Merge pull request #3559 from adriaanm/t1503

SI-1503 don't assume unsound type for ident/literal patterns

7 files changed, 56 insertions, 0 deletions

diff --git a/test/files/neg/t1503.check b/test/files/neg/t1503.check
new file mode 100644
index 0000000000..7adeea20f3
--- /dev/null
+++ b/test/files/neg/t1503.check
@@ -0,0 +1,8 @@
+t1503.scala:7: warning: The value matched by Whatever is bound to n, which may be used under the
+unsound assumption that it has type Whatever.type, whereas we can only safely
+count on it having type Any, as the pattern is matched using `==` (see SI-1503).
+  def matchWhateverCCE(x: Any) = x match { case n @ Whatever => n }
+                                                    ^
+error: No warnings can be incurred under -Xfatal-warnings.
+one warning found
+one error found
diff --git a/test/files/neg/t1503.flags b/test/files/neg/t1503.flags
new file mode 100644
index 0000000000..e93641e931
--- /dev/null
+++ b/test/files/neg/t1503.flags
@@ -0,0 +1 @@
+-Xlint -Xfatal-warnings
\ No newline at end of file
diff --git a/test/files/neg/t1503.scala b/test/files/neg/t1503.scala
new file mode 100644
index 0000000000..9877f99d0a
--- /dev/null
+++ b/test/files/neg/t1503.scala
@@ -0,0 +1,8 @@
+object Whatever {
+  override def equals(x: Any) = true
+}
+
+class Test {
+  // when left to its own devices, and not under -Xfuture, the return type is Whatever.type
+  def matchWhateverCCE(x: Any) = x match { case n @ Whatever => n }
+}
\ No newline at end of file
diff --git a/test/files/run/t1503.check b/test/files/run/t1503.check
new file mode 100644
index 0000000000..43eceb0229
--- /dev/null
+++ b/test/files/run/t1503.check
@@ -0,0 +1 @@
+whoops
diff --git a/test/files/run/t1503.scala b/test/files/run/t1503.scala
new file mode 100644
index 0000000000..1be0e74ac2
--- /dev/null
+++ b/test/files/run/t1503.scala
@@ -0,0 +1,20 @@
+object Whatever {
+  override def equals(x: Any) = true
+}
+
+object Test extends App {
+  // this should make it abundantly clear Any is the best return type we can guarantee
+  def matchWhatever(x: Any): Any = x match { case n @ Whatever => n }
+  // when left to its own devices, and not under -Xfuture, the return type is Whatever.type
+  def matchWhateverCCE(x: Any) = x match { case n @ Whatever => n }
+
+  // just to exercise it a bit
+  assert(matchWhatever(1) == 1)
+  assert(matchWhatever("1") == "1")
+
+  try {
+    matchWhateverCCE("1"): Whatever.type
+  } catch {
+    case _: ClassCastException => println("whoops")
+  }
+}
\ No newline at end of file
diff --git a/test/files/run/t1503_future.flags b/test/files/run/t1503_future.flags
new file mode 100644
index 0000000000..112fc720a0
--- /dev/null
+++ b/test/files/run/t1503_future.flags
@@ -0,0 +1 @@
+-Xfuture
\ No newline at end of file
diff --git a/test/files/run/t1503_future.scala b/test/files/run/t1503_future.scala
new file mode 100644
index 0000000000..1e3daad761
--- /dev/null
+++ b/test/files/run/t1503_future.scala
@@ -0,0 +1,17 @@
+object Whatever {
+  override def equals(x: Any) = true
+}
+
+object Test extends App {
+  // this should make it abundantly clear Any is the best return type we can guarantee
+  def matchWhatever(x: Any): Any = x match { case n @ Whatever => n }
+  // when left to its own devices, and not under -Xfuture, the return type is Whatever.type
+  def matchWhateverCCE(x: Any) = x match { case n @ Whatever => n }
+
+  // just to exercise it a bit
+  assert(matchWhatever(1) == 1)
+  assert(matchWhatever("1") == "1")
+
+  assert(matchWhateverCCE(1) == 1)
+  assert(matchWhateverCCE("1") == "1")
+}
\ No newline at end of file