Fix #4006: Avoid ambiguity between SHAREDterm cases and finally

Author: nicolasstucki

compiler/src/dotty/tools/dotc/core/tasty/TastyFormat.scala

@@ -90,6 +90,7 @@ Standard-Section: "ASTs" TopLevelStat*
                   IF             Length cond_Term then_Term else_Term
                   MATCH          Length sel_Term CaseDef*
                   TRY            Length expr_Term CaseDef* finalizer_Term?
+                  FINALLY               Term
                   RETURN         Length meth_ASTRef expr_Term?
                   REPEATED       Length elem_Type elem_Term*
                   SELECTouter    Length levels_Nat qual_Term underlying_Type
@@ -226,7 +227,7 @@ Standard Section: "Positions" Assoc*
 object TastyFormat {
 
   final val header = Array(0x5C, 0xA1, 0xAB, 0x1F)
-  val MajorVersion = 4
+  val MajorVersion = 5
   val MinorVersion = 0
 
   /** Tags used to serialize names */
@@ -400,6 +401,7 @@ object TastyFormat {
   final val ANNOTATION = 173
   final val TERMREFin = 174
   final val TYPEREFin = 175
+  final val FINALLY = 176
   final val HOLE = 255
 
   final val firstSimpleTreeTag = UNITconst

compiler/src/dotty/tools/dotc/core/tasty/TreePickler.scala

@@ -423,7 +423,11 @@ class TreePickler(pickler: TastyPickler) {
           withLength { pickleSymRef(from.symbol); pickleTreeUnlessEmpty(expr) }
         case Try(block, cases, finalizer) =>
           writeByte(TRY)
-          withLength { pickleTree(block); cases.foreach(pickleTree); pickleTreeUnlessEmpty(finalizer) }
+          withLength {
+            pickleTree(block)
+            cases.foreach(pickleTree)
+            if (!finalizer.isEmpty) writeByte(FINALLY); pickleTreeUnlessEmpty(finalizer)
+          }
         case SeqLiteral(elems, elemtpt) =>
           writeByte(REPEATED)
           withLength { pickleTree(elemtpt); elems.foreach(pickleTree) }

compiler/src/dotty/tools/dotc/core/tasty/TreeUnpickler.scala

@@ -1021,7 +1021,10 @@ class TreeUnpickler(reader: TastyReader,
               val expr = ifBefore(end)(readTerm(), EmptyTree)
               Return(expr, Ident(from.termRef))
             case TRY =>
-              Try(readTerm(), readCases(end), ifBefore(end)(readTerm(), EmptyTree))
+              val block = readTerm()
+              val cases = readCases(end)
+              val finalizer = ifBefore(end)({ assert(readByte() == FINALLY); readTerm() }, EmptyTree)
+              Try(block, cases, finalizer)
             case SELECTouter =>
               val levels = readNat()
               readTerm().outerSelect(levels, SkolemType(readType()))

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

@@ -58,6 +58,7 @@ class CompilationTests extends ParallelTesting {
     compileFile("tests/pos-special/i3323.scala", defaultOptions.and("-Xfatal-warnings")) +
     compileFile("tests/pos-special/i3323b.scala", defaultOptions.and("-Xfatal-warnings")) +
     compileFile("tests/pos-special/i3589-b.scala", defaultOptions.and("-Xfatal-warnings")) +
+    compileFile("tests/pos-special/i4006.scala", defaultOptions.and("-Ytest-pickler")) +
     compileFile("tests/pos-special/completeFromSource/Test.scala", defaultOptions.and("-sourcepath", "tests/pos-special")) +
     compileFile("tests/pos-special/completeFromSource/Test2.scala", defaultOptions.and("-sourcepath", "tests/pos-special")) +
     compileFile("tests/pos-special/completeFromSource/Test3.scala", defaultOptions.and("-sourcepath", "tests/pos-special", "-scansource")) +

tests/pos-special/i4006.scala

@@ -0,0 +1,4 @@
+class Foo {
+  inline def foo: Int = try { 1 } finally println("Hello")
+  foo
+}