This API had rather peculiar behavior in case the provided function
is not callable. For some types of failures, it would silently
return FAILURE (e.g. a function does not exist), while for others
(e.g. a class does not exist) it would generate a warning. Depending
on what the calling code does, this can either result in silent
failure or duplicate errors.
This commit switches the contract such that zend_call_function()
always (*) succeeds, though that success might be in the form of
throwing an exception. Calling a non-callable will now consistently
throw an exception.
There are some rare callers that do want to ignore missing methods,
for legacy APIs that are specific with optional methods. For these
use cases a new zend_call_method_if_exists() API is provided.
Calling code generally does not need to explicitly check for and
report zend_call_function() failures -- it can rely on
zend_call_function() having already done so. However, existing
code that does check for failure should continue to work fine.
(*) The only exception to this is if EG(active) being false during
late engine shutdown. This is not relevant to most code, but code
running in destructors and similar may need to be aware of the
possibility.
Nikita Popov