The "MMap::MMap(FileFd&, unsigned long)" symbol is missing in libapt-pkg.so

[Evgeny Kolesnikov]

The "MMap::MMap(FileFd&, unsigned long)" function is missing in libapt-pkg.so.6.0.0.

nm -D -C /usr/lib/x86_64-linux-gnu/libapt-pkg.so.6.0.0 | grep MMap

00000000001701f0 T pkgCacheGenerator::MakeStatusCache(pkgSourceList&, OpProgress*, MMap**, bool)
000000000016e9c0 T pkgCacheGenerator::MakeOnlyStatusCache(OpProgress*, DynamicMMap**)
0000000000167b10 T pkgCache::pkgCache(MMap*, bool)
0000000000167b10 T pkgCache::pkgCache(MMap*, bool)

[Evgeny Kolesnikov (evgenyz)]

cat /etc/os-release

NAME="Ubuntu"
VERSION="20.04 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal

[Evgeny Kolesnikov (evgenyz)]

nm -D -C libapt-pkg.so.5.0 | grep MMap (Ubuntu 18.04)

...
00000000000c97d0 T MMap::Map(FileFd&)
00000000000c9e10 T MMap::Sync(unsigned long, unsigned long)
00000000000c9b80 T MMap::Sync()
00000000000c9c20 T MMap::Close(bool)
00000000000c97a0 T MMap::MMap(unsigned long)
00000000000c9b40 T MMap::MMap(FileFd&, unsigned long)
00000000000c97a0 T MMap::MMap(unsigned long)
00000000000c9b40 T MMap::MMap(FileFd&, unsigned long)
00000000000c9d20 T MMap::~MMap()
00000000000c9d00 T MMap::~MMap()
00000000000c9d00 T MMap::~MMap()
...

[Julian Andres Klode (juliank)]

Yes, that's by design.

[Julian Andres Klode (juliank)]

MMap is an internal implementation detail that people have been using accidentally when they wanted to open the cache, where they should use pkgCacheFile for.

[Evgeny Kolesnikov (evgenyz)]

Okay, this happens. But I can't help but wonder why it wasn't deprecated first and why it still present in public headers then?