generate well-formed patterns in parser

val pattern: Type = expr desugared to

val x = expr match { case pattern: Type => (var_1, ..., var_N)}

but `pattern: Type` is only a valid pattern if `pattern` is an Ident

thus, we desugar to

val x = (expr: Type) match { case pattern => (var_1, ..., var_N)}

... in this case (see def makePatDef)

also, MaybeBoundType now fails on illegal patterns (to defend against similar regressions)

1 files changed, 1 insertions, 0 deletions

diff --git a/test/files/run/virtpatmat_valdef.check b/test/files/run/virtpatmat_valdef.check
new file mode 100644
index 0000000000..1a45335bd2
--- /dev/null
+++ b/test/files/run/virtpatmat_valdef.check
@@ -0,0 +1 @@
+meh(true,null)