From 2db2c11bc9371857e29453626926b45c4d644718 Mon Sep 17 00:00:00 2001
From: Nicolas Stucki <nicolas.stucki@gmail.com>
Date: Wed, 7 Jun 2023 15:20:52 +0200
Subject: [PATCH] Make quote pattern type variable order deterministic

This changes the order in which the type variables are listed in the
encoded quote pattern. The order of the variables is the same as the
order as they appear in the source.
---
 .../tools/dotc/typer/QuotesAndSplices.scala   | 22 ++++++++++++-------
 1 file changed, 14 insertions(+), 8 deletions(-)

diff --git a/compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala b/compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala
index 070449e3ee96..56a36155dd0a 100644
--- a/compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala
+++ b/compiler/src/dotty/tools/dotc/typer/QuotesAndSplices.scala
@@ -199,10 +199,10 @@ trait QuotesAndSplices {
    *  )
    *  ```
    */
-  private def splitQuotePattern(quoted: Tree)(using Context): (Map[Symbol, Bind], Tree, List[Tree]) = {
+  private def splitQuotePattern(quoted: Tree)(using Context): (collection.Map[Symbol, Bind], Tree, List[Tree]) = {
     val ctx0 = ctx
 
-    val typeBindings: collection.mutable.Map[Symbol, Bind] = collection.mutable.Map.empty
+    val typeBindings: mutable.Map[Symbol, Bind] = mutable.LinkedHashMap.empty
     def getBinding(sym: Symbol): Bind =
       typeBindings.getOrElseUpdate(sym, {
         val bindingBounds = sym.info
@@ -296,13 +296,19 @@ trait QuotesAndSplices {
       }
     }
     val shape0 = splitter.transform(quoted)
-    val patterns = (splitter.freshTypePatBuf.iterator ++ splitter.typePatBuf.iterator ++ splitter.patBuf.iterator).toList
+    val patterns = (splitter.typePatBuf.iterator ++ splitter.freshTypePatBuf.iterator ++ splitter.patBuf.iterator).toList
     val freshTypeBindings = splitter.freshTypeBindingsBuff.result()
 
-    val shape1 = seq(
-      freshTypeBindings,
-      shape0
-    )
+    val shape1 = shape0 match
+      case Block(stats @ ((tdef: TypeDef) :: rest), expr) if tdef.symbol.hasAnnotation(defn.QuotedRuntimePatterns_patternTypeAnnot) =>
+        val (bindings, otherStats) = stats.span {
+          case tdef: TypeDef => tdef.symbol.hasAnnotation(defn.QuotedRuntimePatterns_patternTypeAnnot)
+          case _ => true
+        }
+        cpy.Block(shape0)(bindings ::: freshTypeBindings ::: otherStats, expr)
+      case _ =>
+        seq(freshTypeBindings, shape0)
+
     val shape2 =
       if (freshTypeBindings.isEmpty) shape1
       else {
@@ -319,7 +325,7 @@ trait QuotesAndSplices {
         new TreeTypeMap(typeMap = typeMap).transform(shape1)
       }
 
-    (typeBindings.toMap, shape2, patterns)
+    (typeBindings, shape2, patterns)
   }
 
   /** Type a quote pattern `case '{ <quoted> } =>` qiven the a current prototype. Typing the pattern