That's why you combine it with -Wno-... as appropriate on a per-project as well as per-file basis in addition to a simple way to disable warnings completely.

When using make, it could look something like this:

    CC := clang
    CFLAGS := -std=c99
    WFLAGS := -Weverything -Werror
    NOWARN := vla
    COMPILE = $(CC) -c $(CFLAGS) $(WFLAGS) $(NOWARN:%=-Wno-%) -o $@ $<

    foo.o: NOWARN += padded

    foo.o bar.o: %.o: %.c
        $(COMPILE)

Building without warnings would be achieved via

    make WFLAGS=""