This switch tells the assembler that any Warning messages are to be treated as though they were errors; this causes the assembler to end with a non-zero exit code, and helps prevent any warning conditions from "passing by" unnoticed.
┌────┬──────┬─────┬────┬──────────────────────────────────────────────────┐ │Type│Global│Group│File│Default │ ├────┼──────┼─────┼────┼──────────────────────────────────────────────────┤ │S │Yes │Yes │Yes │-Mwe (warnings are not considered to be errors) │ └────┴──────┴─────┴────┴──────────────────────────────────────────────────┘