Distinct preice::string_views when implicitly constructing from std::string or literal

[mathiskelm]

Description

Several interfaces of the CouplingAdapter such as announceQuantity and getQuantityVector use the new precice::string_view after the port to precice:develop / preCICEv3. One can pass also std::strings or "string"-literals, which are then converted. As literals such as "dataName" are \0-terminated char[], their size is 1 greater than the string and they produce a different string_view.

std::string("dataName") seems to be compatible with precice::string_view("dataName", 8) while "dataName" produces precice::string_view("dataName", 9).

This currently allows to announce the same quantity twice, since the adapter checks whether the string_view has already been announced (false) and preCICE seems to view them both as equal to the name registered in the preCICE config file.

Environment

Ubuntu 22.04 LTS, preCICE:develop, DuMuX 3.8, DuMuX-preCICE:develop

Steps to reproduce

Announce a quantity twice, using once a std::string and once a literal

Expected behavior

If passing a std::string and literal are allowed, they should refer to the same quantity.

Actual behavior

Depending on how the string_view is created, the quantities are treated as distinct.

[fsimonis]

You noticed an implementation detail of using the precice::span-based precice::string_views in the API.

While you are correct about the literals containing the NULL byte, preCICE handles this internally.
In src/precice/Participant.cpp, we convert all precice::string_views to std::string_view before passing them ParticipantImpl.

This step removes the NULL byte and everything past it from given string_views.