fix #15972 (#15994)

* fix #15972

* add testcase

* more

3 files changed, 32 insertions, 0 deletions

diff --git a/tests/stmt/tforloop_tuple_multiple_underscore.nim b/tests/stmt/tforloop_tuple_multiple_underscore.nim
new file mode 100644
index 000000000..2afdb0b77
--- /dev/null
+++ b/tests/stmt/tforloop_tuple_multiple_underscore.nim
@@ -0,0 +1,10 @@
+discard """
+  errormsg: "undeclared identifier: '_'"
+"""
+
+iterator iter(): (int, int, int) =
+  yield (1, 1, 2)
+
+
+for (_, i, _) in iter():
+  echo _
\ No newline at end of file
diff --git a/tests/stmt/tforloop_tuple_underscore.nim b/tests/stmt/tforloop_tuple_underscore.nim
new file mode 100644
index 000000000..8cbb0fc10
--- /dev/null
+++ b/tests/stmt/tforloop_tuple_underscore.nim
@@ -0,0 +1,16 @@
+discard """
+  errormsg: "undeclared identifier: '_'"
+"""
+
+iterator iter(): (int, int) =
+  yield (1, 2)
+  yield (3, 4)
+  yield (1, 2)
+  yield (3, 4)
+  yield (1, 2)
+  yield (3, 4)
+
+
+for (_, i) in iter():
+  echo _
+
diff --git a/tests/stmt/tforloop_underscore.nim b/tests/stmt/tforloop_underscore.nim
new file mode 100644
index 000000000..c5b49da77
--- /dev/null
+++ b/tests/stmt/tforloop_underscore.nim
@@ -0,0 +1,6 @@
+discard """
+  errormsg: "undeclared identifier: '_'"
+"""
+
+for _ in ["a"]:
+  echo _