UnicodeString::tempSubString delete && overloads

[philipp-zimmermann]

Changes

The rvalue overloads for icu::UnicodeString::tempSubString and icu::UnicodeString::tempSubStringBetween are deleted.

Justification

Calling tempSubString on a rvalue violates the precondition ("[...] requires that the original string not be modified or deleted during the lifetime of the returned substring object."). Therefore disallowing usage like this prevents bugs.

A example for the buggy behavior is the following code:

#include <iostream>
#include <unicode/unistr.h>

[[nodiscard]] auto get_string() -> icu::UnicodeString
{
  return icu::UnicodeString {"abcdefg"};
}

auto print (icu::UnicodeString const& unicode_string) -> void
{
  std::string s;
  unicode_string.toUTF8String (s);
  std::cout << s << '\n';
}

int main()
{
  {
    auto const substring {get_string().tempSubString(2)};

    print (substring);
    std::string s;
    substring.toUTF8String (s);
    std::cout << s << '\n';
    print (substring);
  }

  std::cout << "\nCorrect behavior:\n";

  {
    auto const full_string {get_string()};
    auto const substring {full_string.tempSubString(2)};

    print (substring);
    std::string s;
    substring.toUTF8String (s);
    std::cout << s << '\n';
    print (substring);
  }
}

This may lead to output like this:

cdefg
efg
晥gg

Correct behavior:
cdefg
cdefg
cdefg

The above output is from a binary compiled with "Release" mode. When using "Debug" the behavior is correct.
This is tested with https://github.com/unicode-org/icu/releases/download/release-78.2/icu4c-78.2-Ubuntu22.04-x64.tgz.

Jira issue

I am not able to create a new jira issue at all and I'm not able to find a solution for this problem.

TODO: Fill out the checklist below.

Checklist

• Required: Issue filed: ICU-NNNNN
• Required: The PR title must be prefixed with a JIRA Issue number. Example: "ICU-NNNNN Fix xyz"
• Required: Each commit message must be prefixed with a JIRA Issue number. Example: "ICU-NNNNN Fix xyz"
• Issue accepted (done by Technical Committee after discussion)
• [x ] Tests included, if applicable
• API docs and/or User Guide docs changed or added, if applicable
• Approver: Feel free to merge on my behalf

[CLAassistant]

All committers have signed the CLA.

[markusicu]

@philipp-zimmermann please sign the CLA. Otherwise we can't look at your proposed changes.
Note that ICU API is stable; we cannot simply remove public, stable API.

I am not able to create a new jira issue at all and I'm not able to find a solution for this problem.

You need to create a Jira account before you can create a ticket. See https://icu.unicode.org/bugs

[philipp-zimmermann]

@philipp-zimmermann please sign the CLA. Otherwise we can't look at your proposed changes. Note that ICU API is stable; we cannot simply remove public, stable API.

I am not able to create a new jira issue at all and I'm not able to find a solution for this problem.

You need to create a Jira account before you can create a ticket. See https://icu.unicode.org/bugs

Thanks for the Answer.

I still have the issue that the Button "+ Create" is red for me and nothing happens when I click on it. I tried the following things to fix the problem:

• I used my gmail account as well as a newly created account directly on jira.
• I tried disabling all addons on firefox. (on ubuntu)
• I tried it with the jira account on windows and a default edge browser.
• I tried using the google account on windows with a default chrome browser.

Nothing worked so far.

[markusicu]

We have had a couple of other people also report problems with Jira; we are looking into that.

We can create a Jira ticket on your behalf, but we can't look at your changes until you sign the CLA.

[philipp-zimmermann]

We have had a couple of other people also report problems with Jira; we are looking into that.

We can create a Jira ticket on your behalf, but we can't look at your changes until you sign the CLA.

Hi Markus,
Thanks for looking into the issue.

I forgot to add the mail address associated to the commit to my github account. Now it recognizes that I signed the CLA.