[lldb] Inline expression evaluator error visualization (#106470)

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.

1 files changed, 34 insertions, 0 deletions

diff --git a/lldb/unittests/Interpreter/TestCommandObjectExpression.cpp b/lldb/unittests/Interpreter/TestCommandObjectExpression.cpp
new file mode 100644
index 0000000..b0cf22d
--- /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, true, 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"));
+  }
+}