Add configuration to generate Swift error with lower camel case names

Author: crazytonyli

docs/manual/src/swift/configuration.md

@@ -19,6 +19,7 @@ more likely to change than other configurations.
 | `experimental_sendable_value_types` | `false`                  | Whether to mark value types as `Sendable'.                                                                                                                         |
 | `custom_types`                      |                          | A map which controls how custom types are exposed to Swift. See the [custom types section of the manual](../types/custom_types.md#custom-types-in-the-bindings-code) |
 | `omit_localized_error_conformance`  | `false`                  | Whether to make generated error types conform to `LocalizedError`. |
+| `error_enum_use_lower_camel_case`   | `false`                  | Whether to use lower camel case for error enum variants. |
 
 [^1]: `namespace` is the top-level namespace from your UDL file.
 

uniffi_bindgen/src/bindings/swift/gen_swift/mod.rs

@@ -198,6 +198,7 @@ pub struct Config {
     generate_immutable_records: Option<bool>,
     experimental_sendable_value_types: Option<bool>,
     omit_localized_error_conformance: Option<bool>,
+    error_enum_use_lower_camel_case: Option<bool>,
     #[serde(default)]
     custom_types: HashMap<String, CustomTypeConfig>,
 }
@@ -270,6 +271,11 @@ impl Config {
     pub fn omit_localized_error_conformance(&self) -> bool {
         self.omit_localized_error_conformance.unwrap_or(false)
     }
+
+    /// Whether to use lower camel case for error enum variants. Default: false.
+    pub fn error_enum_use_lower_camel_case(&self) -> bool {
+        self.error_enum_use_lower_camel_case.unwrap_or(false)
+    }
 }
 
 /// Generate UniFFI component bindings for Swift, as strings in memory.
@@ -755,8 +761,12 @@ pub mod filters {
     }
 
     /// Same as enum_variant_swift_quoted, because error types are exported as Swift enums.
-    pub fn error_variant_swift_quoted(nm: &str) -> Result<String, rinja::Error> {
-        Ok(quote_general_keyword(oracle().enum_variant_name(nm)))
+    pub fn error_variant_swift_quoted(nm: &str, use_class_name: &bool) -> Result<String, rinja::Error> {
+        if *use_class_name {
+            Ok(quote_general_keyword(oracle().class_name(nm)))
+        } else {
+            Ok(quote_general_keyword(oracle().enum_variant_name(nm)))
+        }
     }
 
     /// Get the idiomatic Swift rendering of an FFI callback function name

uniffi_bindgen/src/bindings/swift/templates/ErrorTemplate.swift

@@ -1,16 +1,17 @@
 {%- call swift::docstring(e, 0) %}
+{% let use_class_name = config.error_enum_use_lower_camel_case() == false %}
 public enum {{ type_name }} {
 
     {% if e.is_flat() %}
     {% for variant in e.variants() %}
     {%- call swift::docstring(variant, 4) %}
-    case {{ variant.name()|error_variant_swift_quoted }}(message: String)
+    case {{ variant.name()|error_variant_swift_quoted(use_class_name) }}(message: String)
     {% endfor %}
 
     {%- else %}
     {% for variant in e.variants() %}
     {%- call swift::docstring(variant, 4) %}
-    case {{ variant.name()|error_variant_swift_quoted }}{% if variant.fields().len() > 0 %}(
+    case {{ variant.name()|error_variant_swift_quoted(use_class_name) }}{% if variant.fields().len() > 0 %}(
         {%- call swift::field_list_decl(variant, variant.has_nameless_fields()) %}
     ){% endif -%}
     {% endfor %}
@@ -32,15 +33,15 @@ public struct {{ ffi_converter_name }}: FfiConverterRustBuffer {
         {% if e.is_flat() %}
 
         {% for variant in e.variants() %}
-        case {{ loop.index }}: return .{{ variant.name()|error_variant_swift_quoted }}(
+        case {{ loop.index }}: return .{{ variant.name()|error_variant_swift_quoted(use_class_name) }}(
             message: try {{ Type::String.borrow()|read_fn }}(from: &buf)
         )
         {% endfor %}
 
         {% else %}
 
         {% for variant in e.variants() %}
-        case {{ loop.index }}: return .{{ variant.name()|error_variant_swift_quoted }}{% if variant.has_fields() %}(
+        case {{ loop.index }}: return .{{ variant.name()|error_variant_swift_quoted(use_class_name) }}{% if variant.has_fields() %}(
             {% for field in variant.fields() -%}
             {%-     if variant.has_nameless_fields() -%}
             try {{ field|read_fn }}(from: &buf)
@@ -63,21 +64,21 @@ public struct {{ ffi_converter_name }}: FfiConverterRustBuffer {
         {% if e.is_flat() %}
 
         {% for variant in e.variants() %}
-        case .{{ variant.name()|error_variant_swift_quoted }}(_ /* message is ignored*/):
+        case .{{ variant.name()|error_variant_swift_quoted(use_class_name) }}(_ /* message is ignored*/):
             writeInt(&buf, Int32({{ loop.index }}))
         {%- endfor %}
 
         {% else %}
 
         {% for variant in e.variants() %}
         {% if variant.has_fields() %}
-        case let .{{ variant.name()|error_variant_swift_quoted }}({% for field in variant.fields() %}{%- call swift::field_name(field, loop.index) -%}{%- if loop.last -%}{%- else -%},{%- endif -%}{% endfor %}):
+        case let .{{ variant.name()|error_variant_swift_quoted(use_class_name) }}({% for field in variant.fields() %}{%- call swift::field_name(field, loop.index) -%}{%- if loop.last -%}{%- else -%},{%- endif -%}{% endfor %}):
             writeInt(&buf, Int32({{ loop.index }}))
             {% for field in variant.fields() -%}
             {{ field|write_fn }}({% call swift::field_name(field, loop.index) %}, into: &buf)
             {% endfor -%}
         {% else %}
-        case .{{ variant.name()|error_variant_swift_quoted }}:
+        case .{{ variant.name()|error_variant_swift_quoted(use_class_name) }}:
             writeInt(&buf, Int32({{ loop.index }}))
         {% endif %}
         {%- endfor %}