From c6021ecdf6de316be62c071b465e04faeae9daed Mon Sep 17 00:00:00 2001
From: Ethan Atkins <contact@ethanatkins.com>
Date: Wed, 2 Sep 2020 11:27:31 -0700
Subject: [PATCH] Allow incompatible mixed scala versions

The zinc scripted project depends on all of the compiler bridges. As a
result the introduction of the strict scala binary version check in
f8139da1920944b8a4912fa54d898c99ae81e36a broke zinc scripted. This
commit reverts to the old behavior in the non scala sandwich case.

I also switched to a for comprehension instead of a pattern match
because this is a rare case where I think it made the code significantly
more readable.
---
 main/src/main/scala/sbt/Defaults.scala | 32 +++++++++++---------------
 1 file changed, 13 insertions(+), 19 deletions(-)

diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index 39120b652..3b37e8ad1 100644
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -3470,25 +3470,19 @@ object Classpaths {
       val data = settingsData.value
       val deps = buildDependencies.value
       deps.classpath(ref) flatMap { dep =>
-        val depProjIdOpt = (dep.project / projectID).get(data)
-        val depSVOpt = (dep.project / scalaVersion).get(data)
-        val depSBVOpt = (dep.project / scalaBinaryVersion).get(data)
-        val depCrossOpt = (dep.project / crossVersion).get(data)
-        (depProjIdOpt, depSVOpt, depSBVOpt, depCrossOpt) match {
-          case (Some(depProjId), Some(depSV), Some(depSBV), Some(depCross)) =>
-            if (sbv == depSBV || depCross != CrossVersion.binary)
-              Some(
-                depProjId.withConfigurations(dep.configuration).withExplicitArtifacts(Vector.empty)
-              )
-            else if (isScala2Scala3Sandwich(sbv, depSBV) && depCross == CrossVersion.binary)
-              Some(
-                depProjId
-                  .withCrossVersion(CrossVersion.constant(depSBV))
-                  .withConfigurations(dep.configuration)
-                  .withExplicitArtifacts(Vector.empty)
-              )
-            else sys.error(s"scalaBinaryVersion mismatch: expected $sbv but found ${depSBV}")
-          case _ => None
+        for {
+          depProjId <- (dep.project / projectID).get(data)
+          depSV <- (dep.project / scalaVersion).get(data)
+          depSBV <- (dep.project / scalaBinaryVersion).get(data)
+          depCross <- (dep.project / crossVersion).get(data)
+        } yield {
+          if (isScala2Scala3Sandwich(sbv, depSBV) && depCross == CrossVersion.binary)
+            depProjId
+              .withCrossVersion(CrossVersion.constant(depSBV))
+              .withConfigurations(dep.configuration)
+              .withExplicitArtifacts(Vector.empty)
+          else
+            depProjId.withConfigurations(dep.configuration).withExplicitArtifacts(Vector.empty)
         }
       }
     }