cpp has -W#warning
cpp handles -w to disable warnings
warn.c provides note_at()
Bitfield size-rounding test
Fix __auto_type retaining its attributes
Run decl cleanups (and VLA destructors) in reverse order
Correctly handle struct containing const - assignment is still an error
Remove unnecessary argument to ustrprintf()
Remove loss-of-precision warning from Wextra
Fix x86 idiv with (negative) 4-byte ints
Fix constant division/modulo with negative integers
Fix finding an invalid trigraph sequence
Correct parsing of hex-floating constants like 0x.[0-9]...
Add -Wgnu
Warn on GNU address-of-label
Disable -Wgnu by default
cpp: fix extra "warning:" message for redef
cpp handles -Wall and -Weverything
cpp errors on redefinition of builtins (__TIME__, etc)
cpp handles backslash-newline with spaces between