Implicitly converting between incompatible function pointers in C is
currently a default-on warning (it is an error in C++). However, this
is very poor security posture. A mismatch in parameters or return
types, or a mismatch in calling conventions, etc can lead to
exploitable security vulnerabilities. Rather than allow this unsafe
practice with a warning, this patch strengthens the warning to be an
error (while still allowing users the ability to disable the error or
the warning entirely to ease migration). Users should either ensure the
signatures are correctly compatible or they should use an explicit cast
if they believe that's more reasonable.
Differential Revision: https://reviews.llvm.org/D131351
Compute and propagate conversion kind to diagnostics helper in C++
to provide more specific diagnostics about incorrect implicit
conversions in assignments, initializations, params, etc...
Duplicated some diagnostics as errors because C++ is more strict.
Tags: #clang
Differential Revision: https://reviews.llvm.org/D74116
