PHP namespaces for nested messages and enums (#4536)

* uses namespaces for nested messages and enums

* fixes namespaces for PHP dist

* fixes namespace for Descriptors, adds Cardinality and Kind

* fixes nested namespaces for reserved words and adds tests

* adds tests and generator fix for php class prefixes

* fixes escaping of protobuf packages, enum comments, misc others

* nice refactor of generated code

* adds class files for backwards compatibility

* simplifies code with templates

* adds compatibility files to makefile

* cleanup of generator and fixes nested namespace bug

* regenerates proto types

* remove internal BC classes

* adds deprecated warning, adds methods back

* simplifies if statement

* fixes dist files

* addresses review comments

* adds back TYPE_URL_PREFIX constant

* adds @deprecated to old nested class files

* skips tests which require a separate process when protobuf.so is enabled

* Adds tests for legacy nested classes that do not require separate processes to test

* uses legacy names for GPBUtil message check

* adds block for IDE @deprecated message

* Namespace for nested message/enum in c extension

* Remove unused code

1 files changed, 6 insertions, 119 deletions

diff --git a/php/src/Google/Protobuf/Field_Kind.php b/php/src/Google/Protobuf/Field_Kind.php
index d0774970..aa202370 100644
--- a/php/src/Google/Protobuf/Field_Kind.php
+++ b/php/src/Google/Protobuf/Field_Kind.php
@@ -4,126 +4,13 @@
 
 namespace Google\Protobuf;
 
-/**
- * Basic field types.
- *
- * Protobuf enum <code>Google\Protobuf\Field\Kind</code>
- */
-class Field_Kind
-{
+if (false) {
     /**
-     * Field type unknown.
-     *
-     * Generated from protobuf enum <code>TYPE_UNKNOWN = 0;</code>
+     * This class is deprecated. Use Google\Protobuf\Field\Kind instead.
+     * @deprecated
      */
-    const TYPE_UNKNOWN = 0;
-    /**
-     * Field type double.
-     *
-     * Generated from protobuf enum <code>TYPE_DOUBLE = 1;</code>
-     */
-    const TYPE_DOUBLE = 1;
-    /**
-     * Field type float.
-     *
-     * Generated from protobuf enum <code>TYPE_FLOAT = 2;</code>
-     */
-    const TYPE_FLOAT = 2;
-    /**
-     * Field type int64.
-     *
-     * Generated from protobuf enum <code>TYPE_INT64 = 3;</code>
-     */
-    const TYPE_INT64 = 3;
-    /**
-     * Field type uint64.
-     *
-     * Generated from protobuf enum <code>TYPE_UINT64 = 4;</code>
-     */
-    const TYPE_UINT64 = 4;
-    /**
-     * Field type int32.
-     *
-     * Generated from protobuf enum <code>TYPE_INT32 = 5;</code>
-     */
-    const TYPE_INT32 = 5;
-    /**
-     * Field type fixed64.
-     *
-     * Generated from protobuf enum <code>TYPE_FIXED64 = 6;</code>
-     */
-    const TYPE_FIXED64 = 6;
-    /**
-     * Field type fixed32.
-     *
-     * Generated from protobuf enum <code>TYPE_FIXED32 = 7;</code>
-     */
-    const TYPE_FIXED32 = 7;
-    /**
-     * Field type bool.
-     *
-     * Generated from protobuf enum <code>TYPE_BOOL = 8;</code>
-     */
-    const TYPE_BOOL = 8;
-    /**
-     * Field type string.
-     *
-     * Generated from protobuf enum <code>TYPE_STRING = 9;</code>
-     */
-    const TYPE_STRING = 9;
-    /**
-     * Field type group. Proto2 syntax only, and deprecated.
-     *
-     * Generated from protobuf enum <code>TYPE_GROUP = 10;</code>
-     */
-    const TYPE_GROUP = 10;
-    /**
-     * Field type message.
-     *
-     * Generated from protobuf enum <code>TYPE_MESSAGE = 11;</code>
-     */
-    const TYPE_MESSAGE = 11;
-    /**
-     * Field type bytes.
-     *
-     * Generated from protobuf enum <code>TYPE_BYTES = 12;</code>
-     */
-    const TYPE_BYTES = 12;
-    /**
-     * Field type uint32.
-     *
-     * Generated from protobuf enum <code>TYPE_UINT32 = 13;</code>
-     */
-    const TYPE_UINT32 = 13;
-    /**
-     * Field type enum.
-     *
-     * Generated from protobuf enum <code>TYPE_ENUM = 14;</code>
-     */
-    const TYPE_ENUM = 14;
-    /**
-     * Field type sfixed32.
-     *
-     * Generated from protobuf enum <code>TYPE_SFIXED32 = 15;</code>
-     */
-    const TYPE_SFIXED32 = 15;
-    /**
-     * Field type sfixed64.
-     *
-     * Generated from protobuf enum <code>TYPE_SFIXED64 = 16;</code>
-     */
-    const TYPE_SFIXED64 = 16;
-    /**
-     * Field type sint32.
-     *
-     * Generated from protobuf enum <code>TYPE_SINT32 = 17;</code>
-     */
-    const TYPE_SINT32 = 17;
-    /**
-     * Field type sint64.
-     *
-     * Generated from protobuf enum <code>TYPE_SINT64 = 18;</code>
-     */
-    const TYPE_SINT64 = 18;
+    class Field_Kind {}
 }
+class_exists(Field\Kind::class);
+@trigger_error('Google\Protobuf\Field_Kind is deprecated and will be removed in the next major release. Use Google\Protobuf\Field\Kind instead', E_USER_DEPRECATED);