Loading external StyledString package removes markdown highlighting

[KristofferC]

This is when having this package as the active project and loading it.

[topolarity]

Do we have a root cause for this yet?

[tecosaur]

I don't, but I have noticed that with StyledStrings as the active project you can see this in a Julia REPL session:

help?> thing
# Observe working syntax highlighting

julia> using StyledStrings

help?> thing
# Syntax highlighting breaks

julia> using Markdown

help?> thing
# Syntax highlighting works again

Checking Base.loaded_modules_order it seems like two versions of StyledStrings, JuliaSyntaxHighlighting, and Markdown are loaded by doing this:

julia> Base.loaded_modules_order
22-element Vector{Module}:
 Core
 Base
 Main
 FileWatching
 Libdl
 Artifacts
 SHA
 Sockets
 LinearAlgebra
 OpenBLAS_jll
 libblastrampoline_jll
 Random
 Base64
 StyledStrings
 JuliaSyntaxHighlighting
 Markdown
 InteractiveUtils
 Unicode
 REPL
 StyledStrings
 JuliaSyntaxHighlighting
 Markdown
 
julia> length(unique(Base.loaded_modules_order))
22

[topolarity]

If I had to guess, StyledStrings has some code that is embedding Face types:

StyledStrings.jl/src/styledmarkup.jl

Line 725 in da41b6a

face = Expr(:call, Face, kwargs...)

but then getface here is effectively doing a isa Face check:

StyledStrings.jl/src/io.jl

Line 237 in da41b6a

face = getface(styles)

which runs into an issue almost exactly like the one I accidentally created with TOML recently (JuliaLang/Pkg.jl#4017 (comment))

Basically require_stdlib means that multiple StyledStrings can exist, which means that the _ansi_writer code has to support the Face type for all of the loaded StyledStrings.