if (default_error_str)
       m_string.assign(default_error_str);
diff --git a/lldb/test/API/lang/objc/modules-compile-error/TestModulesCompileError.py b/lldb/test/API/lang/objc/modules-compile-error/TestModulesCompileError.py
index 620b6e44fc852a..36e302be2525b5 100644
--- a/lldb/test/API/lang/objc/modules-compile-error/TestModulesCompileError.py
+++ b/lldb/test/API/lang/objc/modules-compile-error/TestModulesCompileError.py
@@ -21,7 +21,7 @@ def test(self):
             "expr @import LLDBTestModule",
             error=True,
             substrs=[
-                "module.h:4:1: use of undeclared identifier 'syntax_error_for_lldb_to_find'",
+                "module.h:4:1: error: use of undeclared identifier 'syntax_error_for_lldb_to_find'",
                 "syntax_error_for_lldb_to_find // comment that tests source printing",
                 "could not build module 'LLDBTestModule'",
             ],
diff --git a/lldb/unittests/Expression/DiagnosticManagerTest.cpp b/lldb/unittests/Expression/DiagnosticManagerTest.cpp
index 05fe7c164d6818..4608b779f79a96 100644
--- a/lldb/unittests/Expression/DiagnosticManagerTest.cpp
+++ b/lldb/unittests/Expression/DiagnosticManagerTest.cpp
@@ -19,8 +19,8 @@ class FixItDiag : public Diagnostic {
 
 public:
   FixItDiag(llvm::StringRef msg, bool has_fixits)
-      : Diagnostic(msg, lldb::eSeverityError,
-                   DiagnosticOrigin::eDiagnosticOriginLLDB, custom_diag_id),
+      : Diagnostic(DiagnosticOrigin::eDiagnosticOriginLLDB, custom_diag_id,
+                   DiagnosticDetail{{}, lldb::eSeverityError, msg.str(), {}}),
         m_has_fixits(has_fixits) {}
   bool HasFixIts() const override { return m_has_fixits; }
 };
@@ -30,8 +30,8 @@ namespace {
 class TextDiag : public Diagnostic {
 public:
   TextDiag(llvm::StringRef msg, lldb::Severity severity)
-      : Diagnostic(msg, severity, DiagnosticOrigin::eDiagnosticOriginLLDB,
-                   custom_diag_id) {}
+      : Diagnostic(DiagnosticOrigin::eDiagnosticOriginLLDB, custom_diag_id,
+                   DiagnosticDetail{{}, severity, msg.str(), msg.str()}) {}
 };
 } // namespace
 
@@ -42,8 +42,8 @@ TEST(DiagnosticManagerTest, AddDiagnostic) {
   std::string msg = "foo bar has happened";
   lldb::Severity severity = lldb::eSeverityError;
   DiagnosticOrigin origin = DiagnosticOrigin::eDiagnosticOriginLLDB;
-  auto diag =
-      std::make_unique<Diagnostic>(msg, severity, origin, custom_diag_id);
+  auto diag = std::make_unique<Diagnostic>(
+      origin, custom_diag_id, DiagnosticDetail{{}, severity, msg, {}});
   mgr.AddDiagnostic(std::move(diag));
   EXPECT_EQ(1U, mgr.Diagnostics().size());
   const Diagnostic *got = mgr.Diagnostics().front().get();
@@ -197,3 +197,13 @@ TEST(DiagnosticManagerTest, FixedExpression) {
   mgr.SetFixedExpression("bar");
   EXPECT_EQ("bar", mgr.GetFixedExpression());
 }
+
+TEST(DiagnosticManagerTest, StatusConversion) {
+  DiagnosticManager mgr;
+  mgr.AddDiagnostic(std::make_unique<TextDiag>("abc", lldb::eSeverityError));
+  mgr.AddDiagnostic(std::make_unique<TextDiag>("def", lldb::eSeverityWarning));
+  Status status =
+      Status::FromError(mgr.GetAsError(lldb::eExpressionParseError));
+  EXPECT_EQ(std::string("error: abc\nwarning: def\n"),
+            std::string(status.AsCString()));
+}
diff --git a/lldb/unittests/Utility/StatusTest.cpp b/lldb/unittests/Utility/StatusTest.cpp
index e37c94ac17f2d0..48110b160be93c 100644
--- a/lldb/unittests/Utility/StatusTest.cpp
+++ b/lldb/unittests/Utility/StatusTest.cpp
@@ -55,7 +55,7 @@ TEST(StatusTest, ErrorCodeConstructor) {
   llvm::Error list = llvm::joinErrors(llvm::createStringError("foo"),
                                       llvm::createStringError("bar"));
   Status foobar = Status::FromError(std::move(list));
-  EXPECT_EQ(std::string("foo\nbar"), std::string(foobar.AsCString()));
+  EXPECT_EQ(std::string("foo\nbar\n"), std::string(foobar.AsCString()));
 }
 
 TEST(StatusTest, ErrorConversion) {

>From f84f26610f1bed9ed6647f09fa6f27cde3126653 Mon Sep 17 00:00:00 2001
From: Adrian Prantl <aprantl at apple.com>
Date: Wed, 28 Aug 2024 16:19:21 -0700
Subject: [PATCH 2/2] [lldb] Inline expression evaluator error visualization
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This patch is a reworking of Pete Lawrence's (@PortalPete) proposal
for better expression evaluator error messages:
https://github.com/llvm/llvm-project/pull/80938

Before:

```
$ lldb -o "expr a+b"
(lldb) expr a+b
error: <user expression 0>:1:1: use of undeclared identifier 'a'
a+b
^
error: <user expression 0>:1:3: use of undeclared identifier 'b'
a+b
  ^
```

After:

```
(lldb) expr a+b
            ^ ^
            │ ╰─ error: use of undeclared identifier 'b'
            ╰─ error: use of undeclared identifier 'a'
```

This eliminates the confusing `<user expression 0>:1:3` source
location and avoids echoing the expression to the console again, which
results in a cleaner presentation that makes it easier to grasp what's
going on.
---
 .../lldb/Expression/DiagnosticManager.h       |   1 +
 lldb/include/lldb/Interpreter/CommandObject.h |   8 +
 .../Commands/CommandObjectExpression.cpp      | 157 ++++++++++++++++--
 .../source/Interpreter/CommandInterpreter.cpp |   4 +-
 .../Clang/ClangExpressionParser.cpp           |   8 +-
 .../ctf/CommandObjectThreadTraceExportCTF.h   |   2 +-
 lldb/source/Utility/Status.cpp                |   3 +-
 .../diagnostics/TestExprDiagnostics.py        |  50 ++++++
 .../TestPersistentVariables.py                |   4 +-
 .../TestStaticInitializers.py                 |   2 +-
 .../TestTemplateFunctions.py                  |   2 +-
 .../test/API/lang/mixed/TestMixedLanguages.py |   2 +-
 lldb/test/Shell/Expr/TestObjCIDCast.test      |   2 +-
 .../test/Shell/Expr/TestObjCInCXXContext.test |   2 +-
 .../NativePDB/incomplete-tag-type.cpp         |   4 +-
 .../Expression/DiagnosticManagerTest.cpp      |  33 ++--
 lldb/unittests/Interpreter/CMakeLists.txt     |   1 +
 .../TestCommandObjectExpression.cpp           |  34 ++++
 18 files changed, 274 insertions(+), 45 deletions(-)
 create mode 100644 lldb/unittests/Interpreter/TestCommandObjectExpression.cpp

diff --git a/lldb/include/lldb/Expression/DiagnosticManager.h b/lldb/include/lldb/Expression/DiagnosticManager.h
index 1c0763eea92f05..67e5082dff208e 100644
--- a/lldb/include/lldb/Expression/DiagnosticManager.h
+++ b/lldb/include/lldb/Expression/DiagnosticManager.h
@@ -39,6 +39,7 @@ struct DiagnosticDetail {
     unsigned line = 0;
     uint16_t column = 0;
     uint16_t length = 0;
+    bool hidden = false;
     bool in_user_input = false;
   };
   /// Contains {{}, 1, 3, 3, true} in the example above.
diff --git a/lldb/include/lldb/Interpreter/CommandObject.h b/lldb/include/lldb/Interpreter/CommandObject.h
index 20c4769af90338..c5167e5e0ecb6a 100644
--- a/lldb/include/lldb/Interpreter/CommandObject.h
+++ b/lldb/include/lldb/Interpreter/CommandObject.h
@@ -340,6 +340,13 @@ class CommandObject : public std::enable_shared_from_this<CommandObject> {
       return false;
   }
 
+  /// Set the command input as it appeared in the terminal. This
+  /// is used to have errors refer directly to the original command.
+  void SetOriginalCommandString(std::string s) { m_original_command = s; }
+
+  /// \param offset_in_command is on what column \c args_string
+  /// appears, if applicable. This enables diagnostics that refer back
+  /// to the user input.
   virtual void Execute(const char *args_string,
                        CommandReturnObject &result) = 0;
 
@@ -404,6 +411,7 @@ class CommandObject : public std::enable_shared_from_this<CommandObject> {
   std::string m_cmd_help_short;
   std::string m_cmd_help_long;
   std::string m_cmd_syntax;
+  std::string m_original_command;
   Flags m_flags;
   std::vector<CommandArgumentEntry> m_arguments;
   lldb::CommandOverrideCallback m_deprecated_command_override_callback;
diff --git a/lldb/source/Commands/CommandObjectExpression.cpp b/lldb/source/Commands/CommandObjectExpression.cpp
index 771194638e1b65..b5c6cd143eb06b 100644
--- a/lldb/source/Commands/CommandObjectExpression.cpp
+++ b/lldb/source/Commands/CommandObjectExpression.cpp
@@ -10,6 +10,7 @@
 
 #include "CommandObjectExpression.h"
 #include "lldb/Core/Debugger.h"
+#include "lldb/Expression/DiagnosticManager.h"
 #include "lldb/Expression/ExpressionVariable.h"
 #include "lldb/Expression/REPL.h"
 #include "lldb/Expression/UserExpression.h"
@@ -398,6 +399,122 @@ CanBeUsedForElementCountPrinting(ValueObject &valobj) {
   return Status();
 }
 
+static llvm::raw_ostream &PrintSeverity(Stream &stream,
+                                        lldb::Severity severity) {
+  llvm::HighlightColor color;
+  llvm::StringRef text;
+  switch (severity) {
+  case eSeverityError:
+    color = llvm::HighlightColor::Error;
+    text = "error: ";
+    break;
+  case eSeverityWarning:
+    color = llvm::HighlightColor::Warning;
+    text = "warning: ";
+    break;
+  case eSeverityInfo:
+    color = llvm::HighlightColor::Remark;
+    text = "note: ";
+    break;
+  }
+  return llvm::WithColor(stream.AsRawOstream(), color, llvm::ColorMode::Enable)
+         << text;
+}
+
+namespace lldb_private {
+// Public for unittesting.
+void RenderDiagnosticDetails(Stream &stream,
+                             std::optional<uint16_t> offset_in_command,
+                             bool multiline,
+                             llvm::ArrayRef<DiagnosticDetail> details) {
+  if (details.empty())
+    return;
+
+  if (!offset_in_command) {
+    for (const DiagnosticDetail &detail : details) {
+      PrintSeverity(stream, detail.severity);
+      stream << detail.rendered << '\n';
+    }
+    return;
+  }
+
+  // Print a line with caret indicator(s) below the lldb prompt + command.
+  const size_t padding = *offset_in_command;
+  stream << std::string(padding, ' ');
+
+  size_t offset = 1;
+  std::vector<DiagnosticDetail> remaining_details, other_details,
+      hidden_details;
+  for (const DiagnosticDetail &detail : details) {
+    if (multiline || !detail.source_location) {
+      other_details.push_back(detail);
+      continue;
+    }
+    if (detail.source_location->hidden) {
+      hidden_details.push_back(detail);
+      continue;
+    }
+    if (!detail.source_location->in_user_input) {
+      other_details.push_back(detail);
+      continue;
+    }
+
+    auto &loc = *detail.source_location;
+    remaining_details.push_back(detail);
+    if (offset > loc.column)
+      continue;
+    stream << std::string(loc.column - offset, ' ') << '^';
+    if (loc.length > 1)
+      stream << std::string(loc.length - 1, '~');
+    offset = loc.column + 1;
+  }
+  stream << '\n';
+
+  // Work through each detail in reverse order using the vector/stack.
+  bool did_print = false;
+  for (auto detail = remaining_details.rbegin();
+       detail != remaining_details.rend();
+       ++detail, remaining_details.pop_back()) {
+    // Get the information to print this detail and remove it from the stack.
+    // Print all the lines for all the other messages first.
+    stream << std::string(padding, ' ');
+    size_t offset = 1;
+    for (auto &remaining_detail :
+         llvm::ArrayRef(remaining_details).drop_back(1)) {
+      uint16_t column = remaining_detail.source_location->column;
+      stream << std::string(column - offset, ' ') << "│";
+      offset = column + 1;
+    }
+
+    // Print the line connecting the ^ with the error message.
+    uint16_t column = detail->source_location->column;
+    if (offset <= column)
+      stream << std::string(column - offset, ' ') << "╰─ ";
+
+    // Print a colorized string based on the message's severity type.
+    PrintSeverity(stream, detail->severity);
+
+    // Finally, print the message and start a new line.
+    stream << detail->message << '\n';
+    did_print = true;
+  }
+
+  // Print the non-located details.
+  for (const DiagnosticDetail &detail : other_details) {
+    PrintSeverity(stream, detail.severity);
+    stream << detail.rendered << '\n';
+    did_print = true;
+  }
+
+  // Print the hidden details as a last resort.
+  if (!did_print)
+    for (const DiagnosticDetail &detail : hidden_details) {
+      PrintSeverity(stream, detail.severity);
+      stream << detail.rendered << '\n';
+    }
+}
+} // namespace lldb_private
+
 bool CommandObjectExpression::EvaluateExpression(llvm::StringRef expr,
                                                  Stream &output_stream,
                                                  Stream &error_stream,
@@ -486,19 +603,37 @@ bool CommandObjectExpression::EvaluateExpression(llvm::StringRef expr,
 
         result.SetStatus(eReturnStatusSuccessFinishResult);
       } else {
-        const char *error_cstr = result_valobj_sp->GetError().AsCString();
-        if (error_cstr && error_cstr[0]) {
-          const size_t error_cstr_len = strlen(error_cstr);
-          const bool ends_with_newline = error_cstr[error_cstr_len - 1] == '\n';
-          if (strstr(error_cstr, "error:") != error_cstr)
-            error_stream.PutCString("error: ");
-          error_stream.Write(error_cstr, error_cstr_len);
-          if (!ends_with_newline)
-            error_stream.EOL();
+        // Retrieve the diagnostics.
+        std::vector<DiagnosticDetail> details;
+        llvm::consumeError(
+            llvm::handleErrors(result_valobj_sp->GetError().ToError(),
+                               [&](DetailedExpressionError &error) {
+                                 details.push_back(error.GetDetail());
+                               }));
+        // Find the position of the expression in the command.
+        std::optional<uint16_t> expr_pos;
+        size_t nchar = m_original_command.find(expr);
+        if (nchar != std::string::npos)
+          expr_pos = nchar + GetDebugger().GetPrompt().size();
+
+        if (!details.empty()) {
+          bool multiline = expr.contains('\n');
+          RenderDiagnosticDetails(error_stream, expr_pos, multiline, details);
         } else {
-          error_stream.PutCString("error: unknown error\n");
+          const char *error_cstr = result_valobj_sp->GetError().AsCString();
+          if (error_cstr && error_cstr[0]) {
+            const size_t error_cstr_len = strlen(error_cstr);
+            const bool ends_with_newline =
+                error_cstr[error_cstr_len - 1] == '\n';
+            if (strstr(error_cstr, "error:") != error_cstr)
+              error_stream.PutCString("error: ");
+            error_stream.Write(error_cstr, error_cstr_len);
+            if (!ends_with_newline)
+              error_stream.EOL();
+          } else {
+            error_stream.PutCString("error: unknown error\n");
+          }
         }
-
         result.SetStatus(eReturnStatusFailed);
       }
     }
diff --git a/lldb/source/Interpreter/CommandInterpreter.cpp b/lldb/source/Interpreter/CommandInterpreter.cpp
index b93f47a8a8d5ec..49681f06802443 100644
--- a/lldb/source/Interpreter/CommandInterpreter.cpp
+++ b/lldb/source/Interpreter/CommandInterpreter.cpp
@@ -1887,7 +1887,8 @@ bool CommandInterpreter::HandleCommand(const char *command_line,
                                        CommandReturnObject &result,
                                        bool force_repeat_command) {
   std::string command_string(command_line);
-  std::string original_command_string(command_line);
+  std::string original_command_string(command_string);
+  std::string real_original_command_string(command_string);
 
   Log *log = GetLog(LLDBLog::Commands);
   llvm::PrettyStackTraceFormat stack_trace("HandleCommand(command = \"%s\")",
@@ -2076,6 +2077,7 @@ bool CommandInterpreter::HandleCommand(const char *command_line,
     }
 
     ElapsedTime elapsed(execute_time);
+    cmd_obj->SetOriginalCommandString(real_original_command_string);
     cmd_obj->Execute(remainder.c_str(), result);
   }
 
diff --git a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
index 92bd554767dae2..2aac25543a3a0f 100644
--- a/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
+++ b/lldb/source/Plugins/ExpressionParser/Clang/ClangExpressionParser.cpp
@@ -215,8 +215,6 @@ class ClangDiagnosticManagerAdapter : public clang::DiagnosticConsumer {
     m_os->flush();
 
     DiagnosticDetail detail;
-    bool make_new_diagnostic = true;
-
     switch (DiagLevel) {
     case DiagnosticsEngine::Level::Fatal:
     case DiagnosticsEngine::Level::Error:
@@ -230,9 +228,6 @@ class ClangDiagnosticManagerAdapter : public clang::DiagnosticConsumer {
       detail.severity = lldb::eSeverityInfo;
       break;
     case DiagnosticsEngine::Level::Note:
-      m_manager->AppendMessageToDiagnostic(m_output);
-      make_new_diagnostic = false;
-
       // 'note:' diagnostics for errors and warnings can also contain Fix-Its.
       // We add these Fix-Its to the last error diagnostic to make sure
       // that we later have all Fix-Its related to an 'error' diagnostic when
@@ -250,7 +245,6 @@ class ClangDiagnosticManagerAdapter : public clang::DiagnosticConsumer {
       AddAllFixIts(clang_diag, Info);
       break;
     }
-    if (make_new_diagnostic) {
       // ClangDiagnostic messages are expected to have no whitespace/newlines
       // around them.
       std::string stripped_output =
@@ -270,6 +264,7 @@ class ClangDiagnosticManagerAdapter : public clang::DiagnosticConsumer {
           loc.line = fsloc.getSpellingLineNumber();
           loc.column = fsloc.getSpellingColumnNumber();
           loc.in_user_input = filename == m_filename;
+          loc.hidden = filename.starts_with("<lldb wrapper ");
 
           // Find the range of the primary location.
           for (const auto &range : Info.getRanges()) {
@@ -299,7 +294,6 @@ class ClangDiagnosticManagerAdapter : public clang::DiagnosticConsumer {
         AddAllFixIts(new_diagnostic.get(), Info);
 
       m_manager->AddDiagnostic(std::move(new_diagnostic));
-    }
   }
 
   void BeginSourceFile(const LangOptions &LO, const Preprocessor *PP) override {
diff --git a/lldb/source/Plugins/TraceExporter/ctf/CommandObjectThreadTraceExportCTF.h b/lldb/source/Plugins/TraceExporter/ctf/CommandObjectThreadTraceExportCTF.h
index 1a034e87cfb65b..06834edf14ea16 100644
--- a/lldb/source/Plugins/TraceExporter/ctf/CommandObjectThreadTraceExportCTF.h
+++ b/lldb/source/Plugins/TraceExporter/ctf/CommandObjectThreadTraceExportCTF.h
@@ -48,7 +48,7 @@ class CommandObjectThreadTraceExportCTF : public CommandObjectParsed {
   Options *GetOptions() override { return &m_options; }
 
 protected:
-  void DoExecute(Args &command, CommandReturnObject &result) override;
+  void DoExecute(Args &args, CommandReturnObject &result) override;
 
   CommandOptions m_options;
 };
diff --git a/lldb/source/Utility/Status.cpp b/lldb/source/Utility/Status.cpp
index 3099e54af483ff..e2c3029244735e 100644
--- a/lldb/source/Utility/Status.cpp
+++ b/lldb/source/Utility/Status.cpp
@@ -8,6 +8,7 @@
 
 #include "lldb/Utility/Status.h"
 
+#include "lldb/Expression/DiagnosticManager.h"
 #include "lldb/Utility/LLDBLog.h"
 #include "lldb/Utility/Log.h"
 #include "lldb/Utility/VASPrintf.h"
@@ -279,8 +280,6 @@ ErrorType Status::GetType() const {
     else if (error.convertToErrorCode().category() == lldb_generic_category() ||
              error.convertToErrorCode() == llvm::inconvertibleErrorCode())
       result = eErrorTypeGeneric;
-    else
-      result = eErrorTypeInvalid;
   });
   return result;
 }
diff --git a/lldb/test/API/commands/expression/diagnostics/TestExprDiagnostics.py b/lldb/test/API/commands/expression/diagnostics/TestExprDiagnostics.py
index ddc1c3598480cf..f81d3852946b9a 100644
--- a/lldb/test/API/commands/expression/diagnostics/TestExprDiagnostics.py
+++ b/lldb/test/API/commands/expression/diagnostics/TestExprDiagnostics.py
@@ -183,3 +183,53 @@ def test_source_locations_from_objc_modules(self):
         # The NSLog definition source line should be printed. Return value and
         # the first argument are probably stable enough that this test can check for them.
         self.assertIn("void NSLog(NSString *format", value.GetError().GetCString())
+
+    def test_command_expr_formatting(self):
+        """Test that the source and caret positions LLDB prints are correct"""
+        self.build()
+
+        (target, process, thread, bkpt) = lldbutil.run_to_source_breakpoint(
+            self, "// Break here", self.main_source_spec
+        )
+        frame = thread.GetFrameAtIndex(0)
+
+        def check(input_ref):
+            self.expect(input_ref[0], error=True, substrs=input_ref[1:])
+
+        check(
+            [
+                "expression -- a+b",
+                "              ^ ^",
+                "              │ ╰─ error: use of undeclared identifier 'b'",
+                "              ╰─ error: use of undeclared identifier 'a'",
+            ]
+        )
+
+        check(
+            [
+                "expr -- a",
+                "        ^",
+                "        ╰─ error: use of undeclared identifier 'a'",
+            ]
+        )
+        check(
+            [
+                "expr -i 0 -o 0 -- a",
+                "                  ^",
+                "                  ╰─ error: use of undeclared identifier 'a'",
+            ]
+        )
+
+        self.expect(
+            "expression --top-level -- template<typename T> T FOO(T x) { return x/2;}"
+        )
+        check(
+            [
+                'expression -- FOO("")',
+                "              ^",
+                "              ╰─ note: in instantiation of function template specialization 'FOO<const char *>' requested here",
+                "error: <user expression",
+                "invalid operands to binary expression",
+            ]
+        )
+        check(["expression --\na\n+\nb", "error: <user", "a", "error: <user", "b"])
diff --git a/lldb/test/API/commands/expression/persistent_variables/TestPersistentVariables.py b/lldb/test/API/commands/expression/persistent_variables/TestPersistentVariables.py
index 6a7995ff2a837e..d0d9358589a719 100644
--- a/lldb/test/API/commands/expression/persistent_variables/TestPersistentVariables.py
+++ b/lldb/test/API/commands/expression/persistent_variables/TestPersistentVariables.py
@@ -56,7 +56,7 @@ def test_persistent_variables(self):
         self.expect(
             "expr int $i = 123",
             error=True,
-            substrs=["error: redefinition of persistent variable '$i'"],
+            substrs=["redefinition of persistent variable '$i'"],
         )
         self.expect_expr("$i", result_type="int", result_value="5")
 
@@ -65,7 +65,7 @@ def test_persistent_variables(self):
         self.expect(
             "expr long $i = 123",
             error=True,
-            substrs=["error: redefinition of persistent variable '$i'"],
+            substrs=["redefinition of persistent variable '$i'"],
         )
         self.expect_expr("$i", result_type="int", result_value="5")
 
diff --git a/lldb/test/API/commands/expression/static-initializers/TestStaticInitializers.py b/lldb/test/API/commands/expression/static-initializers/TestStaticInitializers.py
index ea3aa6a4608c41..c734033bd6c028 100644
--- a/lldb/test/API/commands/expression/static-initializers/TestStaticInitializers.py
+++ b/lldb/test/API/commands/expression/static-initializers/TestStaticInitializers.py
@@ -35,7 +35,7 @@ def test_failing_init(self):
         self.expect(
             "expr -p -- struct Foo2 { Foo2() { do_abort(); } }; Foo2 f;",
             error=True,
-            substrs=["error: couldn't run static initializer:"],
+            substrs=["couldn't run static initializer:"],
         )
 
     def test_without_process(self):
diff --git a/lldb/test/API/lang/cpp/template-function/TestTemplateFunctions.py b/lldb/test/API/lang/cpp/template-function/TestTemplateFunctions.py
index 71df90e6a6d161..8d4200b1076d03 100644
--- a/lldb/test/API/lang/cpp/template-function/TestTemplateFunctions.py
+++ b/lldb/test/API/lang/cpp/template-function/TestTemplateFunctions.py
@@ -21,7 +21,7 @@ def do_test_template_function(self, add_cast):
                 "expr b1 <=> b2",
                 error=True,
                 substrs=[
-                    "warning: <user expression 0>:1:4: '<=>' is a single token in C++20; add a space to avoid a change in behavior"
+                    "warning:", "'<=>' is a single token in C++20; add a space to avoid a change in behavior"
                 ],
             )
 
diff --git a/lldb/test/API/lang/mixed/TestMixedLanguages.py b/lldb/test/API/lang/mixed/TestMixedLanguages.py
index 8b73254cce4a93..1637d59a5edcba 100644
--- a/lldb/test/API/lang/mixed/TestMixedLanguages.py
+++ b/lldb/test/API/lang/mixed/TestMixedLanguages.py
@@ -40,7 +40,7 @@ def cleanup():
         self.runCmd("run")
         self.expect("thread backtrace", substrs=["`main", "lang=c"])
         # Make sure evaluation of C++11 fails.
-        self.expect("expr foo != nullptr", error=True, startstr="error")
+        self.expect("expr foo != nullptr", error=True, substrs=["error"])
 
         # Run to BP at foo (in foo.cpp) and test that the language is C++.
         self.runCmd("breakpoint set -n foo")
diff --git a/lldb/test/Shell/Expr/TestObjCIDCast.test b/lldb/test/Shell/Expr/TestObjCIDCast.test
index 0611171da09e2e..19ca404643c1d9 100644
--- a/lldb/test/Shell/Expr/TestObjCIDCast.test
+++ b/lldb/test/Shell/Expr/TestObjCIDCast.test
@@ -6,4 +6,4 @@
 // RUN:   2>&1 | FileCheck %s
 
 // CHECK: (lldb) expression --language objc -- *(id)0x1
-// CHECK: error: Couldn't apply expression side effects : Couldn't dematerialize a result variable: couldn't read its memory
+// CHECK: error:{{.*}}Couldn't apply expression side effects : Couldn't dematerialize a result variable: couldn't read its memory
diff --git a/lldb/test/Shell/Expr/TestObjCInCXXContext.test b/lldb/test/Shell/Expr/TestObjCInCXXContext.test
index 8537799bdeb674..f8cad5b58a1e53 100644
--- a/lldb/test/Shell/Expr/TestObjCInCXXContext.test
+++ b/lldb/test/Shell/Expr/TestObjCInCXXContext.test
@@ -18,4 +18,4 @@
 // CHECK-NEXT: (NSString *){{.*}}= nil
 
 // CHECK:      (lldb) expression NSString
-// CHECK-NEXT: error:{{.*}} use of undeclared identifier 'NSString'
+// CHECK:      error:{{.*}}use of undeclared identifier 'NSString'
diff --git a/lldb/test/Shell/SymbolFile/NativePDB/incomplete-tag-type.cpp b/lldb/test/Shell/SymbolFile/NativePDB/incomplete-tag-type.cpp
index a249057282d890..8c168286903014 100644
--- a/lldb/test/Shell/SymbolFile/NativePDB/incomplete-tag-type.cpp
+++ b/lldb/test/Shell/SymbolFile/NativePDB/incomplete-tag-type.cpp
@@ -13,9 +13,7 @@
 // CHECK: (lldb) expression d
 // CHECK: (D) $1 = {}
 // CHECK: (lldb) expression static_e_ref
-// CHECK: error: {{.*}}incomplete type 'E' where a complete type is required
-// CHECK: static_e_ref
-// CHECK: ^
+// CHECK: error:{{.*}}incomplete type 'E' where a complete type is required
 
 // Complete base class.
 struct A { int x; A(); };
diff --git a/lldb/unittests/Expression/DiagnosticManagerTest.cpp b/lldb/unittests/Expression/DiagnosticManagerTest.cpp
index 4608b779f79a96..2373b8101bf4e2 100644
--- a/lldb/unittests/Expression/DiagnosticManagerTest.cpp
+++ b/lldb/unittests/Expression/DiagnosticManagerTest.cpp
@@ -72,18 +72,25 @@ TEST(DiagnosticManagerTest, HasFixits) {
   EXPECT_TRUE(mgr.HasFixIts());
 }
 
+static std::string toString(DiagnosticManager &mgr) {
+  std::string s = llvm::toString(mgr.GetAsError(""));
+  if (s.empty())
+    return s;
+  return s.substr(1) + "\n";
+}
+
 TEST(DiagnosticManagerTest, GetStringNoDiags) {
   DiagnosticManager mgr;
-  EXPECT_EQ("", mgr.GetString());
+  EXPECT_EQ("", toString(mgr));
   std::unique_ptr<Diagnostic> empty;
   mgr.AddDiagnostic(std::move(empty));
-  EXPECT_EQ("", mgr.GetString());
+  EXPECT_EQ("", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, GetStringBasic) {
   DiagnosticManager mgr;
   mgr.AddDiagnostic(std::make_unique<TextDiag>("abc", lldb::eSeverityError));
-  EXPECT_EQ("error: abc\n", mgr.GetString());
+  EXPECT_EQ("error: abc\n", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, GetStringMultiline) {
@@ -91,15 +98,15 @@ TEST(DiagnosticManagerTest, GetStringMultiline) {
 
   // Multiline diagnostics should only get one severity label.
   mgr.AddDiagnostic(std::make_unique<TextDiag>("b\nc", lldb::eSeverityError));
-  EXPECT_EQ("error: b\nc\n", mgr.GetString());
+  EXPECT_EQ("error: b\nc\n", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, GetStringMultipleDiags) {
   DiagnosticManager mgr;
   mgr.AddDiagnostic(std::make_unique<TextDiag>("abc", lldb::eSeverityError));
-  EXPECT_EQ("error: abc\n", mgr.GetString());
+  EXPECT_EQ("error: abc\n", toString(mgr));
   mgr.AddDiagnostic(std::make_unique<TextDiag>("def", lldb::eSeverityError));
-  EXPECT_EQ("error: abc\nerror: def\n", mgr.GetString());
+  EXPECT_EQ("error: abc\nerror: def\n", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, GetStringSeverityLabels) {
@@ -110,7 +117,7 @@ TEST(DiagnosticManagerTest, GetStringSeverityLabels) {
   mgr.AddDiagnostic(std::make_unique<TextDiag>("bar", lldb::eSeverityWarning));
   // Remarks have no labels.
   mgr.AddDiagnostic(std::make_unique<TextDiag>("baz", lldb::eSeverityInfo));
-  EXPECT_EQ("error: foo\nwarning: bar\nbaz\n", mgr.GetString());
+  EXPECT_EQ("error: foo\nwarning: bar\nbaz\n", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, GetStringPreserveOrder) {
@@ -120,7 +127,7 @@ TEST(DiagnosticManagerTest, GetStringPreserveOrder) {
   mgr.AddDiagnostic(std::make_unique<TextDiag>("baz", lldb::eSeverityInfo));
   mgr.AddDiagnostic(std::make_unique<TextDiag>("bar", lldb::eSeverityWarning));
   mgr.AddDiagnostic(std::make_unique<TextDiag>("foo", lldb::eSeverityError));
-  EXPECT_EQ("baz\nwarning: bar\nerror: foo\n", mgr.GetString());
+  EXPECT_EQ("baz\nwarning: bar\nerror: foo\n", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, AppendMessageNoDiag) {
@@ -139,7 +146,7 @@ TEST(DiagnosticManagerTest, AppendMessageAttachToLastDiag) {
   // This should append to 'bar' and not to 'foo'.
   mgr.AppendMessageToDiagnostic("message text");
 
-  EXPECT_EQ("error: foo\nerror: bar\nmessage text\n", mgr.GetString());
+  EXPECT_EQ("error: foo\nerror: bar\nmessage text\n", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, AppendMessageSubsequentDiags) {
@@ -150,7 +157,7 @@ TEST(DiagnosticManagerTest, AppendMessageSubsequentDiags) {
   // Pushing another diag after the message should work fine.
   mgr.AddDiagnostic(std::make_unique<TextDiag>("foo", lldb::eSeverityError));
 
-  EXPECT_EQ("error: bar\nmessage text\nerror: foo\n", mgr.GetString());
+  EXPECT_EQ("error: bar\nmessage text\nerror: foo\n", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, PutString) {
@@ -159,7 +166,7 @@ TEST(DiagnosticManagerTest, PutString) {
   mgr.PutString(lldb::eSeverityError, "foo");
   EXPECT_EQ(1U, mgr.Diagnostics().size());
   EXPECT_EQ(eDiagnosticOriginLLDB, mgr.Diagnostics().front()->getKind());
-  EXPECT_EQ("error: foo\n", mgr.GetString());
+  EXPECT_EQ("error: foo\n", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, PutStringMultiple) {
@@ -169,7 +176,7 @@ TEST(DiagnosticManagerTest, PutStringMultiple) {
   mgr.PutString(lldb::eSeverityError, "foo");
   mgr.PutString(lldb::eSeverityError, "bar");
   EXPECT_EQ(2U, mgr.Diagnostics().size());
-  EXPECT_EQ("error: foo\nerror: bar\n", mgr.GetString());
+  EXPECT_EQ("error: foo\nerror: bar\n", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, PutStringSeverities) {
@@ -180,7 +187,7 @@ TEST(DiagnosticManagerTest, PutStringSeverities) {
   mgr.PutString(lldb::eSeverityError, "foo");
   mgr.PutString(lldb::eSeverityWarning, "bar");
   EXPECT_EQ(2U, mgr.Diagnostics().size());
-  EXPECT_EQ("error: foo\nwarning: bar\n", mgr.GetString());
+  EXPECT_EQ("error: foo\nwarning: bar\n", toString(mgr));
 }
 
 TEST(DiagnosticManagerTest, FixedExpression) {
diff --git a/lldb/unittests/Interpreter/CMakeLists.txt b/lldb/unittests/Interpreter/CMakeLists.txt
index 54cea995084d3d..14a7d6c5610388 100644
--- a/lldb/unittests/Interpreter/CMakeLists.txt
+++ b/lldb/unittests/Interpreter/CMakeLists.txt
@@ -1,5 +1,6 @@
 add_lldb_unittest(InterpreterTests
   TestCommandPaths.cpp
+  TestCommandObjectExpression.cpp
   TestCompletion.cpp
   TestOptionArgParser.cpp
   TestOptions.cpp
diff --git a/lldb/unittests/Interpreter/TestCommandObjectExpression.cpp b/lldb/unittests/Interpreter/TestCommandObjectExpression.cpp
new file mode 100644
index 00000000000000..9fe0432fd22653
--- /dev/null
+++ b/lldb/unittests/Interpreter/TestCommandObjectExpression.cpp
@@ -0,0 +1,34 @@
+#include "lldb/Expression/DiagnosticManager.h"
+#include "lldb/Utility/StreamString.h"
+#include "gtest/gtest.h"
+
+namespace lldb_private {
+std::string RenderDiagnosticDetails(Stream &stream,
+                                    std::optional<uint16_t> offset_in_command,
+                                    bool multiline,
+                                    llvm::ArrayRef<DiagnosticDetail> details);
+}
+
+using namespace lldb_private;
+using namespace lldb;
+using llvm::StringRef;
+namespace {
+class ErrorDisplayTest : public ::testing::Test {};
+} // namespace
+
+static std::string Render(std::vector<DiagnosticDetail> details) {
+  StreamString stream;
+  RenderDiagnosticDetails(stream, 0, details);
+  return stream.GetData();
+}
+
+TEST_F(ErrorDisplayTest, RenderStatus) {
+  DiagnosticDetail::SourceLocation inline_loc;
+  inline_loc.in_user_input = true;
+  {
+    std::string result =
+        Render({DiagnosticDetail{inline_loc, eSeverityError, "foo", ""}});
+    ASSERT_TRUE(StringRef(result).contains("error:"));
+    ASSERT_TRUE(StringRef(result).contains("foo"));
+  }
+}



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