log!("{x}") treats input as a raw string

[Sliman4]

When you write log!("{x}"), it outputs {x} literally instead of the value of variable x because log! is implemented differently if it has only 1 expression:

near-sdk-rs/near-sdk/src/utils/mod.rs

Lines 36 to 43 in 8a908c3

	macro_rules! log {
	($arg:expr) => {
	$crate::env::log_str($arg.as_ref())
	};
	($($arg:tt)*) => {
	$crate::env::log_str(format!($($arg)*).as_str())
	};
	}

log!("{x}",) (with a trailing comma) bypasses this, but I think it would be nice to maintain 100% compatibility with std::fmt.

If a string allocation makes a significant difference for some contract, is there a reason why they can't just use env::log_str directly? This call will also explicitly mark that this log outputs a lot of data and should not be changed to something that allocates, to avoid situations when at some point you add one {} to the log, and gas usage skyrockets for an unknown reason.

[frol]

@Sliman4 The macro was implemented before string interpolation became a thing in Rust (stable). I agree with your reasoning. Would you like to prepare a PR?