Add option to add backtrace to log messages

[IanButterworth]

Tracking down why a log message is happening can be hard from just the call site info.

The idea here is to expose a way to inject stack traces into the log message without having to edit the code site to manually add an error. For instance in CI where adding an env var is easier than editing code in a dependency that logs.

test.jl including

foo() = bar()
bar() = @error "hello"

This PR:

julia> include("test.jl")

julia> foo()
┌ Error: hello
└ @ Main ~/test.jl:2

julia> ENV["JULIA_LOG_TRACE"]=1
1

julia> foo()
┌ Error: hello
│ Stacktrace:
│   bar() at test.jl:2
│   foo() at test.jl:1
│   top-level scope at REPL[25]:1
└ @ Main ~/test.jl:2

julia> ENV["JULIA_DEBUG"]="loading"
"loading"

julia> using CSV
┌ Debug: Loading object cache file /Users/ian/.julia/compiled/v1.10/Preferences/pWSk8_wG2DL.dylib for Preferences [21216c6a-2e73-6563-6e65-726566657250]
│ Stacktrace:
│   _include_from_serialized(pkg::Base.PkgId, path::String, ocachepath::String, depmods::Vector{Any}) at loading.jl:1000
│   _tryrequire_from_serialized(modkey::Base.PkgId, path::String, ocachepath::String, sourcepath::String, depmods::Vector{Any}) at loading.jl:1298
│   _require_search_from_serialized(pkg::Base.PkgId, sourcepath::String, build_id::UInt128) at loading.jl:1401
│   _require(pkg::Base.PkgId, env::String) at loading.jl:1690
│   _require_prelocked(uuidkey::Base.PkgId, env::String) at loading.jl:1567
│   macro expansion at loading.jl:1555 [inlined]
│   macro expansion at lock.jl:267 [inlined]
│   require(into::Module, mod::Symbol) at loading.jl:1518
└ @ Base loading.jl:1000
...

Ignoring the stackframes from inside the logging code gen might be too crude.

Also, ignoring past an eval as a way to ignore the repl internals might be too, as Base.scrub_repl_backtrace didn't work for some reason.

[IanButterworth]

@oxinabox would this break logging extensions like https://github.com/JuliaLogging/LoggingExtras.jl ?

Edit: Just checked and tests pass with and without JULIA_LOG_TRACE=true

[vtjnash]

Suggested change

	try
	error()
	catch
	return stacktrace(catch_backtrace()), kwargs
	end
	return stacktrace(), kwargs

[KristofferC]

Shouldn't this be done with a custom logger? Or does that not work here? An env variable should be a last resort of setting an option imo.

[oxinabox]

I agree with Kristoffer, I think this can and thus should be done with a custom logger.
I will put one together after my meeting

[oxinabox]

Very basic one, not super-pretty but:
It can be done better by calling into the existing code for stacktraces displaying.

using LoggingExtras

foo() = bar()
bar() = qux()
qux() = @info "Hi"

stacklogger = TransformerLogger(global_logger()) do log
    st = stacktrace()[5:end]  # skip stuff from the logging system  
    pretty_st = ["[$ii] $frame" for (ii, frame) in enumerate(st)]
    kwargs = (;log.kwargs..., stacktrace=pretty_st)
    return merge(log,(;kwargs))
end;


with_logger(stacklogger) do
    foo()
end

More generally i think this goes well with other kind of LoggingExtras stuff, like you probably want to do with with some filters, so only certain modules and certain levels (e.g. warn) are displayed with stacktraces.

[IanButterworth]

That's awesome. Thanks. Yeah makes more sense in LoggingExtras