http://gcc.gnu.org/PR32102 is about the fact that -Wall -Wstrict-overflow is not the same as -Wstrict-overflow -Wall (i.e., the order of the options matter). The reason is that -Wall sets warn_strict_overflow to 1 and -Wstrict-overflow sets warn_strict_overflow to 2.
It is normal and expected that if you specify the same option twice, the later one takes precedence. But it is, perhaps, less expected that a general option like -Wall changes the behaviour of a specific option like -Wstrict-overflow. This of course also applies to the optimization options: -fno-tree-vrp -O2 will cause the -fno-tree-vrp option to be ignored. Does anybody have an opinion on whether the current behaviour is good or bad? The documention suggests that the order of different options does not matter, so if the current behaviour is good, we should fix the documentation. Ian
