https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101940
Bug ID: 101940
Summary: Implement -fignored-attributes
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mpolacek at gcc dot gnu.org
Target Milestone: ---
It is desirable for -Wattributes to warn about e.g.
[[deprecate]] void g(); // typo, should warn
However, -Wattributes also warns about vendor-specific attributes (that's
because lookup_scoped_attribute_spec -> find_attribute_namespace finds
nothing), which, with -Werror, causes grief. We don't want the -Wattributes
warning for
[[company::attr]] void f();
GCC warns because it doesn't know the "company" namespace; it only knows the
"gnu" and "omp" namespaces. We could entirely disable warning about attributes
in unknown scopes but then the compiler would also miss typos like
[[company::attrx]] void f();
or
[[gmu::warn_used_result]] int write();
so that is not a viable solution. A workaround is to use a #pragma:
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wattributes"
[[company::attr]] void f() {}
#pragma GCC diagnostic pop
but that's a mouthful and awkward to use and could also hide typos. In fact,
any macro-based solution doesn't seem like a way forward.
So this RFE asks for -fignored-attributes=, which, IMHO, should take these
arguments:
company::attr
company::
clang
the last is a special option to ignore clang-only attributes. Maybe we could
also accept ::attr.
This option should go well with using @file: we could have a file containing
-fignored-attributes=vendor::attr1,vendor::attr2
and then invoke gcc with '@attrs' or similar.
It might also make sense to implement a #pragma to go along:
#pragma GCC ignored-attributes=vendor::attr1,vendor::attr2.
This should help with various static analysis tools and similar.
