Add -Ydebug-macros option

Author: zeptometer

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

@@ -399,4 +399,6 @@ 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

@@ -105,9 +105,6 @@ import dotty.tools.dotc.util.optional
 object QuoteMatcher {
   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.
    */
@@ -466,7 +463,7 @@ object QuoteMatcher {
               notMatched
       end runMatch
 
-      if (debug)
+      if (ctx.settings.YdebugMacros.value)
         try {
           runMatch()
         } catch {