Fix JET name collisions in @resumable expansion

CHANGELOG.md

@@ -1,5 +1,9 @@
 # News
 
+## v1.0.6 - 2026-04-23
+
+- (internal) switch to a reimplementation of `gensym` that is not replayable by JET.jl (see https://github.com/aviatesk/JET.jl/issues/814)
+
 ## v1.0.5 - 2026-03-20
 
 - Some general cleanup of the code

Project.toml

@@ -5,7 +5,7 @@ license = "MIT"
 desc = "C# sharp style generators a.k.a. semi-coroutines for Julia."
 authors = ["Ben Lauwens and volunteer maintainers"]
 repo = "https://github.com/JuliaDynamics/ResumableFunctions.jl.git"
-version = "1.0.5"
+version = "1.0.6"
 
 [deps]
 Logging = "56ddb016-857b-54e1-b83d-db4d58db5568"

src/macro.jl

@@ -115,7 +115,7 @@ macro resumable(ex::Expr...)
   pushfirst!(args, functional)
 
   # The finite state machine structure definition
-  type_name = gensym(Symbol(func_def[:name], :_FSMI))
+  type_name = fresh_binding_name(Symbol(func_def[:name], :_FSMI))
   constr_def = copy(func_def)
   slot_T = [gensym(s) for s in keys(slots)]
   slot_T_sub = [:($k <: $v) for (k, v) in zip(slot_T, values(slots))]
@@ -152,7 +152,7 @@ macro resumable(ex::Expr...)
     bareconst_expr = nothing
   end
   constr_expr = combinedef(constr_def) |> flatten
-  typed_fsmi = VERSION >= v"1.10.0-DEV.873" ? gensym(:typed_fsmi) : typed_fsmi_fallback
+  typed_fsmi = VERSION >= v"1.10.0-DEV.873" ? fresh_binding_name(:typed_fsmi) : typed_fsmi_fallback
   type_expr = quote
     mutable struct $struct_name
       _state :: UInt8

src/utils.jl

@@ -59,6 +59,14 @@ function forward_args(func_def)
 end
 
 const unused = (Symbol("#temp#"), Symbol("_"), Symbol(""), Symbol("#unused#"), Symbol("#self#"))
+const fresh_binding_counter = Base.Threads.Atomic{UInt}(0)
+
+# JET/Revise can replay macro expansion in a way that makes plain `gensym()`
+# collide for top-level bindings. Use an explicit module-global counter there.
+function fresh_binding_name(prefix=:resumable)
+  id = Base.Threads.atomic_add!(fresh_binding_counter, UInt(1)) + UInt(1)
+  return Symbol("##", prefix, "#", Base.get_world_counter(), "#", id)
+end
 
 function strip_defaults(arg_exprs::Vector{Any})
   return Any[@capture(arg_expr, arg_expr2_ = default_) ? arg_expr2 : arg_expr
@@ -70,7 +78,7 @@ Function returning the slots of a function definition
 """
 function get_slots(func_def::Dict, args::Dict{Symbol, Any}, mod::Module)
   slots = Dict{Symbol, Any}()
-  func_def[:name] = gensym()
+  func_def[:name] = fresh_binding_name(:inferfn)
   func_def[:args] = Any[strip_defaults(func_def[:args])..., strip_defaults(func_def[:kwargs])...]
   func_def[:kwargs] = []
   # replace yield with inference barrier