[C++] Fix ToStringWithoutContextLines to check for :\d+ pattern before removing lines

[HyukjinKwon]

Describe the enhancement requested

arrow/cpp/src/arrow/status.cc

Lines 131 to 134 in 7ebc88c

	// TODO: We may want to check /:\d+ /
	if (message.find(":", last_new_line_position) == std::string::npos) {
	break;
	}

Component(s)

C++

[goldigd05]

Hi, I would like to contribute a fix for Status::ToStringWithoutContextLines().

Currently, this function removes context lines using a heuristic based on colons (:),
which may accidentally remove parts of the original error message.

My fix approach:

1. Update AddContextLine() to prefix context lines with [context].
2. Update ToStringWithoutContextLines() to strip only lines that start with [context].
3. Add a unit test to ensure that original error messages are preserved while context lines are removed.

This change ensures that:

• Original error messages remain intact.
• Only the extra context added via AddContextLine() is removed.
• Works even if the error message contains colons.

I am happy to submit a PR implementing this approach. Thanks!

[HyukjinKwon]

Oh I actually already created a PR for it :-).

[goldigd05]

Great 👍

[kou]

Issue resolved by pull request 48674
#48674