make sure to not normalize impl header in coherence

Author: Shourya742

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -278,10 +278,16 @@ fn overlap<'tcx>(
     // empty environment.
     let param_env = ty::ParamEnv::empty();
 
-    let impl1_header =
-        fresh_impl_header_normalized(selcx.infcx, param_env, impl1_def_id, is_of_trait);
-    let impl2_header =
-        fresh_impl_header_normalized(selcx.infcx, param_env, impl2_def_id, is_of_trait);
+    let impl1_header = if tcx.next_trait_solver_in_coherence() {
+        fresh_impl_header(selcx.infcx, impl1_def_id, is_of_trait)
+    } else {
+        fresh_impl_header_normalized(selcx.infcx, param_env, impl1_def_id, is_of_trait)
+    };
+    let impl2_header = if tcx.next_trait_solver_in_coherence() {
+        fresh_impl_header(selcx.infcx, impl2_def_id, is_of_trait)
+    } else {
+        fresh_impl_header_normalized(selcx.infcx, param_env, impl2_def_id, is_of_trait)
+    };
 
     // Equate the headers to find their intersection (the general type, with infer vars,
     // that may apply both impls).