Keep track of delayed variance obligations and check them after
linking a class is otherwise finished. Obligations may either be
unresolved method compatibility (because the necessecary classes
aren't available yet) or open parent/interface dependencies. The
latter occur because we allow the use of not fully linked classes
as parents/interfaces now.
An important aspect of the implementation is we do not require
classes involved in variance checks to be fully linked in order for
the class to be fully linked. Because the involved types do have to
exist in the class table (as partially linked classes) and we do
check these for correct variance, we have the guarantee that either
those classes will successfully link lateron or generate an error,
but there is no way to actually use them until that point and as
such no possibility of violating the variance contract. This is
important because it ensures that a class declaration always either
errors or will produce an immediately usable class afterwards --
there are no cases where the finalization of the class declaration
has to be delayed until a later time, as earlier variants of this
patch did.
Because variance checks deal with classes in various stages of
linking, we need to use a special instanceof implementation that
supports this, and also introduce finer-grained flags that tell us
which parts have been linked already and which haven't.
Class autoloading for variance checks is delayed into a separate
stage after the class is otherwise linked and before delayed
variance obligations are processed. This separation is needed to
handle cases like A extends B extends C, where B is the autoload
root, but C is required to check variance. This could end up
loading C while the class structure of B is in an inconsistent
state.
This reverts commit e528762c1c.
Dmitry reports that this has a non-trivial impact on parsing
overhead, especially on 32-bit systems. As we don't have a strong
need for this change right now, I'm reverting it.
See also comments on
e528762c1c.
Locations for AST nodes are now tracked with the help of bison
location tracking. This is more accurate than what we currently do
and easier to extend with more information.
A zend_ast_loc structure is introduced, which is used for the location
stack. Currently it only holds the start lineno, but can be extended
to also hold end lineno and offset/column information in the future.
All AST constructors now accept a zend_ast_loc* as first argument, and
will use it to determine their lineno. Previously this used either the
CG(zend_lineno), or the smallest AST lineno of child nodes.
On the parser side, the location structure for a whole rule can be
obtained using the &@$ character salad.
Signed shift of 31 for int and 63 for long is flagged as undefined
behavior by UBSan (-fsanitize=undefined) and seems to be indeed so
according to the standard.
The patch converts such cases to use unsigned.
