Fix #9632: Don't use inDefScopeBraces for staged blocks

inDefScopeBraces blocks can be rewritten, but that would give
illegal code for staged blocks.

Author: odersky

compiler/src/dotty/tools/dotc/parsing/Parsers.scala

@@ -1566,7 +1566,10 @@ object Parsers {
       else t
 
     /** The block in a quote or splice */
-    def stagedBlock() = inDefScopeBraces(block(simplify = true))
+    def stagedBlock() =
+      val saved = lastStatOffset
+      try inBraces(block(simplify = true))
+      finally lastStatOffset = saved
 
     /** SimpleEpxr  ::=  spliceId | ‘$’ ‘{’ Block ‘}’)
      *  SimpleType  ::=  spliceId | ‘$’ ‘{’ Block ‘}’)

compiler/test/dotty/tools/dotc/CompilationTests.scala

@@ -66,7 +66,8 @@ class CompilationTests {
 
     aggregateTests(
       compileFile("tests/rewrites/rewrites.scala", scala2CompatMode.and("-rewrite", "-indent")),
-      compileFile("tests/rewrites/i8982.scala", defaultOptions.and("-indent", "-rewrite"))
+      compileFile("tests/rewrites/i8982.scala", defaultOptions.and("-indent", "-rewrite")),
+      compileFile("tests/rewrites/i9632.scala", defaultOptions.and("-indent", "-rewrite"))
     ).checkRewrites()
   }
 

tests/rewrites/i9632.scala

@@ -0,0 +1,7 @@
+def f(using scala.quoted.QuoteContext) =
+    '{
+        val x = ${
+          ???
+        }
+        x
+     }