fix: Allow duplicate numbers in enums when aliases are enabled

pbjson-build/src/generator/enumeration.rs

@@ -11,6 +11,7 @@ use super::{
 use crate::descriptor::{EnumDescriptor, TypePath};
 use crate::generator::write_fields_array;
 use crate::resolver::Resolver;
+use std::collections::HashSet;
 use std::io::{Result, Write};
 
 pub fn generate_enum<W: Write>(
@@ -22,9 +23,13 @@ pub fn generate_enum<W: Write>(
 ) -> Result<()> {
     let rust_type = resolver.rust_type(path);
 
+    let mut seen_numbers = HashSet::new();
     let variants: Vec<_> = descriptor
         .values
         .iter()
+        // Skip duplicates if we've seen the number before
+        // Protobuf's `allow_alias` option permits duplicates if set
+        .filter(|variant| seen_numbers.insert(variant.number()))
         .map(|variant| {
             let variant_name = variant.name.clone().unwrap();
             let variant_number = variant.number();

pbjson-test/build.rs

@@ -13,6 +13,7 @@ fn main() -> Result<()> {
         root.join("syntax3.proto"),
         root.join("common.proto"),
         root.join("duplicate_name.proto"),
+        root.join("duplicate_number.proto"),
         root.join("escape.proto"),
     ];
 

pbjson-test/protos/duplicate_number.proto

@@ -0,0 +1,16 @@
+syntax = "proto3";
+
+package test.duplicate_number;
+
+message Compressor {
+    enum CompressionLevel {
+        option allow_alias = true;
+
+        DEFAULT = 0;
+        BEST_SPEED = 1;
+        COMPRESSION_LEVEL_1 = 1;
+        COMPRESSION_LEVEL_2 = 2;
+        COMPRESSION_LEVEL_3 = 3;
+        BEST_COMPRESSION = 3;
+    }
+}

pbjson-test/src/lib.rs

@@ -39,6 +39,11 @@ pub mod test {
         include!(concat!(env!("OUT_DIR"), "/test.duplicate_name.serde.rs"));
     }
 
+    pub mod duplicate_number {
+        include!(concat!(env!("OUT_DIR"), "/test.duplicate_number.rs"));
+        include!(concat!(env!("OUT_DIR"), "/test.duplicate_number.serde.rs"));
+    }
+
     pub mod escape {
         include!(concat!(
             env!("OUT_DIR"),