Safe server variable names when used in Swift identifiers (#351)

Safe server variable names when used in Swift identifiers

### Motivation

In the original introduction of server variable support, we didn't properly safe the variable names coming from the OpenAPI document for use as Swift identifiers.

### Modifications

Fix that by running the name server variable name, provided in the OpenAPI document, through the function that safes the string for use as a Swift identifier.

### Result

Documents that use variable names like `protocol` compile again.

### Test Plan

Adapted the tests.


Reviewed by: simonjbeaumont

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#351

Author: czechboy0

Sources/_OpenAPIGeneratorCore/Translator/TypesTranslator/translateServers.swift

@@ -25,10 +25,13 @@ extension TypesFileTranslator {
     /// declare the method under.
     func translateServer(index: Int, server: OpenAPI.Server) -> Declaration {
         let methodName = "\(Constants.ServerURL.propertyPrefix)\(index+1)"
-        let parameters: [ParameterDescription] = server.variables.map { (key, value) in
-            .init(label: key, type: .init(TypeName.string), defaultValue: .literal(value.default))
+        let safeVariables = server.variables.map { (key, value) in
+            (originalKey: key, swiftSafeKey: swiftSafeName(for: key), value: value)
         }
-        let variableInitializers: [Expression] = server.variables.map { (key, value) in
+        let parameters: [ParameterDescription] = safeVariables.map { (originalKey, swiftSafeKey, value) in
+            .init(label: swiftSafeKey, type: .init(TypeName.string), defaultValue: .literal(value.default))
+        }
+        let variableInitializers: [Expression] = safeVariables.map { (originalKey, swiftSafeKey, value) in
             let allowedValuesArg: FunctionArgumentDescription?
             if let allowedValues = value.enum {
                 allowedValuesArg = .init(
@@ -41,13 +44,13 @@ extension TypesFileTranslator {
             return .dot("init")
                 .call(
                     [
-                        .init(label: "name", expression: .literal(key)),
-                        .init(label: "value", expression: .identifierPattern(key)),
+                        .init(label: "name", expression: .literal(originalKey)),
+                        .init(label: "value", expression: .identifierPattern(swiftSafeKey)),
                     ] + (allowedValuesArg.flatMap { [$0] } ?? [])
                 )
         }
         let methodDecl = Declaration.commentable(
-            .functionComment(abstract: server.description, parameters: server.variables.map { ($0, $1.description) }),
+            .functionComment(abstract: server.description, parameters: safeVariables.map { ($1, $2.description) }),
             .function(
                 accessModifier: config.access,
                 kind: .function(name: methodName, isStatic: true),

Tests/OpenAPIGeneratorReferenceTests/Resources/Docs/petstore.yaml

@@ -10,9 +10,11 @@ servers:
   - url: https://example.com/api
     description: Example Petstore implementation service
   - url: /api
-  - url: https://{subdomain}.example.com:{port}/{basePath}
+  - url: '{protocol}://{subdomain}.example.com:{port}/{basePath}'
     description: A custom domain.
     variables:
+      protocol:
+        default: https
       subdomain:
         default: test
         description: A subdomain name.

Tests/OpenAPIGeneratorReferenceTests/Resources/ReferenceSources/Petstore/Types.swift

@@ -153,17 +153,23 @@ public enum Servers {
     /// A custom domain.
     ///
     /// - Parameters:
+    ///   - _protocol:
     ///   - subdomain: A subdomain name.
     ///   - port:
     ///   - basePath: The base API path.
     public static func server3(
+        _protocol: Swift.String = "https",
         subdomain: Swift.String = "test",
         port: Swift.String = "443",
         basePath: Swift.String = "v1"
     ) throws -> Foundation.URL {
         try Foundation.URL(
-            validatingOpenAPIServerURL: "https://{subdomain}.example.com:{port}/{basePath}",
+            validatingOpenAPIServerURL: "{protocol}://{subdomain}.example.com:{port}/{basePath}",
             variables: [
+                .init(
+                    name: "protocol",
+                    value: _protocol
+                ),
                 .init(
                     name: "subdomain",
                     value: subdomain