https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80346
--- Comment #10 from Martin Sebor <msebor at gcc dot gnu.org> --- 108 /* compute the table entries in rsdt */ 109 tables_nr = (rsdt_table->length - sizeof(AcpiRsdtDescriptorRev1)) / 110 sizeof(uint32_t); 111 g_assert_cmpint(tables_nr, >, 0); For GCC to "understand" the assertion it would need to see the condition and be able to prove the allocation that follows cannot be reached (e.g., because the assertion exits the program by calling a noreturn function like abort or exit when the condition is false). From the preprocessed translation unit in attachment 41147 it looks as though the whole g_assert_cmpint expands to an unconditional function call (g_assertion_message_cmpnum) that's not decorated with attribute noreturn, and so the condition doesn't affect the range of the variable. Also, when working with sizes it's best to deal with unsigned types. Storing a size in an int and using it in mixed-type expressions involving size_t (like sizeof) can easily introduce the possibility of overflow (as far as GCC can see) and turn a non-negative range into a negative-positive one. In the attachment, changing the type of the tables_nr local variable from int to size_t eliminates the warning,
