Merge pull request #156 from torfjelde/tor/use-gensym-in-setmacro

Use gensym for `lens` variable in `setmacro`

Author: jw3126

src/sugar.jl

@@ -183,19 +183,20 @@ function setmacro(lenstransform, ex::Expr; overwrite::Bool=false)
     @assert length(ex.args) == 2
     ref, val = ex.args
     obj, lens = parse_obj_lens(ref)
+    lenssym = gensym(:lens)
     dst = overwrite ? obj : gensym("_")
     val = esc(val)
     ret = if ex.head == :(=)
         quote
-            lens = ($lenstransform)($lens)
-            $dst = $set($obj, lens, $val)
+            $lenssym = ($lenstransform)($lens)
+            $dst = $set($obj, $lenssym, $val)
         end
     else
         op = get_update_op(ex.head)
         f = :($_UpdateOp($op,$val))
         quote
-            lens = ($lenstransform)($lens)
-            $dst = $modify($f, $obj, lens)
+            $lenssym = ($lenstransform)($lens)
+            $dst = $modify($f, $obj, $lenssym)
         end
     end
     ret

test/test_setmacro.jl

@@ -46,5 +46,31 @@ using StaticNumbers
     @test m3 === @SMatrix[1 0; 0 0]
 end
 
+function test_all_inferrable(f, argtypes)
+    typed = first(code_typed(f, argtypes))
+    code = typed.first
+    @test all(T -> !(T isa UnionAll || T === Any), code.slottypes)
+end
+
+# Example of macro that caused inference issues before.
+macro test_macro(expr)
+    quote
+        function f($(esc(:x)))
+            $(Setfield.setmacro(identity, expr, overwrite=true))
+            $(Setfield.setmacro(identity, expr, overwrite=true))
+            $(Setfield.setmacro(identity, expr, overwrite=true))
+            $(Setfield.setmacro(identity, expr, overwrite=true))
+            $(Setfield.setmacro(identity, expr, overwrite=true))
+            return $(esc(:x))
+        end
+    end
+end
+
+@testset "setmacro multiple usage" begin
+    let f = @test_macro(x[end] = 1)
+        test_all_inferrable(f, (Vector{Float64}, ))
+    end
+end
+
 end#module