Merge pull request #1379 from FluxML/bc/fwd-undef-ref

Forward mode: don't use `zerolike` fallback for `GlobalRef`s

src/forward/lib.jl

@@ -9,6 +9,9 @@ end
 # TODO figure out why this made a test fail
 zerolike(x::Union{Module,Type}) = nothing
 
+# Required to not get an UndefRefError on 1.10
+zerolike(x::GlobalRef) = nothing
+
 # TODO: `@non_differentiable` and `@linear`
 
 @tangent zerolike(x) = zerolike(x), _ -> zerolike(x)

test/compiler.jl

@@ -17,8 +17,10 @@ trace_contains(st, func, file, line) = any(st) do fr
 end
 
 bad(x) = x
+const bad_def_line = (@__LINE__) + 1
 @adjoint bad(x) = x, Δ -> error("bad")
 
+const bad_call_line = (@__LINE__) + 3
 function badly(x)
   x = x + 1
   x = bad(x)
@@ -30,11 +32,11 @@ y, back = pullback(badly, 2)
 @test_throws Exception back(1)
 bt = try back(1) catch e stacktrace(catch_backtrace()) end
 
-@test trace_contains(bt, nothing, "compiler.jl", 20)
-if VERSION >= v"1.6-"
-  @test_broken trace_contains(bt, :badly, "compiler.jl", 24)
+@test trace_contains(bt, nothing, "compiler.jl", bad_def_line)
+if VERSION <= v"1.6-" || VERSION >= v"1.10-"
+  @test trace_contains(bt, :badly, "compiler.jl", bad_call_line)
 else
-  @test trace_contains(bt, :badly, "compiler.jl", 24)
+  @test_broken trace_contains(bt, :badly, "compiler.jl", bad_call_line)
 end
 
 # Type inference checks
@@ -81,10 +83,14 @@ y, back = @test_inferred pullback(((a,b),) -> a, (5, 10))
 
 # testcase for issue #808
 # testing that methods(Base.show) does not throw. Having something more specific would be too fragile
-buf = IOBuffer()
-Base.show(buf, methods(Base.show))
-str_repr = String(take!(buf))
-@test !isempty(str_repr)
+show_err = try
+  buf = IOBuffer()
+  Base.show(buf, methods(Base.show))
+  nothing
+catch ex
+  ex
+end
+@test show_err === nothing
 
 struct Funky
     x