https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64021
Bug ID: 64021
Summary: Empty struct vs libffi
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: go
Assignee: ian at airs dot com
Reporter: rth at gcc dot gnu.org
CC: cmang at google dot com
In go_struct_to_ffi, an empty struct is maped to ffi_type_void.
On i386, some ABIs return a struct pop 4 bytes of stack. If one
calls a function returning a structure without preparing for this,
the stack will be corrupted.
On sparc32, functions returning a structure return to a different
address. If one calls a function returning a structure without
preparing for this, the instruction after the call will be skipped.
In both cases, this causes reflect/all_test.go returnEmpty to fail.
I wonder what's better: follow C++ and map empty structures to a
single byte (i.e. no more zero-sized structures), or enhance libffi
to be able to deal with empty structures so that we don't have to
lie to libffi about the type being manipulated?
