From 51331ec5b54d89e9891a9ea0e831203d4aacbeb6 Mon Sep 17 00:00:00 2001
From: Dale Wijnand <dale.wijnand@gmail.com>
Date: Wed, 28 Oct 2020 17:30:36 +0000
Subject: [PATCH] Add debug logging to Equiv[MiniSetup]

---
 .../sbt/internal/inc/MiniSetupUtil.scala      | 32 ++++++++++++++-----
 .../inc/IncrementalCompilerImpl.scala         |  1 +
 2 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/internal/zinc-core/src/main/scala/sbt/internal/inc/MiniSetupUtil.scala b/internal/zinc-core/src/main/scala/sbt/internal/inc/MiniSetupUtil.scala
index 4a0c627694..176295a3dd 100644
--- a/internal/zinc-core/src/main/scala/sbt/internal/inc/MiniSetupUtil.scala
+++ b/internal/zinc-core/src/main/scala/sbt/internal/inc/MiniSetupUtil.scala
@@ -15,7 +15,7 @@ package inc
 
 import java.nio.file.Path
 
-import xsbti.T2
+import xsbti.{ Logger, T2 }
 import xsbti.compile.{
   CompileOrder,
   MiniOptions,
@@ -40,19 +40,35 @@ object MiniSetupUtil {
   /* *********************************************************************** */
 
   /* Define first because `Equiv[CompileOrder.value]` dominates `Equiv[MiniSetup]`. */
-  implicit def equivCompileSetup(equivOpts: Equiv[MiniOptions])(
+  def equivCompileSetup(logger: Logger, equivOpts: Equiv[MiniOptions])(
       implicit equivComp: Equiv[String]
   ): Equiv[MiniSetup] = {
     new Equiv[MiniSetup] {
       def equiv(a: MiniSetup, b: MiniSetup) = {
-        def sameOptions = equivOpts.equiv(a.options, b.options)
-        def sameCompiler = equivComp.equiv(a.compilerVersion, b.compilerVersion)
+        def prettyOptions(a: MiniOptions) =
+          s"scala=${a.scalacOptions.mkString(",")} java=${a.javacOptions.mkString(",")}"
+        def sameOptions = {
+          val ret = equivOpts.equiv(a.options, b.options)
+          if (!ret)
+            logger.debug { () =>
+              s"""Found differing options:
+                 |a: ${prettyOptions(a.options)}
+                 |b: ${prettyOptions(b.options)}
+                 |""".stripMargin
+            }
+          ret
+        }
+        def sameCompiler = {
+          val ret = equivComp.equiv(a.compilerVersion, b.compilerVersion)
+          if (!ret)
+            logger.debug { () =>
+              s"Found differing compiler version ${a.compilerVersion} ${b.compilerVersion}"
+            }
+          ret
+        }
         def sameOrder = a.order == b.order
         def sameExtra = equivPairs.equiv(a.extra, b.extra)
-        sameOptions &&
-        sameCompiler &&
-        sameOrder &&
-        sameExtra
+        sameOptions && sameCompiler && sameOrder && sameExtra
       }
     }
   }
diff --git a/zinc/src/main/scala/sbt/internal/inc/IncrementalCompilerImpl.scala b/zinc/src/main/scala/sbt/internal/inc/IncrementalCompilerImpl.scala
index 995ad4f23a..2e0f6c3640 100644
--- a/zinc/src/main/scala/sbt/internal/inc/IncrementalCompilerImpl.scala
+++ b/zinc/src/main/scala/sbt/internal/inc/IncrementalCompilerImpl.scala
@@ -484,6 +484,7 @@ class IncrementalCompilerImpl extends IncrementalCompiler {
         val (analysis, changed) = compileInternal(
           MixedAnalyzingCompiler(config)(logger),
           equivCompileSetup(
+            logger,
             equivOpts0(equivScalacOptions(incrementalOptions.ignoredScalacOptions))
           ),
           equivPairs,