Consider adding a [$file:$line] prefix to logs

[martijneken]

The C++ SDK logs messages in this format:
[$file:$line]::$function $message

Via these macros:
https://github.com/proxy-wasm/proxy-wasm-cpp-sdk/blob/921039ae983ce053bf5cba78a85a3c08ff9791e5/proxy_wasm_api.h#L84-L92

The Rust SDK just logs the message:

proxy-wasm-rust-sdk/src/logger.rs

Lines 66 to 67 in 9b4b4a5

	let message = record.args().to_string();
	hostcalls::log(level, &message).unwrap();

File and line are supported in log::Record:
https://docs.rs/log/latest/log/struct.Record.html

Function is not supported by Rust:
https://stackoverflow.com/a/38088268

[PiotrSikora]

The C++ SDK logs messages [...]

I'm sure you'll find many discrepancies between existing SDKs, since they were developed by different people. What's the real goal and motivation behind the suggested change?

Note that the stacktraces already include this information, and application logs can be unique enough that users can identify the source without the file and line number, so I'm not sure how much value would this be adding, to be honest.

But if there is a real use case and/or customer request behind it, then perhaps we should add set_log_metadata(bool) or something similar (see existing set_log_level)?