if mismatching minor versions, protect PC dynamic loading behind a flag

scalacenter · Sep 27, 2024 · eeb0235 · eeb0235
1 parent ed58c8a
commit eeb0235
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Showing 3 changed files with 59 additions and 17 deletions.
diff --git a/scalafix-rules/src/main/scala-3/scalafix/internal/rule/ExplicitResultTypes.scala b/scalafix-rules/src/main/scala-3/scalafix/internal/rule/ExplicitResultTypes.scala
@@ -40,25 +40,34 @@ final class ExplicitResultTypes(
           "To fix this problem, either remove ExplicitResultTypes from .scalafix.conf or upgrade the compiler in your build."
       )
     } else {
-      config.conf // Support deprecated explicitReturnTypes config
-        .getOrElse("explicitReturnTypes", "ExplicitResultTypes")(
-          ExplicitResultTypesConfig.default
-        )
-        .map(c =>
-          new ExplicitResultTypes(
-            c,
-            Option {
-              if (
-                stripPatchVersion(config.scalaVersion) ==
-                  stripPatchVersion(compilerScalaVersion)
-              )
-                PresentationCompilerTypeInferrer
-                  .static(config, new ScalaPresentationCompiler())
+      config.conf.getOrElse("ExplicitResultTypes")(this.config).andThen {
+        conf =>
+          val majorMinorCompilerScalaVersion =
+            stripPatchVersion(compilerScalaVersion)
+
+          val matchingMinors =
+            majorMinorScalaVersion == majorMinorCompilerScalaVersion
+
+          if (!matchingMinors && !conf.fetchScala3CompilerIfNeeded) {
+            Configured.error(
+              s"The ExplicitResultTypes rule was compiled with a different Scala 3 minor ($majorMinorCompilerScalaVersion) " +
+                s"than the target sources ($majorMinorScalaVersion). To fix this problem, either enable " +
+                "ExplicitResultTypes.fetchScala3CompilerIfNeeded in .scalafix.conf or check if Scalafix can be " +
+                s"loaded with $majorMinorCompilerScalaVersion."
+            )
+          } else {
+            val pcTypeInferrer =
+              if (matchingMinors)
+                PresentationCompilerTypeInferrer.static(
+                  config,
+                  new ScalaPresentationCompiler()
+                )
               else
                 PresentationCompilerTypeInferrer.dynamic(config)
-            }
-          )
-        )
+
+            Configured.Ok(new ExplicitResultTypes(conf, Some(pcTypeInferrer)))
+          }
+      }
     }
   }
 

diff --git a/scalafix-rules/src/main/scala/scalafix/internal/rule/ExplicitResultTypesConfig.scala b/scalafix-rules/src/main/scala/scalafix/internal/rule/ExplicitResultTypesConfig.scala
@@ -39,6 +39,12 @@ case class ExplicitResultTypesConfig(
     rewriteStructuralTypesToNamedSubclass: Boolean = true,
     @Description("If true, adds result types only to implicit definitions.")
     onlyImplicits: Boolean = false,
+    @Description(
+      "If true and the Scalafix minor Scala 3 version differs from the target files," +
+        "attempts to resolve and download compiler artifacts dynamically via Coursier. " +
+        "Disabled by default as this introduces a performance overhead and might not work."
+    )
+    fetchScala3CompilerIfNeeded: Boolean = false,
     @Hidden()
     symbolReplacements: Map[String, String] = Map.empty
 )

diff --git a/...ix-tests/integration/src/test/scala-3/scalafix/tests/rules/ExplicitResultTypesSuite.scala b/...ix-tests/integration/src/test/scala-3/scalafix/tests/rules/ExplicitResultTypesSuite.scala
@@ -2,7 +2,9 @@ package scalafix.tests.rules
 
 import scala.meta.io.AbsolutePath
 
+import metaconfig.typesafeconfig._
 import metaconfig.Configured
+import metaconfig.Conf
 import org.scalatest.funsuite.AnyFunSuite
 import scalafix.internal.rule.ExplicitResultTypes
 import scalafix.v1.Configuration
@@ -34,4 +36,29 @@ class ExplicitResultTypesSuite extends AnyFunSuite {
     assert(rule.withConfiguration(earlyScala3) == Configured.error(expected))
   }
 
+  test("Other Scala 3 minor versions are not supported by default") {
+    val neitherLTSNorNext =
+      config.withScalaVersion("3.5.0")
+
+    val v = buildinfo.RulesBuildInfo.scalaVersion.split('.').take(2).mkString(".")
+
+    val expected =
+      s"The ExplicitResultTypes rule was compiled with a different Scala 3 minor ($v) than the target sources (3.5). " +
+        s"To fix this problem, either enable ExplicitResultTypes.fetchScala3CompilerIfNeeded in .scalafix.conf or check if Scalafix can be loaded with $v."
+
+    assert(
+      rule.withConfiguration(neitherLTSNorNext) == Configured.error(expected)
+    )
+  }
+
+  test("fetchScala3CompilerIfNeeded enables dynamic loading") {
+    val neitherLTSNorNext =
+      config.withScalaVersion("3.5.0")
+
+    val conf = Conf
+      .parseString("ExplicitResultTypes.fetchScala3CompilerIfNeeded = true")
+      .get
+    assert(rule.withConfiguration(neitherLTSNorNext.withConf(conf)).isOk)
+  }
+
 }