Add commands to automatically re-fetch and patch the protobuf

Author: natsukagami

build.sbt

@@ -1,22 +1,50 @@
 ThisBuild / scalafixScalaBinaryVersion :=
   CrossVersion.binaryScalaVersion(scalaVersion.value)
 
+val scalametaVersion = "4.13.9"
+val semanticdbProtoURL =
+  "https://raw.githubusercontent.com/scalameta/scalameta/refs/tags/v%s/semanticdb/semanticdb/shared/src/main/proto/semanticdb.proto"
+    .format(scalametaVersion)
+
 ThisBuild / scalaVersion := "2.13.16"
 
 commands += Command.command("ci") { s =>
-  s"clean" ::
+  s"check-protobuf" ::
+    s"clean" ::
     s"clean-generated" ::
     s"generate" ::
     s
 }
 
 commands += Command.command("generate") { s =>
-  s"generator/protocGenerate" ::
+  s"fetch-protobuf" ::
+    s"generator/protocGenerate" ::
     s"output/scalafix AdjustForScala3" ::
     s"remove-scalameta-proto" ::
     s"output/compile" ::
     s
 }
+
+commands += Command.command("check-protobuf") { s =>
+  import scala.sys.process._
+  val generatorDir = (generator / Compile / baseDirectory).value
+  assert(
+    (("%s/src/main/fetch-proto.sh %s %s %s")
+      .format(generatorDir, semanticdbProtoURL, generatorDir, "true") !) == 0
+  );
+  s
+}
+
+commands += Command.command("fetch-protobuf") { s =>
+  import scala.sys.process._
+  val generatorDir = (generator / Compile / baseDirectory).value
+  assert(
+    (("%s/src/main/fetch-proto.sh %s %s %s")
+      .format(generatorDir, semanticdbProtoURL, generatorDir, "false") !) == 0
+  );
+  s
+}
+
 commands += Command.command("clean-generated") { s =>
   IO.delete(
     (output / Compile / baseDirectory).value / "src" / "main" / "scala" / "generated"

generator/src/main/fetch-proto.sh

@@ -0,0 +1,33 @@
+#!/usr/bin/env sh
+set -e
+
+# Usage: ./fetch-proto.sh {url} {generator-base-directory} {check-only:true/false}
+
+URL="$1"
+GENERATOR_DIR="$2"
+CHECK_ONLY="$3"
+
+PATCH_FILE="$GENERATOR_DIR/src/main/scalameta-to-compiler.patch"
+TARGET="$GENERATOR_DIR/src/main/protobuf/scalameta.proto"
+
+# Fetch the proto file
+tmpfile=$(mktemp)
+curl -L "$URL" > $tmpfile
+
+# Patch it
+patch -u $tmpfile "$PATCH_FILE"
+
+# Check if the content is identical
+if diff -wq $tmpfile "$TARGET"; then
+  echo "Fetched file and current .proto are identical"
+  exit 0
+fi
+
+if test "$CHECK_ONLY" = "true"; then
+  echo "Fetched file and current .proto differ"
+  exit 1
+fi
+
+echo "Updating $TARGET."
+mv $tmpfile "$TARGET"
+

generator/src/main/scalameta-to-compiler.patch

@@ -0,0 +1,18 @@
+--- ../scalameta/semanticdb/semanticdb/shared/src/main/proto/semanticdb.proto	2025-09-01 13:27:15.488562021 +0200
++++ generator/src/main/protobuf/scalameta.proto	2025-09-01 13:45:57.842972500 +0200
+@@ -1,11 +1,13 @@
+ syntax = "proto3";
+ 
+-package scala.meta.internal.semanticdb;
++package dotty.tools.dotc.semanticdb;
+ 
+ import "scalapb/scalapb.proto";
+ 
+ option (scalapb.options) = {
+   preserve_unknown_fields: false
++  import: "dotty.tools.dotc.semanticdb.internal._"
++  import: "scala.annotation.internal.sharable"
+ };
+ 
+ enum Schema {
+