Convert iterable into an internal alias for Traversable|array (#7309)

This does a compile time transformation of ``iterable`` into ``Traversable|array`` which simplifies some of the LSP variance handling.

The arginfo generation script from stubs is updated to produce a union type when it encounters the type ``iterable``
Extension functions which do not regenerate the arginfo, or write them manually are still supported by mimicking the compile time transformation while registering the function.

Type Reflection is preserved for single ``iterable`` (and ``?iterable``) to produce a ReflectionNamedType with name ``iterable``, however usage of ``iterable`` in union types will be converted to ``array|Traversable``

Author: Girgias

Zend/Optimizer/zend_inference.c

@@ -2114,9 +2114,6 @@ static uint32_t zend_convert_type_declaration_mask(uint32_t type_mask) {
 	if (type_mask & MAY_BE_CALLABLE) {
 		result_mask |= MAY_BE_STRING|MAY_BE_OBJECT|MAY_BE_ARRAY|MAY_BE_ARRAY_KEY_ANY|MAY_BE_ARRAY_OF_ANY|MAY_BE_ARRAY_OF_REF;
 	}
-	if (type_mask & MAY_BE_ITERABLE) {
-		result_mask |= MAY_BE_OBJECT|MAY_BE_ARRAY|MAY_BE_ARRAY_KEY_ANY|MAY_BE_ARRAY_OF_ANY|MAY_BE_ARRAY_OF_REF;
-	}
 	if (type_mask & MAY_BE_STATIC) {
 		result_mask |= MAY_BE_OBJECT;
 	}

Zend/tests/return_types/generators001.phpt

@@ -26,13 +26,18 @@ function test6() : object|callable {
     yield 6;
 }
 
+function test7() : iterable {
+    yield 7;
+}
+
 var_dump(
     test1(),
     test2(),
     test3(),
     test4(),
     test5(),
     test6(),
+    test7(),
 );
 ?>
 --EXPECTF--
@@ -48,3 +53,5 @@ object(Generator)#%d (%d) {
 }
 object(Generator)#%d (%d) {
 }
+object(Generator)#%d (%d) {
+}

Zend/tests/type_declarations/intersection_types/invalid_types/invalid_iterable_type.phpt

@@ -7,4 +7,4 @@ function foo(): iterable&Iterator {}
 
 ?>
 --EXPECTF--
-Fatal error: Type iterable cannot be part of an intersection type in %s on line %d
+Fatal error: Type Traversable|array cannot be part of an intersection type in %s on line %d

Zend/tests/type_declarations/intersection_types/variance/invalid5.phpt

@@ -15,4 +15,4 @@ class Test2 extends Test {
 
 ?>
 --EXPECTF--
-Fatal error: Declaration of Test2::method(): X&Y must be compatible with Test::method(): iterable in %s on line %d
+Fatal error: Declaration of Test2::method(): X&Y must be compatible with Test::method(): Traversable|array in %s on line %d

Zend/tests/type_declarations/iterable_001.phpt renamed to Zend/tests/type_declarations/iterable/iterable_001.phpt

@@ -45,4 +45,4 @@ object(ArrayIterator)#1 (1) {
     int(3)
   }
 }
-test(): Argument #1 ($iterable) must be of type iterable, int given, called in %s on line %d
+test(): Argument #1 ($iterable) must be of type Traversable|array, int given, called in %s on line %d

Zend/tests/type_declarations/iterable_002.phpt renamed to Zend/tests/type_declarations/iterable/iterable_002.phpt

@@ -17,4 +17,4 @@ function baz(iterable $iterable = 1) {
 
 ?>
 --EXPECTF--
-Fatal error: Cannot use int as default value for parameter $iterable of type iterable in %s on line %d
+Fatal error: Cannot use int as default value for parameter $iterable of type Traversable|array in %s on line %d

Zend/tests/type_declarations/iterable_003.phpt renamed to Zend/tests/type_declarations/iterable/iterable_003.phpt

@@ -29,4 +29,4 @@ array(0) {
 }
 object(Generator)#2 (0) {
 }
-baz(): Return value must be of type iterable, int returned
+baz(): Return value must be of type Traversable|array, int returned

Zend/tests/type_declarations/iterable_004.phpt renamed to Zend/tests/type_declarations/iterable/iterable_004.phpt

@@ -21,4 +21,4 @@ class Bar extends Foo {
 
 ?>
 --EXPECTF--
-Fatal error: Declaration of Bar::testScalar(iterable $iterable) must be compatible with Foo::testScalar(int $int) in %s on line %d
+Fatal error: Declaration of Bar::testScalar(Traversable|array $iterable) must be compatible with Foo::testScalar(int $int) in %s on line %d

Zend/tests/type_declarations/iterable_005.phpt renamed to Zend/tests/type_declarations/iterable/iterable_005.phpt

@@ -29,4 +29,4 @@ class TestScalar extends Test {
 
 ?>
 --EXPECTF--
-Fatal error: Declaration of TestScalar::method(): int must be compatible with Test::method(): iterable in %s on line %d
+Fatal error: Declaration of TestScalar::method(): int must be compatible with Test::method(): Traversable|array in %s on line %d

Zend/tests/type_declarations/iterable/or_null.phpt

@@ -0,0 +1,46 @@
+--TEST--
+Test "or null"/"or be null" in type-checking errors for userland functions with iterable
+--FILE--
+<?php
+
+// This should test every branch in zend_execute.c's `zend_verify_arg_type`, `zend_verify_return_type` and `zend_verify_missing_return_type` functions which produces an "or null"/"or be null" part in its error message
+
+function iterableF(?iterable $param) {}
+try {
+    iterableF(1);
+} catch (\TypeError $e) {
+    echo $e, PHP_EOL;
+}
+
+function returnIterable(): ?iterable {
+    return 1;
+}
+
+try {
+    returnIterable();
+} catch (\TypeError $e) {
+    echo $e, PHP_EOL;
+}
+
+function returnMissingIterable(): ?iterable {
+}
+
+try {
+    returnMissingIterable();
+} catch (\TypeError $e) {
+    echo $e, PHP_EOL;
+}
+?>
+--EXPECTF--
+TypeError: iterableF(): Argument #1 ($param) must be of type Traversable|array|null, int given, called in %s on line %d and defined in %s:%d
+Stack trace:
+#0 %s(%d): iterableF(1)
+#1 {main}
+TypeError: returnIterable(): Return value must be of type Traversable|array|null, int returned in %s:%d
+Stack trace:
+#0 %s(%d): returnIterable()
+#1 {main}
+TypeError: returnMissingIterable(): Return value must be of type Traversable|array|null, none returned in %s:%d
+Stack trace:
+#0 %s(%d): returnMissingIterable()
+#1 {main}