Is fastcall broken?

[Andrew Haley]

Daniel Lohmann writes:
 > Angus schrieb:
 > > 
 > >    BTW, in my opinion it is dangerous. Usually one can rely on
 > > compile or link errors to catch mismatched function
 > > characteristics, but with attributes there is no such
 > > checking. So even if you aren't doing something *really*
 > > dangerous, like working with virtual methods, you might do what I
 > > did, and you'll never know about it until you notice you've
 > > mismatched your attributes. So if you ask me, attributes like
 > > this one should be used sparingly, and with much caution.
 > 
 > I would consider this as a significant defect of gcc's attribute handling. 
 > Attributes that change a function to a non-standard calling convention 
 > effectively modify the interface of the function, which should be encoded 
 > into the (mangled) symbol name. Thereby incompatible prototypes on on the 
 > caller and callee side could be detected at link-time.

But attributes such as fastcall are used in C programs, and C doesn't
do mangling.  I don't know that many people combine C++ and weirdo
attributes like fastcall.  Otherwise it's not such a bad idea, but it
is an ABI change: such changes, being non-backwards compatible, are
usually unpopular.

Andrew.