I expected to see a diagnostic for the following program regardless of whether the template is instantiated or not, or whether the nested type is used or not. Gcc only diagnoses the attribute when the type is used.
That said, rather than diagnosing it, it'd be even more useful to allow non type template parameters and other constant integral expressions as arguments to the attribute. $ cat t.cpp && g++ t.cpp && echo PASS && g++ -DUSE_IT t.cpp template <int N> struct A { struct S { short f[3]; } __attribute__ ((aligned (N))); }; int main () { A<123> a; #ifdef USE_IT A<123>::S s; #endif } PASS t.cpp: In instantiation of A<123>::S: t.cpp:10: instantiated from here t.cpp:3: error: N was not declared in this scope t.cpp:3: error: requested alignment is not a constant -- Summary: missing diagnostic on invalid __attribute__((aligned(N))) Product: gcc Version: 4.3.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: sebor at roguewave dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36625