Introduce a new compiler option -Ydebug-macros

This compiler option shows debug information when quote pattern matching fails.
This commmit also fix a bug of current imiplementation of debug print

[Cherry-picked be0c98a]

Author: zeptometer

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

@@ -398,5 +398,7 @@ private sealed trait YSettings:
   val YinstrumentDefs: Setting[Boolean] = BooleanSetting("-Yinstrument-defs", "Add instrumentation code that counts method calls; needs -Yinstrument to be set, too.")
 
   val YforceInlineWhileTyping: Setting[Boolean] = BooleanSetting("-Yforce-inline-while-typing", "Make non-transparent inline methods inline when typing. Emulates the old inlining behavior of 3.0.0-M3.")
+
+  val YdebugMacros: Setting[Boolean] = BooleanSetting("-Ydebug-macros", "Show debug info when quote pattern match fails")
 end YSettings
 

compiler/src/scala/quoted/runtime/impl/QuoteMatcher.scala

@@ -102,12 +102,9 @@ import dotty.tools.dotc.util.optional
  *
  *   ```
  */
-object QuoteMatcher {
+class QuoteMatcher(debug: Boolean) {
   import tpd.*
 
-  // TODO use flag from Context. Maybe -debug or add -debug-macros
-  private inline val debug = false
-
   /** Sequence of matched expressions.
    *  These expressions are part of the scrutinee and will be bound to the quote pattern term splices.
    */
@@ -134,7 +131,6 @@ object QuoteMatcher {
         given Env = Map.empty
         scrutinee =?= pat1
       }.map { matchings =>
-        import QuoteMatcher.MatchResult.*
         lazy val spliceScope = SpliceScope.getCurrent
         // After matching and doing all subtype checks, we have to approximate all the type bindings
         // that we have found, seal them in a quoted.Type and add them to the result
@@ -234,7 +230,7 @@ object QuoteMatcher {
           case _ => None
       end TypeTreeTypeTest
 
-      val res = pattern match
+      def runMatch(): optional[MatchingExprs] = pattern match
 
         /* Term hole */
         // Match a scala.internal.Quoted.patternHole typed as a repeated argument and return the scrutinee tree
@@ -426,24 +422,32 @@ object QuoteMatcher {
             // No Match
             case _ =>
               notMatched
+      end runMatch
+
+      if debug then
+        try {
+          runMatch()
+        } catch {
+          case e: util.boundary.Break[?] =>
+            val quotes = QuotesImpl()
+            println(
+              s""">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
+                  |Scrutinee
+                  |  ${scrutinee.show}
+                  |did not match pattern
+                  |  ${pattern.show}
+                  |
+                  |with environment: ${summon[Env]}
+                  |
+                  |Scrutinee: ${quotes.reflect.Printer.TreeStructure.show(scrutinee.asInstanceOf)}
+                  |Pattern: ${quotes.reflect.Printer.TreeStructure.show(pattern.asInstanceOf)}
+                  |
+                  |""".stripMargin)
+            throw e
+        }
+      else
+        runMatch()
 
-      if (debug && res == notMatched)
-        val quotes = QuotesImpl()
-        println(
-          s""">>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
-              |Scrutinee
-              |  ${scrutinee.show}
-              |did not match pattern
-              |  ${pattern.show}
-              |
-              |with environment: ${summon[Env]}
-              |
-              |Scrutinee: ${quotes.reflect.Printer.TreeStructure.show(scrutinee.asInstanceOf)}
-              |Pattern: ${quotes.reflect.Printer.TreeStructure.show(pattern.asInstanceOf)}
-              |
-              |""".stripMargin)
-
-      res
     end =?=
 
   end extension

compiler/src/scala/quoted/runtime/impl/QuotesImpl.scala

@@ -39,13 +39,14 @@ object QuotesImpl {
 class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler, QuoteMatching:
 
   private val xCheckMacro: Boolean = ctx.settings.XcheckMacros.value
+  private val yDebugMacro: Boolean = ctx.settings.YdebugMacros.value
 
   extension [T](self: scala.quoted.Expr[T])
     def show: String =
       reflect.Printer.TreeCode.show(reflect.asTerm(self))
 
     def matches(that: scala.quoted.Expr[Any]): Boolean =
-      QuoteMatcher.treeMatch(reflect.asTerm(self), reflect.asTerm(that)).nonEmpty
+      QuoteMatcher(yDebugMacro).treeMatch(reflect.asTerm(self), reflect.asTerm(that)).nonEmpty
 
     def valueOrAbort(using fromExpr: FromExpr[T]): T =
       def reportError =
@@ -3155,14 +3156,14 @@ class QuotesImpl private (using val ctx: Context) extends Quotes, QuoteUnpickler
     def unapply[TypeBindings, Tup <: Tuple](scrutinee: scala.quoted.Expr[Any])(using pattern: scala.quoted.Expr[Any]): Option[Tup] =
       val scrutineeTree = reflect.asTerm(scrutinee)
       val patternTree = reflect.asTerm(pattern)
-      QuoteMatcher.treeMatch(scrutineeTree, patternTree).asInstanceOf[Option[Tup]]
+      QuoteMatcher(yDebugMacro).treeMatch(scrutineeTree, patternTree).asInstanceOf[Option[Tup]]
   end ExprMatch
 
   object TypeMatch extends TypeMatchModule:
     def unapply[TypeBindings, Tup <: Tuple](scrutinee: scala.quoted.Type[?])(using pattern: scala.quoted.Type[?]): Option[Tup] =
       val scrutineeTree = reflect.TypeTree.of(using scrutinee)
       val patternTree = reflect.TypeTree.of(using pattern)
-      QuoteMatcher.treeMatch(scrutineeTree, patternTree).asInstanceOf[Option[Tup]]
+      QuoteMatcher(yDebugMacro).treeMatch(scrutineeTree, patternTree).asInstanceOf[Option[Tup]]
   end TypeMatch
 
 end QuotesImpl