How to suppress a warning in clang++? - warnings

Question

I compiled the following c++ program:
int main() { 2==3; }
with:
clang++-5.0 -std=c++17 -Wunused-comparison prog.cpp
and got the warning:
warning: equality comparison result unused [-Wunused-comparison]
2==3;
~^~~
... so, probably this is not the correct way to suppress a warning in CLANG.
In the clang manual, this part is a "TODO".
What is the correct command-line flag to disable a warning?

Answer 1

In the clang diagnostic that you get from:
$ cat main.cpp
int main()
{
2==3;
return 0;
}
$ clang++ -c main.cpp
main.cpp:3:6: warning: equality comparison result unused [-Wunused-comparison]
2==3;
~^~~
1 warning generated.
the bracketed:
-Wunused-comparison
tells you that -Wunused-comparison is the enabled warning (in this case enabled by default) that was responsible for the diagnostic. So to suppress the diagnostic you explicitly disable that warning with the matching -Wno-... flag:
$ clang++ -c -Wno-unused-comparison main.cpp; echo Done
Done
The same applies for GCC.
In general, it is reckless to suppress warnings. One should rather enable them generously - -Wall -Wextra [-pedantic] - and then fix offending code.

Answer 2

add no warning flag as : -Wno-xxx :
https://releases.llvm.org/12.0.0/tools/clang/docs/DiagnosticsReference.html#diagnostic-flags
e.g.
enable the c++17 extension warning:
-Wc++17-extensions
suppress the c++17 extension warning:
-Wno-c++17-extensions