From de41649b0e044729583e8c5061593bc7ebff594d Mon Sep 17 00:00:00 2001
From: Matthew Baulch <baulch.matt@gmail.com>
Date: Thu, 14 Jul 2016 20:51:40 +1000
Subject: [PATCH] Use target field types in tuple conversions.

---
 compiler/semexprs.nim          |  4 ++++
 tests/tuples/tconver_tuple.nim | 19 +++++++++++++++++++
 2 files changed, 23 insertions(+)
 create mode 100644 tests/tuples/tconver_tuple.nim

diff --git a/compiler/semexprs.nim b/compiler/semexprs.nim
index 17feab85d7..5a27d86218 100644
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -198,6 +198,10 @@ proc semConv(c: PContext, n: PNode): PNode =
       # separate proc from fitNode?
       if op.kind == nkSym and op.sym.isGenericRoutine:
         result.sons[1] = fitNode(c, result.typ, result.sons[1])
+      elif op.kind == nkPar and targetType.kind == tyTuple:
+        # Set type of each field in case any have type tyEmpty (eg. `@[]`)
+        for i in 0..<op.sons.len:
+          op.sons[i][1].typ = targetType.sons[i]
     of convNotNeedeed:
       message(n.info, hintConvFromXtoItselfNotNeeded, result.typ.typeToString)
     of convNotLegal:
diff --git a/tests/tuples/tconver_tuple.nim b/tests/tuples/tconver_tuple.nim
new file mode 100644
index 0000000000..b37be968a5
--- /dev/null
+++ b/tests/tuples/tconver_tuple.nim
@@ -0,0 +1,19 @@
+# Bug 4479
+
+type
+  MyTuple = tuple
+    num: int
+    strings: seq[string]
+    ints: seq[int]
+
+var foo = MyTuple((
+  num: 7,
+  strings: @[],
+  ints: @[],
+))
+
+var bar = (
+  num: 7,
+  strings: @[],
+  ints: @[],
+).MyTuple