Cleanup post #3810

### Description

#3810 was merged with comments still open; this small PR does a few minute clean-ups to address some remaining nits.

PR-URL: https://github.com/hasura/graphql-engine-mono/pull/3941
GitOrigin-RevId: 3d15eb399828123640a73247b848bc4ddff02c38

server/src-lib/Data/HashMap/Strict/NonEmpty.hs

@@ -14,7 +14,7 @@ module Data.HashMap.Strict.NonEmpty
     (!?),
     keys,
 
-    -- * Compose
+    -- * Combine
     unionWith,
 
     -- * Transformations

server/src-lib/Hasura/GraphQL/Execute/RemoteJoin/Collect.hs

@@ -8,7 +8,7 @@ module Hasura.GraphQL.Execute.RemoteJoin.Collect
   )
 where
 
-import Control.Lens (Traversal', preview, (^?), _2)
+import Control.Lens (Traversal', preview, _2)
 import Control.Monad.Writer
 import Data.HashMap.Strict qualified as Map
 import Data.HashMap.Strict.InsOrd qualified as OMap
@@ -532,6 +532,15 @@ transformActionFields fields = do
                    in Just (a, annotatedColumn)
        in (fmap snd annotatedJoinColumns, phantomFields_)
 
+-- | Constructs a 'JoinColumnAlias' for a given field in a selection set.
+--
+-- If the field was already requested, we leave it unchanged, to avoid
+-- double-fetching the same information. However, if this field is a "phantom"
+-- field, that we only add for the purpose of fetching a join key, we rename it
+-- in a way that is guaranteed to avoid conflicts.
+--
+-- NOTE: if the @fieldName@ argument is a valid GraphQL name, then the
+-- constructed alias MUST also be a valid GraphQL name.
 getJoinColumnAlias ::
   (Eq field, Hashable field) =>
   FieldName ->
@@ -549,7 +558,7 @@ getJoinColumnAlias fieldName field selectedFields allAliases =
     --
     -- If we generate a unique name for each field name which is longer than
     -- the longest alias in the selection set, the generated name would be
-    -- unique
+    -- unique.
     uniqueAlias :: FieldName
     uniqueAlias =
       let suffix =
@@ -668,8 +677,12 @@ transformObjectSelectionSet typename selectionSet = do
     annotateLHSJoinField fieldName lhsJoinField =
       let columnAlias =
             getJoinColumnAlias fieldName lhsJoinField noArgsGraphQLFields allAliases
+          -- This alias is generated in 'getJoinColumnAlias', and is guaranteed
+          -- to be a valid GraphQLName.
+          columnGraphQLName =
+            G.unsafeMkName $ getFieldNameTxt $ getAliasFieldName columnAlias
        in ( mkGraphQLField
-              (Just $ G.unsafeMkName $ getFieldNameTxt $ getAliasFieldName columnAlias)
+              (Just columnGraphQLName)
               lhsJoinField
               mempty
               mempty
@@ -679,7 +692,7 @@ transformObjectSelectionSet typename selectionSet = do
 
     (joinColumnAliases, phantomFields) =
       let lhsJoinFields =
-            Map.unions $ map _srrsLHSJoinFields $ mapMaybe (^? _FieldRemote) $ toList selectionSet
+            Map.unions $ map _srrsLHSJoinFields $ mapMaybe (preview _FieldRemote) $ toList selectionSet
           annotatedJoinColumns = Map.mapWithKey annotateLHSJoinField lhsJoinFields
        in (fmap snd annotatedJoinColumns, fmap fst annotatedJoinColumns)
 

server/src-test/Hasura/GraphQL/Schema/RemoteTest.hs

@@ -17,15 +17,12 @@ import Hasura.GraphQL.Parser.Internal.Parser qualified as P
 import Hasura.GraphQL.Parser.Schema
 import Hasura.GraphQL.Parser.TestUtils
 import Hasura.GraphQL.RemoteServer (identityCustomizer)
-import Hasura.GraphQL.Schema.Common
 import Hasura.GraphQL.Schema.Remote
 import Hasura.Prelude
 import Hasura.RQL.IR.RemoteSchema
 import Hasura.RQL.IR.Root
 import Hasura.RQL.Types.RemoteSchema
 import Hasura.RQL.Types.SchemaCache
-import Hasura.RQL.Types.Source
-import Hasura.RQL.Types.SourceCustomization
 import Hasura.Session
 import Language.GraphQL.Draft.Parser qualified as G
 import Language.GraphQL.Draft.Syntax qualified as G
@@ -107,16 +104,6 @@ buildQueryParsers ::
 buildQueryParsers introspection = do
   let introResult = IntrospectionResult introspection $$(G.litName "Query") Nothing Nothing
       remoteSchemaInfo = RemoteSchemaInfo (ValidatedRemoteSchemaDef N.nullURI [] False 60 Nothing) identityCustomizer
-      sourceContext =
-        -- without relationships to sources, this won't be evaluated
-        ( adminRoleName :: RoleName,
-          mempty :: SourceCache,
-          undefined :: QueryContext,
-          mempty :: CustomizeRemoteFieldName,
-          mempty :: RemoteSchemaMap,
-          mempty :: MkTypename,
-          mempty :: MkRootFieldName
-        )
   ParsedIntrospection query _ _ <-
     runError $
       buildRemoteParser introResult remoteSchemaInfo