Why does daisy chaining a json.template get<std::string>().c_str() mangle some strings but doing it in two steps doesnt?

[Bracket-H]

Showing the example would be too much of a hassle...but

auto name = i["name"].template get<std::string>();
auto name_c_style = name.c_str();

Instead of

auto name = i["name"].template get<std::string>().c_str(); //edit I accidentally put colons here instead of semicolons but that's not the reason for it not working, that's just me being bushed n pooped

was the only way I could end up with some weird mangled strings that were okay as a
'gotten' std::string or a dumped one.

But not as a daisy chained c_str() one, yet, they still worked when done in two steps.

I know I could probably be more helpful, but I'm a bit frustrated, worn out, dazzled, discombobulated and other things from several plates of programming BS I had to eat today.

Does template metaprogramming mess with 'syntactic sugar' (if it really is that) ?
Shouldn't these two operations be, under the hood, the same thing?

Why would "Environmental Suit" as a value for name, not work when daisy chain converted, but "Kenneth" or "Chicken Chicken bok bok bok" did?
This makes NO sense to me whatsoever...and I actually feel like crying a lil right now.

[nlohmann]

get returns a temporary, and then using c_str is not safe. Use get_ref instead.

[Bracket-H]

But then passing that c_str should make a copy?
Mmmmmm...well I'll use get_ref but that's still kinda weird.

I mean, if get returns a temporary...and thus is not safe...then why would it be safe to store the returned string in a string for keeping?
I don't get it.

[gregmarr]

auto name = i["name"].template get<std::string>().c_str();

But then passing that c_str should make a copy?

The template get<std::string>() bit creates a temporary that is destroyed when the statement completes. The .c_str() returns a char * pointing to the data stored in the temporary. The auto name = make a copy of the POINTER VALUE, not the string itself, and then the temporary string is destroyed, so name holds a pointer into memory that has been freed.

When you did auto name = i["name"].template get<std::string>(); then you had a non-temporary copy of the string, and auto name_c_style = name.c_str(); is valid for as long as name is valid, or at least until you modified the name string.

[Bracket-H]

Also, there doesn't even seem to be a 'get_ref' function, or at least, not as a drop in replacement.
And I see nothing in the readme file other than someone implementing it.

I am on the latest stable version...

interop.cpp:812:85: error: no matching function for call to ‘nlohmann::json_abi_v3_11_2::basic_json<>::get_ref<std::string>()’
  812 |             auto specialization  = i["specialization"].template get_ref<std::string>();
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~        

I checked the json header and the get_ref function seems to be in there but I'm clearly too inept to grok/use it.

[Bracket-H]

I found the actual documentation in the meantime, and I now realize that with get_ref I actually have to request a ref (ampersand)

Closing this issue.