1 files changed, 122 insertions, 0 deletions
diff --git a/tests/constructors/tinvalid_construction.nim b/tests/constructors/tinvalid_construction.nim
new file mode 100644
index 000000000..bb3b1bebb
--- /dev/null
+++ b/tests/constructors/tinvalid_construction.nim
@@ -0,0 +1,122 @@
+template accept(x) =
+  static: assert compiles(x)
+
+template reject(x) =
+  static: assert(not compiles(x))
+
+type
+  TRefObj = ref object
+    x: int
+
+  THasNotNils = object of TObject
+    a: TRefObj not nil
+    b: TRefObj not nil
+    c: TRefObj
+
+  THasNotNilsRef = ref THasNotNils
+
+  TChoice = enum A, B, C, D, E, F
+
+  TBaseHasNotNils = object of THasNotNils
+    case choice: TChoice
+    of A:
+      moreNotNils: THasNotNils
+    of B:
+      indirectNotNils: ref THasNotNils
+    else:
+      discard
+
+  TObj = object
+    case choice: TChoice
+    of A:
+      a: int
+    of B, C:
+      bc: int
+    of D:
+      d: TRefObj
+    of E:
+      e1: TRefObj
+      e2: int
+    else:
+      f: string
+
+  TNestedChoices = object
+    case outerChoice: bool
+    of true:
+      truthy: int
+    else:
+      case innerChoice: TChoice
+      of A:
+        a: int
+      of B:
+        b: int
+      else:
+        notnil: TRefObj not nil
+
+var x = D
+var nilRef: TRefObj
+var notNilRef = TRefObj(x: 20)
+
+proc makeHasNotNils: ref THasNotNils =
+  result.a = TRefObj(x: 10)
+  result.b = TRefObj(x: 20)
+
+accept TObj()
+accept TObj(choice: A)
+reject TObj(choice: A, bc: 10)  # bc is in the wrong branch
+accept TObj(choice: B, bc: 20)
+reject TObj(a: 10)              # branch selected without providing discriminator
+reject TObj(choice: x, a: 10)   # the discrimantor must be a compile-time value when a branch is selected
+accept TObj(choice: x)          # it's OK to use run-time value when a branch is not selected
+accept TObj(choice: F, f: "")   # match an else clause
+reject TObj(f: "")              # the discriminator must still be provided for an else clause
+reject TObj(a: 10, f: "")       # conflicting fields
+accept TObj(choice: E, e1: TRefObj(x: 10), e2: 10)
+
+accept THasNotNils(a: notNilRef, b: notNilRef, c: nilRef)
+# XXX: the "not nil" logic in the compiler is not strong enough to catch this one yet:
+# reject THasNotNils(a: notNilRef, b: nilRef, c: nilRef)
+reject THasNotNils(b: notNilRef, c: notNilRef)              # there is a missing not nil field
+reject THasNotNils()                                        # again, missing fields
+accept THasNotNils(a: notNilRef, b: notNilRef)              # it's OK to omit a non-mandatory field
+
+# missing not nils in base
+reject TBaseHasNotNils()
+
+# once you take care of them, it's ok
+accept TBaseHasNotNils(a: notNilRef, b: notNilRef, choice: D)
+
+# this one is tricky!
+# it has to be rejected, because choice gets value A by default (0) and this means
+# that the THasNotNils field will be active (and it will demand more initialized fields).
+reject TBaseHasNotNils(a: notNilRef, b: notNilRef)
+
+# you can select a branch without mandatory fields
+accept TBaseHasNotNils(a: notNilRef, b: notNilRef, choice: B)
+accept TBaseHasNotNils(a: notNilRef, b: notNilRef, choice: B, indirectNotNils: nil)
+
+# but once you select a branch with mandatory fields, you must specify them
+reject TBaseHasNotNils(a: notNilRef, b: notNilRef, choice: A)
+reject TBaseHasNotNils(a: notNilRef, b: notNilRef, choice: A, indirectNotNils: nil)
+reject TBaseHasNotNils(a: notNilRef, b: notNilRef, choice: A, moreNotNils: THasNotNils())
+accept TBaseHasNotNils(a: notNilRef, b: notNilRef, choice: A, moreNotNils: THasNotNils(a: notNilRef, b: notNilRef))
+
+# all rules apply to sub-objects as well
+accept TBaseHasNotNils(a: notNilRef, b: notNilRef, choice: B, indirectNotNils: makeHasNotNils())
+reject TBaseHasNotNils(a: notNilRef, b: notNilRef, choice: B, indirectNotNils: THasNotNilsRef())
+accept TBaseHasNotNils(a: notNilRef, b: notNilRef, choice: B, indirectNotNils: THasNotNilsRef(a: notNilRef, b: notNilRef))
+
+# this will be accepted, because the false outer branch will be taken and the inner A branch
+accept TNestedChoices()
+
+# but if we supply a run-time value for the inner branch, the compiler won't be able to prove
+# that the notnil field was initialized
+reject TNestedChoices(outerChoice: false, innerChoice: x) # XXX: The error message is not very good here
+reject TNestedChoices(outerChoice: true,  innerChoice: A) # XXX: The error message is not very good here
+
+accept TNestedChoices(outerChoice: false, innerChoice: B)
+
+reject TNestedChoices(outerChoice: false, innerChoice: C)
+accept TNestedChoices(outerChoice: false, innerChoice: C, notnil: notNilRef)
+reject TNestedChoices(outerChoice: false, innerChoice: C, notnil: nil)
+