Throw error also for return occuring before yield

Previously only an error was thrown when return occured after yield. Also
returns before the first yield would fail for by-ref generator

Throw error also for return occuring before yield

Previously only an error was thrown when return occured after yield. Also
returns before the first yield would fail for by-ref generators.

Now the error message is handled in pass_two, so all returns are checked.

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Remove reference restrictions from foreach

foreach only allowed variables to be traversed by reference. This never
really made sense because

a) Expressions like array(&$a, &

Remove reference restrictions from foreach

foreach only allowed variables to be traversed by reference. This never
really made sense because

a) Expressions like array(&$a, &$b) can be meaningfully iterated by-ref
b) Function calls can return by-ref (so they can also be meaningfully
iterated)
c) Iterators could at least in theory also be iterated by-ref (not
sure if any iterator makes use of this)

With by-ref generators the restriction makes even less sense, so I removed
it altogether.

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Require parenthesis around yield expressions

If yield is used in an expression context parenthesis are now required.
This ensures that the code is unambiguos.

Yield statements c

Require parenthesis around yield expressions

If yield is used in an expression context parenthesis are now required.
This ensures that the code is unambiguos.

Yield statements can still be used without parenthesis (which should be
the most common case).

Also yield expressions without value can be used without parenthesis,
too (this should be the most common case for coroutines).

If the yield expression is used in a context where parenthesis are required
anyway, no additional parenthesis have to be inserted.

Examples:

// Statements don't need parenthesis
yield $foo;
yield $foo => $bar;

// Yield without value doesn't need parenthesis either
$data = yield;

// Parentheses don't have to be duplicated
foo(yield $bar);
if (yield $bar) { ... }

// But we have to use parentheses here
$foo = (yield $bar);

This commit also fixes an issue with by-ref passing of $foo[0] like
variables. They previously weren't properly fetched for write.

Additionally this fixes valgrind warnings which were caused by access to
uninitialized memory in zend_is_function_or_method_call().

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Remove asterix modifier (*) for generators

Generators are now automatically detected by the presence of a `yield`
expression in their body.

This removes the ZEND_SUSPEND_AND_RET

Remove asterix modifier (*) for generators

Generators are now automatically detected by the presence of a `yield`
expression in their body.

This removes the ZEND_SUSPEND_AND_RETURN_GENERATOR opcode. Instead
additional checks for ZEND_ACC_GENERATOR are added to the fcall_common
helper and zend_call_function.

This also adds a new function zend_generator_create_zval, which handles
the actual creation of the generator zval from an op array.

I feel like I should deglobalize the zend_create_execute_data_from_op_array
code a bit. It currently changes EG(current_execute_data) and
EG(opline_ptr) which is somewhat confusing (given the name).

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Add support by yielding by-reference

Fixed the common misspelling of the word occurred (occured -> occurred)

Add sceleton for yield* expression

This does not yet actually implement any delegation.

typo

typo

typo

Add support for yielding keys

Keys are yielded using the

yield $key => $value

syntax. Currently this is implemented as a statement only and not as an
expression, be

Add support for yielding keys

Keys are yielded using the

yield $key => $value

syntax. Currently this is implemented as a statement only and not as an
expression, because conflicts arise considering nesting and use in arrays:

yield yield $a => $b;
// could be either
yield (yield $a) => $b;
// or
yield (yield $a => $b);

Once I find some way to resolve these conflicts this should be available
as an expression too.

Also the key yielding code is rather copy-and-past-y for the value yielding
code, so that should be factored out.

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Allow to use yield without value

If the generator is used as a coroutine it often doesn't make sense to yield
anything. In this case one can simply receive values using

$val

Allow to use yield without value

If the generator is used as a coroutine it often doesn't make sense to yield
anything. In this case one can simply receive values using

$value = yield;

The yield here will simply yield NULL.

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Add support for $generator->send()

Yield now is an expression and the return value is the value passed to
$generator->send(). By default (i.e. if ->next() is called) the value is
NUL

Add support for $generator->send()

Yield now is an expression and the return value is the value passed to
$generator->send(). By default (i.e. if ->next() is called) the value is
NULL.

Unlike in Python ->send() can be run without priming the generator with a
->next() call first.

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Implement return for generators

For generators ZEND_RETURN directly calls ZEND_VM_RETURN(), thus passing
execution back to the caller (zend_generator_resume).

This commit also a

Implement return for generators

For generators ZEND_RETURN directly calls ZEND_VM_RETURN(), thus passing
execution back to the caller (zend_generator_resume).

This commit also adds a check that only return; is used in generators and
not return $value;.

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Add YIELD opcode implementation

Use emalloc instead of malloc

Fixed bug #61998 (Using traits with method aliases appears to result in crash during execution)

Add ZEND_SUSPEND_AND_RETURN_GENERATOR opcode

If the function is a generator this opcode will be invoked right after
receiving the function arguments.

The current implementation

Add ZEND_SUSPEND_AND_RETURN_GENERATOR opcode

If the function is a generator this opcode will be invoked right after
receiving the function arguments.

The current implementation is just a dummy.

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Add zend_do_suspend_if_generator calls

The execution of generator functions will be suspended right after the
arguments were RECVed. This will be done in zend_do_suspend_if_generator.

Add error if yield is used outside a generator

The yield statement can only be used in generator functions, which are
marked with an asterix.

Minor code cleanup

The block for the foreach separator was nested unnecessary. This commit
simply removes that nesting.

Add flag for generator functions

Generator functions have to specify the * (asterix) modifier after the
function keyword. If they do so the ZEND_ACC_GENERATOR flag is added to
the fn

Add flag for generator functions

Generator functions have to specify the * (asterix) modifier after the
function keyword. If they do so the ZEND_ACC_GENERATOR flag is added to
the fn_flags.

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Add T_YIELD "yield" keyword

Allow arbitrary expressions for empty()

This change is as per RFC https://wiki.php.net/rfc/empty_isset_exprs.

The change allows passing the result of function calls and other
ex

Allow arbitrary expressions for empty()

This change is as per RFC https://wiki.php.net/rfc/empty_isset_exprs.

The change allows passing the result of function calls and other
expressions to the empty() language construct. This is accomplished by
simply rewriting empty(expr) to !expr.

The change does not affect the suppression of errors when using empty()
on variables. empty($undefinedVar) will continue not to throw errors.
When an expression is used inside empty() on the other hand, errors will
not be suppressed. Thus empty($undefinedVar + $somethingElse) *will*
throw a notice.

The change also does not make empty() into a real function, so using
'empty' as a callback is still not possible.

In addition to the empty() changes the commit adds nicer error messages
when isset() is used on function call results or other expressions.

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Fixed bug #61761 ('Overriding' a private static method with a different signature causes crash)