Propagate allowOptimizedExpansion to CASE results (#34304)

* Propagate `allowOptimizedExpansion` to `CASE` results

If the `CASE` is used in a context that allows optimizations (predicates, where
NULL and FALSE are equivalent), the same holds for each of its results.

Author: ranma42

src/EFCore.Relational/Query/SqlNullabilityProcessor.cs

@@ -531,7 +531,7 @@ protected virtual SqlExpression VisitCase(CaseExpression caseExpression, bool al
                 continue;
             }
 
-            var newResult = Visit(whenClause.Result, out var resultNullable);
+            var newResult = Visit(whenClause.Result, allowOptimizedExpansion, out var resultNullable);
 
             nullable |= resultNullable;
             whenClauses.Add(new CaseWhenClause(test, newResult));
@@ -554,7 +554,7 @@ protected virtual SqlExpression VisitCase(CaseExpression caseExpression, bool al
         SqlExpression? elseResult = null;
         if (!testEvaluatesToTrue)
         {
-            elseResult = Visit(caseExpression.ElseResult, out var elseResultNullable);
+            elseResult = Visit(caseExpression.ElseResult, allowOptimizedExpansion, out var elseResultNullable);
             nullable |= elseResultNullable;
 
             // if there is no 'else' there is a possibility of null, when none of the conditions are met

test/EFCore.SqlServer.FunctionalTests/Query/GearsOfWarQuerySqlServerTest.cs

@@ -956,7 +956,7 @@ public override async Task Null_propagation_optimization2(bool async)
 FROM [Gears] AS [g]
 WHERE CASE
     WHEN [g].[LeaderNickname] IS NULL THEN NULL
-    WHEN [g].[LeaderNickname] LIKE N'%us' AND [g].[LeaderNickname] IS NOT NULL THEN CAST(1 AS bit)
+    WHEN [g].[LeaderNickname] LIKE N'%us' THEN CAST(1 AS bit)
     ELSE CAST(0 AS bit)
 END = CAST(1 AS bit)
 """);
@@ -7708,10 +7708,7 @@ WHERE CASE
     WHEN [g].[HasSoulPatch] = @__prm_0 AND (
         SELECT TOP(1) [w].[Name]
         FROM [Weapons] AS [w]
-        WHERE [w].[Id] = [g].[SquadId]) = @__prm2_1 AND (
-        SELECT TOP(1) [w].[Name]
-        FROM [Weapons] AS [w]
-        WHERE [w].[Id] = [g].[SquadId]) IS NOT NULL THEN CAST(1 AS bit)
+        WHERE [w].[Id] = [g].[SquadId]) = @__prm2_1 THEN CAST(1 AS bit)
     ELSE CAST(0 AS bit)
 END = CAST(1 AS bit)
 """);

test/EFCore.SqlServer.FunctionalTests/Query/NullSemanticsQuerySqlServerTest.cs

@@ -2823,7 +2823,7 @@ ELSE CAST(0 AS bit)
         END
         ELSE [e].[BoolC]
     END <> [e].[BoolB] THEN [e].[BoolA]
-    WHEN ([e].[NullableBoolB] = [e].[NullableBoolC] AND [e].[NullableBoolB] IS NOT NULL AND [e].[NullableBoolC] IS NOT NULL) OR ([e].[NullableBoolB] IS NULL AND [e].[NullableBoolC] IS NULL) THEN CAST(1 AS bit)
+    WHEN [e].[NullableBoolB] = [e].[NullableBoolC] OR ([e].[NullableBoolB] IS NULL AND [e].[NullableBoolC] IS NULL) THEN CAST(1 AS bit)
     ELSE CAST(0 AS bit)
 END = CAST(1 AS bit)
 """,
@@ -4342,7 +4342,7 @@ public override async Task Is_null_on_column_followed_by_OrElse_optimizes_nullab
 FROM [Entities1] AS [e]
 WHERE CASE
     WHEN [e].[NullableStringA] IS NULL OR [e].[NullableStringB] IS NULL THEN CASE
-        WHEN ([e].[NullableStringA] = [e].[NullableStringB] AND [e].[NullableStringA] IS NOT NULL AND [e].[NullableStringB] IS NOT NULL) OR ([e].[NullableStringA] IS NULL AND [e].[NullableStringB] IS NULL) THEN CAST(1 AS bit)
+        WHEN [e].[NullableStringA] = [e].[NullableStringB] OR ([e].[NullableStringA] IS NULL AND [e].[NullableStringB] IS NULL) THEN CAST(1 AS bit)
         ELSE CAST(0 AS bit)
     END
     WHEN ([e].[NullableStringA] <> [e].[NullableStringB] OR [e].[NullableStringA] IS NULL OR [e].[NullableStringB] IS NULL) AND ([e].[NullableStringA] IS NOT NULL OR [e].[NullableStringB] IS NOT NULL) THEN CAST(1 AS bit)
@@ -4361,7 +4361,7 @@ public override async Task Is_null_on_column_followed_by_OrElse_optimizes_nullab
 FROM [Entities1] AS [e]
 WHERE CASE
     WHEN ([e].[NullableStringA] IS NULL OR [e].[NullableStringB] IS NULL) AND [e].[NullableBoolC] IS NULL THEN CASE
-        WHEN ([e].[NullableStringA] = [e].[NullableStringB] AND [e].[NullableStringA] IS NOT NULL AND [e].[NullableStringB] IS NOT NULL) OR ([e].[NullableStringA] IS NULL AND [e].[NullableStringB] IS NULL) THEN CAST(1 AS bit)
+        WHEN [e].[NullableStringA] = [e].[NullableStringB] OR ([e].[NullableStringA] IS NULL AND [e].[NullableStringB] IS NULL) THEN CAST(1 AS bit)
         ELSE CAST(0 AS bit)
     END
     WHEN ([e].[NullableStringA] <> [e].[NullableStringB] OR [e].[NullableStringA] IS NULL OR [e].[NullableStringB] IS NULL) AND ([e].[NullableStringA] IS NOT NULL OR [e].[NullableStringB] IS NOT NULL) THEN CAST(1 AS bit)

test/EFCore.SqlServer.FunctionalTests/Query/TPCGearsOfWarQuerySqlServerTest.cs

@@ -1336,7 +1336,7 @@ FROM [Officers] AS [o]
 ) AS [u]
 WHERE CASE
     WHEN [u].[LeaderNickname] IS NULL THEN NULL
-    WHEN [u].[LeaderNickname] LIKE N'%us' AND [u].[LeaderNickname] IS NOT NULL THEN CAST(1 AS bit)
+    WHEN [u].[LeaderNickname] LIKE N'%us' THEN CAST(1 AS bit)
     ELSE CAST(0 AS bit)
 END = CAST(1 AS bit)
 """);
@@ -10264,10 +10264,7 @@ WHERE CASE
     WHEN [u].[HasSoulPatch] = @__prm_0 AND (
         SELECT TOP(1) [w].[Name]
         FROM [Weapons] AS [w]
-        WHERE [w].[Id] = [u].[SquadId]) = @__prm2_1 AND (
-        SELECT TOP(1) [w].[Name]
-        FROM [Weapons] AS [w]
-        WHERE [w].[Id] = [u].[SquadId]) IS NOT NULL THEN CAST(1 AS bit)
+        WHERE [w].[Id] = [u].[SquadId]) = @__prm2_1 THEN CAST(1 AS bit)
     ELSE CAST(0 AS bit)
 END = CAST(1 AS bit)
 """);

test/EFCore.SqlServer.FunctionalTests/Query/TPTGearsOfWarQuerySqlServerTest.cs

@@ -1163,7 +1163,7 @@ FROM [Gears] AS [g]
 LEFT JOIN [Officers] AS [o] ON [g].[Nickname] = [o].[Nickname] AND [g].[SquadId] = [o].[SquadId]
 WHERE CASE
     WHEN [g].[LeaderNickname] IS NULL THEN NULL
-    WHEN [g].[LeaderNickname] LIKE N'%us' AND [g].[LeaderNickname] IS NOT NULL THEN CAST(1 AS bit)
+    WHEN [g].[LeaderNickname] LIKE N'%us' THEN CAST(1 AS bit)
     ELSE CAST(0 AS bit)
 END = CAST(1 AS bit)
 """);
@@ -8724,10 +8724,7 @@ WHERE CASE
     WHEN [g].[HasSoulPatch] = @__prm_0 AND (
         SELECT TOP(1) [w].[Name]
         FROM [Weapons] AS [w]
-        WHERE [w].[Id] = [g].[SquadId]) = @__prm2_1 AND (
-        SELECT TOP(1) [w].[Name]
-        FROM [Weapons] AS [w]
-        WHERE [w].[Id] = [g].[SquadId]) IS NOT NULL THEN CAST(1 AS bit)
+        WHERE [w].[Id] = [g].[SquadId]) = @__prm2_1 THEN CAST(1 AS bit)
     ELSE CAST(0 AS bit)
 END = CAST(1 AS bit)
 """);

test/EFCore.SqlServer.FunctionalTests/Query/TemporalGearsOfWarQuerySqlServerTest.cs

@@ -1452,10 +1452,7 @@ WHERE CASE
     WHEN [g].[HasSoulPatch] = @__prm_0 AND (
         SELECT TOP(1) [w].[Name]
         FROM [Weapons] FOR SYSTEM_TIME AS OF '2010-01-01T00:00:00.0000000' AS [w]
-        WHERE [w].[Id] = [g].[SquadId]) = @__prm2_1 AND (
-        SELECT TOP(1) [w].[Name]
-        FROM [Weapons] FOR SYSTEM_TIME AS OF '2010-01-01T00:00:00.0000000' AS [w]
-        WHERE [w].[Id] = [g].[SquadId]) IS NOT NULL THEN CAST(1 AS bit)
+        WHERE [w].[Id] = [g].[SquadId]) = @__prm2_1 THEN CAST(1 AS bit)
     ELSE CAST(0 AS bit)
 END = CAST(1 AS bit)
 """);
@@ -7768,7 +7765,7 @@ public override async Task Null_propagation_optimization2(bool async)
 FROM [Gears] FOR SYSTEM_TIME AS OF '2010-01-01T00:00:00.0000000' AS [g]
 WHERE CASE
     WHEN [g].[LeaderNickname] IS NULL THEN NULL
-    WHEN [g].[LeaderNickname] LIKE N'%us' AND [g].[LeaderNickname] IS NOT NULL THEN CAST(1 AS bit)
+    WHEN [g].[LeaderNickname] LIKE N'%us' THEN CAST(1 AS bit)
     ELSE CAST(0 AS bit)
 END = CAST(1 AS bit)
 """);

test/EFCore.Sqlite.FunctionalTests/Query/GearsOfWarQuerySqliteTest.cs

@@ -3340,7 +3340,7 @@ public override async Task Null_propagation_optimization2(bool async)
 FROM "Gears" AS "g"
 WHERE CASE
     WHEN "g"."LeaderNickname" IS NULL THEN NULL
-    ELSE "g"."LeaderNickname" LIKE '%us' AND "g"."LeaderNickname" IS NOT NULL
+    ELSE "g"."LeaderNickname" LIKE '%us'
 END
 """);
     }
@@ -6766,11 +6766,7 @@ WHERE CASE
         SELECT "w"."Name"
         FROM "Weapons" AS "w"
         WHERE "w"."Id" = "g"."SquadId"
-        LIMIT 1) = @__prm2_1 AND (
-        SELECT "w"."Name"
-        FROM "Weapons" AS "w"
-        WHERE "w"."Id" = "g"."SquadId"
-        LIMIT 1) IS NOT NULL
+        LIMIT 1) = @__prm2_1
     ELSE 0
 END
 """);

test/EFCore.Sqlite.FunctionalTests/Query/NullSemanticsQuerySqliteTest.cs

@@ -988,7 +988,7 @@ WHEN CASE
         WHEN "e"."BoolA" THEN ("e"."NullableBoolA" <> "e"."NullableBoolB" OR "e"."NullableBoolA" IS NULL OR "e"."NullableBoolB" IS NULL) AND ("e"."NullableBoolA" IS NOT NULL OR "e"."NullableBoolB" IS NOT NULL)
         ELSE "e"."BoolC"
     END <> "e"."BoolB" THEN "e"."BoolA"
-    ELSE ("e"."NullableBoolB" = "e"."NullableBoolC" AND "e"."NullableBoolB" IS NOT NULL AND "e"."NullableBoolC" IS NOT NULL) OR ("e"."NullableBoolB" IS NULL AND "e"."NullableBoolC" IS NULL)
+    ELSE "e"."NullableBoolB" = "e"."NullableBoolC" OR ("e"."NullableBoolB" IS NULL AND "e"."NullableBoolC" IS NULL)
 END
 """,
             //