Tests: Fix new GCC 12 warnings

Tests/Kernel/TestSigAltStack.cpp

@@ -22,17 +22,13 @@ static void signal_handler(int)
     _exit(0);
 }
 
-#ifdef __clang__
-#    pragma clang diagnostic push
-#    pragma clang diagnostic ignored "-Winfinite-recursion"
-#endif
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Winfinite-recursion"
 static size_t infinite_recursion(size_t input)
 {
     return infinite_recursion(input) + 1;
 }
-#ifdef __clang__
-#    pragma clang diagnostic pop
-#endif
+#pragma GCC diagnostic pop
 
 // This test can only pass with sigaltstack correctly enabled, as otherwise the SIGSEGV signal handler itself would also fault due to the overflown stack.
 TEST_CASE(success_case)

Tests/Kernel/crash.cpp

@@ -139,7 +139,10 @@ int main(int argc, char** argv)
                 return Crash::Failure::UnexpectedError;
 
             free(uninitialized_memory);
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wuse-after-free"
             [[maybe_unused]] volatile auto x = uninitialized_memory[4][0];
+#pragma GCC diagnostic pop
             return Crash::Failure::DidNotCrash;
         }).run(run_type);
     }
@@ -161,8 +164,11 @@ int main(int argc, char** argv)
             if (!uninitialized_memory)
                 return Crash::Failure::UnexpectedError;
 
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wuse-after-free"
             free(uninitialized_memory);
             uninitialized_memory[4][0] = 1;
+#pragma GCC diagnostic pop
             return Crash::Failure::DidNotCrash;
         }).run(run_type);
     }

Tests/Kernel/siginfo-example.cpp

@@ -21,8 +21,7 @@ bool volatile signal_was_delivered = false;
 
 static void signal_handler(int sig, siginfo_t* sig_info, void* u_context)
 {
-    int x;
-    stack_ptr = &x;
+    stack_ptr = __builtin_frame_address(0);
     signal_was_delivered = true;
 
     saved_signal = sig;