Drop support for multiple generators yielding from one generator

Zend/tests/generators/bug70965.phpt

@@ -1,5 +1,5 @@
 --TEST--
-Bug #70965 (yield from with a common iterator primes too much)
+Bug #70965 (yield from with a common iterator primes too much) (no longer supported)
 --FILE--
 <?php
 
@@ -23,10 +23,12 @@ do {
 } while ($gen->valid());
 
 ?>
---EXPECT--
+--EXPECTF--
 int(1)
-int(2)
-int(3)
-int(4)
-int(5)
-int(5)
+
+Fatal error: Uncaught Error: A different generator already yields from this generator in %s:%d
+Stack trace:
+#0 [internal function]: bar(Object(Generator))
+#1 %s(%d): Generator->current()
+#2 {main}
+  thrown in %s on line %d

Zend/tests/generators/bug74954.phpt

@@ -1,5 +1,5 @@
 --TEST--
-Bug #74954 (crash after update of generator yielding from finished generator)
+Bug #74954 (crash after update of generator yielding from finished generator) (no longer supported)
 --FILE--
 <?php
 
@@ -30,16 +30,9 @@ do {
 
 ?>
 --EXPECTF--
-Caught exception!
-Exception in %s:%d
-Stack trace:
-#0 %s(%d): from()
-#1 [internal function]: gen(Object(Generator))
-#2 %s(%d): Generator->next()
-#3 {main}
-Caught exception!
-ClosedGeneratorException: Generator yielded from aborted, no return value available in %s:%d
+Fatal error: Uncaught Error: A different generator already yields from this generator in %s:%d
 Stack trace:
 #0 [internal function]: gen(Object(Generator))
-#1 %s(%d): Generator->next()
+#1 %s(%d): Generator->current()
 #2 {main}
+  thrown in %s on line %d

Zend/tests/generators/gc_with_root_parent_mismatch.phpt

@@ -1,5 +1,5 @@
 --TEST--
-Generator GC when the yield from parent chain does not reach the root
+Generator GC when the yield from parent chain does not reach the root (no longer supported)
 --FILE--
 <?php
 
@@ -22,6 +22,13 @@ $gen1->next();
 gc_collect_cycles();
 
 ?>
---EXPECT--
-int(1)
+--EXPECTF--
 int(1)
+
+Fatal error: Uncaught Error: A different generator already yields from this generator in %s:%d
+Stack trace:
+#0 %s(%d): delegate(Object(Generator))
+#1 [internal function]: delegate(Object(Generator))
+#2 %s(%d): Generator->current()
+#3 {main}
+  thrown in %s on line %d

Zend/tests/generators/multiple_yield_from_on_same_generator.phpt

@@ -1,5 +1,5 @@
 --TEST--
-Multiple yield from on a same Generator instance
+Multiple yield from on a same Generator instance (no longer supported)
 --FILE--
 <?php
 
@@ -30,14 +30,12 @@ do {
 var_dump($gens[1]->valid());
 
 ?>
---EXPECT--
+--EXPECTF--
 int(1)
-int(2)
-int(4)
-int(6)
-int(3)
-int(5)
-int(3)
-int(5)
-NULL
-bool(false)
+
+Fatal error: Uncaught Error: A different generator already yields from this generator in %s:%d
+Stack trace:
+#0 [internal function]: bar(Object(Generator))
+#1 %s(%d): Generator->current()
+#2 {main}
+  thrown in %s on line %d

Zend/tests/generators/mutli_yield_from_with_exception.phpt

@@ -1,5 +1,5 @@
 --TEST--
-Multiple yield from on a same Generator throwing an Exception
+Multiple yield from on a same Generator throwing an Exception (no longer supported)
 --FILE--
 <?php
 function from() {
@@ -30,20 +30,9 @@ do {
 } while($gens[0]->valid());
 ?>
 --EXPECTF--
-Generator 0
-int(1)
-Caught exception!
-Exception in %s:%d
-Stack trace:
-#0 %s(%d): from()
-#1 [internal function]: gen(Object(Generator))
-#2 %s(%d): Generator->next()
-#3 {main}
-Generator 1
-Caught exception!
-ClosedGeneratorException: Generator yielded from aborted, no return value available in %s:%d
+Fatal error: Uncaught Error: A different generator already yields from this generator in %s:%d
 Stack trace:
 #0 [internal function]: gen(Object(Generator))
 #1 %s(%d): Generator->current()
 #2 {main}
-NULL
+  thrown in %s on line %d

Zend/tests/generators/yield_from_multi_child_destroyed.phpt

@@ -0,0 +1,27 @@
+--TEST--
+Yield from by multiple generators where a child is destroyed before the parent (no longer supported)
+--FILE--
+<?php
+
+function gen() {
+    yield 42;
+}
+
+function yield_from($gen) {
+    yield from $gen;
+}
+
+$gen = gen();
+var_dump(yield_from($gen)->current());
+var_dump(yield_from($gen)->current());
+
+?>
+--EXPECTF--
+int(42)
+
+Fatal error: Uncaught Error: A different generator already yields from this generator in %s:%d
+Stack trace:
+#0 [internal function]: yield_from(Object(Generator))
+#1 %s(%d): Generator->current()
+#2 {main}
+  thrown in %s on line %d