https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94745
Bug ID: 94745
Summary: No error emitted for unknown -Wno-meow argument
Product: gcc
Version: 10.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ldionne.2 at gmail dot com
Target Milestone: ---
GCC does not diagnose unsupported -Wno-meow command line flags unless another
error happens during compilation.
For example, the following compiles just fine even though -Wno-foo doesn't
exist:
$ echo | g++ -xc++ - -Werror -fsyntax-only -Wno-foo
<nothing>
If, however, another error happens during compilation, the unsupported
command-line flag is reported:
$ echo '#error' | g++ -xc++ - -Werror -fsyntax-only -Wno-foo
<stdin>:1:2: error: #error
cc1plus: error: unrecognized command line option '-Wno-foo' [-Werror]
cc1plus: all warnings being treated as errors
This makes detecting whether GCC supports a given warning flag very challenging
in build systems. This issue popped up while trying to support GCC when running
the libc++ Standard Library conformance test suite.
