@@ -4,7 +4,7 @@ using System.Collections.Generic;
 #nullable disable
 #pragma warning disable CS1591 // Missing XML comment for publicly visible type or member
 #pragma warning disable RS0016 // Add public types and members to the declared API
-#pragma warning disable 618 // Member is obsolete
+#pragma warning disable CS0618 // Member is obsolete
 
 namespace Npgsql
 {
@@ -13,18 +13,18 @@ namespace Npgsql
         private partial int Init()
         {
             // Set the strongly-typed properties to their default values
-            {{
+            {{~
                for p in properties
                  if p.is_obsolete
                    continue
                  end
 
                  if (p.default_value != null)
-            }}
+            ~}}
             {{ p.name }} = {{ p.default_value }};
-            {{
+            {{~
                  end
-               end }}
+               end ~}}
 
             // Setting the strongly-typed properties here also set the string-based properties in the base class.
             // Clear them (default settings = empty connection string)
@@ -33,91 +33,59 @@ namespace Npgsql
             return 0;
         }
 
-        private partial int GeneratedSetter(string keyword, object value)
+        private partial bool GeneratedActions(GeneratedAction action, string keyword, ref object value)
         {
             switch (keyword)
             {
-            {{ for kv in properties_by_keyword }}
+            {{~ for kv in properties_by_keyword ~}}
             case "{{ kv.key }}":
-            {{ p = kv.value }}
-            {{ if p.is_enum }}
+            {{~ for alternative in kv.value.alternatives ~}}
+            case "{{ alternative }}":
+            {{~ end ~}}
             {
-                {{ p.name }} = value is string s
-                    ? ({{ p.type_name }})Enum.Parse(typeof({{ p.type_name }}), s, ignoreCase: true)
-                    : ({{ p.type_name }})Convert.ChangeType(value, typeof({{ p.type_name }}));
-            }
-            {{ else }}
-                {{ p.name }} = ({{ p.type_name }})Convert.ChangeType(value, typeof({{ p.type_name }}));
-            {{ end }}
-                break;
-            {{ end }}
-
-                default:
-                    throw new KeyNotFoundException();
-            }
-
-            return 0;
-        }
-
-        private partial bool TryGetValueGenerated(string keyword, out object value)
-        {
-            switch (keyword)
-            {
-            {{ for kv in properties_by_keyword }}
-            case "{{ kv.key }}":
-            {{ p = kv.value }}
-                value = (object){{ p.name }} ?? "";
+            {{~ p = kv.value ~}}
+                const string canonicalName = "{{ p.canonical_name }}";
+                switch(action)
+                {
+                case GeneratedAction.Remove: 
+                    var removed = base.ContainsKey(canonicalName);
+                    {{~ if p.default_value == null ~}}
+                    {{ p.name }} = default;
+                    {{~ else ~}}
+                    {{ p.name }} = {{ p.default_value }};
+                    {{~ end ~}}
+                    {{~ if p.type_name != "String" ~}}
+                    base.Remove(canonicalName);
+                    {{~ else ~}}
+                    // String property setters call SetValue, which itself calls base.Remove().
+                    {{~ end ~}}
+                    return removed;
+                case GeneratedAction.Set:
+                {{~ if p.is_enum ~}}
+                    {{ p.name }} = ({{ p.type_name }})GetValue(typeof({{ p.type_name }}), value);
+                {{~ else ~}}
+                    {{ p.name }} = ({{ p.type_name }})Convert.ChangeType(value, typeof({{ p.type_name }}));
+                {{~ end ~}}
+                    break;
+                case GeneratedAction.Get:
+                    value = (object){{ p.name }} ?? "";
+                    break;
+                case GeneratedAction.GetCanonical:
+                    value = canonicalName;
+                    break;
+                }
                 return true;
-            {{ end }}
             }
-
-            value = null;
-            return false;
-        }
-
-        private partial bool ContainsKeyGenerated(string keyword)
-            => keyword switch
-            {
-                {{ for kv in properties_by_keyword }}
-                "{{ kv.key }}" => true,
-                {{ end }}
-
-                _ => false
-            };
-
-        private partial bool RemoveGenerated(string keyword)
-        {
-            switch (keyword)
-            {
-            {{ for kv in properties_by_keyword }}
-            case "{{ kv.key }}":
-            {
-                {{ p = kv.value }}
-                var removed = base.ContainsKey("{{ p.canonical_name }}");
-                // Note that string property setters call SetValue, which itself calls base.Remove().
-                {{ if p.default_value == null }}
-                {{ p.name }} = default;
-                {{ else }}
-                {{ p.name }} = {{ p.default_value }};
-                {{ end }}
-                base.Remove("{{ p.canonical_name }}");
-                return removed;
-            }
-            {{ end }}
-
-            default:
-                throw new KeyNotFoundException();
+            {{~ end ~}}
             }
+            if (action is GeneratedAction.Get or GeneratedAction.GetCanonical)
+                return false;
+            throw new KeyNotFoundException();
+            
+            static object GetValue(Type type, object value)
+                => value is string s
+                    ? Enum.Parse(type, s, ignoreCase: true)
+                    : Convert.ChangeType(value, type);
         }
-
-        private partial string ToCanonicalKeyword(string keyword)
-            => keyword switch
-            {
-                {{ for kv in properties_by_keyword }}
-                "{{ kv.key }}" => "{{ kv.value.canonical_name }}",
-                {{ end }}
-
-                _ => throw new KeyNotFoundException()
-            };
     }
 }
@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
@@ -89,11 +90,24 @@ public void Execute(GeneratorExecutionContext context)
 
             propertiesByKeyword[displayName.ToUpperInvariant()] = propertyDetails;
             if (property.Name != displayName)
-                propertiesByKeyword[property.Name.ToUpperInvariant()] = propertyDetails;
+            {
+                var propertyName = property.Name.ToUpperInvariant();
+                if (!propertiesByKeyword.ContainsKey(propertyName))
+                    propertyDetails.Alternatives.Add(propertyName);
+            }
+
             if (propertyAttribute.ConstructorArguments.Length == 1)
+            {
                 foreach (var synonymArg in propertyAttribute.ConstructorArguments[0].Values)
+                {
                     if (synonymArg.Value is string synonym)
-                        propertiesByKeyword[synonym.ToUpperInvariant()] = propertyDetails;
+                    {
+                        var synonymName = synonym.ToUpperInvariant();
+                        if (!propertiesByKeyword.ContainsKey(synonymName))
+                            propertyDetails.Alternatives.Add(synonymName);
+                    }
+                }
+            }
         }
 
         var template = Template.Parse(EmbeddedResource.GetContent("NpgsqlConnectionStringBuilder.snbtxt"), "NpgsqlConnectionStringBuilder.snbtxt");
@@ -115,5 +129,18 @@ sealed class PropertyDetails
         public bool IsEnum { get; set; }
         public bool IsObsolete { get; set; }
         public object? DefaultValue { get; set; }
+
+        public HashSet<string> Alternatives { get; } = new(StringComparer.Ordinal);
+
+        public PropertyDetails Clone()
+            => new()
+            {
+                Name = Name,
+                CanonicalName = CanonicalName,
+                TypeName = TypeName,
+                IsEnum = IsEnum,
+                IsObsolete = IsObsolete,
+                DefaultValue = DefaultValue
+            };
     }
-}
+}
@@ -63,6 +63,19 @@ public NpgsqlConnectionStringBuilder(string? connectionString)
     // Method fake-returns an int only to make sure it's code-generated
     private partial int Init();
 
+    /// <summary>
+    /// GeneratedAction and GeneratedActions exist to be able to produce a streamlined binary footprint for NativeAOT.
+    /// An idiomatic approach where each action has its own method would double the binary size of NpgsqlConnectionStringBuilder.
+    /// </summary>
+    enum GeneratedAction
+    {
+        Set,
+        Get,
+        Remove,
+        GetCanonical
+    }
+    private partial bool GeneratedActions(GeneratedAction action, string keyword, ref object? value);
+
     #endregion
 
     #region Non-static property handling
@@ -91,7 +104,8 @@ public override object this[string keyword]
 
             try
             {
-                GeneratedSetter(keyword.ToUpperInvariant(), value);
+                var val = value;
+                GeneratedActions(GeneratedAction.Set, keyword.ToUpperInvariant(), ref val);
             }
             catch (Exception e)
             {
@@ -100,9 +114,6 @@ public override object this[string keyword]
         }
     }
 
-    // Method fake-returns an int only to make sure it's code-generated
-    private partial int GeneratedSetter(string keyword, object? value);
-
     object? IDictionary<string, object?>.this[string keyword]
     {
         get => this[keyword];
@@ -125,9 +136,10 @@ public void Add(KeyValuePair<string, object?> item)
     /// <param name="keyword">The key of the key/value pair to be removed from the connection string in this DbConnectionStringBuilder.</param>
     /// <returns><b>true</b> if the key existed within the connection string and was removed; <b>false</b> if the key did not exist.</returns>
     public override bool Remove(string keyword)
-        => RemoveGenerated(keyword.ToUpperInvariant());
-
-    private partial bool RemoveGenerated(string keyword);
+    {
+        object? value = null;
+        return GeneratedActions(GeneratedAction.Remove, keyword.ToUpperInvariant(), ref value);
+    }
 
     /// <summary>
     /// Removes the entry from the DbConnectionStringBuilder instance.
@@ -153,11 +165,10 @@ public override void Clear()
     /// <param name="keyword">The key to locate in the <see cref="NpgsqlConnectionStringBuilder"/>.</param>
     /// <returns><b>true</b> if the <see cref="NpgsqlConnectionStringBuilder"/> contains an entry with the specified key; otherwise <b>false</b>.</returns>
     public override bool ContainsKey(string keyword)
-        => keyword is null
-            ? throw new ArgumentNullException(nameof(keyword))
-            : ContainsKeyGenerated(keyword.ToUpperInvariant());
-
-    private partial bool ContainsKeyGenerated(string keyword);
+    {
+        object? value = null;
+        return GeneratedActions(GeneratedAction.GetCanonical, (keyword ?? throw new ArgumentNullException(nameof(keyword))).ToUpperInvariant(), ref value);
+    }
 
     /// <summary>
     /// Determines whether the <see cref="NpgsqlConnectionStringBuilder"/> contains a specific key-value pair.
@@ -176,25 +187,24 @@ public bool Contains(KeyValuePair<string, object?> item)
     /// <returns><b>true</b> if keyword was found within the connection string, <b>false</b> otherwise.</returns>
     public override bool TryGetValue(string keyword, [NotNullWhen(true)] out object? value)
     {
-        if (keyword == null)
-            throw new ArgumentNullException(nameof(keyword));
-
-        return TryGetValueGenerated(keyword.ToUpperInvariant(), out value);
+        object? v = null;
+        var result = GeneratedActions(GeneratedAction.Get, (keyword ?? throw new ArgumentNullException(nameof(keyword))).ToUpperInvariant(), ref v);
+        value = v;
+        return result;
     }
 
-    private partial bool TryGetValueGenerated(string keyword, [NotNullWhen(true)] out object? value);
-
     void SetValue(string propertyName, object? value)
     {
-        var canonicalKeyword = ToCanonicalKeyword(propertyName.ToUpperInvariant());
+        object? canonicalKeyword = null;
+        var result = GeneratedActions(GeneratedAction.GetCanonical, (propertyName ?? throw new ArgumentNullException(nameof(propertyName))).ToUpperInvariant(), ref canonicalKeyword);
+        if (!result)
+            throw new KeyNotFoundException();
         if (value == null)
-            base.Remove(canonicalKeyword);
+            base.Remove((string)canonicalKeyword!);
         else
-            base[canonicalKeyword] = value;
+            base[(string)canonicalKeyword!] = value;
     }
 
-    private partial string ToCanonicalKeyword(string keyword);
-
     #endregion
 
     #region Properties - Connection