2) Is it feasible yet with the current set of supported compilers to support flexible arrays?
My impression is that flexible arrays are already supported (as seen in UnitTestFrameworkPkg/PrivateInclude/UnitTestFrameworkTypes.h). Please correct me if I am wrong.
Would you mind letting me know why this is applicable here? We are trying to seek ideas on how to catch developer mistakes caused by this change. So any input is appreciated.
Huh, interesting. Last time I tried I was told about incompatibilities with MSVC, but I know some have been dropped since then (2005 and 2008 if I recall correctly?), so that'd be great to allow globally.
I too am surprised to see "UnitTestFrameworkPkg/PrivateInclude/UnitTestFrameworkTypes.h". The flexible array member is a C99 feature, and I didn't even know that we disallowed it for the sake of particular VS toolchains -- I thought we had a more general reason than just "not supported by VS versions X and Y".
The behavior of OFFSET_OF() would be interesting -- the OFFSET_OF() macro definition for non-gcc / non-clang:
borders on undefined behavior as far as I can tell, so its behavior is totally up to the compiler. It works thus far okay on Visual Studio, but I couldn't say if it extended correctly to flexible array members.
Yes, it's UB by the standard, but this is actually how MS implements them (or used to anyway?). I don't see why it'd cause issues with flexible arrays, as only the start of the array is relevant (which is constant for all instances of the structure no matter the amount of elements actually stored). Any specific concern? If so, they could be addressed by appropriate STATIC_ASSERTs.
No specific concern; my point was that two aspects of the same "class" of undefined behavior didn't need to be consistent with each other.
