Attach a warning when Nothing is used in a Filter_Condition (#8865)

Attach a warning when Nothing is used as a value in a comparison or `is_in` Filter_Condition.

CHANGELOG.md

@@ -605,6 +605,8 @@
 - [Added text_left and text_right to Column][8691]
 - [Implement relational `NULL` semantics for `Nothing` for in-memory Column
   operations.][5156]
+- [Attach a warning when Nothing is used as a value in a comparison or `is_in`
+  `Filter_Condition`.][8865]
 
 [debug-shortcuts]:
   https://github.com/enso-org/enso/blob/develop/app/gui/docs/product/shortcuts.md#debug
@@ -869,6 +871,7 @@
 [8606]: https://github.com/enso-org/enso/pull/8606
 [8627]: https://github.com/enso-org/enso/pull/8627
 [8691]: https://github.com/enso-org/enso/pull/8691
+[8865]: https://github.com/enso-org/enso/pull/8865
 
 #### Enso Compiler
 

distribution/lib/Standard/Table/0.0.0-dev/src/Errors.enso

@@ -793,3 +793,14 @@ type Not_All_Rows_Downloaded
     to_display_text : Text
     to_display_text self =
         "The query has returned more than the maximum of "+self.max_rows.to_text+" rows, so some rows have been dropped from the result. If you want to get the full result, change the row limit."
+
+type Nothing_Value_In_Filter_Condition
+    ## PRIVATE
+       Indicates that a Nothing/NULL value was used as a parameter to a
+       `Filter_Condition` comparison or `is_in` operation.
+    Error (filter_condition:Filter_Condition)
+
+    ## PRIVATE
+    to_display_text : Text
+    to_display_text self =
+        "Using `Nothing` as an argument to a `"+self.filter_condition.to_text+"` cannot match anything."

distribution/lib/Standard/Table/0.0.0-dev/src/Internal/Filter_Condition_Helpers.enso

@@ -4,6 +4,7 @@ import Standard.Base.Errors.Common.Type_Error
 from Standard.Base.Data.Filter_Condition.Filter_Condition import all
 
 import project.Data.Type.Value_Type.Value_Type
+from project.Errors import Nothing_Value_In_Filter_Condition
 
 ## PRIVATE
    A helper function gathering the common logic that generates a boolean mask
@@ -15,15 +16,17 @@ import project.Data.Type.Value_Type.Value_Type
 make_filter_column source_column filter_condition on_problems = case filter_condition of
     # Equality
     Equal value ->
-        Warning.with_suspended source_column source_column->
-            Warning.with_suspended value value->
-                on_problems.escalate_warnings <|
-                    source_column == value
+        warn_on_nothing_in_comparison filter_condition value <|
+            Warning.with_suspended source_column source_column->
+                Warning.with_suspended value value->
+                    on_problems.escalate_warnings <|
+                        source_column == value
     Not_Equal value ->
-        Warning.with_suspended source_column source_column->
-            Warning.with_suspended value value->
-                on_problems.escalate_warnings <|
-                    source_column != value
+        warn_on_nothing_in_comparison filter_condition value <|
+            Warning.with_suspended source_column source_column->
+                Warning.with_suspended value value->
+                    on_problems.escalate_warnings <|
+                        source_column != value
     # Nothing
     Is_Nothing -> source_column.is_nothing
     Not_Nothing -> source_column.is_nothing.not
@@ -32,11 +35,22 @@ make_filter_column source_column filter_condition on_problems = case filter_cond
         Value_Type.expect_boolean source_column <| source_column
     Is_False -> source_column.not
     # Comparisons
-    Less value -> (source_column < value)
-    Equal_Or_Less value -> (source_column <= value)
-    Equal_Or_Greater value -> (source_column >= value)
-    Greater value -> (source_column > value)
-    Between lower upper -> source_column.between lower upper
+    Less value ->
+        warn_on_nothing_in_comparison filter_condition value <|
+            source_column < value
+    Equal_Or_Less value ->
+        warn_on_nothing_in_comparison filter_condition value <|
+            source_column <= value
+    Equal_Or_Greater value ->
+        warn_on_nothing_in_comparison filter_condition value <|
+            source_column >= value
+    Greater value ->
+        warn_on_nothing_in_comparison filter_condition value <|
+            source_column > value
+    Between lower upper ->
+        warn_on_nothing_in_comparison filter_condition lower <|
+            warn_on_nothing_in_comparison filter_condition upper <|
+                source_column.between lower upper
     # Text
     Equal_Ignore_Case value locale ->
         source_column.equals_ignore_case value locale
@@ -67,5 +81,24 @@ make_filter_column source_column filter_condition on_problems = case filter_cond
         if is_nan_column.is_error then is_infinite_column.not else
             (is_infinite_column || is_nan_column).not
     # Vector
-    Is_In values -> source_column.is_in values
-    Not_In values -> source_column.is_in values . not
+    Is_In values ->
+        warn_on_nothing_in_comparison_vector filter_condition values <|
+            source_column.is_in values
+    Not_In values ->
+        warn_on_nothing_in_comparison_vector filter_condition values <|
+            source_column.is_in values . not
+
+## Attach a warning if the provided value is `Nothing`.
+warn_on_nothing_in_comparison : Filter_Condition -> Any -> Any -> Any
+warn_on_nothing_in_comparison filter_condition value ~action =
+    case value of
+        Nothing -> Warning.attach (Nothing_Value_In_Filter_Condition.Error filter_condition) action
+        _ -> action
+
+## Attach a warning if the provided value is a `Vector` that contains `Nothing`.
+warn_on_nothing_in_comparison_vector : Filter_Condition -> Vector Any -> Any -> Any
+warn_on_nothing_in_comparison_vector filter_condition values ~action =
+    case values of
+        _ : Vector ->
+            values.fold action (flip (warn_on_nothing_in_comparison filter_condition))
+        _ -> action

test/Table_Tests/src/Common_Table_Operations/Filter_Spec.enso

@@ -453,6 +453,28 @@ add_specs suite_builder setup =
             err2 = t2.filter "Y" (Filter_Condition.Not_Equal 5) on_problems=Problem_Behavior.Report_Error
             err2.should_fail_with Floating_Point_Equality
 
+        group_builder.specify "should attach a warning when Nothing is used as a value in a comparison or `is_in` `Filter_Condition`" <|
+            t = table_builder [["x", [1, 2, 3]]]
+            fcs = [Filter_Condition.Equal Nothing, Filter_Condition.Not_Equal Nothing]
+                + [Filter_Condition.Less Nothing, Filter_Condition.Equal_Or_Less Nothing]
+                + [Filter_Condition.Equal_Or_Greater Nothing, Filter_Condition.Greater Nothing]
+                + [Filter_Condition.Between Nothing Nothing , Filter_Condition.Is_In [Nothing]]
+                + [Filter_Condition.Not_In [Nothing]]
+                + [Filter_Condition.Is_In [1, Nothing, 2]]
+            fcs.map fc->
+                Test.with_clue fc.to_text <|
+                    Problems.expect_warning Nothing_Value_In_Filter_Condition (t.filter "x" fc . at "x")
+
+        group_builder.specify "should not attach a warning when comparing with a column containing Nothing in a comparison `Filter_Condition`" <|
+            t = table_builder [["x", [1, 2, 3]], ["y", [1, Nothing, 2]]]
+            Problems.assume_no_problems (t.filter "x" (Filter_Condition.Equal (t.at "y")))
+
+        group_builder.specify "should not attach a warning when Nothing is not used as a value in a comparison or `is_in` `Filter_Condition`" <|
+            t = table_builder [["x", [1, 2, 3]], ["y", [1, Nothing, 2]]]
+            Problems.assume_no_problems (t.filter "x" (Filter_Condition.Equal 12))
+            Problems.assume_no_problems (t.filter "x" (Filter_Condition.Equal [Nothing, Nothing]))
+            Problems.assume_no_problems (t.filter "x" (Filter_Condition.Is_In [[Nothing, Nothing]]))
+
     suite_builder.group prefix+"Table.filter_by_expression" group_builder->
         data = Data.setup create_connection_fn