From d33fa70dddcb29d5fd85188e119f034e585ccccf Mon Sep 17 00:00:00 2001
From: Adrian Prantl <aprantl@apple.com>
Date: Fri, 27 Sep 2024 16:32:35 -0700
Subject: [lldb] Inline expression evaluator error visualization (#106470)
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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. You can't see it here, bug the word "error" is now also in
color, if so desired.

Depends on https://github.com/llvm/llvm-project/pull/106442.
---
 lldb/source/Commands/CommandObjectExpression.cpp | 41 ++++++++++++++++--------
 1 file changed, 28 insertions(+), 13 deletions(-)

(limited to 'lldb/source/Commands/CommandObjectExpression.cpp')

diff --git a/lldb/source/Commands/CommandObjectExpression.cpp b/lldb/source/Commands/CommandObjectExpression.cpp
index 7711946..9722c85 100644
--- a/lldb/source/Commands/CommandObjectExpression.cpp
+++ b/lldb/source/Commands/CommandObjectExpression.cpp
@@ -6,10 +6,10 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/ADT/StringRef.h"
-
 #include "CommandObjectExpression.h"
+#include "DiagnosticRendering.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"
@@ -486,19 +486,34 @@ 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(),
+            [&](ExpressionError &error) { details = error.GetDetails(); }));
+        // 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 show_inline =
+              GetDebugger().GetShowInlineDiagnostics() && !expr.contains('\n');
+          RenderDiagnosticDetails(error_stream, expr_pos, show_inline, details);
         } else {
-          error_stream.PutCString("error: unknown error\n");
+          const char *error_cstr = result_valobj_sp->GetError().AsCString();
+          llvm::StringRef error(error_cstr);
+          if (!error.empty()) {
+            if (!error.starts_with("error:"))
+              error_stream << "error: ";
+            error_stream << error;
+            if (!error.ends_with('\n'))
+              error_stream.EOL();
+          } else {
+            error_stream << "error: unknown error\n";
+          }
         }
-
         result.SetStatus(eReturnStatusFailed);
       }
     }
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