JULIA_DEBUG=logging doesn't work

[simonbyrne]

The example in https://github.com/JuliaLang/julia/blob/c819cde083a8161aebd7bec626527dbec47fed44/stdlib/Logging/docs/src/index.md#environment-variables doesn't work (using JULIA_DEBUG=all does work).

It would be good to document what values are valid, and also add it to https://github.com/JuliaLang/julia/blob/master/doc/src/manual/environment-variables.md

[vtjnash]

There's not a lot of @debug statements in the logging file (and these look like they'd be inside comments). I don't think we can readily document what files are on your system though.

~/julia$ grep '@debug' `find base stdlib/ -name logging.jl`
base/logging.jl:    @debug,
base/logging.jl:    @debug message  [key=value | value ...]
base/logging.jl:logging macros `@debug`, `@info`, `@warn` and `@error` are defined which log at
base/logging.jl:@debug "Verbose debugging information.  Invisible by default"
base/logging.jl:@debug begin
base/logging.jl:    @debug "Algorithm1" i progress=i/10000
base/logging.jl:@eval @doc $_logmsg_docs :(@debug)
stdlib//Test/src/logging.jl:            @debug "Iteration \$i"

[DilumAluthge]

I'm guessing that @simonbyrne was referring to this example:

JULIA_DEBUG=loading julia -e 'using OhMyREPL'

That produces no output, but both of these produce the correct output:

JULIA_DEBUG=all julia -e 'using OhMyREPL'
JULIA_DEBUG=Base julia -e 'using OhMyREPL'

Since the file loading.jl is part of the Base module, this seems like a bug.

[DilumAluthge]

Yeah it's definitely a bug.

@simonbyrne Can you try the example (JULIA_DEBUG=loading julia -e 'using OhMyREPL') with #34485?