remove protobuf support

benchmark/src/main/scala/firrtl/benchmark/util/package.scala

@@ -4,14 +4,10 @@ package firrtl
 package benchmark
 
 import firrtl.ir.Circuit
-import scala.util.control.NonFatal
 
 package object util {
-  def filenameToCircuit(filename: String): Circuit = try {
-    proto.FromProto.fromFile(filename)
-  } catch {
-    case NonFatal(_) => Parser.parseFile(filename, Parser.IgnoreInfo)
-  }
+  def filenameToCircuit(filename: String): Circuit =
+    Parser.parseFile(filename, Parser.IgnoreInfo)
 
   def mean(xs: Iterable[Double]): Double = xs.sum / xs.size
 

build.sbt

@@ -64,13 +64,6 @@ lazy val mimaSettings = Seq(
   mimaPreviousArtifacts := Set("edu.berkeley.cs" %% "firrtl" % "1.6.0-RC2")
 )
 
-lazy val protobufSettings = Seq(
-  // The parentheses around the version help avoid version ambiguity in release scripts
-  ProtobufConfig / version := ("3.18.3"), // CVE-2021-22569
-  ProtobufConfig / sourceDirectory := baseDirectory.value / "src" / "main" / "proto",
-  ProtobufConfig / protobufRunProtoc := (args => com.github.os72.protocjar.Protoc.runProtoc("-v351" +: args.toArray))
-)
-
 lazy val assemblySettings = Seq(
   assembly / assemblyJarName := "firrtl.jar",
   assembly / test := {},
@@ -162,7 +155,6 @@ lazy val docSettings = Seq(
 )
 
 lazy val firrtl = (project in file("."))
-  .enablePlugins(ProtobufPlugin)
   .enablePlugins(ScalaUnidocPlugin)
   .enablePlugins(Antlr4Plugin)
   .settings(
@@ -171,7 +163,6 @@ lazy val firrtl = (project in file("."))
   )
   .settings(commonSettings)
   .settings(firrtlSettings)
-  .settings(protobufSettings)
   .settings(antlrSettings)
   .settings(assemblySettings)
   .settings(inConfig(Test)(baseAssemblySettings))

project/plugins.sbt

@@ -18,8 +18,6 @@ addSbtPlugin("com.eed3si9n" % "sbt-assembly" % "2.0.0")
 
 addSbtPlugin("com.simplytyped" % "sbt-antlr4" % "0.8.2")
 
-addSbtPlugin("com.github.sbt" % "sbt-protobuf" % "0.7.2")
-
 addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.10.4")
 
 addSbtPlugin("com.thoughtworks.sbt-api-mappings" % "sbt-api-mappings" % "3.0.2")
@@ -29,5 +27,3 @@ addSbtPlugin("org.scalameta" % "sbt-scalafmt" % "2.5.0")
 addSbtPlugin("com.typesafe" % "sbt-mima-plugin" % "1.1.1")
 
 addSbtPlugin("com.github.sbt" % "sbt-ci-release" % "1.5.11")
-
-libraryDependencies += "com.github.os72" % "protoc-jar" % "3.11.4"