https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90882
--- Comment #1 from Kevin Dewald <kevin.dewald at ieee dot org> --- When compiling and running the attached code using GCC 7.4.0, the output prints both 'true' and 'false'. When testing if the variable 'boolean' is false, an XOR 1,EAX instruction is executed on that memory position. Given that that position is currently storing 0x02 instead of 0x01, it's new value is 0x03, evaluating true by the TEST opcode. From what I've read, modifying a boolean variable with an int pointer is undefined. Nevertheless, this feels unexpected from a programmers point of view, and I might worry it might be exploited as a security flaw on applications compiled with GCC. I've tested the same code on clang and it behaves as expected, only printing 'true'.
