This change includes the following:

* Updates links to `/programming-guides/proto2.md` throughout topics
* Adds content to `editions/features.md` about group-like field behaviors.
* Adds content to `editions/features.md` about the `features.(pb.cpp).string_type` feature.
* Adds a new topic, `reference/go/size.md`
* Updates guidance on releases in `support/version-support.md`

PiperOrigin-RevId: 626374994
Change-Id: I1a43714f5aafd15acb2e80b1f900f42434eb11dd

Author: Protocol Buffer Team

content/editions/features.md

@@ -238,6 +238,15 @@ This feature sets the behavior for encoding fields when serializing.
 This feature doesn't impact proto3 files, so this section doesn't have a before
 and after of a proto3 file.
 
+Depending on the language, fields that are "group-like" may have some unexpected
+capitalization in generated code and in text-format, in order to provide
+backwards compatibility with proto2. Message fields are "group-like" if all of
+the following conditions are met:
+
+*   Has `DELIMITED` message encoding specified
+*   Message type is defined in the same scope as the field
+*   Field name is exactly the lowercased type name
+
 **Values available:**
 
 *   `LENGTH_PREFIXED`: Fields are encoded using the LEN wire type described in
@@ -455,6 +464,78 @@ message Msg {
 }
 ```
 
+#### `features.(pb.cpp).string_type` {#string_type}
+
+**Languages:** C++
+
+This feature determines how generated code should treat string fields. This
+replaces the `ctype` option from proto2 and proto3, and offers a new
+`string_view` feature. In Edition 2023, either `ctype` or `string_view` may be
+specified on a field, but not both.
+
+**Values available:**
+
+*   `VIEW`: Generates `string_view` accessors for the field. This will be the
+    default in a future edition.
+*   `CORD`: Generates `Cord` accessors for the field.
+*   `STRING`: Generates `string` accessors for the field.
+
+**Applicable to the following scopes:** File, Field
+
+**Default behavior in Edition 2023:** `STRING`
+
+**Behavior in proto2:** `STRING`
+
+**Behavior in proto3:** `STRING`
+
+The following code sample shows a proto2 file:
+
+```proto
+syntax = "proto2";
+
+message Foo {
+  optional string bar = 6;
+  optional string baz = 7 [ctype = CORD];
+}
+```
+
+After running Prototiller, the equivalent code might look like this:
+
+```proto
+edition = "2023";
+
+import "google/protobuf/cpp_features.proto";
+
+message Foo {
+  optional string bar = 6;
+  optional string baz = 7 [features.(pb.cpp).string_type = CORD];
+}
+```
+
+The following shows a proto3 file:
+
+```proto
+syntax = "proto3"
+
+message Foo {
+  string bar = 6;
+  string baz = 7 [ctype = CORD];
+}
+```
+
+After running Prototiller, the equivalent code might look like this:
+
+```proto
+edition = "2023";
+
+import "google/protobuf/cpp_features.proto";
+
+message Foo {
+  string bar = 6;
+  string baz = 7 [features.(pb.cpp).string_type = CORD];
+}
+```
+
 #### `features.(pb.java).utf8_validation` {#java-utf8_validation}
 
 **Languages:** Java

content/getting-started/cpptutorial.md

@@ -16,7 +16,7 @@ shows you how to
 
 This isn't a comprehensive guide to using protocol buffers in C++. For more
 detailed reference information, see the
-[Protocol Buffer Language Guide (proto2)](/programming-guides/proto),
+[Protocol Buffer Language Guide (proto2)](/programming-guides/proto2),
 the
 [Protocol Buffer Language Guide (proto3)](/programming-guides/proto3),
 the [C++ API Reference](/reference/cpp/api-docs), the
@@ -169,7 +169,7 @@ most messages defined in proto2 syntax use `optional` and `repeated` only.
 
 You'll find a complete guide to writing `.proto` files -- including all the
 possible field types -- in the
-[Protocol Buffer Language Guide](/programming-guides/proto).
+[Protocol Buffer Language Guide](/programming-guides/proto2).
 Don't go looking for facilities similar to class inheritance, though -- protocol
 buffers don't do that.
 
@@ -557,7 +557,7 @@ some rules you need to follow. In the new version of the protocol buffer:
     buffer, not even by deleted fields).
 
 (There are
-[some exceptions](/programming-guides/proto#updating) to
+[some exceptions](/programming-guides/proto2#updating) to
 these rules, but they are rarely used.)
 
 If you follow these rules, old code will happily read new messages and simply

content/getting-started/javatutorial.md

@@ -16,7 +16,7 @@ shows you how to
 
 This isn't a comprehensive guide to using protocol buffers in Java. For more
 detailed reference information, see the
-[Protocol Buffer Language Guide (proto2)](/programming-guides/proto),
+[Protocol Buffer Language Guide (proto2)](/programming-guides/proto2),
 the
 [Protocol Buffer Language Guide (proto3)](/programming-guides/proto3),
 the
@@ -189,7 +189,7 @@ most messages defined in proto2 syntax use `optional` and `repeated` only.
 
 You'll find a complete guide to writing `.proto` files -- including all the
 possible field types -- in the
-[Protocol Buffer Language Guide](/programming-guides/proto).
+[Protocol Buffer Language Guide](/programming-guides/proto2).
 Don't go looking for facilities similar to class inheritance, though -- protocol
 buffers don't do that.
 
@@ -580,7 +580,7 @@ some rules you need to follow. In the new version of the protocol buffer:
     not even by deleted fields).
 
 (There are
-[some exceptions](/programming-guides/proto#updating) to
+[some exceptions](/programming-guides/proto2#updating) to
 these rules, but they are rarely used.)
 
 If you follow these rules, old code will happily read new messages and simply

content/getting-started/pythontutorial.md

@@ -16,7 +16,7 @@ shows you how to
 
 This isn't a comprehensive guide to using protocol buffers in Python. For more
 detailed reference information, see the
-[Protocol Buffer Language Guide (proto2)](/programming-guides/proto),
+[Protocol Buffer Language Guide (proto2)](/programming-guides/proto2),
 the
 [Protocol Buffer Language Guide (proto3)](/programming-guides/proto3),
 the [Python API Reference](https://googleapis.dev/python/protobuf/latest/), the
@@ -167,7 +167,7 @@ most messages defined in proto2 syntax use `optional` and `repeated` only.
 
 You'll find a complete guide to writing `.proto` files -- including all the
 possible field types -- in the
-[Protocol Buffer Language Guide](/programming-guides/proto).
+[Protocol Buffer Language Guide](/programming-guides/proto2).
 Don't go looking for facilities similar to class inheritance, though -- protocol
 buffers don't do that.
 
@@ -443,7 +443,7 @@ some rules you need to follow. In the new version of the protocol buffer:
     not even by deleted fields).
 
 (There are
-[some exceptions](/programming-guides/proto#updating) to
+[some exceptions](/programming-guides/proto2#updating) to
 these rules, but they are rarely used.)
 
 If you follow these rules, old code will happily read new messages and simply

content/news/2022-08-03.md

@@ -12,15 +12,15 @@ changes that are being considered for the 22.x release line.
 ## Platform Support Changes {#platform-changes}
 
 We've added guidance about the platforms that we support in
-[this section](/programming-guides/proto#platforms) of
+[this section](/programming-guides/proto2#platforms) of
 the documentation. The section currently covers C++ and PHP, but may be expanded
 with information about other platforms in the future.
 
 ## Official C++ Support Matrix {#cpp-support-matrix}
 
 With the policy, mentioned earlier in this announcement, of using Google's
 official
-[foundational C++ support policy](/programming-guides/proto#platforms),
+[foundational C++ support policy](/programming-guides/proto2#platforms),
 our
 [C++ compiler and toolchain support matrix will change](https://github.com/google/oss-policies-info/blob/8067c719150dfec6a836dd82230c5eb0ba11acd7/foundational-cxx-support-matrix.md).
 

content/programming-guides/api.md

@@ -61,7 +61,7 @@ Document the constraints, expectations and interpretation of each field in as
 few words as possible.
 
 You can use custom proto annotations.
-See [Custom Options](/programming-guides/proto#options)
+See [Custom Options](/programming-guides/proto2#options)
 to define cross-language constants like `max_length` in the example above.
 Supported in proto2 and proto3.
 
@@ -291,7 +291,7 @@ worse—write one.
 
 More generally, choose the right primitive type. See the Scalar Value Types
 table in the
-[Protocol Buffer Language Guide](/programming-guides/proto#scalar).
+[Protocol Buffer Language Guide](/programming-guides/proto2#scalar).
 
 ### Returning HTML in a Front-End Proto {#returning-html}
 

content/programming-guides/enum.md

@@ -9,7 +9,7 @@ Enums behave differently in different language libraries. This topic covers the
 different behaviors as well as the plans to move protobufs to a state where they
 are consistent across all languages. If you're looking for information on how to
 use enums in general, see the corresponding sections in the
-[proto2](/programming-guides/proto#enum) and
+[proto2](/programming-guides/proto2#enum) and
 [proto3](/programming-guides/proto3#enum) language guide
 topics.
 

content/reference/cpp/arenas.md

@@ -11,7 +11,7 @@ buffer compiler generates in addition to the code described in the
 [C++ Generated Code Guide](/reference/cpp/cpp-generated)
 when arena allocation is enabled. It assumes that you are familiar with the
 material in the
-[language guide](/programming-guides/proto) and the
+[language guide](/programming-guides/proto2) and the
 [C++ Generated Code Guide](/reference/cpp/cpp-generated).
 
 ## Why Use Arena Allocation? {#why}

content/reference/csharp/csharp-generated.md

@@ -14,7 +14,7 @@ before reading this document.
 {{% alert title="Note" color="note" %}}
 The protobuf compiler can generate C\# interfaces for definitions using `proto2`
 syntax starting from release 3.10. Refer to the
-[proto2 language guide](/programming-guides/proto) for
+[proto2 language guide](/programming-guides/proto2) for
 details of the semantics of `proto2` definitions, and see
 `docs/csharp/proto2.md`
 ([view on GitHub](https://github.com/protocolbuffers/protobuf/blob/master/docs/csharp/proto2.md))

content/reference/dart/dart-generated.md

@@ -10,8 +10,9 @@ Any differences between
 proto2 and proto3 generated code are highlighted - note that these differences
 are in the generated code as described in this document, not the base API, which
 are the same in both versions. You should read the
-[proto2 language guide](/programming-guides/proto) and/or
-the [proto3 language guide](/programming-guides/proto3)
+[proto2 language guide](/programming-guides/proto2)
+and/or the
+[proto3 language guide](/programming-guides/proto3)
 before reading this document.
 
 ## Compiler Invocation {#invocation}
@@ -129,7 +130,7 @@ The compiler will generate the following accessor methods in the message class:
 
 For other simple field types, the corresponding Dart type is chosen according to
 the
-[scalar value types table](/programming-guides/proto#scalar).
+[scalar value types table](/programming-guides/proto2#scalar).
 For message and enum types, the value type is replaced with the message or enum
 class.
 
@@ -394,7 +395,7 @@ The protocol buffer compiler will generate a class called `Bar`, which extends
 ## Extensions (proto2 only) {#extension}
 
 Given a file `foo_test.proto` including a message with an
-[extension range](/programming-guides/proto#extensions)
+[extension range](/programming-guides/proto2#extensions)
 and a top-level extension definition:
 
 ```proto