Builder#parse_env does not override manually set filter level

[BramBonne]

Consider the following example (runnable version):

std::env::set_var("RUST_LOG", "debug");

let mut builder = env_logger::Builder::new();
builder.filter_level(log::LevelFilter::Trace);

// The following call should override the log level to Debug, as read from the environment
builder.parse_default_env();

builder.init();
assert_eq!(log::max_level(), log::LevelFilter::Trace);

According to the documentation, the parse_env function "allows a builder to be configured with default parameters, to be then overridden by the environment". For this example, that would mean that log::max_level() should be set to Debug at the end of this example. In reality, it's set to Trace instead.

Removing the call to builder.filter_level(log::LevelFilter::Trace) correctly sets the log level to Debug instead.

[jplatte]

Yeah, the docs are pretty clear here. A PR fixing this would be welcome.

[BramBonne]

I provided both #199 and #200 as alternative potential fixes to this problem, depending on whether we want directive names to be unique in general (#200), or not (#199).

[BramBonne]

Hey @jplatte, friendly ping on this. Would #200 be an acceptable way to fix this, or is there a better approach? Thanks for taking a look :-)

Kind regards, Bram

[mainrs]

I'll have time on the weekend to take a look at the PR.

[BramBonne]

Thank you! But no rush, I was just checking it was still being considered 🙂

[mainrs]

@jplatte I've taken a look at both of the PRs. Both look good.

I don't have strong preference for either PR, but if I'd have to choose I'd say we should merge #200, as it means more cosistent behaviour across the library in general by always overwriting previous directives. I can't think of an example off the top of my head where this might not be wanted.

[jplatte]

I've had a look, I agree that #200 seems like the better solution.

[BramBonne]

Hey,

Just checking if anything is expected/needed from my end here.

Kind regards, Bram

[jplatte]

No. I merged #200. Sorry about the long delay.