Simplify NOT (CASE ... THEN const) by pushing NOT into the THEN/ELSE

src/EFCore.Relational/Query/SqlNullabilityProcessor.cs

@@ -2032,7 +2032,30 @@ protected virtual SqlExpression OptimizeNonNullableNotExpression(SqlUnaryExpress
                         sqlBinaryOperand.TypeMapping)!;
                 }
             }
-                break;
+            break;
+
+            case CaseExpression caseExpression:
+            {
+                if (caseExpression.Type == typeof(bool)
+                    && caseExpression.ElseResult is SqlConstantExpression elseResult
+                    && caseExpression.WhenClauses.All(clause => clause.Result is SqlConstantExpression)
+                )
+                {
+                    var clauses = caseExpression.WhenClauses
+                        .Select(clause => new CaseWhenClause(
+                            clause.Test,
+                            _sqlExpressionFactory.Constant(!(bool)(clause.Result as SqlConstantExpression)!.Value!, clause.Result.TypeMapping))
+                        )
+                        .ToList();
+                    var newElseResult = _sqlExpressionFactory.Constant(!(bool)elseResult.Value!, elseResult.TypeMapping);
+
+                    return caseExpression.Operand is null
+                        ? _sqlExpressionFactory.Case(clauses, newElseResult)
+                        : _sqlExpressionFactory.Case(caseExpression.Operand, clauses, newElseResult);
+                }
+            }
+
+            break;
         }
 
         return sqlUnaryExpression;
@@ -2369,7 +2392,7 @@ private SqlExpression ProcessNullNotNull(SqlUnaryExpression sqlUnaryExpression,
                     return result;
                 }
             }
-                break;
+            break;
         }
 
         return sqlUnaryExpression;

test/EFCore.Cosmos.FunctionalTests/Query/NorthwindWhereQueryCosmosTest.cs

@@ -2100,6 +2100,20 @@ public override Task Where_ternary_boolean_condition_with_false_as_result_false(
 SELECT c
 FROM root c
 WHERE ((c["Discriminator"] = "Product") AND false)
+""");
+            });
+
+    public override Task Where_ternary_boolean_condition_negated(bool async)
+        => Fixture.NoSyncTest(
+            async, async a =>
+            {
+                await base.Where_ternary_boolean_condition_negated(a);
+
+                AssertSql(
+                    """
+SELECT c
+FROM root c
+WHERE ((c["Discriminator"] = "Product") AND NOT(((c["UnitsInStock"] >= 20) ? false : true)))
 """);
             });
 

test/EFCore.Specification.Tests/Query/NorthwindWhereQueryTestBase.cs

@@ -1465,6 +1465,15 @@ public virtual Task Where_ternary_boolean_condition_with_false_as_result_false(b
             assertEmpty: true);
     }
 
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    public virtual Task Where_ternary_boolean_condition_negated(bool async)
+    {
+        return AssertQuery(
+            async,
+            ss => ss.Set<Product>().Where(p => !(p.UnitsInStock >= 20 ? false : true)));
+    }
+
     [ConditionalTheory]
     [MemberData(nameof(IsAsyncData))]
     public virtual Task Where_compare_constructed_equal(bool async)

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

@@ -4127,9 +4127,9 @@ FROM [LevelTwo] AS [l0]
     ) AS [l1]
     GROUP BY [l1].[Key]
 ) AS [l2] ON [l].[Id] = [l2].[Key] AND CASE
-    WHEN [l2].[Sum] <= 10 THEN CAST(1 AS bit)
-    ELSE CAST(0 AS bit)
-END = CAST(0 AS bit)
+    WHEN [l2].[Sum] <= 10 THEN CAST(0 AS bit)
+    ELSE CAST(1 AS bit)
+END = CAST(1 AS bit)
 """);
     }
 

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

@@ -975,9 +975,9 @@ WHERE [l2].[OneToOne_Required_PK_Date] IS NOT NULL AND [l2].[Level1_Required_Id]
     ) AS [s]
     GROUP BY [s].[Key]
 ) AS [s1] ON [l].[Id] = [s1].[Key] AND CASE
-    WHEN [s1].[Sum] <= 10 THEN CAST(1 AS bit)
-    ELSE CAST(0 AS bit)
-END = CAST(0 AS bit)
+    WHEN [s1].[Sum] <= 10 THEN CAST(0 AS bit)
+    ELSE CAST(1 AS bit)
+END = CAST(1 AS bit)
 """);
     }
 

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

@@ -1706,6 +1706,21 @@ FROM [Products] AS [p]
 """);
     }
 
+    public override async Task Where_ternary_boolean_condition_negated(bool async)
+    {
+        await base.Where_ternary_boolean_condition_negated(async);
+
+        AssertSql(
+            """
+SELECT [p].[ProductID], [p].[Discontinued], [p].[ProductName], [p].[SupplierID], [p].[UnitPrice], [p].[UnitsInStock]
+FROM [Products] AS [p]
+WHERE CASE
+    WHEN [p].[UnitsInStock] >= CAST(20 AS smallint) THEN CAST(1 AS bit)
+    ELSE CAST(0 AS bit)
+END = CAST(1 AS bit)
+""");
+    }
+
     public override async Task Where_compare_constructed_equal(bool async)
     {
         //  Anonymous type to constant comparison. Issue #14672.

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

@@ -2543,9 +2543,9 @@ public override async Task Negated_order_comparison_on_nullable_arguments_doesnt
 SELECT [e].[Id]
 FROM [Entities1] AS [e]
 WHERE CASE
-    WHEN [e].[NullableIntA] > @__i_0 THEN CAST(1 AS bit)
-    ELSE CAST(0 AS bit)
-END = CAST(0 AS bit)
+    WHEN [e].[NullableIntA] > @__i_0 THEN CAST(0 AS bit)
+    ELSE CAST(1 AS bit)
+END = CAST(1 AS bit)
 """,
             //
             """
@@ -2554,9 +2554,9 @@ ELSE CAST(0 AS bit)
 SELECT [e].[Id]
 FROM [Entities1] AS [e]
 WHERE CASE
-    WHEN [e].[NullableIntA] >= @__i_0 THEN CAST(1 AS bit)
-    ELSE CAST(0 AS bit)
-END = CAST(0 AS bit)
+    WHEN [e].[NullableIntA] >= @__i_0 THEN CAST(0 AS bit)
+    ELSE CAST(1 AS bit)
+END = CAST(1 AS bit)
 """,
             //
             """
@@ -2565,9 +2565,9 @@ ELSE CAST(0 AS bit)
 SELECT [e].[Id]
 FROM [Entities1] AS [e]
 WHERE CASE
-    WHEN [e].[NullableIntA] < @__i_0 THEN CAST(1 AS bit)
-    ELSE CAST(0 AS bit)
-END = CAST(0 AS bit)
+    WHEN [e].[NullableIntA] < @__i_0 THEN CAST(0 AS bit)
+    ELSE CAST(1 AS bit)
+END = CAST(1 AS bit)
 """,
             //
             """
@@ -2576,9 +2576,9 @@ ELSE CAST(0 AS bit)
 SELECT [e].[Id]
 FROM [Entities1] AS [e]
 WHERE CASE
-    WHEN [e].[NullableIntA] <= @__i_0 THEN CAST(1 AS bit)
-    ELSE CAST(0 AS bit)
-END = CAST(0 AS bit)
+    WHEN [e].[NullableIntA] <= @__i_0 THEN CAST(0 AS bit)
+    ELSE CAST(1 AS bit)
+END = CAST(1 AS bit)
 """);
     }
 

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

@@ -878,10 +878,10 @@ public override async Task String_Contains_negated_in_predicate(bool async)
             """
 SELECT "c"."CustomerID", "c"."Address", "c"."City", "c"."CompanyName", "c"."ContactName", "c"."ContactTitle", "c"."Country", "c"."Fax", "c"."Phone", "c"."PostalCode", "c"."Region"
 FROM "Customers" AS "c"
-WHERE NOT (CASE
-    WHEN instr("c"."CompanyName", "c"."ContactName") > 0 THEN 1
-    ELSE 0
-END)
+WHERE CASE
+    WHEN instr("c"."CompanyName", "c"."ContactName") > 0 THEN 0
+    ELSE 1
+END
 """);
     }
 
@@ -891,10 +891,10 @@ public override async Task String_Contains_negated_in_projection(bool async)
 
         AssertSql(
             """
-SELECT "c"."CustomerID" AS "Id", NOT (CASE
-    WHEN instr("c"."CompanyName", "c"."ContactName") > 0 THEN 1
-    ELSE 0
-END) AS "Value"
+SELECT "c"."CustomerID" AS "Id", CASE
+    WHEN instr("c"."CompanyName", "c"."ContactName") > 0 THEN 0
+    ELSE 1
+END AS "Value"
 FROM "Customers" AS "c"
 """);
     }

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

@@ -14,6 +14,21 @@ public NorthwindWhereQuerySqliteTest(NorthwindQuerySqliteFixture<NoopModelCustom
         Fixture.TestSqlLoggerFactory.SetTestOutputHelper(testOutputHelper);
     }
 
+    public override async Task Where_ternary_boolean_condition_negated(bool async)
+    {
+        await base.Where_ternary_boolean_condition_negated(async);
+
+        AssertSql(
+            """
+SELECT "p"."ProductID", "p"."Discontinued", "p"."ProductName", "p"."SupplierID", "p"."UnitPrice", "p"."UnitsInStock"
+FROM "Products" AS "p"
+WHERE CASE
+    WHEN "p"."UnitsInStock" >= 20 THEN 1
+    ELSE 0
+END
+""");
+    }
+
     public override Task Where_datetimeoffset_now_component(bool async)
         => AssertTranslationFailed(() => base.Where_datetimeoffset_now_component(async));
 

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

@@ -475,43 +475,43 @@ public override async Task Negated_order_comparison_on_nullable_arguments_doesnt
 
 SELECT "e"."Id"
 FROM "Entities1" AS "e"
-WHERE NOT (CASE
-    WHEN "e"."NullableIntA" > @__i_0 THEN 1
-    ELSE 0
-END)
+WHERE CASE
+    WHEN "e"."NullableIntA" > @__i_0 THEN 0
+    ELSE 1
+END
 """,
             //
             """
 @__i_0='1' (Nullable = true)
 
 SELECT "e"."Id"
 FROM "Entities1" AS "e"
-WHERE NOT (CASE
-    WHEN "e"."NullableIntA" >= @__i_0 THEN 1
-    ELSE 0
-END)
+WHERE CASE
+    WHEN "e"."NullableIntA" >= @__i_0 THEN 0
+    ELSE 1
+END
 """,
             //
             """
 @__i_0='1' (Nullable = true)
 
 SELECT "e"."Id"
 FROM "Entities1" AS "e"
-WHERE NOT (CASE
-    WHEN "e"."NullableIntA" < @__i_0 THEN 1
-    ELSE 0
-END)
+WHERE CASE
+    WHEN "e"."NullableIntA" < @__i_0 THEN 0
+    ELSE 1
+END
 """,
             //
             """
 @__i_0='1' (Nullable = true)
 
 SELECT "e"."Id"
 FROM "Entities1" AS "e"
-WHERE NOT (CASE
-    WHEN "e"."NullableIntA" <= @__i_0 THEN 1
-    ELSE 0
-END)
+WHERE CASE
+    WHEN "e"."NullableIntA" <= @__i_0 THEN 0
+    ELSE 1
+END
 """);
     }