Merge pull request #3645 from retronym/ticket/8430

SI-8430 Less non-determinism in patmat exhautiveness warnings

3 files changed, 60 insertions, 0 deletions

diff --git a/test/files/neg/t8430.check b/test/files/neg/t8430.check
new file mode 100644
index 0000000000..7c6a73ce53
--- /dev/null
+++ b/test/files/neg/t8430.check
@@ -0,0 +1,27 @@
+t8430.scala:15: warning: match may not be exhaustive.
+It would fail on the following inputs: ??, LetC, LetF, LetL(IntLit), LetP
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+                  ^
+t8430.scala:16: warning: match may not be exhaustive.
+It would fail on the following inputs: ??, LetC, LetF, LetL(IntLit), LetP
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+                  ^
+t8430.scala:17: warning: match may not be exhaustive.
+It would fail on the following inputs: ??, LetC, LetF, LetL(IntLit), LetP
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+                  ^
+t8430.scala:18: warning: match may not be exhaustive.
+It would fail on the following inputs: ??, LetC, LetF, LetL(IntLit), LetP
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+                  ^
+t8430.scala:19: warning: match may not be exhaustive.
+It would fail on the following inputs: ??, LetC, LetF, LetL(IntLit), LetP
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+                  ^
+t8430.scala:20: warning: match may not be exhaustive.
+It would fail on the following inputs: ??, LetC, LetF, LetL(IntLit), LetP
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+                  ^
+error: No warnings can be incurred under -Xfatal-warnings.
+6 warnings found
+one error found
diff --git a/test/files/neg/t8430.flags b/test/files/neg/t8430.flags
new file mode 100644
index 0000000000..85d8eb2ba2
--- /dev/null
+++ b/test/files/neg/t8430.flags
@@ -0,0 +1 @@
+-Xfatal-warnings
diff --git a/test/files/neg/t8430.scala b/test/files/neg/t8430.scala
new file mode 100644
index 0000000000..4166b08a0a
--- /dev/null
+++ b/test/files/neg/t8430.scala
@@ -0,0 +1,32 @@
+sealed trait CL3Literal
+case object IntLit extends CL3Literal
+case object CharLit extends CL3Literal
+case object BooleanLit extends CL3Literal
+case object UnitLit extends CL3Literal
+ 
+ 
+sealed trait Tree
+case class LetL(value: CL3Literal) extends Tree
+case object LetP extends Tree
+case object LetC extends Tree
+case object LetF extends Tree
+ 
+object Test {
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+  (tree: Tree) => tree match {case LetL(CharLit) => ??? }
+  // After the first patch for SI-8430, we achieve stability: all of 
+  // these get the same warning:
+  //
+  // ??, LetC, LetF, LetL(IntLit), LetP
+  //
+  // Before, it was non-deterministic.
+  //
+  // However, we our list of counter examples is itself non-exhaustive.
+  // We need to rework counter example generation to fix that.
+  //
+  // That work is the subject of SI-7746
+}