From 8683d6f1abfebc018c849ae2700f641952367770 Mon Sep 17 00:00:00 2001
From: Tim Holy <tim.holy@gmail.com>
Date: Sun, 10 Feb 2019 22:25:21 -0600
Subject: [PATCH] Handle world-age errors in incremental lowering

---
 src/interpret.jl   | 11 +++++++++++
 test/juliatests.jl | 12 +++++++-----
 test/utils.jl      |  2 +-
 3 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/src/interpret.jl b/src/interpret.jl
index 83ed8eed2851f..9ea3977698e0a 100644
--- a/src/interpret.jl
+++ b/src/interpret.jl
@@ -406,6 +406,17 @@ function _step_expr!(stack, frame, @nospecialize(node), pc::JuliaProgramCounter,
             rhs = @lookup(frame, node)
         end
     catch err
+        # Check for world age errors, which generally indicate a failure to go back to toplevel
+        if isa(err, MethodError)
+            is_arg_types = isa(err.args, DataType)
+            arg_types = is_arg_types ? err.args : Base.typesof(err.args...)
+            if (err.world != typemax(UInt) &&
+                hasmethod(err.f, arg_types) &&
+                !hasmethod(err.f, arg_types, world = err.world))
+                @warn "likely failure to return to toplevel, try Base.invokelatest"
+                rethrow(err)
+            end
+        end
         isempty(frame.exception_frames) && rethrow(err)
         frame.last_exception[] = err
         return JuliaProgramCounter(frame.exception_frames[end])
diff --git a/test/juliatests.jl b/test/juliatests.jl
index 0b22c18b3e3db..ef921af9d376b 100644
--- a/test/juliatests.jl
+++ b/test/juliatests.jl
@@ -13,14 +13,16 @@ else
     @warn "Julia's test/ directory not found, skipping Julia tests"
 end
 
-module JuliaTests end
+module JuliaTests
+using Test
+end
 
 @testset "Julia tests" begin
     stack = JuliaStackFrame[]
     function runtest(frame)
         empty!(stack)
-        empty!(JuliaInterpreter.framedict)
-        empty!(JuliaInterpreter.genframedict)
+        # empty!(JuliaInterpreter.framedict)
+        # empty!(JuliaInterpreter.genframedict)
         return JuliaInterpreter.finish_and_return!(stack, frame, true)
     end
     function dotest!(failed, test)
@@ -29,13 +31,13 @@ module JuliaTests end
         if isexpr(ex, :error)
             @warn "error parsing $test: $ex"
         else
-            ex = Expr(:toplevel, :(using Test), ex)
             try
                 lower_incrementally(runtest, JuliaTests, ex)
                 println("Succeeded on ", test)
             catch err
                 @show test err
                 push!(failed, (test, err))
+                # rethrow(err)
             end
         end
     end
@@ -44,7 +46,7 @@ module JuliaTests end
         delayed = []
         failed = []
         for test in tests
-            if startswith(test, "compiler")
+            if startswith(test, "compiler") || test == "subarray"
                 push!(delayed, test)
             else
                 dotest!(failed, test)
diff --git a/test/utils.jl b/test/utils.jl
index 57ff7d2ca4d48..345ed0baa2a56 100644
--- a/test/utils.jl
+++ b/test/utils.jl
@@ -76,7 +76,7 @@ function lower!(@nospecialize(f), docexprs, mod::Module, ex::Expr)
     lwr = Meta.lower(mod, ex)
     if isexpr(lwr, :thunk)
         frame = JuliaInterpreter.prepare_thunk(mod, lwr)
-        f(frame)
+        Base.invokelatest(f, frame)  # if previous thunks define new methods, we need to update world age
     elseif isa(lwr, Expr) && (lwr.head == :export || lwr.head == :using || lwr.head == :import)
     elseif isa(lwr, Symbol) || isa(lwr, Nothing)
     else