fix: minimized warnings generated by macro expanded code (#103)

Author: soumyamahunt

.gitignore

@@ -58,7 +58,7 @@ Package.resolved
 .build/
 *.o
 *.d
-*.swiftdeps
+*.swiftdeps*
 
 # CocoaPods
 #

Examples/Podfile

@@ -3,7 +3,8 @@ IPHONEOS_DEPLOYMENT_TARGET = '14.0'
 
 GITHUB_REPOSITORY = ENV['GITHUB_REPOSITORY'] || 'SwiftyLab/MetaCodable'
 GITHUB_SERVER_URL = ENV['GITHUB_SERVER_URL'] || 'https://github.com'
-METACODABLE_DEV_BRANCH = ENV['GITHUB_HEAD_REF'] || ENV['GITHUB_REF_NAME']
+GITHUB_HEAD_REF = ENV['GITHUB_HEAD_REF']
+METACODABLE_DEV_BRANCH = GITHUB_HEAD_REF&.empty? ? ENV['GITHUB_REF_NAME'] : GITHUB_HEAD_REF
 DEV_SOURCE = METACODABLE_DEV_BRANCH ? { :git => "#{GITHUB_SERVER_URL}/#{GITHUB_REPOSITORY}.git", :branch => METACODABLE_DEV_BRANCH } : { :path => "../" }
 
 def add_metacodable

Package.swift

@@ -31,6 +31,7 @@ let package = Package(
             name: "PluginCore",
             dependencies: [
                 .product(name: "SwiftSyntax", package: "swift-syntax"),
+                .product(name: "SwiftOperators", package: "swift-syntax"),
                 .product(name: "SwiftDiagnostics", package: "swift-syntax"),
                 .product(name: "SwiftSyntaxBuilder", package: "swift-syntax"),
                 .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),

Package@swift-5.swift

@@ -30,6 +30,7 @@ let package = Package(
             name: "PluginCore",
             dependencies: [
                 .product(name: "SwiftSyntax", package: "swift-syntax"),
+                .product(name: "SwiftOperators", package: "swift-syntax"),
                 .product(name: "SwiftDiagnostics", package: "swift-syntax"),
                 .product(name: "SwiftSyntaxBuilder", package: "swift-syntax"),
                 .product(name: "SwiftSyntaxMacros", package: "swift-syntax"),

Sources/PluginCore/Diagnostics/MetaCodableMessage.swift

@@ -98,10 +98,11 @@ struct MetaCodableMessage: Error, DiagnosticMessage, FixItMessage {
         message: String, id: MessageID
     ) -> MetaCodableMessage {
         return .init(
-            macro: macro,
-            message: message,
-            messageID: id,
-            severity: .warning
+            macro: macro, message: message, messageID: id, severity: .warning
         )
     }
 }
+
+#if !canImport(SwiftSyntax600)
+extension MetaCodableMessage: @unchecked Sendable {}
+#endif

Sources/PluginCore/Expansion/AttributeExpander.swift

@@ -64,11 +64,22 @@ struct AttributeExpander {
         let decodable = variable.protocol(named: dProtocol, in: protocols)
         let encodable = variable.protocol(named: eProtocol, in: protocols)
 
-        return [
+        var extensions = [
             decoding(type: type, conformingTo: decodable, in: context),
             encoding(type: type, conformingTo: encodable, in: context),
             codingKeys(for: type, confirmingTo: protocols, in: context),
         ].compactMap { $0 }
+        for index in extensions.indices {
+            // attach available attributes from original declaration
+            // to generated expanded declaration
+            extensions[index].attributes = AttributeListSyntax {
+                for attr in options.availableAttributes {
+                    .attribute(attr)
+                }
+                extensions[index].attributes
+            }
+        }
+        return extensions
     }
 
     /// Provides the `Decodable` extension declaration.

Sources/PluginCore/Expansion/Options/Options.swift

@@ -11,6 +11,9 @@ extension AttributeExpander {
         /// The list of modifiers generator for
         /// conformance implementation declarations.
         let modifiersGenerator: DeclModifiersGenerator
+        /// The list of `@available` attributes attached to
+        /// original expanded declaration.
+        let availableAttributes: [AttributeSyntax]
 
         /// Memberwise initialization generator with provided options.
         ///
@@ -29,6 +32,17 @@ extension AttributeExpander {
         /// - Returns: The newly created options.
         init(for decl: some DeclGroupSyntax) {
             self.modifiersGenerator = .init(decl: decl)
+            self.availableAttributes = decl.attributes.compactMap { attribute in
+                switch attribute {
+                case .attribute(let attr):
+                    guard
+                        attr.attributeName.trimmed.description == "available"
+                    else { fallthrough }
+                    return attr
+                default:
+                    return nil
+                }
+            }
         }
     }
 }

Sources/PluginCore/Variables/Enum/Case/BasicEnumCaseVariable.swift

@@ -1,3 +1,4 @@
+import SwiftOperators
 import SwiftSyntax
 import SwiftSyntaxMacros
 
@@ -117,7 +118,17 @@ struct BasicEnumCaseVariable: EnumCaseVariable {
         let label = SwitchCaseLabelSyntax(
             caseItems: .init {
                 for value in location.values {
-                    let pattern = ExpressionPatternSyntax(expression: value)
+                    let expr =
+                        OperatorTable.standardOperators
+                        .foldAll(value) { _ in }.as(ExprSyntax.self) ?? value
+                    let pattern =
+                        if let asExpr = expr.as(AsExprSyntax.self) {
+                            ExpressionPatternSyntax(
+                                expression: asExpr.expression.trimmed
+                            )
+                        } else {
+                            ExpressionPatternSyntax(expression: expr)
+                        }
                     SwitchCaseItemSyntax(pattern: pattern)
                 }
             }

Sources/PluginCore/Variables/Enum/Switcher/InternallyTaggedEnumSwitcher.swift

@@ -114,7 +114,10 @@ where Variable: PropertyVariable {
         let containerVariable = ContainerVariable(
             encodeContainer: encodeContainer, base: output.variable
         )
-        node.register(variable: containerVariable, keyPath: keys)
+        node.register(
+            variable: containerVariable, keyPath: keys,
+            immutableEncodeContainer: true
+        )
         self.node = node
     }
 

Sources/PluginCore/Variables/Enum/Switcher/TaggedEnumSwitcherVariable.swift

@@ -101,12 +101,17 @@ extension EnumSwitcherVariable {
                 let label = SwitchCaseLabelSyntax {
                     .init(pattern: pattern, whereClause: whereClause)
                 }
-                let caseSyntax = CodeBlockItemListSyntax {
-                    preSyntax("\(value.encodeExprs.first!)")
-                    generated.code.combined()
-                }
+
+                let generatedCode = generated.code.combined()
                 SwitchCaseSyntax(label: .case(label)) {
-                    !caseSyntax.isEmpty ? caseSyntax : "break"
+                    if !generatedCode.isEmpty {
+                        CodeBlockItemListSyntax {
+                            preSyntax("\(value.encodeExprs.first!)")
+                            generatedCode
+                        }
+                    } else {
+                        "break"
+                    }
                 }
             }
             if `default` || !allEncodable || anyEncodeCondition {