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Scala compiler plugin for annotation-based warning suppression
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package com.github.ghik.silencer
import java.util.regex.PatternSyntaxException
import scala.collection.mutable
import scala.collection.mutable.ListBuffer
import scala.reflect.internal.util.Position
import scala.reflect.io.AbstractFile
import scala.tools.nsc.plugins.{Plugin, PluginComponent}
import scala.tools.nsc.{Global, Phase, Properties}
import scala.util.matching.Regex
class SilencerPlugin(val global: Global) extends Plugin with SilencerPluginCompat { plugin =>
import global._
val name = "silencer"
val description = "Scala compiler plugin for warning suppression"
val components: List[PluginComponent] = List(extractSuppressions, checkUnusedSuppressions)
private final val InitDefault1 = TermName("$default$1").encodedName
private val scala211: Boolean = Properties.versionNumberString.startsWith("2.11")
private val globalFilters = ListBuffer.empty[Regex]
private val lineContentFilters = ListBuffer.empty[Regex]
private val pathFilters = ListBuffer.empty[Regex]
private val sourceRoots = ListBuffer.empty[AbstractFile]
private var checkUnused = false
private var searchMacroExpansions = false
private lazy val reporter = new SuppressingReporter(global.reporter,
globalFilters.result(), lineContentFilters.result(), pathFilters.result(), sourceRoots.result())
private def split(s: String): Iterator[String] = s.split(';').iterator
override def processOptions(options: List[String], error: String => Unit): Unit = {
options.foreach(_.split("=", 2) match {
case Array("globalFilters", pattern) =>
globalFilters ++= split(pattern).map(_.r)
case Array("lineContentFilters", pattern) =>
lineContentFilters ++= split(pattern).map(_.r)
case Array("pathFilters", pattern) =>
pathFilters ++= split(pattern).map(_.r)
case Array("sourceRoots", rootPaths) =>
sourceRoots ++= split(rootPaths).flatMap { path =>
val res = Option(AbstractFile.getDirectory(path))
if (res.isEmpty) {
reporter.warning(NoPosition, s"Invalid source root: $path is not a directory")
}
res
}
case Array("checkUnused") =>
checkUnused = true
case Array("searchMacroExpansions") =>
searchMacroExpansions = true
case _ =>
})
global.reporter = reporter
}
override val optionsHelp: Option[String] = Some(
""" -P:silencer:globalFilters=... Semicolon separated regexes for filtering warning messages globally
| -P:silencer:pathFilters=... Semicolon separated regexes for filtering source paths
| -P:silencer:sourceRoots=... Semicolon separated paths of source root directories to relativize path filters
| -P:silencer:checkUnused Enables reporting of unused @silent annotations
""".stripMargin)
private object extractSuppressions extends PluginComponent {
val global: plugin.global.type = plugin.global
val runsAfter = List("typer")
override val runsBefore = List("patmat")
val phaseName = "silencer"
override def description: String = "inspect @silent annotations for warning suppression"
private lazy val silentSym =
try rootMirror.staticClass("com.github.ghik.silencer.silent") catch {
case _: ScalaReflectionException => NoSymbol
}
private lazy val compatNowarnSym =
if (!scala211) NoSymbol // leave @nowarn to be processed by scalac
else try rootMirror.staticClass("scala.annotation.nowarn") catch {
case _: ScalaReflectionException => NoSymbol
}
private lazy val checkAnnotation: Unit = {
if (silentSym == NoSymbol && compatNowarnSym == NoSymbol && globalFilters.isEmpty && pathFilters.isEmpty) {
plugin.reporter.warning(NoPosition,
"`silencer-plugin` was enabled but @silent annotation was not found on classpath" +
" - have you added `silencer-lib` as a library dependency?"
)
}
}
def newPhase(prev: Phase): StdPhase = new StdPhase(prev) {
override def run(): Unit = { checkAnnotation: Unit; super.run() }
def apply(unit: CompilationUnit): Unit = applySuppressions(unit)
}
def applySuppressions(unit: CompilationUnit): Unit = {
val suppressions = if (silentSym == NoSymbol && compatNowarnSym == NoSymbol) Nil else {
def mkSuppression(tree: Tree, annot: Tree, annotPos: Position, inMacroExpansion: Boolean): Suppression = {
val annotSym = annot.tpe.typeSymbol
val range = treeRangePos(tree)
val msgPattern = annot match {
case Apply(_, Nil) => None
case Apply(_, List(MaybeNamedArg(Literal(Constant(arg: String))))) =>
// partial support for Scala 2.13.2 @nowarn annotation
// only interpreting the 'msg' filter, other filters simply suppress everything
val regexOpt =
if (annotSym == compatNowarnSym)
arg.split("&").iterator.filter(_.startsWith("msg=")).map(_.substring(4)).toList.headOption
else
Some(arg)
regexOpt.flatMap { regex =>
try Some(regex.r) catch {
case pse: PatternSyntaxException =>
reporter.error(annotPos, s"invalid message pattern $regex in @${annotSym.nameString} annotation: ${pse.getMessage}")
None
}
}
case Apply(_, List(Select(pref, InitDefault1)))
if annotSym == compatNowarnSym && pref.symbol == compatNowarnSym.companion =>
None
case _ =>
reporter.error(annotPos, s"expected literal string as @${annotSym.nameString} annotation argument")
None
}
new Suppression(annotPos, range, msgPattern, inMacroExpansion)
}
def treeRangePos(tree: Tree): Position = {
// compute approximate range
var start = unit.source.length
var end = 0
tree.foreach { child =>
val pos = child.pos
if (pos.isDefined) {
start = start min pos.start
end = end max pos.end
}
}
end = end max start
Position.range(unit.source, start, start, end)
}
val suppressionsBuf = new ListBuffer[Suppression]
object FindSuppressions extends Traverser {
private val suppressionPositionsVisited = new mutable.HashSet[Int]
private var inMacroExpansion: Boolean = false
private def addSuppression(tree: Tree, annot: Tree, annotPos: Position): Unit = {
if (annot.tpe eq null) return // issue #56
val actualAnnotPos = if (annotPos != NoPosition) annotPos else tree.pos
val annotSym = annot.tpe.typeSymbol
if (annotSym != NoSymbol && (annotSym == silentSym || annotSym == compatNowarnSym) &&
suppressionPositionsVisited.add(actualAnnotPos.point)
) {
suppressionsBuf += mkSuppression(tree, annot, actualAnnotPos, inMacroExpansion)
}
}
override def traverse(t: Tree): Unit = {
val expandee = analyzer.macroExpandee(t)
val macroExpansion = expandee != EmptyTree && expandee != t
if (macroExpansion) {
traverse(expandee)
}
if (!macroExpansion || searchMacroExpansions) {
val wasInMacroExpansion = inMacroExpansion
inMacroExpansion = inMacroExpansion || macroExpansion
//NOTE: it's important to first traverse the children so that nested suppression ranges come before
//containing suppression ranges
super.traverse(t)
t match {
case Annotated(annot, arg) =>
addSuppression(arg, annot, annot.pos)
case typed@Typed(_, tpt) if tpt.tpe != null =>
tpt.tpe.annotations.foreach(ai => addSuppression(typed, ai.tree, ai.pos))
case md: MemberDef =>
val annots = md.symbol.annotations
// search for @silent annotations in trees of other annotations
// you would expect that super.traverse should do that but it doesn't because apparently
// at typer phase annotations are no longer available in the tree itself and must be fetched from symbol
annots.foreach(ai => traverse(ai.tree))
annots.foreach(ai => addSuppression(md, ai.tree, ai.pos))
case _ =>
}
inMacroExpansion = wasInMacroExpansion
}
}
}
FindSuppressions.traverse(unit.body)
suppressionsBuf.toList
}
plugin.reporter.setSuppressions(unit.source, suppressions)
}
}
private object checkUnusedSuppressions extends PluginComponent {
val global: plugin.global.type = plugin.global
val runsAfter = List("jvm")
override val runsBefore = List("terminal")
val phaseName = "silencerCheckUnused"
override def description: String = "report unused @silent/@nowarn annotations"
def newPhase(prev: Phase): StdPhase = new StdPhase(prev) {
def apply(unit: CompilationUnit): Unit =
if (checkUnused) {
reporter.checkUnused(unit.source)
}
}
}
}