Simplify COALESCE

Drop all of the arguments after the first non-nullable sub-expressions. Simplify unary `COALESCE` to its argument.
dotnet · Jun 27, 2024 · 38d9f0f · 38d9f0f
1 parent 50da67b
commit 38d9f0f
Showing 1 changed file with 15 additions and 2 deletions.
diff --git a/src/EFCore.Relational/Query/SqlNullabilityProcessor.cs b/src/EFCore.Relational/Query/SqlNullabilityProcessor.cs
@@ -1422,12 +1422,25 @@ protected virtual SqlExpression VisitSqlFunction(
             foreach (var argument in sqlFunctionExpression.Arguments)
             {
                 coalesceArguments.Add(Visit(argument, out var argumentNullable));
-                coalesceNullable = coalesceNullable && argumentNullable;
+                if (!argumentNullable)
+                {
+                    coalesceNullable = false;
+                    break;
+                }
             }
 
             nullable = coalesceNullable;
 
-            return sqlFunctionExpression.Update(sqlFunctionExpression.Instance, coalesceArguments);
+            return coalesceArguments switch
+            {
+                [var singleArgument] => singleArgument,
+
+                _ => sqlFunctionExpression.Update(
+                    sqlFunctionExpression.Instance,
+                    coalesceArguments,
+                    argumentsPropagateNullability: coalesceArguments.Select(_ => false).ToArray()
+                ),
+            };
         }
 
         var useNullabilityPropagation = sqlFunctionExpression is { InstancePropagatesNullability: true };