log feature emits logs when the log crate doesn't, ignoring log::max_level()

[Florob]

Bug Report

Version

0.1.16, seems to be no different on master

Platform

Linux 4.19.0-xilinx #2 SMP PREEMPT Wed Jul 22 19:10:58 CEST 2020 armv7l GNU/Linux

Description

I was surprised by hyper emitting Trace level logs in conjunction with the syslog crate, while the level filter was set to Info. This turned out to be caused by hyper using the tracing crate instead of the log crate directly. In particular log::max_level() seems to be ignored.

In tracing/macros.rs tracing_log!() computes whether to log differently from the log crate.
While the log crate checks for lvl <= log::STATIC_MAX_LEVEL && lvl <= log::max_level(), tracing instead checks for lvl <= log::STATIC_MAX_LEVEL and later the output of logger.enabled(). This causes differences in what is being logged including unexpected log output.

[hawkw]

Yup, that's definitely a bug, thanks for reporting it!

I think we haven't noticed this in the past, since most people seem to be using env_logger, which disables these logs from Log::enabled.