I have a function that allocates a closure somewhere in it (as shown by the result of -profile=gc).

I can't make the function nogc as it calls a lot of other GC using code.

profilegc.log only gives me the line number of the function signature, which doesn't give me any hint as to where in the function the closure is allocated.

Anyone have any nice tricks to help narrow this down.

On Wednesday, 2 October 2019 at 15:19:43 UTC, John Colvin wrote:
> profilegc.log only gives me the line number of the function signature, which doesn't give me any hint as to where in the function the closure is allocated.

You'll wanna check any nested functions declared in that function. Kinda easier said than done with text tools (I should make a helper tool to do this more reliably like dscanner style), but they will have either the symbol { (hence why it is such a pain) or => and will reference a local variable in the function.

So it is kinda sucky but first is prolly search =>, maybe get lucky, then just start going down the { symbols and find a thing there.

It is tedious but it shouldn't be too bad, at least if the compile is quick enough that you can comment the body, recompile and see if the -vgc still lists the function, or have a reliable way of scanning for local variables.

On Wednesday, 2 October 2019 at 15:19:43 UTC, John Colvin wrote:
> I have a function that allocates a closure somewhere in it (as shown by the result of -profile=gc).
>
> I can't make the function nogc as it calls a lot of other GC using code.
>
> profilegc.log only gives me the line number of the function signature, which doesn't give me any hint as to where in the function the closure is allocated.
>
> Anyone have any nice tricks to help narrow this down.

This hack seems to show the detailed info of @nogc also in normal code.

------------------------------------------------
diff --git a/src/dmd/func.d b/src/dmd/func.d
index 832cd0bf7..e1fad8cdc 100644
--- a/src/dmd/func.d
+++ b/src/dmd/func.d
@@ -1975,7 +1975,7 @@ extern (C++) class FuncDeclaration : Declaration
         else
         {
             printGCUsage(loc, "using closure causes GC allocation");
-            return false;
+//            return false;
         }

         FuncDeclarations a;
------------------------------------------------