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

* closes #11267; add testcase

* closes #11259

* closes #11085

(cherry picked from commit a600dfa5b7)

tests/arc/tarc_orc.nim

@@ -33,3 +33,15 @@ proc bug20303() =
   doAssert res == "are"
 
 bug20303()
+
+proc main() = # todo bug with templates
+  block: # bug #11267
+    var a: seq[char] = block: @[]
+    doAssert a == @[]
+    # 2
+    proc b: seq[string] =
+      discard
+      @[]
+    doAssert b() == @[]
+static: main()
+main()

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:
+    {}