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artemcmartemcm
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Merge pull request #3174 from artemcm/WarningControlScopes
Add 'SwiftWarningControl' library for source-level lexical warning group behavior settings
2 parents ef033f4 + a92c94c commit bd53a85

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‎.spi.yml‎

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@@ -18,6 +18,7 @@ builder:
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- SwiftParser
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- SwiftParserDiagnostics
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- SwiftRefactor
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- SwiftWarningControl
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- SwiftSyntaxBuilder
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- SwiftSyntaxMacros
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- SwiftSyntaxMacroExpansion

‎Package.swift‎

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@@ -29,6 +29,7 @@ if buildDynamicLibrary {
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.library(name: "SwiftDiagnostics", targets: ["SwiftDiagnostics"]),
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.library(name: "SwiftIDEUtils", targets: ["SwiftIDEUtils"]),
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.library(name: "SwiftIfConfig", targets: ["SwiftIfConfig"]),
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.library(name: "SwiftWarningControl", targets: ["SwiftWarningControl"]),
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.library(name: "SwiftLexicalLookup", targets: ["SwiftLexicalLookup"]),
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.library(name: "SwiftOperators", targets: ["SwiftOperators"]),
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.library(name: "SwiftParser", targets: ["SwiftParser"]),
@@ -180,6 +181,24 @@ let package = Package(
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]
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),
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// MARK: SwiftWarningControl
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.target(
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name: "SwiftWarningControl",
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dependencies: ["SwiftSyntax", "SwiftParser"],
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exclude: ["CMakeLists.txt"]
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),
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.testTarget(
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name: "SwiftWarningControlTest",
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dependencies: [
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"_SwiftSyntaxTestSupport",
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"SwiftWarningControl",
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"SwiftParser",
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"SwiftSyntaxMacrosGenericTestSupport",
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]
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),
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// MARK: SwiftLexicalLookup
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.target(

‎Sources/CMakeLists.txt‎

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@@ -24,4 +24,5 @@ add_subdirectory(SwiftSyntaxMacroExpansion)
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add_subdirectory(SwiftCompilerPluginMessageHandling)
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add_subdirectory(SwiftIDEUtils)
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add_subdirectory(SwiftCompilerPlugin)
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add_subdirectory(SwiftWarningControl)
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add_subdirectory(VersionMarkerModules)

‎Sources/SwiftWarningControl/CMakeLists.txt‎

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# This source file is part of the Swift.org open source project
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#
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# Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
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# Licensed under Apache License v2.0 with Runtime Library Exception
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#
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# See http://swift.org/LICENSE.txt for license information
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# See http://swift.org/CONTRIBUTORS.txt for Swift project authors
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add_swift_syntax_library(SwiftWarningControl
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WarningGroupBehavior.swift
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WarningControlDeclSyntax.swift
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WarningControlRegionBuilder.swift
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WarningControlRegions.swift
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SyntaxProtocol+WarningControl.swift
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)
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target_link_swift_syntax_libraries(SwiftWarningControl PUBLIC
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SwiftSyntax
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SwiftParser)

‎Sources/SwiftWarningControl/SwiftWarningControl.md‎

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# SwiftWarningControl
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A library to evaluate `@warn` diagnostic group controls within a Swift syntax tree.
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## Overview
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Swift provides a mechanism to control the behavior of specific diagnostic groups for a given declaration's lexical scope with the `@warn` attribute.
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The syntax tree and its parser do not reason about warning group controls. The syntax tree produced by the parser represents the `@warn` attribute in a generic fashion, as it would any other basic attribute on a declaration. The per-declaration nature of the attribute means that for any given lexical scope, the behavior of a given diagnostic group can be queried by checking for the presence of this attribute in its parent declaration scope.
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```swift
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@warn(Deprecate, as: error)
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func foo() {
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...
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@warn(Deprecate, as: warning)
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func bar() {
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...
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@warn("Deprecate", as: ignored, reason: "Foo")
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func baz() {
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...
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}
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}
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}
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```
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The `SwiftWarningControl` library provides a utility to determine, for a given source location and diagnostic group identifier, whether or not its behavior is affected by an `@warn` attribute of any of its parent declaration scope.
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* `SyntaxProtocol.getWarningGroupControl(for diagnosticGroupIdentifier:)` produces the behavior specifier (`WarningGroupBehavior`: `error`, `warning`, `ignored`) which applies at this node.
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* `SyntaxProtocol.warningGroupControlRegionTree` holds a computed `WarningControlRegionTree` data structure value that can be used to efficiently test for the specified `WarningGroupBehavior` at a given source location and a given diagnostic group.

‎Sources/SwiftWarningControl/SyntaxProtocol+WarningControl.swift‎

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//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import SwiftDiagnostics
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import SwiftSyntax
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extension SyntaxProtocol {
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/// Get the warning emission behavior for the specified diagnostic group
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/// by determining its containing `WarningControlRegion`, if one is present.
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@_spi(ExperimentalLanguageFeatures)
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public func warningGroupBehavior(
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for diagnosticGroupIdentifier: DiagnosticGroupIdentifier
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) -> WarningGroupBehavior? {
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let warningControlRegions = root.warningGroupControlRegionTreeImpl(containing: self.position)
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return warningControlRegions.warningGroupBehavior(at: self.position, for: diagnosticGroupIdentifier)
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}
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}

‎Sources/SwiftWarningControl/WarningControlDeclSyntax.swift‎

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//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import SwiftSyntax
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extension WithAttributesSyntax {
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/// Compute a dictionary of all `@warn` diagnostic group behaviors
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/// specified on this warning control declaration scope.
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var allWarningGroupControls: [DiagnosticGroupIdentifier: WarningGroupBehavior] {
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attributes.reduce(into: [DiagnosticGroupIdentifier: WarningGroupBehavior]()) { result, attr in
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// `@warn` attributes
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guard case .attribute(let attributeSyntax) = attr,
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attributeSyntax.attributeName.as(IdentifierTypeSyntax.self)?.name.text == "warn"
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else {
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return
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}
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// First argument is the unquoted diagnostic group identifier
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guard
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let diagnosticGroupID = attributeSyntax.arguments?
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.as(LabeledExprListSyntax.self)?.first?.expression
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.as(DeclReferenceExprSyntax.self)?.baseName.text
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else {
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return
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}
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// Second argument is the `as: ` behavior specifier
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guard
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let asParamExprSyntax = attributeSyntax
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.arguments?.as(LabeledExprListSyntax.self)?
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.dropFirst().first
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else {
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return
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}
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guard
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asParamExprSyntax.label?.text == "as",
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let behaviorText = asParamExprSyntax
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.expression.as(DeclReferenceExprSyntax.self)?
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.baseName.text,
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let behavior = WarningGroupBehavior(rawValue: behaviorText)
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else {
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return
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}
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result[DiagnosticGroupIdentifier(diagnosticGroupID)] = behavior
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}
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}
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}

‎Sources/SwiftWarningControl/WarningControlRegionBuilder.swift‎

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//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift.org open source project
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//
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// Copyright (c) 2014 - 2025 Apple Inc. and the Swift project authors
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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import SwiftSyntax
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/// Compute the full set of warning control regions in this syntax node
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extension SyntaxProtocol {
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@_spi(ExperimentalLanguageFeatures)
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public func warningGroupControlRegionTree() -> WarningControlRegionTree {
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return warningGroupControlRegionTreeImpl()
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}
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/// Implementation of constructing a region tree with an optional parameter
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/// to specify that the constructed tree must only contain nodes which contain
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/// a specific absolute position - meant to speed up tree generation for individual
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/// queries.
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func warningGroupControlRegionTreeImpl(containing position: AbsolutePosition? = nil) -> WarningControlRegionTree {
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let visitor = WarningControlRegionVisitor(self.range, containing: position)
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visitor.walk(self)
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return visitor.tree
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}
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}
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/// Add this warning control decl syntax node warning group controls (as specified with `@warn`)
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/// to the tree.
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extension WarningControlRegionTree {
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mutating func addWarningControlRegions(for syntax: some WithAttributesSyntax) {
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addWarningGroupControls(
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range: syntax.range,
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controls: syntax.allWarningGroupControls
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)
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}
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}
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/// Helper class that walks a syntax tree looking for warning behavior control regions.
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private class WarningControlRegionVisitor: SyntaxAnyVisitor {
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/// The tree of warning control regions we have found so far
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var tree: WarningControlRegionTree
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let containingPosition: AbsolutePosition?
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init(_ topLevelRange: Range<AbsolutePosition>, containing position: AbsolutePosition? = nil) {
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self.tree = WarningControlRegionTree(range: topLevelRange)
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containingPosition = position
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super.init(viewMode: .fixedUp)
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}
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override func visitAny(_ node: Syntax) -> SyntaxVisitorContinueKind {
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if let containingPosition,
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!node.range.contains(containingPosition)
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{
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return .skipChildren
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}
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if let withAttributesSyntax = node.asProtocol(WithAttributesSyntax.self) {
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tree.addWarningControlRegions(for: withAttributesSyntax)
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}
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return .visitChildren
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}
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}

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