disabled filter that's causing heisenbug (close #4347)

codegen.ml

@@ -1809,9 +1809,10 @@ module UnificationCallback = struct
 				e
 		in
 		let check e = match e.eexpr with
-			| TBinop((OpAssign | OpAssignOp _ as op),e1,e2) ->
+			| TBinop((OpAssign | OpAssignOp _),e1,e2) ->
+				assert false; (* this trigger #4347, to be fixed before enabling
 				let e2 = f e2 e1.etype in
-				{e with eexpr = TBinop(op,e1,e2)}
+				{e with eexpr = TBinop(op,e1,e2)} *)
 			| TVar(v,Some ev) ->
 				let eo = Some (f ev v.v_type) in
 				{ e with eexpr = TVar(v,eo) }

filters.ml

@@ -1163,7 +1163,6 @@ let run com tctx main =
 	if use_static_analyzer then begin
 		(* PASS 1: general expression filters *)
 		let filters = [
-			Codegen.UnificationCallback.run (check_unification tctx);
 			Codegen.AbstractCast.handle_abstract_casts tctx;
 			Optimizer.inline_constructors tctx;
 			Optimizer.reduce_expression tctx;
@@ -1183,7 +1182,6 @@ let run com tctx main =
 	end else begin
 		(* PASS 1: general expression filters *)
 		let filters = [
-			Codegen.UnificationCallback.run (check_unification tctx);
 			Codegen.AbstractCast.handle_abstract_casts tctx;
 			blockify_ast;
 			check_local_vars_init;