Deviations from the compliance:

* functions are not always reentrant.
* structures cannot be assigned values directly, cannot be passed as function parameters or assigned to each other and cannot be a return value from a function, e.g.:

struct s { ... };
struct s s1, s2;
foo()
{
...
s1 = s2 ; /* is invalid in SDCC although allowed in ANSI */
...
}
struct s foo1 (struct s parms) /* invalid in SDCC although allowed in ANSI */
{
struct s rets;
...
return rets;/* is invalid in SDCC although allowed in ANSI */
}

* 'long long' (64 bit integers) not supported.
* 'double' precision floating point not supported.
* No support for setjmp and longjmp (for now).
* Old K&R style function declarations are NOT allowed.

foo(i,j) /* this old style of function declarations */
int i,j; /* are valid in ANSI but not valid in SDCC */
{
...
}

* functions declared as pointers must be dereferenced during the call.

int (*foo)();
...
/* has to be called like this */
(*foo)(); /* ANSI standard allows calls to be made like 'foo()' */