W
- warnings
- message tags, 3.4.18 –errtags[={yes|no}]
- suppress messages, 3.4.105 –w[n]
- suppress with -erroff, 3.4.17 –erroff[={%all|%none|taglist}]
- undeclared variables, 3.4.98 –u
- use of non-standard extensions, 3.4.2 –ansi
- WEAK directive, 2.3.1.4 The WEAK Directive
- weak linker symbols, 2.3.1.4 The WEAK Directive
- widestneed (interval arithmetic), 3.4.130 –xinterval[={widestneed|strict|no}]