Fix bug in `StdStream.print` #4180

leonardoce · 2022-08-21T08:40:33Z

When printing via StdStream.print strings containing the null
terminator, we were just printing the string until the null terminator
and replacing the unprinted characters by padding the printed string
with space characters.

This behavior made String.size() inconsistent with what fprintf was
really printing.

This behavior has been introduced in #1768, which ensure we respected
the buffer size.

Closes #4171

leonardoce · 2022-08-21T08:41:30Z

Hi guys, this is my first PR here and I'm not totally sure this is the behavior we want.
Any advise is deeply appreciated.
Thank you!

ponylang-main · 2022-08-21T19:14:12Z

Hi @leonardoce,

The changelog - fixed label was added to this pull request; all PRs with a changelog label need to have release notes included as part of the PR. If you haven't added release notes already, please do.

Release notes are added by creating a uniquely named file in the .release-notes directory. We suggest you call the file 4180.md to match the number of this pull request.

The basic format of the release notes (using markdown) should be:

## Title

End user description of changes, why it's important,
problems it solves etc.

If a breaking change, make sure to include 1 or more
examples what code would look like prior to this change
and how to update it to work after this change.

Thanks.

When printing via `StdStream.print` strings containing the null terminator, we were just printing the string until the null terminator and replacing the unprinted characters by padding the printed string with space characters. This behavior made `String.size()` inconsistent with what `fprintf` was really printing. This behavior has been introduced in #1768, which ensure we respected the buffer size. Closes #4171

leonardoce · 2022-08-21T21:27:55Z

Added the release notes snippet

.release-notes/4180.md

SeanTAllen · 2022-08-26T18:13:29Z

.release-notes/4180.md

+
+That behavior was introduced in release 0.12.0, fixing a left-over from when Pony strings were null terminated.
+
+Now  `Stdstream.print` is effectively printing every character in the string plus an ending newline character.


I'm not sure what this is supposed to mean. What is "effectively printing"? Does "effectively" here mean "more or less"? If yes, that would be a disturbing release note and I think it should be rewritten.

I would rewrite this, but I'm not sure what the intent is...

.release-notes/4180.md

SeanTAllen · 2022-08-26T18:19:44Z

We don't have a way to test this right now in an automated fashion so I will build this branch and test by hand:

actor Main
  new create(env: Env) =>
    env.out.print("Hello,\x00world!")

.release-notes/4180.md

SeanTAllen · 2022-08-26T20:12:02Z

Tested. This is looking good.

SeanTAllen · 2022-08-26T20:12:38Z

I'll merge this later.

SeanTAllen · 2022-08-26T20:12:57Z

Thanks @leonardoce.

ponylang-main added the discuss during sync Should be discussed during an upcoming sync label Aug 21, 2022

SeanTAllen added the changelog - fixed Automatically add "Fixed" CHANGELOG entry on merge label Aug 21, 2022