[XPTI][NFC] Fix -Wconversion warnings

[AlexeySachkov]

-Wconversion is a must-have flag for us in according with internal guidelines (see AddSecurityFlags.cmake), but we have never built with it + -Werror so there are multiple places in xpti subproject where we did potentially incorrect implicit conversions.

[uditagarwal97]

How about we add -Wconversion flag while building compiler in CI?
CC: @sarnex

[sarnex]

Agree it's a good idea but who is gonna do it :)

[uditagarwal97]

Agree it's a good idea but who is gonna do it :)

I'll file a ticket for now and can work on it when I get some free time.
Edit:- ticket: #18788

[frasercrmck]

This appears to be causing compilation issues on my system:

/llvm/xpti/src/xpti_proxy.cpp:236:16: error: 'invalid_id' does not name a template but is followed by template arguments
  return xpti::invalid_id<uint16_t>;
               ^         ~~~~~~~~~~
/build/include/xpti/xpti_data_types.h:315:15: note: non-template declaration found by name lookup
constexpr int invalid_id = -1;
              ^

Is this a header inclusion order issue? That looks like the wrong invalid_id to find.

[frasercrmck]

This appears to be causing compilation issues on my system:

/llvm/xpti/src/xpti_proxy.cpp:236:16: error: 'invalid_id' does not name a template but is followed by template arguments
  return xpti::invalid_id<uint16_t>;
               ^         ~~~~~~~~~~
/build/include/xpti/xpti_data_types.h:315:15: note: non-template declaration found by name lookup
constexpr int invalid_id = -1;
              ^

Is this a header inclusion order issue? That looks like the wrong invalid_id to find.

Interesting - I tried rebuilding several times and it eventually fixed itself. I suspect there's a missing build dependency on copying the headers to the build directory. It was probably including an old xpti/xpti_data_types.h.