Summary:
Boolean vectors as implemented in clang can be bit-casted to an integer
that is rounded up to the next primitive sized integer. Users can do
this themselves, but since the counting bits are very likely to be used
with bitmasks like this and the generic forms are expected to be
generic it seems reasonable that we handle this case directly.

This breaks a ton of libc++ tests otherwise, since calling
std::destroy_at will currently end the lifetime of the entire array not
just the given element.

See https://github.com/llvm/llvm-project/issues/147528

The isGLValue() check made us ignore expressions we shouldn't ignore.

To match the diagnostics of the current interpreter.

Only initialize pointers that can be initialized.

…types usi… (#144676)"

This reverts commit 68471d29eed2c49f9b439e505b3f24d387d54f97.

IntegralAP contains a union:
  union {
    uint64_t *Memory = nullptr;
    uint64_t Val;
  };

On 64bit systems, both Memory and Val have the same size. However, on 32
bit system, Val is 64bit and Memory only 32bit. Which means the default
initializer for Memory will only zero half of Val. We fixed this by
zero-initializing Val explicitly in the IntegralAP(unsigned BitWidth)
constructor.


See also the discussion in
https://github.com/llvm/llvm-project/pull/144246

This reverts commit 7c15edb306932e41c159f3d69c161ed0d89d47b7.

This still breaks clang-armv8-quick:
https://lab.llvm.org/buildbot/#/builders/154/builds/17587

…ng an allocator (#144246)"

This reverts commit 57828fec760f086b334ce0cb1c465fc559dcaea4.