From 9dd92be3eaf7418adbf52cdab5e385f6e91a0b8e Mon Sep 17 00:00:00 2001
From: David Freese <freese@google.com>
Date: Tue, 20 Dec 2022 09:02:59 -0800
Subject: [PATCH] Allow file descriptor be generated without
 --include_source_info (#786)

* Allow file descriptor be generated without --include_source_info

The file descriptor sets generated by rules_proto in bazel don't have
this by default, so this allows some flexibility for users to reuse
results that are already available to them.  It's fairly trivial
adjustment so it seemed reasonable to me to allow the flexibility.

* revert breaking changes and add default
---
 prost-build/src/ast.rs            |  2 +-
 prost-build/src/code_generator.rs | 44 ++++++++++++++++++-------------
 prost-build/src/lib.rs            |  3 +--
 3 files changed, 27 insertions(+), 22 deletions(-)

diff --git a/prost-build/src/ast.rs b/prost-build/src/ast.rs
index 8a7fa2acd..7685a2e5a 100644
--- a/prost-build/src/ast.rs
+++ b/prost-build/src/ast.rs
@@ -5,7 +5,7 @@ use pulldown_cmark::{CodeBlockKind, Event, Options, Parser, Tag};
 use regex::Regex;
 
 /// Comments on a Protobuf item.
-#[derive(Debug, Clone)]
+#[derive(Debug, Default, Clone)]
 pub struct Comments {
     /// Leading detached blocks of comments.
     pub leading_detached: Vec<Vec<String>>,
diff --git a/prost-build/src/code_generator.rs b/prost-build/src/code_generator.rs
index 69a80ed3c..235b3da74 100644
--- a/prost-build/src/code_generator.rs
+++ b/prost-build/src/code_generator.rs
@@ -29,7 +29,7 @@ enum Syntax {
 pub struct CodeGenerator<'a> {
     config: &'a mut Config,
     package: String,
-    source_info: SourceCodeInfo,
+    source_info: Option<SourceCodeInfo>,
     syntax: Syntax,
     message_graph: &'a MessageGraph,
     extern_paths: &'a ExternPaths,
@@ -51,16 +51,14 @@ impl<'a> CodeGenerator<'a> {
         file: FileDescriptorProto,
         buf: &mut String,
     ) {
-        let mut source_info = file
-            .source_code_info
-            .expect("no source code info in request");
-        source_info.location.retain(|location| {
-            let len = location.path.len();
-            len > 0 && len % 2 == 0
+        let source_info = file.source_code_info.map(|mut s| {
+            s.location.retain(|loc| {
+                let len = loc.path.len();
+                len > 0 && len % 2 == 0
+            });
+            s.location.sort_by(|a, b| a.path.cmp(&b.path));
+            s
         });
-        source_info
-            .location
-            .sort_by_key(|location| location.path.clone());
 
         let syntax = match file.syntax.as_ref().map(String::as_str) {
             None | Some("proto2") => Syntax::Proto2,
@@ -569,14 +567,13 @@ impl<'a> CodeGenerator<'a> {
         self.buf.push_str("}\n");
     }
 
-    fn location(&self) -> &Location {
-        let idx = self
-            .source_info
+    fn location(&self) -> Option<&Location> {
+        let source_info = self.source_info.as_ref()?;
+        let idx = source_info
             .location
             .binary_search_by_key(&&self.path[..], |location| &location.path[..])
             .unwrap();
-
-        &self.source_info.location[idx]
+        Some(&source_info.location[idx])
     }
 
     fn append_doc(&mut self, fq_name: &str, field_name: Option<&str>) {
@@ -589,7 +586,9 @@ impl<'a> CodeGenerator<'a> {
             self.config.disable_comments.get(fq_name).next().is_none()
         };
         if append_doc {
-            Comments::from_location(self.location()).append_with_indent(self.depth, self.buf)
+            if let Some(comments) = self.location().map(Comments::from_location) {
+                comments.append_with_indent(self.depth, self.buf);
+            }
         }
     }
 
@@ -715,7 +714,7 @@ impl<'a> CodeGenerator<'a> {
 
         for variant in variant_mappings.iter() {
             self.push_indent();
-            self.buf.push_str("\"");
+            self.buf.push('\"');
             self.buf.push_str(variant.proto_name);
             self.buf.push_str("\" => Some(Self::");
             self.buf.push_str(&variant.generated_variant_name);
@@ -742,7 +741,10 @@ impl<'a> CodeGenerator<'a> {
         let name = service.name().to_owned();
         debug!("  service: {:?}", name);
 
-        let comments = Comments::from_location(self.location());
+        let comments = self
+            .location()
+            .map(Comments::from_location)
+            .unwrap_or_default();
 
         self.path.push(2);
         let methods = service
@@ -751,8 +753,12 @@ impl<'a> CodeGenerator<'a> {
             .enumerate()
             .map(|(idx, mut method)| {
                 debug!("  method: {:?}", method.name());
+
                 self.path.push(idx as i32);
-                let comments = Comments::from_location(self.location());
+                let comments = self
+                    .location()
+                    .map(Comments::from_location)
+                    .unwrap_or_default();
                 self.path.pop();
 
                 let name = method.name.take().unwrap();
diff --git a/prost-build/src/lib.rs b/prost-build/src/lib.rs
index e8f51d0fc..34e509f63 100644
--- a/prost-build/src/lib.rs
+++ b/prost-build/src/lib.rs
@@ -664,8 +664,7 @@ impl Config {
 
     /// In combination with with `file_descriptor_set_path`, this can be used to provide a file
     /// descriptor set as an input file, rather than having prost-build generate the file by calling
-    /// protoc.  Prost-build does require that the descriptor set was generated with
-    /// --include_source_info.
+    /// protoc.
     ///
     /// In `build.rs`:
     ///