fix(csharp): Fallback init to set

fern/pages/changelogs/csharp-sdk/2025-03-31.mdx

@@ -0,0 +1,5 @@
+## 1.15.12
+**`(fix):`** Fallback from `init` to `set` on .NET Framework & .NET Standard 2.0 for public and protected properties.
+This ensures the properties can be set on older TFMs without compilation errors.
+
+

generators/csharp/base/src/asIs/FileParameter.Template.cs

@@ -14,17 +14,17 @@ public record FileParameter :
     /// <summary>
     /// The name of the file to be uploaded.
     /// </summary>
-    public string? FileName { get; init; }
+    public string? FileName { get; set; }
 
     /// <summary>
     /// The content type of the file to be uploaded.
     /// </summary>
-    public string? ContentType { get; init; }
+    public string? ContentType { get; set; }
 
     /// <summary>
     /// The content of the file to be uploaded.
     /// </summary>
-    public required Stream Stream { get; init; }
+    public required Stream Stream { get; set; }
 
     /// <inheritdoc/>
     public void Dispose()

generators/csharp/base/src/asIs/GrpcRequestOptions.Template.cs

@@ -8,25 +8,60 @@ public partial class GrpcRequestOptions
     /// <summary>
     /// The maximum number of retry attempts.
     /// </summary>
-    public int? MaxRetries { get; init; }
+    public int? MaxRetries {
+        get;
+#if NET5_0_OR_GREATER
+        init;
+#else
+        set;
+#endif
+    }
 
     /// <summary>
     /// The timeout for the request.
     /// </summary>
-    public TimeSpan? Timeout { get; init; }
+    public TimeSpan? Timeout {
+        get;
+#if NET5_0_OR_GREATER
+        init;
+#else
+        set;
+#endif
+    }
 
     /// <summary>
     /// Options for write operations.
     /// </summary>
-    public WriteOptions? WriteOptions { get; init; }
+    public WriteOptions? WriteOptions {
+        get;
+#if NET5_0_OR_GREATER
+        init;
+#else
+        set;
+#endif
+    }
 
     /// <summary>
     /// Client-side call credentials. Provide authorization with per-call granularity.
     /// </summary>
-    public CallCredentials? CallCredentials { get; init; }
+    public CallCredentials? CallCredentials {
+        get;
+#if NET5_0_OR_GREATER
+        init;
+#else
+        set;
+#endif
+    }
 
     /// <summary>
     /// Headers to be sent with this particular request.
     /// </summary>
-    internal Headers Headers { get; init; } = new();
+    internal Headers Headers {
+        get;
+#if NET5_0_OR_GREATER
+        init;
+#else
+        set;
+#endif
+    } = new();
 }

generators/csharp/codegen/src/ast/Field.ts

@@ -208,10 +208,27 @@ export class Field extends AstNode {
                 writer.write("get; ");
             }
             if (this.init) {
-                if (!this.hasSameAccess(this.init)) {
-                    writer.write(`${this.init} `);
+                // if init is accessible to the end user (public, or protected through inheritance),
+                // we should not expose init to the user on .NET Framework
+                const needsFallback =
+                    (this.access === Access.Public || this.access === Access.Protected) &&
+                    (this.init === true || this.init === Access.Public || this.init === Access.Protected);
+                if (needsFallback) {
+                    writer.writeLine();
+                    writer.writeNoIndent("#if NET5_0_OR_GREATER\n");
+                    if (!this.hasSameAccess(this.init)) {
+                        writer.write(`${this.init} `);
+                    }
+                    writer.writeTextStatement("init");
+                    writer.writeNoIndent("#else\n");
+                    writer.writeTextStatement("set");
+                    writer.writeNoIndent("#endif\n");
+                } else {
+                    if (!this.hasSameAccess(this.init)) {
+                        writer.write(`${this.init} `);
+                    }
+                    writer.write("init; ");
                 }
-                writer.write("init; ");
             }
             if (this.set) {
                 if (!this.hasSameAccess(this.set)) {

generators/csharp/sdk/src/root-client/RootClientGenerator.ts

@@ -111,7 +111,6 @@ export class RootClientGenerator extends FileGenerator<CSharpFile, SdkCustomConf
                 csharp.field({
                     access: csharp.Access.Public,
                     get: true,
-                    init: true,
                     name: subpackage.name.pascalCase.safeName,
                     type: csharp.Type.reference(this.context.getSubpackageClassReference(subpackage))
                 })

generators/csharp/sdk/versions.yml

@@ -7,6 +7,15 @@
 #         Set `enable-forward-compatible-enums` to `false` in the configuration to generate the old enums.
 #   irVersion: 53
 
+- version: 1.15.12
+  createdAt: "2025-03-31"
+  irVersion: 57
+  changelogEntry:
+    - type: fix
+      summary: |
+        Fallback from `init` to `set` on .NET Framework & .NET Standard 2.0 for public and protected properties.
+        This ensures the properties can be set on older TFMs without compilation errors.
+
 - version: 1.15.11
   createdAt: "2025-03-25"
   irVersion: 57