REPL-only: Print a hint if the user types exit in the REPL using an AST transform

stdlib/REPL/src/REPL.jl

@@ -124,7 +124,46 @@ end
 # Temporary alias until Documenter updates
 const softscope! = softscope
 
-const repl_ast_transforms = Any[softscope] # defaults for new REPL backends
+"""
+    print_exit_hint(ex)
+
+Print a hint about how to exit Julia if the user just types "exit" while using the REPL.
+
+To remove this functionality, use
+`filter!(!=(REPL.print_exit_hint), Base.active_repl_backend.ast_transforms)`
+
+# Example
+```julia
+julia> exit
+suggestion: To exit Julia, use Ctrl-D, or type exit() and press enter.
+exit (generic function with 2 methods)
+
+julia> using REPL
+
+julia> filter!(!=(REPL.print_exit_hint), Base.active_repl_backend.ast_transforms)
+1-element Vector{Any}:
+ softscope (generic function with 1 method)
+
+julia> exit
+exit (generic function with 2 methods)
+```
+"""
+function print_exit_hint(@nospecialize ex)
+    # Look to see if user just typed "exit". ex.args[1] is a LineNumberNode
+    if ex isa Expr && ex.head === :toplevel && length(ex.args) == 2 && ex.args[2] === :exit
+        quote
+            if Main.exit === Base.exit
+                println("suggestion: To exit Julia, use Ctrl-D, or type exit() and press enter.")
+            end
+            # Return the method exit
+            exit
+        end
+    else
+        return ex
+    end
+end
+
+const repl_ast_transforms = Any[softscope, print_exit_hint] # defaults for new REPL backends
 
 # Allows an external package to add hooks into the code loading.
 # The hook should take a Vector{Symbol} of package names and