fix(csharp): Fallback init to set (#6613)

* fix(csharp): Fallback init to set

Author: Swimburger

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

packages/cli/cli/versions.yml

@@ -22,32 +22,32 @@
 - changelogEntry:
   - summary: |
       Bump undici timeouts to make sure docs sites get published. This addresses an issue where large documentation sites were timing out during the publishing process. By increasing the timeout values for the undici HTTP client, we ensure that even complex documentation sites have enough time to complete the publishing process.
-        
+
     type: fix
   irVersion: 57
   version: 0.57.8
 
 - changelogEntry:
   - summary: |
       Add support for `anyOf` in the new OpenAPI parser. This allows for undiscriminated unions in the OpenAPI schema, where a type can be one of several possible types without a discriminator field. The parser now handles both `oneOf` and `anyOf` schemas in the same way, converting them to undiscriminated unions in the IR.
-        
+
     type: fix
   irVersion: 57
   version: 0.57.7
 
 - changelogEntry:
   - summary: |
       Reduce CLI output from the legacy OpenAPI parser when using the experimental `openapiParserV3` option. This makes the logs cleaner and more focused on relevant information when using the newer parser.
-        
+
     type: fix
   irVersion: 57
   version: 0.57.6
 
 - changelogEntry:
   - summary: |
       Fix an issue where endpoint ids were not globally unique because they didn't take into account namespaces. This only affects
-      the new OpenAPI -> IR parser. 
-        
+      the new OpenAPI -> IR parser.
+
     type: fix
   irVersion: 57
   version: 0.57.5
@@ -66,7 +66,7 @@
       ```
 
       Each namespace creates a separate package in the generated IR, allowing for clear separation between different versions or components of your API.
-        
+
     type: feat
   irVersion: 57
   version: 0.57.4
@@ -80,9 +80,9 @@
 
 - changelogEntry:
   - summary: |
-      Add support for parsing `type: enum` in OpenAPI schemas. This allows for proper conversion of enum types that use the 
+      Add support for parsing `type: enum` in OpenAPI schemas. This allows for proper conversion of enum types that use the
       non-standard `type: enum` format instead of the standard `type: string` with `enum` values.
-        
+
     type: feat
   irVersion: 57
   version: 0.57.2
@@ -97,7 +97,7 @@
         You are an AI assistant.
         Only respond to questions using information from the documents.
         Include markdown footnotes to the sources of your information.
-        
+
     type: feat
   irVersion: 57
   version: 0.57.1
@@ -203,8 +203,8 @@
 
 - changelogEntry:
   - summary: |
-      The `fern init --openapi` command now references the OpenAPI file in 
-      place using the new `specs` syntax in generators.yml instead of copying the file into the 
+      The `fern init --openapi` command now references the OpenAPI file in
+      place using the new `specs` syntax in generators.yml instead of copying the file into the
       Fern directory. This makes it easier to maintain the source OpenAPI file separately from the Fern configuration.
     type: fix
   irVersion: 57
@@ -327,8 +327,8 @@
 
 - changelogEntry:
   - summary: |
-      Updated the CLI to gracefully handle unsupported security schemes (e.g. cookie-based auth) by skipping them 
-      instead of throwing an error. This allows the CLI to continue processing the rest of the API definition even when 
+      Updated the CLI to gracefully handle unsupported security schemes (e.g. cookie-based auth) by skipping them
+      instead of throwing an error. This allows the CLI to continue processing the rest of the API definition even when
       it encounters security schemes it cannot convert.
     type: fix
   irVersion: 56
@@ -373,14 +373,14 @@
     type: fix
   irVersion: 56
   version: 0.56.0
-  
+
 - changelogEntry:
   - summary: |
-      Hidden sections are now removed from the docs sitemap. 
+      Hidden sections are now removed from the docs sitemap.
     type: fix
   irVersion: 56
   version: 0.56.0-rc6
-  
+
 - changelogEntry:
   - summary: |
       Fixed duplicate validation messages in docs validation by deduplicating violations