Add structural constraints as where statements for givens, so Conjure…

… can complain about invalid instance data (ref #446)

src/Conjure/UI/Model.hs

@@ -1776,13 +1776,12 @@ rule_ChooseRepr config = Rule "choose-repr" (const theRule) where
             addStructurals :: (MonadLog m, MonadFailDoc m, NameGen m, EnumerateDomain m)
                            => Model -> m Model
             addStructurals
-                | forg == Given = return
                 | usedBefore = return
                 | otherwise = \ m -> do
                     structurals <- mkStructurals
                     return $ if null structurals
                         then m
-                        else m { mStatements = mStatements m ++ [SuchThat structurals] }
+                        else m { mStatements = mStatements m ++ [SuchThat structurals | forg == Find] ++ [Where structurals | forg == Given] }
 
             channels =
                 [ make opEq this that

tests/custom/issues/446/inst.param

@@ -0,0 +1 @@
+letting s be sequence(1,2,3,4,5)

tests/custom/issues/446/model.essence

@@ -0,0 +1 @@
+given s: sequence (size 5, surjective) of int(1..10)

tests/custom/issues/446/run.sh

@@ -0,0 +1,3 @@
+rm -rf conjure-output
+conjure solve model.essence inst.param
+rm -rf conjure-output *.solution

tests/custom/issues/446/stderr.expected

@@ -0,0 +1,3 @@
+Error:
+    Invalid instance, a where statement evaluated to false.
+    (It can be an implicit where statement added by Conjure.)

tests/custom/issues/446/stdout.expected

@@ -0,0 +1,4 @@
+Generating models for model.essence
+Generated models: model000001.eprime
+Saved under: conjure-output
+Savile Row: model000001.eprime inst.param