Collaboration diagram for Performance Constraints:

Macros
#define	ein_allocating
	Declares a function potentially allocates heap memory. Prevents inference of `nonallocating`.

#define	ein_blocking
	Declares a function potentially blocks. Prevents inference of ein_nonblocking.

#define	ein_nonblocking
	Declares a function does not block.

#define	ein_noblock(__x)
	a `bool` parameterized version of ein_nonblocking

#define	ein_nonallocating
	Declares a function does not allocate heap memory.

#define	ein_noalloc(__x)
	a `bool` parameterized version of ein_nonallocating

Detailed Description

When assigning or otherwise converting to a function pointer of nonblocking or nonallocating type, the source must also be a function or function pointer of that type, unless it is a null pointer, i.e. the attributes should not be “spoofed”. Conversions that remove the attributes are transparent and valid.
An override of a nonblocking or nonallocating virtual method must also be declared with that same attribute (or a stronger one.) An overriding method may add an attribute.
A redeclaration of a nonblocking or nonallocating function must also be declared with the same attribute (or a stronger one). A redeclaration may add an attribute.