Failure on streaming a list of empty strings about libpqxx

[jtv]

That's a nasty one! Thanks for the report. It's not clear to me why you pass the field as a std::variant, but I can reproduce the problem without that. Debugging.

[jtv]

Found it! It wasn't even the streaming that was the problem. It was the code that represents an array as a string. Its buffer budget calculation was just a little too tight, leading the conversion to allocate slightly too little memory. This wasn't normally an issue, but empty strings happen to be an extreme case in budgeting conversions.

[vahancho]

Yeah, I noticed that it tries to convert a vector of strings to a single string with comma separated elements and inserts at some point (depending on the number of strings) a null character in the middle.

I use std:: variant because I don't know the field value upfront. Sometimes it can be empty too.

[jtv]

The overloading gets a bit confusing and I kind of regret it now. I may do some deprecation go get a stricter separation between "a container or tuple is a row" and "a container or tuple is a value."

@vahancho does the fix address all your use-cases?

[vahancho]

@jtv I didn't test it yet, but the case of using more than three empty strings in the container was the only one I had issues with.
Thank you for the comprehensive analysis and quick fix.

[jtv]

Excellent. Thanks @vahancho.