2.8 Assertions

A line of the form:

#assert predicate (token-sequence)

associates the token-sequence with the predicate in the assertion name space (separate from the space used for macro definitions). The predicate must be an identifier token.

#assert predicate

asserts that predicate exists, but does not associate any token sequence with it.

The compiler provides the following predefined predicates by default (not in -Xc mode):

#assert system (unix)
#assert machine (sparc)
#assert machine (i386)(x86)
#assert cpu (sparc)
#assert cpu (i386)(x86)

lint provides the following predefinition predicate by default (not in -Xc mode):

#assert lint (on)

Any assertion may be removed by using #unassert, which uses the same syntax as assert. Using #unassert with no argument deletes all assertions on the predicate; specifying an assertion deletes only that assertion.

An assertion may be tested in a #if statement with the following syntax:

#if #predicate(non-empty token-list)

For example, the predefined predicate system can be tested with the following line:

#if #system(unix)

which evaluates true.