Revert "support repl_ast_transforms in Julia 1.5 (#947)"

This reverts commit 4fd955a.

Author: stevengj

docs/src/library/internals.md

@@ -10,16 +10,6 @@ IJulia.init
 
 ## Cell execution hooks
 
-These functions can be used to modify the behavior of IJulia
-by executing custom code before or after cells are executed
-(or errors are handled).
-
-In Julia 1.5 or later, you can *also* add a transformation
-function to `REPL.repl_ast_transforms` which takes every parsed
-expression and transforms it to another expression.  These
-transformations are [used in the Julia REPL](https://github.com/JuliaLang/julia/issues/37047) (technically, they are the deaults for `Base.active_repl_backend.ast_transforms` in new REPL instances),
-and are also executed by IJulia on each parsed code-cell expression.
-
 ```@docs
 IJulia.pop_posterror_hook
 IJulia.pop_postexecute_hook
@@ -29,6 +19,7 @@ IJulia.push_postexecute_hook
 IJulia.push_preexecute_hook
 ```
 
+
 ## Messaging
 
 ```@docs

docs/src/manual/usage.md

@@ -122,15 +122,6 @@ It defaults to `Main`.
 
 By default, IJulia evaluates user code using "soft" global scope, via the [SoftGlobalScope.jl package](https://github.com/stevengj/SoftGlobalScope.jl): this means that you don't need explicit `global` declarations to modify global variables in `for` loops and similar, which is convenient for interactive use.
 
-To opt out of this behavior, making notebooks behave similarly to global code in Julia `.jl` files or the REPL in Julia 1.0…1.4,
+To opt out of this behavior, making notebooks behave similarly to global code in Julia `.jl` files,
 you can set `IJulia.SOFTSCOPE[] = false` at runtime, or include the environment variable `IJULIA_SOFTSCOPE=no`
 environment of the IJulia kernel when it is launched.
-
-In Julia 1.5 or later, [soft-scope became the default
-in the Julia REPL](https://julialang.org/blog/2020/08/julia-1.5-highlights/#the_return_of_quotsoft_scopequot_in_the_repl), and
-IJulia once again matches the REPL behavior.   The `IJULIA_SOFTSCOPE`
-and `IJulia.SOFTSCOPE[]` can still be used to disable soft scope
-in IJulia, however.   More generally, the soft scoping can
-be disabled in both the REPL and in IJulia by removing the
-`REPL.softscope` function from the variable `REPL.repl_ast_transforms`
-in your [`~/.julia/config/startup.jl`](https://docs.julialang.org/en/v1/manual/getting-started/) file.

src/execute_request.jl

@@ -11,30 +11,11 @@ execute_msg = Msg(["julia"], Dict("username"=>"jlkernel", "session"=>uuid4()), D
 # request
 const stdio_bytes = Ref(0)
 
-import REPL
 import REPL: helpmode
 
 # use a global array to accumulate "payloads" for the execute_reply message
 const execute_payloads = Dict[]
 
-function execute_code(code::AbstractString, filename::AbstractString)
-    @static if !isdefined(REPL, :repl_ast_transforms)
-        return SOFTSCOPE[] ? softscope_include_string(current_module[], code, "In[$n]") :
-                             include_string(current_module[], code, "In[$n]")
-    else
-        # use the default REPL ast transformations in Julia 1.5,
-        # which include the soft-scope transformation.
-        include_string(current_module[], code, "In[$n]") do ast
-            for xf in REPL.repl_ast_transforms
-                if xf !== REPL.softscope || SOFTSCOPE[]
-                    ast = Base.invokelatest(xf, ast)
-                end
-            end
-            ast
-        end
-    end
-end
-
 function execute_request(socket, msg)
     code = msg.content["code"]
     @vprintln("EXECUTING ", code)
@@ -84,7 +65,8 @@ function execute_request(socket, msg)
         else
             #run the code!
             occursin(magics_regex, code) && match(magics_regex, code).offset == 1 ? magics_help(code) :
-                execute_code(code, "In[$n]")
+                SOFTSCOPE[] ? softscope_include_string(current_module[], code, "In[$n]") :
+                include_string(current_module[], code, "In[$n]")
         end
 
         if silent