refactor: Revert "disable self-assign warning for tests"

This reverts commit 53372f2176.

src/test/arith_uint256_tests.cpp

@@ -580,20 +580,6 @@ BOOST_AUTO_TEST_CASE(conversion)
 
 BOOST_AUTO_TEST_CASE(operator_with_self)
 {
-    /* Clang 16 and earlier detects v -= v and v /= v as self-assignments
-       to 0 and 1 respectively.
-       See: https://github.com/llvm/llvm-project/issues/42469
-       and the fix in commit c5302325b2a62d77cf13dd16cd5c19141862fed0 .
-
-       This makes some sense for arithmetic classes, but could be considered a bug
-       elsewhere. Disable the warning here so that the code can be tested, but the
-       warning should remain on as there will likely always be a better way to
-       express this.
-    */
-#if defined(__clang__)
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wself-assign-overloaded"
-#endif
     arith_uint256 v{2};
     v *= v;
     BOOST_CHECK_EQUAL(v, arith_uint256{4});
@@ -603,9 +589,6 @@ BOOST_AUTO_TEST_CASE(operator_with_self)
     BOOST_CHECK_EQUAL(v, arith_uint256{2});
     v -= v;
     BOOST_CHECK_EQUAL(v, arith_uint256{0});
-#if defined(__clang__)
-#pragma clang diagnostic pop
-#endif
 }
 
 BOOST_AUTO_TEST_SUITE_END()

src/test/fuzz/muhash.cpp

@@ -199,19 +199,7 @@ FUZZ_TARGET(muhash)
         },
         [&] {
             // Test that dividing a MuHash by itself brings it back to its initial state
-
-            // See note about clang + self-assignment in test/uint256_tests.cpp
-            #if defined(__clang__)
-            #    pragma clang diagnostic push
-            #    pragma clang diagnostic ignored "-Wself-assign-overloaded"
-            #endif
-
             muhash /= muhash;
-
-            #if defined(__clang__)
-            #    pragma clang diagnostic pop
-            #endif
-
             muhash.Finalize(out);
             out2 = initial_state_hash;
         },