Auto merge of #22948 - rprichard:simple-panic-opt, r=alexcrichton

Reduce code size overhead from core::panicking::panic

core::panicking::panic currently creates an Arguments structure using
format_args!("{}", expr), which formats the expr str using the Display::fmt.
Display::fmt pulls in Formatter::pad, which then also pulls in string-related
code for truncation and padding.

If core::panicking::panic instead creates an Arguments structure with a string
piece, it is possible that the Display::fmt function for str can be optimized
out of the program.

In my testing with a 32-bit x86 bare metal program, the change tended to save
between ~100 bytes and ~5500 bytes, depending on what other panic* functions
the program invokes and whether the panic_fmt lang item uses the Arguments
value.

0 files changed, 0 insertions, 0 deletions