The comment made a reference to the case tables that used to exist in qbytearray.cpp prior to commit 9dd8e655cdd26eeaae30645b7fe013d9a696547f ("Limit QByteArray's 8-bit support to ASCII"). Now that the parameter is a function pointer, not a table, inlining is actually beneficial: we definitely don't want the compiler to emit function calls via the function pointer. At least GCC 11 was already doing constant-propagation of the parameter: While it didn't inline the function, it cloned it and propagated the constant in each of the two clones. There were 4 copies of this function: const and non-const, upper and lower. Change-Id: I0e5f6bec596a4a78bd3bfffd16c912a16602e20a Reviewed-by: Marc Mutz <marc.mutz@qt.io> Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>