问题
warning: #pragma once in main file
We're running our headers through clang to get a partial AST.
Is it possible to disable that warning?
回答1:
Use the -Wno-pragma-once-outside-header command line argument. Consult the Clang documentation here.
回答2:
I had this thing when I accidentally included a header file in compile sources (this header has #pragma once line). To fix this remove header from compile sources (and probably you need to replace it with .cpp file)
回答3:
There's no -W option for "#pragma once in main file", so you can't turn it off via the usual means. (However, the Clang developers are very aware that warnings without -W options suck, and there's a general rule that new warnings always get -W options. Cleaning up the old code, unfortunately, is left as an exercise for frustrated users.)
If you don't mind shell hackery, you could always do something like this:
# This gives the warning...
clang -c myheader.h
# ...This doesn't.
echo '#include "myheader.h"' | clang -c -x c++-header -o myheader.h.gch -
The trailing -, as usual, means "read from stdin". The -x c++ tells Clang what language you're using (since it can't tell from the file extension when there is no file), and changing c++ to c++-header means that we want to produce a .gch file instead of an .o file.
The two .gch files thus produced are NOT bit-for-bit identical. I don't know enough about gch files to tell you what might be observably different about their behavior. However, since all you care about is Clang's AST, I bet you'll be fine with it. :)
回答4:
Use the -w (lowercase w not uppercase W) option while compiling the source to suppress such warnings.
回答5:
There are no option to control it, so just ban this warning in your code.
来源：https://stackoverflow.com/questions/16726352/is-is-possible-to-disable-this-warning-in-clang-warning-pragma-once-in-main-f