Clean up SourceFile creation and error handling

Author: som-snytt

compiler/src/dotty/tools/dotc/Run.scala

@@ -308,11 +308,8 @@ class Run(comp: Compiler, ictx: Context) extends ImplicitRunInfo with Constraint
     def sourceFile(source: String, isJava: Boolean): SourceFile = {
       val uuid = java.util.UUID.randomUUID().toString
       val ext = if (isJava) ".java" else ".scala"
-      val virtualFile = new VirtualFile(s"compileFromString-$uuid.$ext")
-      val writer = new BufferedWriter(new OutputStreamWriter(virtualFile.output, StandardCharsets.UTF_8.nn.name)) // buffering is still advised by javadoc
-      writer.write(source)
-      writer.close()
-      new SourceFile(virtualFile, Codec.UTF8)
+      val name = s"compileFromString-$uuid.$ext"
+      SourceFile.virtual(name, source)
     }
     val sources =
       scalaSources.map(sourceFile(_, isJava = false)) ++

compiler/src/dotty/tools/dotc/interactive/InteractiveDriver.scala

@@ -299,11 +299,8 @@ class InteractiveDriver(val settings: List[String]) extends Driver {
 
   private def toSource(uri: URI, sourceCode: String): SourceFile = {
     val path = Paths.get(uri)
-    val virtualFile = new VirtualFile(path.getFileName.toString, path.toString)
-    val writer = new BufferedWriter(new OutputStreamWriter(virtualFile.output, StandardCharsets.UTF_8.name))
-    writer.write(sourceCode)
-    writer.close()
-    new SourceFile(virtualFile, Codec.UTF8)
+    val name = path.getFileName.toString // path.toString, no API for path
+    SourceFile.virtual(name, sourceCode)
   }
 
   /**

compiler/src/dotty/tools/dotc/util/SourceFile.scala

@@ -13,9 +13,10 @@ import Chars._
 import scala.annotation.internal.sharable
 import scala.collection.mutable
 import scala.collection.mutable.ArrayBuffer
+import scala.util.chaining.given
 
-import java.io.IOException
 import java.nio.charset.StandardCharsets
+import java.nio.file.{FileSystemException, NoSuchFileException}
 import java.util.Optional
 import java.util.concurrent.atomic.AtomicInteger
 import java.util.regex.Pattern
@@ -71,15 +72,6 @@ class SourceFile(val file: AbstractFile, computeContent: => Array[Char]) extends
 
   def maybeIncomplete: Boolean = _maybeInComplete
 
-  def this(file: AbstractFile, codec: Codec) =
-    // It would be cleaner to check if the file exists instead of catching
-    // an exception, but it turns out that Files.exists is remarkably slow,
-    // at least on Java 8 (https://rules.sonarsource.com/java/tag/performance/RSPEC-3725),
-    // this is significant enough to show up in our benchmarks.
-    this(file,
-      try new String(file.toByteArray, codec.charSet).toCharArray
-      catch case _: java.nio.file.NoSuchFileException => Array[Char]())
-
   /** Tab increment; can be overridden */
   def tabInc: Int = 8
 
@@ -226,9 +218,8 @@ object SourceFile {
   implicit def fromContext(using Context): SourceFile = ctx.source
 
   def virtual(name: String, content: String, maybeIncomplete: Boolean = false) =
-    val src = new SourceFile(new VirtualFile(name, content.getBytes(StandardCharsets.UTF_8)), scala.io.Codec.UTF8)
-    src._maybeInComplete = maybeIncomplete
-    src
+    SourceFile(new VirtualFile(name, content.getBytes(StandardCharsets.UTF_8)), content.toCharArray)
+      .tap(_._maybeInComplete = maybeIncomplete)
 
   /** Returns the relative path of `source` within the `reference` path
    *
@@ -273,17 +264,20 @@ object SourceFile {
     ScriptSourceFile.hasScriptHeader(content)
 
   def apply(file: AbstractFile | Null, codec: Codec): SourceFile =
-    // see note above re: Files.exists is remarkably slow
+    // Files.exists is slow on Java 8 (https://rules.sonarsource.com/java/tag/performance/RSPEC-3725),
+    // so cope with failure; also deal with path prefix "Not a directory".
     val chars =
-    try
-      new String(file.toByteArray, codec.charSet).toCharArray
-    catch
-      case _: java.nio.file.NoSuchFileException => Array[Char]()
+      try new String(file.toByteArray, codec.charSet).toCharArray
+      catch
+        case _: NoSuchFileException => Array.empty[Char]
+        case fse: FileSystemException if fse.getMessage.endsWith("Not a directory") => Array.empty[Char]
 
     if isScript(file, chars) then
       ScriptSourceFile(file, chars)
     else
-      new SourceFile(file, chars)
+      SourceFile(file, chars)
+
+  def apply(file: AbstractFile | Null, computeContent: => Array[Char]): SourceFile = new SourceFile(file, computeContent)
 }
 
 @sharable object NoSource extends SourceFile(NoAbstractFile, Array[Char]()) {

scaladoc/src/dotty/tools/scaladoc/DocContext.scala

@@ -40,8 +40,7 @@ def throwableToString(t: Throwable)(using CompilerContext): String =
 
 private def sourcePostionFor(f: File)(using CompilerContext) =
     val relPath = relativePath(f.toPath)
-    val virtualFile = new VirtualFile(relPath.toString, relPath.toString)
-    val sourceFile = new SourceFile(virtualFile, Codec.UTF8)
+    val sourceFile = SourceFile.virtual(relPath.toString, content = "")
     SourcePosition(sourceFile, Spans.NoSpan)
 
 // TODO (https://github.com/lampepfl/scala3doc/issues/238): provide proper error handling