only do the getfield optimization when it is safe

src/JuliaInterpreter.jl

@@ -761,8 +761,10 @@ function lookup_global_refs!(ex::Expr)
     for (i, a) in enumerate(ex.args)
         ex.head == :(=) && i == 1 && continue # Don't look up globalrefs on the LHS of an assignment (issue #98)
         if isa(a, GlobalRef)
-            r = getfield(a.mod, a.name)
-            ex.args[i] = QuoteNode(r)
+            if isdefined(a.mod, a.name) && isconst(a.mod, a.name)
+                r = getfield(a.mod, a.name)
+                ex.args[i] = QuoteNode(r)
+            end
         elseif isa(a, Expr)
             lookup_global_refs!(a)
         end

test/interpret.jl

@@ -357,3 +357,22 @@ f113(;x) = x
     @test length(locals) == 3
     @test JuliaInterpreter.Variable(3, :x, false) in locals
 end
+
+@testset "getfield replacements" begin
+    f_gf(x) = false ? y : x
+    @test @interpret f_gf(2) == 2
+
+    function g_gf()
+        eval(:(z = 2))
+        return z
+    end
+    @test @interpret g_gf() == 2
+end
+
+# This can not be put in a testset
+q_gf = 0
+function h_gf()
+    eval(:(q_gf = 2))
+    return q_gf
+end
+@test @interpret h_gf() == 2