Port coverage filter options

- Add `-coverage-exclude-packages` option that excludes packages and classes
  from generating coverage
- Add `-coverage-exclude-files` option that excludes files from
  generating coverage

Author: KacperFKorban

compiler/src/dotty/tools/dotc/config/ScalaSettings.scala

@@ -127,6 +127,8 @@ trait CommonScalaSettings:
 
   /* Coverage settings */
   val coverageOutputDir = PathSetting("-coverage-out", "Destination for coverage classfiles and instrumentation data.", "", aliases = List("--coverage-out"))
+  val coverageExcludePackages: Setting[List[String]] = MultiStringSetting("-coverage-exclude-packages", "packages", "Semicolon separated list of regexes for packages to exclude from coverage.", aliases = List("--coverage-exclude-packages"))
+  val coverageExcludeFiles: Setting[List[String]] = MultiStringSetting("-coverage-exclude-files", "files", "Semicolon separated list of regexes for files to exclude from coverage.", aliases = List("--coverage-exclude-files"))
 
   /* Other settings */
   val encoding: Setting[String] = StringSetting("-encoding", "encoding", "Specify character encoding used by source files.", Properties.sourceEncoding, aliases = List("--encoding"))

compiler/src/dotty/tools/dotc/transform/InstrumentCoverage.scala

@@ -13,12 +13,14 @@ import core.Constants.Constant
 import core.NameOps.isContextFunction
 import core.StdNames.nme
 import core.Types.*
+import core.Decorators.*
 import coverage.*
 import typer.LiftCoverage
 import util.{SourcePosition, SourceFile}
 import util.Spans.Span
 import localopt.StringInterpolatorOpt
 import inlines.Inlines
+import scala.util.matching.Regex
 
 /** Implements code coverage by inserting calls to scala.runtime.coverage.Invoker
   * ("instruments" the source code).
@@ -58,6 +60,18 @@ class InstrumentCoverage extends MacroTransform with IdentityDenotTransformer:
 
     Serializer.serialize(coverage, outputPath, ctx.settings.sourceroot.value)
 
+  private def isClassIncluded(sym: Symbol)(using Context): Boolean =
+    val excludedClassNamePatterns = ctx.settings.coverageExcludePackages.value.map(_.r.pattern)
+    excludedClassNamePatterns.isEmpty || !excludedClassNamePatterns.exists(
+      _.matcher(sym.fullName.toText(ctx.printerFn(ctx)).show).nn.matches
+    )
+
+  private def isFileIncluded(file: SourceFile)(using Context): Boolean =
+    val excludedFilePatterns = ctx.settings.coverageExcludeFiles.value.map(_.r.pattern)
+    excludedFilePatterns.isEmpty || !excludedFilePatterns.exists(
+      _.matcher(file.path.replace(".scala", "")).nn.matches
+    )
+
   override protected def newTransformer(using Context) =
     CoverageTransformer(ctx.settings.coverageOutputDir.value)
 
@@ -269,8 +283,17 @@ class InstrumentCoverage extends MacroTransform with IdentityDenotTransformer:
             transformDefDef(tree)
 
           case tree: PackageDef =>
-            // only transform the statements of the package
-            cpy.PackageDef(tree)(tree.pid, transform(tree.stats))
+            if (isFileIncluded(tree.srcPos.sourcePos.source) && isClassIncluded(tree.symbol))
+              // only transform the statements of the package
+              cpy.PackageDef(tree)(tree.pid, transform(tree.stats))
+            else
+              tree
+
+          case tree: TypeDef =>
+            if (isFileIncluded(tree.srcPos.sourcePos.source) && isClassIncluded(tree.symbol))
+              super.transform(tree)
+            else
+              tree
 
           case tree: Assign =>
             // only transform the rhs