fix overlapping definitions of Base.active_module and REPL.active_module (#55316)

also avoid calling `active_module` from low-level printing functions
fix #54888

Author: JeffBezanson

base/Enums.jl

@@ -44,7 +44,7 @@ Base.print(io::IO, x::Enum) = print(io, _symbol(x))
 function Base.show(io::IO, x::Enum)
     sym = _symbol(x)
     if !(get(io, :compact, false)::Bool)
-        from = get(io, :module, Base.active_module())
+        from = get(io, :module, Main)
         def = parentmodule(typeof(x))
         if from === nothing || !Base.isvisible(sym, def, from)
             show(io, def)

base/show.jl

@@ -514,24 +514,16 @@ function _show_default(io::IO, @nospecialize(x))
 end
 
 function active_module()
-    REPL = REPL_MODULE_REF[]
-    REPL === Base && return Main
-    return invokelatest(REPL.active_module)::Module
+    if ccall(:jl_is_in_pure_context, Bool, ())
+        error("active_module() should not be called from a pure context")
+    end
+    if !@isdefined(active_repl) || active_repl === nothing
+        return Main
+    end
+    return invokelatest(active_module, active_repl)::Module
 end
 
-# Check if a particular symbol is exported from a standard library module
-function is_exported_from_stdlib(name::Symbol, mod::Module)
-    !isdefined(mod, name) && return false
-    orig = getfield(mod, name)
-    while !(mod === Base || mod === Core)
-        activemod = active_module()
-        parent = parentmodule(mod)
-        if mod === activemod || mod === parent || parent === activemod
-            return false
-        end
-        mod = parent
-    end
-    return isexported(mod, name) && isdefined(mod, name) && !isdeprecated(mod, name) && getfield(mod, name) === orig
+module UsesCoreAndBaseOnly
 end
 
 function show_function(io::IO, f::Function, compact::Bool, fallback::Function)
@@ -544,13 +536,13 @@ function show_function(io::IO, f::Function, compact::Bool, fallback::Function)
         print(io, mt.name)
     elseif isdefined(mt, :module) && isdefined(mt.module, mt.name) &&
         getfield(mt.module, mt.name) === f
-        mod = active_module()
-        if is_exported_from_stdlib(mt.name, mt.module) || mt.module === mod
-            show_sym(io, mt.name)
-        else
+        # this used to call the removed internal function `is_exported_from_stdlib`, which effectively
+        # just checked for exports from Core and Base.
+        mod = get(io, :module, UsesCoreAndBaseOnly)
+        if !(isvisible(mt.name, mt.module, mod) || mt.module === mod)
             print(io, mt.module, ".")
-            show_sym(io, mt.name)
         end
+        show_sym(io, mt.name)
     else
         fallback(io, f)
     end
@@ -737,9 +729,9 @@ end
 function show_typealias(io::IO, name::GlobalRef, x::Type, env::SimpleVector, wheres::Vector)
     if !(get(io, :compact, false)::Bool)
         # Print module prefix unless alias is visible from module passed to
-        # IOContext. If :module is not set, default to Main (or current active module).
+        # IOContext. If :module is not set, default to Main.
         # nothing can be used to force printing prefix.
-        from = get(io, :module, active_module())
+        from = get(io, :module, Main)
         if (from === nothing || !isvisible(name.name, name.mod, from))
             show(io, name.mod)
             print(io, ".")
@@ -1053,9 +1045,9 @@ function show_type_name(io::IO, tn::Core.TypeName)
     quo = false
     if !(get(io, :compact, false)::Bool)
         # Print module prefix unless type is visible from module passed to
-        # IOContext If :module is not set, default to Main (or current active module).
+        # IOContext If :module is not set, default to Main.
         # nothing can be used to force printing prefix
-        from = get(io, :module, active_module())
+        from = get(io, :module, Main)
         if isdefined(tn, :module) && (from === nothing || !isvisible(sym, tn.module, from::Module))
             show(io, tn.module)
             print(io, ".")
@@ -2535,7 +2527,7 @@ function show_signature_function(io::IO, @nospecialize(ft), demangle=false, farg
     uw = unwrap_unionall(ft)
     if ft <: Function && isa(uw, DataType) && isempty(uw.parameters) && _isself(uw)
         uwmod = parentmodule(uw)
-        if qualified && !is_exported_from_stdlib(uw.name.mt.name, uwmod) && uwmod !== Main
+        if qualified && !isexported(uwmod, uw.name.mt.name) && uwmod !== Main
             print_within_stacktrace(io, uwmod, '.', bold=true)
         end
         s = sprint(show_sym, (demangle ? demangle_function_name : identity)(uw.name.mt.name), context=io)

stdlib/REPL/src/REPL.jl

@@ -329,7 +329,7 @@ function warn_on_non_owning_accesses(current_mod, ast)
     end
     return ast
 end
-warn_on_non_owning_accesses(ast) = warn_on_non_owning_accesses(REPL.active_module(), ast)
+warn_on_non_owning_accesses(ast) = warn_on_non_owning_accesses(Base.active_module(), ast)
 
 const repl_ast_transforms = Any[softscope, warn_on_non_owning_accesses] # defaults for new REPL backends
 
@@ -497,7 +497,7 @@ end
 function display(d::REPLDisplay, mime::MIME"text/plain", x)
     x = Ref{Any}(x)
     with_repl_linfo(d.repl) do io
-        io = IOContext(io, :limit => true, :module => active_module(d)::Module)
+        io = IOContext(io, :limit => true, :module => Base.active_module(d)::Module)
         if d.repl isa LineEditREPL
             mistate = d.repl.mistate
             mode = LineEdit.mode(mistate)
@@ -527,7 +527,7 @@ show_repl(io::IO, ::MIME"text/plain", ex::Expr) =
 function print_response(repl::AbstractREPL, response, show_value::Bool, have_color::Bool)
     repl.waserror = response[2]
     with_repl_linfo(repl) do io
-        io = IOContext(io, :module => active_module(repl)::Module)
+        io = IOContext(io, :module => Base.active_module(repl)::Module)
         print_response(io, response, show_value, have_color, specialdisplay(repl))
     end
     return nothing
@@ -628,7 +628,7 @@ function run_repl(repl::AbstractREPL, @nospecialize(consumer = x -> nothing); ba
             Core.println(Core.stderr, e)
             Core.println(Core.stderr, catch_backtrace())
         end
-    get_module = () -> active_module(repl)
+    get_module = () -> Base.active_module(repl)
     if backend_on_current_task
         t = @async run_frontend(repl, backend_ref)
         errormonitor(t)
@@ -760,14 +760,9 @@ REPLCompletionProvider() = REPLCompletionProvider(LineEdit.Modifiers())
 mutable struct ShellCompletionProvider <: CompletionProvider end
 struct LatexCompletions <: CompletionProvider end
 
-function active_module() # this method is also called from Base
-    isdefined(Base, :active_repl) || return Main
-    Base.active_repl === nothing && return Main
-    return active_module(Base.active_repl::AbstractREPL)
-end
-active_module((; mistate)::LineEditREPL) = mistate === nothing ? Main : mistate.active_module
-active_module(::AbstractREPL) = Main
-active_module(d::REPLDisplay) = active_module(d.repl)
+Base.active_module((; mistate)::LineEditREPL) = mistate === nothing ? Main : mistate.active_module
+Base.active_module(::AbstractREPL) = Main
+Base.active_module(d::REPLDisplay) = Base.active_module(d.repl)
 
 setmodifiers!(c::CompletionProvider, m::LineEdit.Modifiers) = nothing
 
@@ -1206,7 +1201,7 @@ enable_promptpaste(v::Bool) = JL_PROMPT_PASTE[] = v
 
 function contextual_prompt(repl::LineEditREPL, prompt::Union{String,Function})
     function ()
-        mod = active_module(repl)
+        mod = Base.active_module(repl)
         prefix = mod == Main ? "" : string('(', mod, ") ")
         pr = prompt isa String ? prompt : prompt()
         prefix * pr