Am Freitag, den 04.10.2019, 12:29 +0200 schrieb Richard Biener: > On Wed, Oct 2, 2019 at 8:24 PM Uecker, Martin > <martin.uec...@med.uni-goettingen.de> wrote: > > > > Am Mittwoch, den 02.10.2019, 17:37 +0200 schrieb Richard Biener:
> > > > ... > > > > > > > Oh, and LTO does _not_ merge types declared inside a function, > > > > > so > > > > > > > > > > void foo () { struct S { int i; }; } > > > > > void bar () { struct S { int i; }; } > > > > > > > > > > the two S are distinct and objects of that type do not conflict. > > > > > > > > This is surprising as these types are compatible across TUs. So > > > > if some pointer is passed between these functions this is > > > > supposed to work. > > > > > > So if they are compatible the frontend needs to mark them so in this case. > > > > It can't. The front end never sees the other TU. > > If the type "leaves" the CU via a call the called function has a prototype > through which it "sees" the CU. The prototype could be local to the function or it could be a void* (or other pointer type) argument. TU1----------------------- #include <stdio.h> extern void f(void *p); int main() { struct foo { int x; } b; b.x = 2; f(&b); printf("%d\n", b.x); } TU2----------------------------- extern void f(void *p) { struct foo { int x; } *q = p; q->x = 3; } Best, Martin