closes #11267; closes #11259; closes #11085; add testcases (#20505)

* closes #11267; add testcase

* closes #11259

* closes #11085

tests/types/ttopdowninference.nim

@@ -193,3 +193,27 @@ block: # templates
   doAssert a == float(1)
   doAssert b == byte(2)
   doAssert c == cstring("abc")
+
+
+proc foo(): set[char] = # bug #11259
+  discard "a"
+  {}
+
+discard foo()
+
+block: # bug #11085
+  const ok1: set[char] = {}
+  var ok1b: set[char] = {}
+
+  const ok2: set[char] = block:
+    {}
+
+  const ok3: set[char] = block:
+    var x: set[char] = {}
+    x
+  var ok3b: set[char] = block:
+    var x: set[char] = {}
+    x
+
+  var bad: set[char] = block:
+    {}