Nope. clang has "-Weverything", and gcc has "-Wextra", both of which go beyond "-Wall".

https://stackoverflow.com/questions/11714827/how-can-i-turn-...

-Wextra is also in Clang and is definitely not everything in either compiler.

-Weverything is everything but that is only really useful to discover new warning flags (in combination with lots of -Wno...) for which you are better off reading GCC/Clang's release notes and/or documentation.