don't consider Std.string to have side effects (enable to remove some inlined trace arguments)

optimizer.ml

@@ -33,6 +33,7 @@ let has_side_effect e =
 	let rec loop e =
 		match e.eexpr with
 		| TConst _ | TLocal _ | TField _ | TTypeExpr _ | TFunction _ -> ()
+		| TCall ({ eexpr = TField(_,FStatic({ cl_path = ([],"Std") },{ cf_name = "string" })) },args) -> Type.iter loop e
 		| TPatMatch _ | TNew _ | TCall _ | TBinop ((OpAssignOp _ | OpAssign),_,_) | TUnop ((Increment|Decrement),_,_) -> raise Exit
 		| TReturn _ | TBreak | TContinue | TThrow _ | TCast (_,Some _) -> raise Exit
 		| TArray _ | TEnumParameter _ | TCast (_,None) | TBinop _ | TUnop _ | TParenthesis _ | TMeta _ | TWhile _ | TFor _ | TIf _ | TTry _ | TSwitch _ | TArrayDecl _ | TVar _ | TBlock _ | TObjectDecl _ -> Type.iter loop e