more thorough type_goto. fixes JuliaLang#7810

base/inference.jl

@@ -1333,10 +1333,6 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
  toprec = false
 
  s = { () for i=1:n }
- recpts = IntSet() # statements that depend recursively on our value
- W = IntSet()
- # initial set of pc
- push!(W,1)
  # initial types
  s[1] = ObjectIdDict()
  for v in vars
@@ -1386,10 +1382,19 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
  sv = StaticVarInfo(sparams, cenv, vars, label_counter(body))
  frame.sv = sv
 
+ recpts = IntSet() # statements that depend recursively on our value
+ W = IntSet()
+
+ @label typeinf_top
+
+ old_s1 = nothing
+
  # exception handlers
  cur_hand = ()
  handler_at = { () for i=1:n }
 
+ push!(W,1) # initial set of pc
+
  while !isempty(W)
  pc = first(W)
  while true
@@ -1442,26 +1447,24 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
  end
  end
  elseif is(hd,:type_goto)
- l = findlabel(labels,stmt.args[1])
  for i = 2:length(stmt.args)
  var = stmt.args[i]
  if isa(var,SymbolNode)
  var = var.name
  end
- # type_goto provides a special update rule for the
- # listed vars: it feeds types directly to the
- # target statement as long as they are *different*,
- # not !issubtype like usual. this is because we want
- # the specific type inferred at the point of the
- # type_goto, not just any type containing it.
- # Otherwise "None" doesn't work; see issue #3821
+ # Store types that need to be fed back via type_goto
+ # in position s[1]. After finishing inference, if any
+ # of these types changed, start over with the fed-back
+ # types known from the beginning.
+ # See issue #3821 (using !typeseq instead of !subtype),
+ # and issue #7810.
  vt = changes[var]
- ot = get(s[l],var,NF)
- if ot === NF || !typeseq(vt,ot)
- # l+1 is the statement after the label, where the
- # static_typeof occurs.
- push!(W, l+1)
- s[l+1][var] = vt
+ ot = s[1][var]
+ if !typeseq(vt,ot)
+ if old_s1 === nothing
+  old_s1 = copy(s[1])
+ end
+ s[1][var] = vt
  end
  end
  elseif is(hd,:return)
@@ -1515,6 +1518,20 @@ function typeinf(linfo::LambdaStaticData,atypes::Tuple,sparams::Tuple, def, cop)
  end
  end
  end
+
+ if old_s1 !== nothing
+ # if any type_gotos changed, clear state and restart.
+ for (v_,t_) in s[1]
+ if !typeseq(t_, old_s1[v_])
+ for ll = 2:length(s)
+ s[ll] = ()
+ end
+ empty!(W)
+ @goto typeinf_top
+ end
+ end
+ end
+
  #print("\n",ast,"\n")
  #if dbg print("==> ", frame.result,"\n") end
  if (toprec && typeseq(curtype, frame.result)) || !isa(frame.prev,CallStack)

test/core.jl

@@ -1804,6 +1804,12 @@ i7652() = a7652.(1) = 3.0
 i7652()
 @test a7652.a == 3
 
-
 # issue #7679
 @test map(f->f(), { ()->i for i=1:3 }) == {1,2,3}
+
+# issue #7810
+type Foo7810{T<:AbstractVector}
+ v::T
+end
+bar7810() = [Foo7810([(a,b) for a in 1:2]) for b in 3:4]
+@test Base.return_types(bar7810,())[1] == Array{Foo7810{Array{(Int64,Int64),1}},1}