rt_format! returns error which refers on temprorary data

[MikailBag]

Hello!
I'm using your library like this:

let res = rt_format!(file_tpl, id);
match res {
//...
}

and I'm getting following error (with -Z external-macro-backtrace):

error[E0716]: temporary value dropped while borrowed
  --> <::runtime_fmt::macros::rt_format_args macros>:22:44
   |
1  | /    (
2  | |    @ [ $ spec : expr ] [ $ ( $ args : tt ) * ] $ name : tt = $ e : expr , $ (
3  | |    $ rest : tt ) * ) => {
4  | |    rt_format_args ! (
...  |
19 | /    rt_format_args ! (
20 | |    @ [ $ spec ] [ $ ( $ args ) * $ crate :: Param :: normal ( & $ e ) , ] ) } ; (
   | |___________________________________________________________________________- in this macro invocation (#4)
21 |      @ [ $ spec : expr ] [ $ ( $ args : tt ) * ] ) => {
22 | |    $ crate :: FormatBuf :: new ( & $ spec , & [ $ ( $ args ) * ] ) } ; (
   | |                                               ^^^^^^^^^^^^^^^^^^ creates a temporary which is freed while still in use
23 | |    $ spec : expr , $ ( $ rest : tt ) * ) => {
24 | |    rt_format_args ! ( @ [ $ spec ] [  ] $ ( $ rest ) * ) } ; ( $ spec : expr ) =>
   | |    -----------------------------------------------------
   | |    |
   | |    in this macro invocation (#3)
25 | |    { $ crate :: FormatBuf :: new ( & $ spec , & [  ] ) } ;
   | |                                                          -
   | |                                                          |
   | |                                                          in this expansion of `rt_format_args!` (#2)
   | |__________________________________________________________in this expansion of `rt_format_args!` (#3)
   |                                                            in this expansion of `rt_format_args!` (#4)
   | 
  ::: tt/src/cfg.rs:77:51
   |
77 |                      let res = rt_format!(file_tpl, id);
   |                                ------------------------- temporary value is freed at the end of this statement
   |                                |
   |                                in this macro invocation (#1)
78 |                      match res {
   |                            --- borrow later used here
   | 
  ::: <::runtime_fmt::macros::rt_format macros>:1:1
   |
1  |    / ( $ ( $ rest : tt ) * ) => {
2  |    | rt_format_args ! ( $ ( $ rest ) * ) . map (
   |    | -----------------------------------
   |    | |
   |    | in this macro invocation (#2)
3  |    | | x | x . with ( :: std :: fmt :: format ) ) }
   |    |______________________________________________- in this expansion of `rt_format!` (#1)
   |
   = note: consider using a `let` binding to create a longer lived value

Some additional points:

• explicit reborrow doesn't fix error
• but transforming possible error into e.g. String (via rt_format!(...).map_err(|e| e.to_string())) fixes
  So, AFAIU, during invokation of macro, temporary string is created, and lifetime of error is bound to that temporary.