https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86277
--- Comment #30 from Mikael Morin <mikael at gcc dot gnu.org> --- (In reply to anlauf from comment #29) > (In reply to Mikael Morin from comment #28) > > (In reply to anlauf from comment #27) > > > (In reply to Mikael Morin from comment #25) > > > > (In reply to Mikael Morin from comment #24) > > > > > (In reply to Mikael Morin from comment #23) > > > > > > > > > > > > This regresses on pr108065.f90 (that's a few extra analyzer > > > > > > warnings), > > > > > > and on pr69955.f90 (that's one extra __builtin_malloc). > > > > > > > > > > This removes the regressions. Not fully retested again. > > > > > > > > > Comment #23 is probably the more correct one. > > > > Comment #24 works because of the double temporary. Even if the first > > > > temporary has NULL data component, the second one uses malloc > > > > unconditionally to set data, and the argument is seen as present. > > > > > > Are you sure that you haven't mixed up those two? > > > > > > When trying with my extended testcase, and looking at the tree dump, > > > I see a double temporary for the call > > > > > > call i ([real:: y]) > > > > > > where the data pointer to the first allocation is clobbered later. > > > So I would rather go with the version from comment #24. > > > > > Let's rephrase: > > When (or rather if) we manage to remove the double temporary, we'll regress > > with comment #24, not with comment #23. > > The reallocation remains by the way, it's only pushed one step away. > > Try this for example: > > > > call i([real:: y, y]) > > I do see the reallocation, but in the case of the patch in #24 it is a > realloc of a NULL, which is well-defined nowadays. > > But I do not see a regression. On the contrary, every else seems unchanged. > > > > > > If you don't object, I'll package the patch with testcases and submit. > > > > No problem, I think we are safe with the second temporary. > > Besides the issue with one or two temporaries, is there anything else? Now that I think again, I'm not even sure we would regress. My concern was that the data would remain NULL after the realloc(NULL, 0), and the argument would not be seen as present. With the second temporary, all is well. That's all there is.
