https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89624
Jonathan Wakely <redi at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Last reconfirmed| |2019-03-07 Ever confirmed|0 |1 --- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> --- (In reply to Jonathan Wakely from comment #0) > This will be an ABI break for -fshort-enums though, but that's already > happened for PR 88996 because the new definition is a scoped enum, which > always has a fixed underlying type. To be clear, the recent break can be easily fixed: --- a/libstdc++-v3/include/bits/atomic_base.h +++ b/libstdc++-v3/include/bits/atomic_base.h @@ -53,7 +53,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION /// Enumeration for memory_order #if __cplusplus > 201703L - enum class memory_order : int + // This determines the underlying type of memory_order, + // because its size can change when -fshort-enums is used. + enum __unscoped_memory_order { __unscoped_memory_order_max = 5 }; + + enum class memory_order : __underlying_type(__unscoped_memory_order) { relaxed, consume, But that wouldn't solve the problem for the HLE bits.