Without this patch, we pass G.getEndianness() as one of the parameters
to DWARFContext::create. The problem is that G.getEndianness() is of:
enum endianness {big, little, native};
whereas DWARFContext::create is expecting "bool isLittleEndian". That
is, we are relying on an implicit conversion to convert big and little
to false and true, respectively.
When we migrate llvm::support::endianness to std::endian in future, we
can no longer rely on an implicit conversion because std::endian is
declared with "enum class". Even if we could, the conversion would
not be guaranteed to work because, for example, libcxx defines:
enum class endian {
little = 0xDEAD,
big = 0xFACE,
:
where big and little are not boolean values.
This patch fixes the problem by properly converting G.getEndianness()
to a boolean value.
At line 191, `addSymbol` takes the name by reference but does not make
an internal copy to the string, meaning the local
`optional<std::string>` would get freed and leave Orc with a dangling
pointer. Fix this by just using an `optional<StringRef>` instead.
This re-applies db51e572893, which was reverted in 05b1a2cb3e6 due to bot
failures. The DebuggerSupportPlugin now depends on DWARF, so it has been moved
to the new OrcDebugging library (as has the enableDebuggerSupport API).
