Append diagnostic for correct errors for unsupported features

Sources/SwiftMockMacros/Constants.swift

@@ -11,6 +11,9 @@ let emptyArrayExpt = ExprSyntax(
 
 let publicModifier = DeclModifierSyntax(name: .keyword(.public))
 let privateModifier = DeclModifierSyntax(name: .keyword(.private))
+let fileprivateModifier = DeclModifierSyntax(name: .keyword(.fileprivate))
+let internalModifier = DeclModifierSyntax(name: .keyword(.internal))
+
 let finalModifier = DeclModifierSyntax(name: .keyword(.final))
 
 let anyFunctionCallExpr = ExprSyntax(

Sources/SwiftMockMacros/Diagnostic/AssociatedTypeDiagnostic.swift

@@ -0,0 +1,18 @@
+//
+//  AssociatedTypeDiagnostic.swift
+//  
+//
+//  Created by Alexandr Zalutskiy on 19/10/2023.
+//
+
+import SwiftCompilerPlugin
+import SwiftDiagnostics
+import SwiftSyntax
+
+extension Diagnostic {
+	static func validateAssociatedTypeDecl(_ declaration: AssociatedTypeDeclSyntax) throws {
+		let diagnostic = Diagnostic(node: declaration, message: DiagnosticMessage.associatedtypeIsNotSupported)
+		throw DiagnosticError(diagnostic: diagnostic)
+	}
+}
+

Sources/SwiftMockMacros/Diagnostic/DiagnosticError.swift

@@ -0,0 +1,129 @@
+//
+//  DiagnosticMessage.swift
+//
+//
+//  Created by Alexandr Zalutskiy on 17/10/2023.
+//
+
+import SwiftDiagnostics
+
+struct DiagnosticError: Error {
+	let diagnostic: Diagnostic
+}
+
+enum DiagnosticMessage: String, SwiftDiagnostics.DiagnosticMessage {
+	case notAProtocol
+	case `private`
+	case filePrivate
+	// FIXME: add support for internal protocols
+	case notAPublicProtocol
+	// TODO: support for attributes
+	case attributesIsNotSupported
+	// TODO: support primary associated types
+	case primaryAssociatedTypesIsNotSupported
+	case inheritanceIsNotSupported
+
+	// TODO: support for generic parameters
+	case genericParametersIsNotSupported
+	// TODO: support for rethrows
+	case rethrowsIsNotSupported
+	// TODO: support for reasync
+	case reasyncIsNotSupported
+
+	// TODO: support for associated types
+	case associatedtypeIsNotSupported
+
+	case propertyAccessorsNotSpecified
+	case propertyAccessorMustBeGetOrSet
+	// TODO: support for get async in properties
+	case asyncPropertiesIsNotSupported
+	// TODO: support for get throws in properties
+	case throwsPropertiesIsNotSupported
+
+	case unknownEffectSpecifierInPropertyDeclaration
+
+	var severity: DiagnosticSeverity {
+		switch self {
+		case .notAProtocol:
+			return .error
+		case .private:
+			return .error
+		case .filePrivate:
+			return .error
+		case .notAPublicProtocol:
+			return .error
+		case .attributesIsNotSupported:
+			return .error
+		case .primaryAssociatedTypesIsNotSupported:
+			return .error
+		case .inheritanceIsNotSupported:
+			return .error
+
+		case .genericParametersIsNotSupported:
+			return .error
+		case .rethrowsIsNotSupported:
+			return .error
+		case .reasyncIsNotSupported:
+			return .error
+
+		case .associatedtypeIsNotSupported:
+			return .error
+
+		case .propertyAccessorsNotSpecified:
+			return .error
+		case .propertyAccessorMustBeGetOrSet:
+			return .error
+		case .asyncPropertiesIsNotSupported:
+			return .error
+		case .throwsPropertiesIsNotSupported:
+			return .error
+		case .unknownEffectSpecifierInPropertyDeclaration:
+			return .error
+		}
+	}
+
+	var message: String {
+		switch self {
+		case .notAProtocol:
+			return "'@Mock' can only be applied to a 'protocol'"
+		case .private:
+			return "'@Mock' cannot be applied to a 'private protocol'"
+		case .filePrivate:
+			return "'@Mock' cannot be applied to a 'fileprivate protocol'"
+		case .notAPublicProtocol:
+			return "'@Mock' can only be applied to a 'public protocol'"
+		case .attributesIsNotSupported:
+			return "'@Mock' doesn't support attributes"
+		case .primaryAssociatedTypesIsNotSupported:
+			return "'@Mock' cannot be applied to a 'protocol' with primary associated types"
+		case .inheritanceIsNotSupported:
+			return "'@Mock' can only be applied to a non-inherited 'protocol'"
+
+		case .genericParametersIsNotSupported:
+			return "'@Mock' doesn't support generic parameters"
+		case .rethrowsIsNotSupported:
+			return "'@Mock' doesn't support rethrows methods"
+		case .reasyncIsNotSupported:
+			return "'@Mock' doesn't support reasync methods"
+
+		case .associatedtypeIsNotSupported:
+			return "'@Mock' doesn't support associatedtypes"
+
+		case .propertyAccessorsNotSpecified:
+			return "Property in protocol must have explicit { get } or { get set } specifier"
+		case .propertyAccessorMustBeGetOrSet:
+			return "Expected get or set in a protocol property"
+
+		case .asyncPropertiesIsNotSupported:
+			return "'@Mock' doesn't support async properties"
+		case .throwsPropertiesIsNotSupported:
+			return "'@Mock' doesn't support throws properties"
+		case .unknownEffectSpecifierInPropertyDeclaration:
+			return "'@Mock' found unknown effect specifier in property declaration, please report in issue in GitHub"
+		}
+	}
+
+	var diagnosticID: MessageID {
+		MessageID(domain: "SwiftMockMacros", id: rawValue)
+	}
+}

Sources/SwiftMockMacros/Diagnostic/FunctionDiagnostic.swift

@@ -0,0 +1,36 @@
+//
+//  FunctionDiagnostic.swift
+//  
+//
+//  Created by Alexandr Zalutskiy on 18/10/2023.
+//
+
+import SwiftCompilerPlugin
+import SwiftDiagnostics
+import SwiftSyntax
+
+extension Diagnostic {
+	static func validateFunctionDecl(_ declaration: FunctionDeclSyntax) throws {
+		if let attribute = declaration.attributes.first {
+			let diagnostic = Diagnostic(node: attribute, message: DiagnosticMessage.attributesIsNotSupported)
+			throw DiagnosticError(diagnostic: diagnostic)
+		}
+
+		if let genericParameterClause = declaration.genericParameterClause {
+			let diagnostic = Diagnostic(node: genericParameterClause, message: DiagnosticMessage.genericParametersIsNotSupported)
+			throw DiagnosticError(diagnostic: diagnostic)
+		}
+
+		if let effectSpecifiers = declaration.signature.effectSpecifiers {
+			if let asyncSpecifier = effectSpecifiers.asyncSpecifier, asyncSpecifier.isReasync {
+				let diagnostic = Diagnostic(node: asyncSpecifier, message: DiagnosticMessage.reasyncIsNotSupported)
+				throw DiagnosticError(diagnostic: diagnostic)
+			}
+
+			if let throwsSpecifier = effectSpecifiers.throwsSpecifier, throwsSpecifier.isRethrows {
+				let diagnostic = Diagnostic(node: throwsSpecifier, message: DiagnosticMessage.rethrowsIsNotSupported)
+				throw DiagnosticError(diagnostic: diagnostic)
+			}
+		}
+	}
+}

Sources/SwiftMockMacros/Diagnostic/PropertyDiagnostic.swift

@@ -0,0 +1,51 @@
+//
+//  PropertyDiagnostic.swift
+//
+//
+//  Created by Alexandr Zalutskiy on 19/10/2023.
+//
+
+import SwiftCompilerPlugin
+import SwiftDiagnostics
+import SwiftSyntax
+
+extension Diagnostic {
+	static func validatePropertyDeclaration(_ declaration: VariableDeclSyntax) throws {
+		for binding in declaration.bindings {
+			// Protocols must contains accessor block by language design
+			guard let accessorBlock = binding.accessorBlock else {
+				let diagnostic = Diagnostic(node: declaration, message: DiagnosticMessage.propertyAccessorsNotSpecified)
+				throw DiagnosticError(diagnostic: diagnostic)
+			}
+			// Protocols must contains accessor block by language design
+			guard case let .`accessors`(accessorList) = accessorBlock.accessors else {
+				let diagnostic = Diagnostic(
+					node: declaration,
+					message: DiagnosticMessage.propertyAccessorsNotSpecified
+				)
+				throw DiagnosticError(diagnostic: diagnostic)
+			}
+
+			for accessorDecl in accessorList {
+				let accessorSpecifier = accessorDecl.accessorSpecifier
+				guard accessorSpecifier.isGet || accessorSpecifier.isSet else {
+					let diagnostic = Diagnostic(node: accessorSpecifier, message: DiagnosticMessage.propertyAccessorMustBeGetOrSet)
+					throw DiagnosticError(diagnostic: diagnostic)
+				}
+
+				if let effectSpecifiers = accessorDecl.effectSpecifiers {
+					if let asyncSpecifier = effectSpecifiers.asyncSpecifier {
+						let diagnostic = Diagnostic(node: asyncSpecifier, message: DiagnosticMessage.asyncPropertiesIsNotSupported)
+						throw DiagnosticError(diagnostic: diagnostic)
+					}
+					if let throwsSpecifier = effectSpecifiers.throwsSpecifier {
+						let diagnostic = Diagnostic(node: throwsSpecifier, message: DiagnosticMessage.throwsPropertiesIsNotSupported)
+						throw DiagnosticError(diagnostic: diagnostic)
+					}
+					let diagnostic = Diagnostic(node: effectSpecifiers, message: DiagnosticMessage.unknownEffectSpecifierInPropertyDeclaration)
+					throw DiagnosticError(diagnostic: diagnostic)
+				}
+			}
+		}
+	}
+}

Sources/SwiftMockMacros/Diagnostic/ProtocolDiagnostic.swift

@@ -0,0 +1,84 @@
+//
+//  ProtocolDiagnostic.swift
+//
+//
+//  Created by Alexandr Zalutskiy on 18/10/2023.
+//
+
+import SwiftCompilerPlugin
+import SwiftDiagnostics
+import SwiftSyntax
+
+extension Diagnostic {
+	static func extractProtocolDecl(_ declaration: some DeclSyntaxProtocol) throws -> ProtocolDeclSyntax {
+		guard let declaration = declaration.as(ProtocolDeclSyntax.self) else {
+			let diagnostic = Diagnostic(node: declaration, message: DiagnosticMessage.notAProtocol)
+			throw DiagnosticError(diagnostic: diagnostic)
+		}
+
+		return declaration
+	}
+
+	static func validateProtocolDecl(_ declaration: ProtocolDeclSyntax) throws {
+		if let modifier = declaration.modifiers.first(where: { $0.name.text == privateModifier.name.text }) {
+			let diagnostic = Diagnostic(node: modifier, message: DiagnosticMessage.private)
+			throw DiagnosticError(diagnostic: diagnostic)
+		}
+		if let modifier = declaration.modifiers.first(where: { $0.name.text == fileprivateModifier.name.text }) {
+			let diagnostic = Diagnostic(node: modifier, message: DiagnosticMessage.filePrivate)
+			throw DiagnosticError(diagnostic: diagnostic)
+		}
+
+		// Start
+		// FIXME: add support for internal protocols
+		// They can be used using `@testable import`
+		if !declaration.modifiers.contains(where: { $0.name.text == publicModifier.name.text }) {
+			if let modifier = declaration.modifiers.first {
+				let diagnostic = Diagnostic(node: modifier, message: DiagnosticMessage.notAPublicProtocol)
+				throw DiagnosticError(diagnostic: diagnostic)
+			} else {
+				let diagnostic = Diagnostic(node: declaration.protocolKeyword, message: DiagnosticMessage.notAPublicProtocol)
+				throw DiagnosticError(diagnostic: diagnostic)
+			}
+		}
+		// End
+
+		// TODO: support for attributes
+		if let attribute = declaration.attributes.first(where: { !$0.isMock }) {
+			let diagnostic = Diagnostic(node: attribute, message: DiagnosticMessage.attributesIsNotSupported)
+			throw DiagnosticError(diagnostic: diagnostic)
+		}
+
+		// TODO: support for primary associated types
+		if let primaryAssociatedTypeClause = declaration.primaryAssociatedTypeClause {
+			let diagnostic = Diagnostic(node: primaryAssociatedTypeClause, message: DiagnosticMessage.primaryAssociatedTypesIsNotSupported)
+			throw DiagnosticError(diagnostic: diagnostic)
+		}
+
+		if let inheritanceClause = declaration.inheritanceClause, inheritanceClause.inheritedTypes.contains(where: { !$0.type.isAnyObject }) {
+			let diagnostic = Diagnostic(node: inheritanceClause, message: DiagnosticMessage.inheritanceIsNotSupported)
+			throw DiagnosticError(diagnostic: diagnostic)
+		}
+
+		for member in declaration.memberBlock.members {
+			if let functionDecl = member.decl.as(FunctionDeclSyntax.self) {
+				try Diagnostic.validateFunctionDecl(functionDecl)
+			} else if let associatedTypeDecl = member.decl.as(AssociatedTypeDeclSyntax.self) {
+				try Diagnostic.validateAssociatedTypeDecl(associatedTypeDecl)
+			} else if let variableDeclaration = member.decl.as(VariableDeclSyntax.self) {
+				try Diagnostic.validatePropertyDeclaration(variableDeclaration)
+			}
+		}
+	}
+}
+
+private extension AttributeListSyntax.Element {
+	var isMock: Bool {
+		switch self {
+		case .attribute(let attribute):
+			return attribute.attributeName.isMock
+		case .ifConfigDecl:
+			return false
+		}
+	}
+}