Now a declaration like 'struct Foo;' can be used to establish the
name of a struct type, without providing a definition. One can
pass pointers to such types around the system, but can't do much
else with them (as in C/C++).
Issue #125.
Now, if a struct member has an explicit 'uniform' or 'varying'
qualifier, then that member has that variability, regardless of
the variability of the struct's variability. Members without
'uniform' or 'varying' have unbound variability, and in turn
inherit the variability of the struct.
As a result of this, now structs can properly be 'varying' by default,
just like all the other types, while still having sensible semantics.
Pointers can be either uniform or varying, and behave correspondingly.
e.g.: "uniform float * varying" is a varying pointer to uniform float
data in memory, and "float * uniform" is a uniform pointer to varying
data in memory. Like other types, pointers are varying by default.
Pointer-based expressions, & and *, sizeof, ->, pointer arithmetic,
and the array/pointer duality all bahave as in C. Array arguments
to functions are converted to pointers, also like C.
There is a built-in NULL for a null pointer value; conversion from
compile-time constant 0 values to NULL still needs to be implemented.
Other changes:
- Syntax for references has been updated to be C++ style; a useful
warning is now issued if the "reference" keyword is used.
- It is now illegal to pass a varying lvalue as a reference parameter
to a function; references are essentially uniform pointers.
This case had previously been handled via special case call by value
return code. That path has been removed, now that varying pointers
are available to handle this use case (and much more).
- Some stdlib routines have been updated to take pointers as
arguments where appropriate (e.g. prefetch and the atomics).
A number of others still need attention.
- All of the examples have been updated
- Many new tests
TODO: documentation
