Tom Lane <t...@sss.pgh.pa.us> writes: > =?utf-8?Q?Dagfinn_Ilmari_Manns=C3=A5ker?= <ilm...@ilmari.org> writes: >> Tom Lane <t...@sss.pgh.pa.us> writes: >>> libpq-fe.h has to be compilable by application code that has never >>> heard of pg_config.h let alone c.h, so we'd have to tread carefully >>> about not breaking that property. But it seems like this would be >>> worth looking into. > >> The fallback code isn't exactly complicated, so we could just duplicate >> it in libpq-fe.h: > >> #ifndef __has_attribute >> #define __has_attribute(attribute) 0 >> #endif > > The problem with that approach is the likelihood of stomping on > symbols that a calling application will use later. I think we > really need a controlling #ifdef check on some PG_FOO symbol > that we can be sure no outside application will have defined. > Roughly speaking, > > #ifdef PG_USE_ALLOCATOR_CHECKS
As long as we're not checking for too many attributes, we could avoid introducing the __has_attribute symbol by doing: #if defined(__has_attribute) && __has_attribute(malloc) > #define pg_attribute_malloc __attribute__((malloc)) > ... > #else > #define pg_attribute_malloc > ... > #endif > > and then we could make definition of PG_USE_ALLOCATOR_CHECKS > be conditional on having the right compiler behavior, rather > than trusting that a nest of #ifdef checks is sufficient to > detect that. But I just looked at the clang attribute docs (https://clang.llvm.org/docs/AttributeReference.html#malloc), and it only has the argumentless version, not the one that that declares the matching deallocator, so you're right we need a more comprehensive check. > regards, tom lane - ilmari
