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 is a minimal variance implementation: It does not support any
cyclic type dependencies. Additionally the preloading requirements
are much more restrictive than necessary. Hopefully we can relax
these in the future.
Fixes bug #76451, and more importantly lays necessary groundwork for
covariant/contravariant types. Bug #76451 is just an edge case, but
once covariance is introduced this will become a common problem instead.
Make the check covariant (insofar as it is allowed now, i.e.
nullability and iterable) and call it with appropriate argument
order for both parameter and return types.
This makes it simpler to extend to full variance support.
Abstract ctor signatures should always be respected by all children,
independently of whether it comes from an interface or an abstract
class. Previously abstract ctor signatures (if they didn't come from
an interface) were only checked to one level of inheritance.
This avoids writing this cache at runtime, which is illegal if
preloading is used.
Not every serialize/unserialize function actually belongs to the
Serializable interface, but I think it's not a problem to assign
these anyway -- whether they are used ultimately depends on whether
Serializable is implemented.
Alternatively it might make sense to just drop these entirely. I
don't think this is performance critical functionality.
This patch removes the so called local variables defined per
file basis for certain editors to properly show tab width, and
similar settings. These are mainly used by Vim and Emacs editors
yet with recent changes the once working definitions don't work
anymore in Vim without custom plugins or additional configuration.
Neither are these settings synced across the PHP code base.
A simpler and better approach is EditorConfig and fixing code
using some code style fixing tools in the future instead.
This patch also removes the so called modelines for Vim. Modelines
allow Vim editor specifically to set some editor configuration such as
syntax highlighting, indentation style and tab width to be set in the
first line or the last 5 lines per file basis. Since the php test
files have syntax highlighting already set in most editors properly and
EditorConfig takes care of the indentation settings, this patch removes
these as well for the Vim 6.0 and newer versions.
With the removal of local variables for certain editors such as
Emacs and Vim, the footer is also probably not needed anymore when
creating extensions using ext_skel.php script.
Additionally, Vim modelines for setting php syntax and some editor
settings has been removed from some *.phpt files. All these are
mostly not relevant for phpt files neither work properly in the
middle of the file.
