From 80e87531d35aaf730d4eead08901657bfb774017 Mon Sep 17 00:00:00 2001
From: Rikito Taniguchi <rikiriki1238@gmail.com>
Date: Fri, 18 Mar 2022 02:23:08 +0900
Subject: [PATCH] Don't fire publishDiagnostic if there's no problems both in
 current and previous compilation

---
 main/src/main/scala/sbt/Defaults.scala        |  8 +++--
 .../internal/server/BuildServerReporter.scala | 30 +++++++++++--------
 2 files changed, 23 insertions(+), 15 deletions(-)

diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index facf6637a..2e3f463f1 100644
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -2310,10 +2310,11 @@ object Defaults extends BuildCommon {
     val ci = (compile / compileInputs).value
     val ping = earlyOutputPing.value
     val reporter = (compile / bspReporter).value
+    val prevAnalysis = previousCompile.value.analysis.toOption.getOrElse(Analysis.empty)
     BspCompileTask.compute(bspTargetIdentifier.value, thisProjectRef.value, configuration.value) {
       task =>
         // TODO - Should readAnalysis + saveAnalysis be scoped by the compile task too?
-        compileIncrementalTaskImpl(task, s, ci, ping, reporter)
+        compileIncrementalTaskImpl(task, s, ci, ping, reporter, prevAnalysis)
     }
   }
   private val incCompiler = ZincUtil.defaultIncrementalCompiler
@@ -2342,7 +2343,8 @@ object Defaults extends BuildCommon {
       s: TaskStreams,
       ci: Inputs,
       promise: PromiseWrap[Boolean],
-      reporter: BuildServerReporter
+      reporter: BuildServerReporter,
+      prev: CompileAnalysis
   ): CompileResult = {
     lazy val x = s.text(ExportStream)
     def onArgs(cs: Compilers) = {
@@ -2364,7 +2366,7 @@ object Defaults extends BuildCommon {
       .withSetup(onProgress(setup))
     try {
       val result = incCompiler.compile(i, s.log)
-      reporter.sendSuccessReport(result.getAnalysis)
+      reporter.sendSuccessReport(result.getAnalysis, prev)
       result
     } catch {
       case e: Throwable =>
diff --git a/main/src/main/scala/sbt/internal/server/BuildServerReporter.scala b/main/src/main/scala/sbt/internal/server/BuildServerReporter.scala
index dba366578..8184b090c 100644
--- a/main/src/main/scala/sbt/internal/server/BuildServerReporter.scala
+++ b/main/src/main/scala/sbt/internal/server/BuildServerReporter.scala
@@ -38,7 +38,7 @@ sealed trait BuildServerReporter extends Reporter {
 
   protected def publishDiagnostic(problem: Problem): Unit
 
-  def sendSuccessReport(analysis: CompileAnalysis): Unit
+  def sendSuccessReport(analysis: CompileAnalysis, prev: CompileAnalysis): Unit
 
   def sendFailureReport(sources: Array[VirtualFile]): Unit
 
@@ -86,20 +86,26 @@ final class BuildServerReporterImpl(
     if (ref.id().contains("<")) None
     else Some(converter.toPath(ref))
 
-  override def sendSuccessReport(analysis: CompileAnalysis): Unit = {
+  override def sendSuccessReport(analysis: CompileAnalysis, prev: CompileAnalysis): Unit = {
+    val prevInfos = prev.readSourceInfos().getAllSourceInfos().asScala
     for {
       (source, infos) <- analysis.readSourceInfos.getAllSourceInfos.asScala
       filePath <- toSafePath(source)
     } {
-      val diagnostics = infos.getReportedProblems.toSeq.flatMap(toDiagnostic)
-      val params = PublishDiagnosticsParams(
-        textDocument = TextDocumentIdentifier(filePath.toUri),
-        buildTarget,
-        originId = None,
-        diagnostics.toVector,
-        reset = true
-      )
-      exchange.notifyEvent("build/publishDiagnostics", params)
+      val prevProblems = prevInfos.get(source).map(_.getReportedProblems()).getOrElse(Array.empty)
+      val dontPublish = prevProblems.length == 0 && infos.getReportedProblems().length == 0
+
+      if (!dontPublish) {
+        val diagnostics = infos.getReportedProblems.toSeq.flatMap(toDiagnostic)
+        val params = PublishDiagnosticsParams(
+          textDocument = TextDocumentIdentifier(filePath.toUri),
+          buildTarget,
+          originId = None,
+          diagnostics.toVector,
+          reset = true
+        )
+        exchange.notifyEvent("build/publishDiagnostics", params)
+      }
     }
   }
 
@@ -179,7 +185,7 @@ final class BuildServerForwarder(
     protected override val underlying: Reporter
 ) extends BuildServerReporter {
 
-  override def sendSuccessReport(analysis: CompileAnalysis): Unit = ()
+  override def sendSuccessReport(analysis: CompileAnalysis, prev: CompileAnalysis): Unit = ()
 
   override def sendFailureReport(sources: Array[VirtualFile]): Unit = ()