fix #19897, regression in generated function reflection

due to #19846

base/methodshow.jl

@@ -39,9 +39,7 @@ function arg_decl_parts(m::Method)
  else
  tv = Any[tv...]
  end
- if m.isstaged
- src = m.unspecialized.inferred
- elseif isdefined(m, :source)
+ if isdefined(m, :source)
  src = m.source
  else
  src = nothing
@@ -63,7 +61,7 @@ function kwarg_decl(m::Method, kwtype::DataType)
  kwli = ccall(:jl_methtable_lookup, Any, (Any, Any, UInt), kwtype.name.mt, sig, max_world(m))
  if kwli !== nothing
  kwli = kwli::Method
- src = kwli.isstaged ? kwli.unspecialized.inferred : kwli.source
+ src = kwli.source
  kws = filter(x->!('#' in string(x)), src.slotnames[kwli.nargs+1:end])
  # ensure the kwarg... is always printed last. The order of the arguments are not
  # necessarily the same as defined in the function

base/reflection.jl

@@ -345,7 +345,7 @@ Returns an array of lowered ASTs for the methods matching the given generic func
 function code_lowered(f::ANY, t::ANY=Tuple)
  asts = map(methods(f, t)) do m
  m = m::Method
- return uncompressed_ast(m, m.isstaged ? m.unspecialized.inferred : m.source)
+ return uncompressed_ast(m, m.source)
  end
  return asts
 end

base/serialize.jl

@@ -340,11 +340,7 @@ function serialize(s::AbstractSerializer, meth::Method)
  serialize(s, meth.nargs)
  serialize(s, meth.isva)
  serialize(s, meth.isstaged)
- if meth.isstaged
- serialize(s, uncompressed_ast(meth, meth.unspecialized.inferred))
- else
- serialize(s, uncompressed_ast(meth, meth.source))
- end
+ serialize(s, uncompressed_ast(meth, meth.source))
  nothing
 end
 
@@ -642,13 +638,12 @@ function deserialize(s::AbstractSerializer, ::Type{Method})
  meth.nargs = nargs
  meth.isva = isva
  # TODO: compress template
+ meth.source = template
  if isstaged
  linfo = ccall(:jl_new_method_instance_uninit, Ref{Core.MethodInstance}, ())
  linfo.specTypes = Tuple
  linfo.inferred = template
- meth.unspecialized = linfo
- else
- meth.source = template
+ meth.generator = linfo
  end
  ftype = ccall(:jl_first_argument_datatype, Any, (Any,), sig)::DataType
  if isdefined(ftype.name, :mt) && nothing === ccall(:jl_methtable_lookup, Any, (Any, Any, UInt), ftype.name.mt, sig, typemax(UInt))

base/show.jl

@@ -294,7 +294,7 @@ end
 
 function show(io::IO, l::Core.MethodInstance)
  if isdefined(l, :def)
- if l.def.isstaged && l === l.def.unspecialized
+ if l.def.isstaged && l === l.def.generator
  print(io, "MethodInstance generator for ")
  show(io, l.def)
  else

test/staged.jl

@@ -210,3 +210,6 @@ let
  decorate(bar)
  @test in(typeof(bar), decorated)
 end
+
+# issue #19897
+@test code_lowered(staged_t1, (Int,Int)) isa Array # check no error thrown