fixes #2125

1 files changed, 68 insertions, 0 deletions

diff --git a/tests/generics/twrong_field_caching.nim b/tests/generics/twrong_field_caching.nim
new file mode 100644
index 000000000..595c58eb7
--- /dev/null
+++ b/tests/generics/twrong_field_caching.nim
@@ -0,0 +1,68 @@
+discard """
+  output: '''a23: 2x3
+a32: 3x2
+transpose A
+t32: 3x2
+transpose B
+x23: 2x3 (2x3)
+x32: 3x2 (3x2)'''
+"""
+
+# bug #2125
+# Suppose we have the following type for a rectangular array:
+
+type
+  RectArray*[R, C: static[int], T] = distinct array[R * C, T]
+ 
+var a23: RectArray[2, 3, int]
+var a32: RectArray[3, 2, int]
+ 
+echo "a23: ", a23.R, "x", a23.C
+echo "a32: ", a32.R, "x", a32.C
+
+# Output:
+# a23: 2x3
+# a32: 3x2
+
+# Looking good. Let's add a proc:
+proc transpose*[R, C, T](m: RectArray[R, C, T]): RectArray[C, R, T] =
+  echo "transpose A"
+
+var t32 = a23.transpose
+
+echo "t32: ", t32.R, "x", t32.C
+
+# Output:
+# t32: 3x2
+ 
+ 
+# Everything is still OK. Now let's use the rectangular array inside another
+# generic type:
+type
+  Matrix*[R, C: static[int], T] = object
+    theArray*: RectArray[R, C, T]
+
+#var m23: Matrix[2, 3, int]
+#var m32: Matrix[3, 2, int]
+
+#echo "m23: ", m23.R, "x", m23.C, " (", m23.theArray.R, "x", m23.theArray.C, ")"
+#echo "m32: ", m32.R, "x", m32.C, " (", m32.theArray.R, "x", m32.theArray.C, ")"
+
+# Output:
+# m23: 2x3 (2x3)
+# m32: 3x2 (3x2)
+
+
+# Everything is still as expected. Now let's add the following proc:
+proc transpose*[R, C, T](m: Matrix[R, C, T]): Matrix[C, R, T] =
+  echo "transpose B"
+
+var x23: Matrix[2, 3, int]
+var x32 = x23.transpose
+
+echo "x23: ", x23.R, "x", x23.C, " (", x23.theArray.R, "x", x23.theArray.C, ")"
+echo "x32: ", x32.R, "x", x32.C, " (", x32.theArray.R, "x", x32.theArray.C, ")"
+ 
+# Output:
+# x23: 2x3 (2x3)
+# x32: 3x2 (3x2)  <--- this is incorrect. R and C do not match!