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//===----------------------------------------------------------------------===//
//
// This source file is part of the Swift.org open source project
//
// Copyright (c) 2014 - 2024 Apple Inc. and the Swift project authors
// Licensed under Apache License v2.0 with Runtime Library Exception
//
// See https://swift.org/LICENSE.txt for license information
// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
//
//===----------------------------------------------------------------------===//
#if swift(>=6)
internal import SwiftDiagnostics
public import SwiftSyntax
#else
import SwiftDiagnostics
import SwiftSyntax
#endif
enum DeclReferenceError: DiagnosticMessage {
case nonLiteral
var message: String {
switch self {
case .nonLiteral:
return "only literals are permitted"
}
}
var diagnosticID: MessageID {
.init(domain: "SwiftMacros", id: "\(self)")
}
var severity: DiagnosticSeverity {
.error
}
}
/// Check sub-expressions to ensure all expressions are literals, and call
/// `diagnoseNonLiteral` for all other expressions.
class OnlyLiteralExprChecker: SyntaxAnyVisitor {
var diagnostics: [Diagnostic] = []
init() {
super.init(viewMode: .fixedUp)
}
// Integer literals
override func visit(_ node: IntegerLiteralExprSyntax) -> SyntaxVisitorContinueKind {
.visitChildren
}
// Floating point literals
override func visit(_ node: FloatLiteralExprSyntax) -> SyntaxVisitorContinueKind {
.visitChildren
}
// Negative numbers
override func visit(_ node: PrefixOperatorExprSyntax) -> SyntaxVisitorContinueKind {
switch node.operator.tokenKind {
case .prefixOperator("-")
// only allow negation on numbers, not other literal types
where node.expression.is(IntegerLiteralExprSyntax.self)
|| node.expression.is(FloatLiteralExprSyntax.self):
return .visitChildren
default:
return diagnoseNonLiteral(node)
}
}
// Bool literals
override func visit(_ node: BooleanLiteralExprSyntax) -> SyntaxVisitorContinueKind {
.visitChildren
}
// nil literals
override func visit(_ node: NilLiteralExprSyntax) -> SyntaxVisitorContinueKind {
.visitChildren
}
// String literals
override func visit(_ node: StringLiteralExprSyntax) -> SyntaxVisitorContinueKind {
.visitChildren
}
// String interpolation
override func visit(_ node: StringLiteralSegmentListSyntax) -> SyntaxVisitorContinueKind {
guard node.count == 1,
case .stringSegment = node.first!
else {
return diagnoseNonLiteral(node)
}
return .visitChildren
}
// Array literals
override func visit(_ node: ArrayExprSyntax) -> SyntaxVisitorContinueKind {
.visitChildren
}
// Dictionary literals
override func visit(_ node: DictionaryExprSyntax) -> SyntaxVisitorContinueKind {
.visitChildren
}
// Tuple literals
override func visit(_ node: TupleExprSyntax) -> SyntaxVisitorContinueKind {
.visitChildren
}
// Regex literals
override func visit(_ node: RegexLiteralExprSyntax) -> SyntaxVisitorContinueKind {
.visitChildren
}
// Macro uses.
override func visit(_ node: MacroExpansionExprSyntax) -> SyntaxVisitorContinueKind {
.visitChildren
}
// References to declarations.
override func visit(_ node: DeclReferenceExprSyntax) -> SyntaxVisitorContinueKind {
return diagnoseNonLiteral(node)
}
override func visitAny(_ node: Syntax) -> SyntaxVisitorContinueKind {
if node.is(ExprSyntax.self) {
// We have an expression that is not one of the allowed forms, so
// diagnose it.
return diagnoseNonLiteral(node)
}
return .visitChildren
}
func diagnoseNonLiteral(_ node: some SyntaxProtocol) -> SyntaxVisitorContinueKind {
diagnostics.append(
Diagnostic(
node: node,
message: DeclReferenceError.nonLiteral
)
)
return .skipChildren
}
}
extension MacroExpansionExprSyntax {
/// For compiler to check a macro expression used as default argument.
///
/// Only literals are permitted as arguments to these expressions.
///
/// If there are diagnostics, they will be wrapped into an error and thrown.
@_spi(Compiler)
public func checkDefaultArgumentMacroExpression() throws {
let visitor = OnlyLiteralExprChecker()
visitor.walk(arguments)
if !visitor.diagnostics.isEmpty {
throw DiagnosticsError(diagnostics: visitor.diagnostics)
}
}
}
|
