From b6f8d3209f0e59a176c0e3a4b168eec07722b7cc Mon Sep 17 00:00:00 2001
From: Dave Syer <david_syer@hotmail.com>
Date: Fri, 26 Sep 2025 08:12:16 +0000
Subject: [PATCH 1/3] [protobuf2] Verification and declaration keywords

Fixes #4629.
---
 protobuf/protobuf2/Protobuf2.g4 | 43 ++++++++++++++++++++++++++++++++-
 1 file changed, 42 insertions(+), 1 deletion(-)

diff --git a/protobuf/protobuf2/Protobuf2.g4 b/protobuf/protobuf2/Protobuf2.g4
index 83892abb5b..188460ff6c 100644
--- a/protobuf/protobuf2/Protobuf2.g4
+++ b/protobuf/protobuf2/Protobuf2.g4
@@ -132,7 +132,28 @@ type_
 // Extensions
 
 extensions
-    : EXTENSIONS ranges SEMI
+    : EXTENSIONS ranges (LB (verificationDef | declarationsDef) RB)? SEMI
+    ;
+
+verificationDef
+    : VERIFICATION EQ verification
+    ;
+
+verification
+    : DECLARATION_LIT
+    | UNVERIFIED_LIT
+    ;
+
+declarationsDef
+    : declarationDef (COMMA declarationDef)*
+    ;
+
+declarationDef
+    : DECLARATION EQ LC (declaration (declaration)*)? RC
+    ;
+
+declaration
+    : fieldName COLON constant (COMMA)?
     ;
 
 // Reserved
@@ -472,6 +493,22 @@ MAX
     : 'max'
     ;
 
+VERIFICATION
+    : 'verification'
+    ;
+
+DECLARATION
+    : 'declaration'
+    ;
+
+DECLARATION_LIT
+    : 'DECLARATION'
+    ;
+
+UNVERIFIED_LIT
+    : 'UNVERIFIED'
+    ;
+
 ENUM
     : 'enum'
     ;
@@ -707,4 +744,8 @@ keywords
     | STREAM
     | RETURNS
     | BOOL_LIT
+    | DECLARATION
+    | VERIFICATION
+    | DECLARATION_LIT
+    | UNVERIFIED_LIT
     ;

From d9b8d722faa96221146950af5ceceb3eb7b564ab Mon Sep 17 00:00:00 2001
From: Dave Syer <david_syer@hotmail.com>
Date: Fri, 26 Sep 2025 08:51:55 +0000
Subject: [PATCH 2/3] Add example that fails build on master

---
 protobuf/protobuf2/examples/extension.proto | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)
 create mode 100644 protobuf/protobuf2/examples/extension.proto

diff --git a/protobuf/protobuf2/examples/extension.proto b/protobuf/protobuf2/examples/extension.proto
new file mode 100644
index 0000000000..41b2936aa4
--- /dev/null
+++ b/protobuf/protobuf2/examples/extension.proto
@@ -0,0 +1,16 @@
+syntax = 'proto2';
+
+message UserContent {
+  extensions 100 to 199 [verification = DECLARATION];
+}
+
+message OtherContent {
+  extensions 100 to 199 [
+    declaration = {
+      number: 126,
+      full_name: ".kittens.kitten_videos",
+      type: ".kittens.Video",
+      repeated: true
+    }
+  ];
+}
\ No newline at end of file

From 72088a4974b19ee00a852195a207598e58ddf6c3 Mon Sep 17 00:00:00 2001
From: Dave Syer <david_syer@hotmail.com>
Date: Fri, 26 Sep 2025 09:00:30 +0000
Subject: [PATCH 3/3] Simplify extension declaration a bit

Duplicates one of the changes from #4632
---
 protobuf/protobuf2/Protobuf2.g4 | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/protobuf/protobuf2/Protobuf2.g4 b/protobuf/protobuf2/Protobuf2.g4
index 188460ff6c..253cc8b43a 100644
--- a/protobuf/protobuf2/Protobuf2.g4
+++ b/protobuf/protobuf2/Protobuf2.g4
@@ -132,7 +132,7 @@ type_
 // Extensions
 
 extensions
-    : EXTENSIONS ranges (LB (verificationDef | declarationsDef) RB)? SEMI
+    : EXTENSIONS ranges (LB (verificationDef | declarations) RB)? SEMI
     ;
 
 verificationDef
@@ -144,16 +144,12 @@ verification
     | UNVERIFIED_LIT
     ;
 
-declarationsDef
-    : declarationDef (COMMA declarationDef)*
-    ;
-
-declarationDef
-    : DECLARATION EQ LC (declaration (declaration)*)? RC
+declarations
+    : declaration (COMMA declaration)*
     ;
 
 declaration
-    : fieldName COLON constant (COMMA)?
+    : DECLARATION EQ blockLit
     ;
 
 // Reserved