From 939c0d7c6a4923459b95fbd83bce403dec40195f Mon Sep 17 00:00:00 2001
From: Kristoffer Carlsson <kcarlsson89@gmail.com>
Date: Sat, 9 May 2020 11:34:08 +0200
Subject: [PATCH] add closed over variables to locals and fix code evaluation
 on them (#388)

---
 src/types.jl      |  7 ++++++-
 src/utils.jl      | 18 +++++++++++++++++-
 test/eval_code.jl | 19 ++++++++++++++++++-
 3 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/src/types.jl b/src/types.jl
index fd1b829a1c2a74..d6a065be070b9f 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -263,15 +263,20 @@ Important fields:
 - `value::Any`: the value of the local variable.
 - `name::Symbol`: the name of the variable as given in the source code.
 - `isparam::Bool`: if the variable is a type parameter, for example `T` in `f(x::T) where {T} = x`.
+- `is_captured_closure::Bool`: if the variable has been captured by a closure
 """
 struct Variable
     value::Any
     name::Symbol
     isparam::Bool
+    is_captured_closure::Bool
 end
+Variable(value, name) = Variable(value, name, false, false)
+Variable(value, name, isparam) = Variable(value, name, isparam, false)
 Base.show(io::IO, var::Variable) = (print(io, var.name, " = "); show(io,var.value))
 Base.isequal(var1::Variable, var2::Variable) =
-    var1.value == var2.value && var1.name == var2.name && var1.isparam == var2.isparam
+    var1.value == var2.value && var1.name == var2.name && var1.isparam == var2.isparam &&
+    var1.is_captured_closure == var2.is_captured_closure
 
 # A type that is unique to this package for which there are no valid operations
 struct Unassigned end
diff --git a/src/utils.jl b/src/utils.jl
index ee3bc7ee0a131c..0286c9d05110af 100644
--- a/src/utils.jl
+++ b/src/utils.jl
@@ -371,7 +371,7 @@ function locals(frame::Frame)
     slotnames = code.src.slotnames::SlotNamesType
     for (sym, counter, val) in zip(slotnames, data.last_reference, data.locals)
         counter == 0 && continue
-        var = Variable(something(val), sym, false)
+        var = Variable(something(val), sym)
         idx = get(varlookup, sym, 0)
         if idx > 0
             if counter > var_counter[idx]
@@ -392,6 +392,13 @@ function locals(frame::Frame)
             end
         end
     end
+    for var in vars
+        if var.name == Symbol("#self#")
+            for field in fieldnames(typeof(var.value))
+                push!(vars, Variable(getfield(var.value, field), field, false, true))
+            end
+        end
+    end
     return vars
 end
 
@@ -484,6 +491,15 @@ function eval_code(frame::Frame, expr)
         if v.isparam
             data.sparams[j] = res[i]
             j += 1
+        elseif v.is_captured_closure
+            selfidx = findfirst(v -> v.name === Symbol("#self#"), vars)
+            @assert selfidx !== nothing
+            self = vars[selfidx].value
+            closed_over_var = getfield(self, v.name)
+            if closed_over_var isa Core.Box
+                setfield!(closed_over_var, :contents, res[i])
+            end
+            # We cannot rebind closed over variables that the frontend identified as constant
         else
             slot_indices = code.slotnamelists[v.name]
             idx = argmax(data.last_reference[slot_indices])
diff --git a/test/eval_code.jl b/test/eval_code.jl
index e57092f60b6fc3..e585553b7dd98a 100644
--- a/test/eval_code.jl
+++ b/test/eval_code.jl
@@ -55,4 +55,21 @@ JuliaInterpreter.step_expr!(frame)
 eval_code(frame, "x = 3")
 @test eval_code(frame, "x") == 3
 JuliaInterpreter.finish!(frame)
-@test JuliaInterpreter.get_return(frame) == 2
\ No newline at end of file
+@test JuliaInterpreter.get_return(frame) == 2
+
+function debugfun(non_accessible_variable)
+    garbage = ones(10)
+    map(1:10) do i
+        1+1
+        a = 5
+        @bp
+        garbage[i] + non_accessible_variable[i]
+        non_accessible_variable = 2
+    end
+end
+fr = JuliaInterpreter.enter_call(debugfun, [1,2])
+fr, bp = debug_command(fr, :c)
+@test eval_code(fr, "non_accessible_variable") == [1,2]
+@test eval_code(fr, "garbage") == ones(10)
+eval_code(fr, "non_accessible_variable = 5.0")
+@test eval_code(fr, "non_accessible_variable") == 5.0