Never set a default for sourcePositionMappers

build.sbt

@@ -1033,6 +1033,8 @@ lazy val mainProj = (project in file("main"))
       // internal impl
       exclude[IncompatibleSignatureProblem]("sbt.internal.Act.configIdent"),
       exclude[IncompatibleSignatureProblem]("sbt.internal.Act.taskAxis"),
+      // private[sbt] method, used to call the correct sourcePositionMapper
+      exclude[DirectMissingMethodProblem]("sbt.Defaults.foldMappers"),
     )
   )
   .configure(

main/src/main/scala/sbt/Defaults.scala

@@ -422,12 +422,7 @@ object Defaults extends BuildCommon {
       )
     },
     fileConverter := MappedFileConverter(rootPaths.value, allowMachinePath.value),
-    sourcePositionMappers ++= {
-      val fc = fileConverter.value
-      if (reportAbsolutePath.value) {
-        List(toAbsoluteSourceMapper(fc) _)
-      } else Nil
-    },
+    sourcePositionMappers := Nil, // Never set a default sourcePositionMapper, see #6352! Whatever you are trying to solve, do it in the foldMappers method.
     // The virtual file value cache needs to be global or sbt will run out of direct byte buffer memory.
     classpathDefinesClassCache := VirtualFileValueCache.definesClassCache(fileConverter.value),
     fullServerHandlers := {
@@ -474,7 +469,7 @@ object Defaults extends BuildCommon {
     },
   )
 
-  private[sbt] def toAbsoluteSourceMapper(fc: FileConverter)(pos: Position): Option[Position] = {
+  private[sbt] def toAbsoluteSource(fc: FileConverter)(pos: Position): Position = {
     def isValid(path: String): Boolean = {
       Try(Paths.get(path)).map(_ => true).getOrElse(false)
     }
@@ -503,9 +498,21 @@ object Defaults extends BuildCommon {
           override def sourcePath(): Optional[String] = Optional.of(path)
 
           override def sourceFile(): Optional[File] = pos.sourceFile()
+
+          override def startOffset(): Optional[Integer] = pos.startOffset()
+
+          override def endOffset(): Optional[Integer] = pos.endOffset()
+
+          override def startLine(): Optional[Integer] = pos.startLine()
+
+          override def startColumn(): Optional[Integer] = pos.startColumn()
+
+          override def endLine(): Optional[Integer] = pos.endLine()
+
+          override def endColumn(): Optional[Integer] = pos.endColumn()
         }
       }
-      .orElse(Some(pos))
+      .getOrElse(pos)
   }
 
   // csrCacheDirectory is scoped to ThisBuild to allow customization.
@@ -2365,7 +2372,9 @@ object Defaults extends BuildCommon {
           scalacOptions.value.toArray,
           javacOptions.value.toArray,
           maxErrors.value,
-          f1(foldMappers(sourcePositionMappers.value)),
+          f1(
+            foldMappers(sourcePositionMappers.value, reportAbsolutePath.value, fileConverter.value)
+          ),
           compileOrder.value,
           None.toOptional: Optional[NioPath],
           Some(fileConverter.value).toOptional,
@@ -2377,7 +2386,7 @@ object Defaults extends BuildCommon {
         new ManagedLoggedReporter(
           maxErrors.value,
           streams.value.log,
-          foldMappers(sourcePositionMappers.value)
+          foldMappers(sourcePositionMappers.value, reportAbsolutePath.value, fileConverter.value)
         )
       },
       compileInputs := {
@@ -2394,15 +2403,25 @@ object Defaults extends BuildCommon {
     )
   }
 
-  private[sbt] def foldMappers[A](mappers: Seq[A => Option[A]]) =
-    mappers.foldRight({ p: A =>
-      p
+  private[sbt] def foldMappers(
+      mappers: Seq[Position => Option[Position]],
+      reportAbsolutePath: Boolean,
+      fc: FileConverter
+  ) = {
+    def withAbsoluteSource(p: Position): Position =
+      if (reportAbsolutePath) toAbsoluteSource(fc)(p) else p
+
+    mappers.foldRight({ p: Position =>
+      withAbsoluteSource(p) // Fallback if sourcePositionMappers is empty
     }) {
-      (mapper, mappers) =>
-        { p: A =>
-          mapper(p).getOrElse(mappers(p))
+      (mapper, previousPosition) =>
+        { p: Position =>
+          // To each mapper we pass the position with the absolute source (only if reportAbsolutePath = true of course)
+          mapper(withAbsoluteSource(p)).getOrElse(previousPosition(p))
         }
     }
+  }
+
   private[sbt] def none[A]: Option[A] = (None: Option[A])
   private[sbt] def jnone[A]: Optional[A] = none[A].toOptional
   def compileAnalysisSettings: Seq[Setting[_]] = Seq(
@@ -2429,7 +2448,11 @@ object Defaults extends BuildCommon {
       val problems =
         analysis.infos.allInfos.values
           .flatMap(i => i.getReportedProblems ++ i.getUnreportedProblems)
-      val reporter = new ManagedLoggedReporter(max, streams.value.log, foldMappers(spms))
+      val reporter = new ManagedLoggedReporter(
+        max,
+        streams.value.log,
+        foldMappers(spms, reportAbsolutePath.value, fileConverter.value)
+      )
       problems.foreach(p => reporter.log(p))
     }
 

sbt/src/sbt-test/reporter/source-mapper/build.sbt

@@ -1,46 +1,41 @@
-import java.util.Optional
-import xsbti.Position
+import sbt.internal.util.ConsoleAppender
+
+extraAppenders := { s => Seq(ConsoleAppender(FakePrintWriter)) }
+
+val assertEmptySourcePositionMappers = taskKey[Unit]("checks that sourcePositionMappers is empty")
 
 val assertAbsolutePathConversion = taskKey[Unit]("checks source mappers convert to absolute path")
 
-val assertHandleFakePos = taskKey[Unit]("checks source mappers handle fake position")
+val assertVirtualFile = taskKey[Unit]("checks source mappers handle virtual files")
+
+val resetMessages = taskKey[Unit]("empties the messages list")
+
+assertEmptySourcePositionMappers := {
+  assert {
+    sourcePositionMappers.value.isEmpty
+  }
+}
 
 assertAbsolutePathConversion := {
-  val converter = fileConverter.value
   val source = (Compile/sources).value.head
-  val position = newPosition(converter.toVirtualFile(source.toPath).id, source)
-  val mappedPos = sourcePositionMappers.value
-    .foldLeft(Option(position)) {
-      case (pos, mapper) => pos.flatMap(mapper)
-    }
   assert {
-    mappedPos.get.sourcePath.asScala.contains(source.getAbsolutePath)
+    FakePrintWriter.messages.exists(_.contains(s"${source.getAbsolutePath}:3:15: comparing values of types Int and String using `==` will always yield false"))
+  }
+  assert {
+    FakePrintWriter.messages.forall(!_.contains("${BASE}"))
   }
 }
 
-assertHandleFakePos := {
-  val position = newPosition("<macro>", new File("<macro>"))
-  val mappedPos = sourcePositionMappers.value
-    .foldLeft(Option(position)) {
-      case (pos, mapper) => pos.flatMap(mapper)
-    }
+assertVirtualFile := {
+  val source = (Compile/sources).value.head
   assert {
-    mappedPos.get.sourcePath.asScala.get.contains("<macro>")
+    FakePrintWriter.messages.exists(_.contains("${BASE}/src/main/scala/Foo.scala:3:15: comparing values of types Int and String using `==` will always yield false"))
+  }
+  assert {
+    FakePrintWriter.messages.forall(!_.contains(source.getAbsolutePath))
   }
 }
 
-def newPosition(path: String, file: File): Position = new Position {
-  override def line(): Optional[Integer] = Optional.empty()
-
-  override def lineContent() = ""
-
-  override def offset(): Optional[Integer] = Optional.empty()
-
-  override def pointer(): Optional[Integer] = Optional.empty()
-
-  override def pointerSpace(): Optional[String] = Optional.empty()
-
-  override def sourcePath(): Optional[String] = Optional.of(path)
-
-  override def sourceFile(): Optional[File] = Optional.of(file)
-}
+resetMessages := {
+  FakePrintWriter.resetMessages
+}

sbt/src/sbt-test/reporter/source-mapper/project/FakePrintWriter.scala

@@ -0,0 +1,6 @@
+object FakePrintWriter extends java.io.PrintWriter("fake-print-writer") {
+  @volatile var messages = List.empty[String]
+  def resetMessages = messages = List.empty[String]
+  override def println(x: String): Unit = messages = x :: messages
+  override def print(x: String): Unit = messages = x :: messages
+}

sbt/src/sbt-test/reporter/source-mapper/src/main/scala/Foo.scala

@@ -0,0 +1,4 @@
+object Foo {
+  // Will cause a warning
+  val bar = 1 == ""
+}

sbt/src/sbt-test/reporter/source-mapper/test

@@ -1,2 +1,12 @@
+> assertEmptySourcePositionMappers
+
+> printWarnings
 > assertAbsolutePathConversion
-> assertHandleFakePos
+
+> resetMessages
+
+> set reportAbsolutePath := false
+> printWarnings
+> assertVirtualFile
+
+> resetMessages