2.4.3. Controlling the output of messages during PCH processing
When the compiler creates or uses a PCH file, it displays the following message:
test.c: creating precompiled header file test.pch
You can suppress this message by using the command‑line option ‑‑no_pch_messages.
When you use the ‑‑pch_verbose option, the compiler displays a message for each PCH file that is considered, but cannot be used, giving the reason why it cannot be used.