Remove string literal tags. (#420)

As discussed [in the forums](https://forums.swift.org/t/removal-of-string-literal-tag-definitions/71667),
we are removing string literal tags. This PR removes the interfaces for
them. It preserves `Tag.Kind` because that may prove to be a useful
abstraction in the future, e.g. if we come up with a new kind of tag
that isn't a member of `Tag`.

Resolves rdar://125730118.

### Checklist:

- [x] Code and documentation should follow the style of the [Style
Guide](https://github.com/apple/swift-testing/blob/main/Documentation/StyleGuide.md).
- [x] If public symbols are renamed or modified, DocC references should
be updated.

Author: grynspan

Sources/Testing/Testing.docc/AddingTags.md

@@ -26,8 +26,8 @@ source files, and even test targets.
 
 ## Add a tag
 
-To add a tag to a test, use the ``Trait/tags(_:)-505n9`` trait. This trait takes
-a sequence of tags as its argument, and those tags are then applied to the
+To add a tag to a test, use the ``Trait/tags(_:)`` trait. This trait takes a
+sequence of tags as its argument, and those tags are then applied to the
 corresponding test at runtime. If any tags are applied to a test suite, then all
 tests in that suite inherit those tags.
 

Sources/Testing/Testing.docc/DefiningTests.md

@@ -65,7 +65,7 @@ line, supply a string literal as an argument to the `@Test` attribute:
 ```
 
 To further customize the appearance and behavior of a test function, use
- [traits](doc:Traits) such as ``Trait/tags(_:)-505n9``.
+[traits](doc:Traits) such as ``Trait/tags(_:)``.
 
 ### Write concurrent or throwing tests
 

Sources/Testing/Testing.docc/OrganizingTests.md

@@ -27,9 +27,9 @@ A test function can be added to a test suite in one of two ways:
 The `@Suite` attribute isn't required for the testing library to recognize that
 a type contains test functions, but adding it allows customization of a test
 suite's appearance in the IDE and at the command line. If a trait such as
-``Trait/tags(_:)-505n9`` or ``Trait/disabled(_:fileID:filePath:line:column:)``
-is applied to a test suite, it's automatically inherited by the tests contained
-in the suite.
+``Trait/tags(_:)`` or ``Trait/disabled(_:fileID:filePath:line:column:)`` is
+applied to a test suite, it's automatically inherited by the tests contained in
+the suite.
 
 In addition to containing test functions and any other members that a Swift type
 might contain, test suite types can also contain additional test suites nested
@@ -51,7 +51,7 @@ To customize a test suite's name, supply a string literal as an argument to the
 ```
 
 To further customize the appearance and behavior of a test function, use
- [traits](doc:Traits) such as ``Trait/tags(_:)-505n9``.
+[traits](doc:Traits) such as ``Trait/tags(_:)``.
 
 ## Test functions in test suite types
 

Sources/Testing/Testing.docc/Traits/Trait.md

@@ -26,8 +26,7 @@ See https://swift.org/CONTRIBUTORS.txt for Swift project authors
 
 ### Categorizing tests
 
-- ``Trait/tags(_:)-505n9``
-- ``Trait/tags(_:)-yg0i``
+- ``Trait/tags(_:)``
 
 ### Associating bugs
 

Sources/Testing/Traits/Tags/Tag.List.swift

@@ -11,10 +11,7 @@
 extension Tag {
   /// A type representing one or more tags applied to a test.
   ///
-  /// To add this trait to a test, use one of the following functions:
-  ///
-  /// - ``Trait/tags(_:)-505n9``
-  /// - ``Trait/tags(_:)-yg0i``
+  /// To add this trait to a test, use the ``Trait/tags(_:)`` function.
   public struct List {
     /// The list of tags contained in this instance.
     ///
@@ -66,27 +63,4 @@ extension Trait where Self == Tag.List {
   public static func tags(_ tags: Tag...) -> Self {
     Self(tags: tags)
   }
-
-  /// Construct a list of tags to apply to a test from a list of string values.
-  ///
-  /// - Parameters:
-  ///   - stringValues: The list of string values to convert to tags and apply
-  ///     to the test.
-  ///
-  /// - Returns: An instance of ``Tag/List`` containing the specified string
-  ///   literals as tags.
-  ///
-  /// This function is provided as a convenience to allow specifying tags as
-  /// string values. To specify a mix of tags identified by symbol (such as
-  /// `.example`) and tags identified by string value (such as `"important"`),
-  /// use two separate calls to this function and pass symbols separately from
-  /// string values:
-  ///
-  /// ```swift
-  /// @Test("Wheels spin", .tags("mechanical"), .tags(.critical))
-  /// func wheelsSpin() {}
-  /// ```
-  public static func tags(_ stringValues: _const String...) -> Self {
-    Self(tags: stringValues.map { Tag(kind: .stringLiteral($0)) })
-  }
 }

Sources/Testing/Traits/Tags/Tag.swift

@@ -10,10 +10,7 @@
 
 /// A type representing a tag that can be applied to a test.
 ///
-/// To apply tags to a test, use one of the following functions:
-///
-/// - ``Trait/tags(_:)-505n9``
-/// - ``Trait/tags(_:)-yg0i``
+/// To apply tags to a test, use the ``Trait/tags(_:)`` function.
 public struct Tag: Sendable {
   /// An enumeration describing the various kinds of tag that can be applied to
   /// a test.
@@ -26,12 +23,6 @@ public struct Tag: Sendable {
     ///   - name: The (almost) fully-qualified name of the static member. The
     ///     leading `"Testing.Tag."` is not included as it is redundant.
     case staticMember(_ name: String)
-
-    /// The tag is a string literal declared directly in source.
-    ///
-    /// - Parameters:
-    ///   - stringLiteral: The string literal specified by the test author.
-    case stringLiteral(_ stringLiteral: String)
   }
 
   /// The kind of this tag.
@@ -51,8 +42,8 @@ public struct Tag: Sendable {
   ///
   /// Use this initializer when a user has provided an arbitrary string and it
   /// is necessary to convert it into a tag. A simple heuristic is applied such
-  /// that the resulting instance may represent a (possibly non-existent) static
-  /// member of ``Tag`` or may represent a string literal.
+  /// that the resulting instance will represent a (possibly non-existent)
+  /// static member of ``Tag``.
   @_spi(ForToolsIntegrationOnly)
   public init(userProvidedStringValue stringValue: String) {
     self.init(_codableStringValue: stringValue)
@@ -66,8 +57,6 @@ extension Tag: CustomStringConvertible {
     switch kind {
     case let .staticMember(name):
       ".\(name)"
-    case let .stringLiteral(stringLiteral):
-      #""\#(stringLiteral)""#
     }
   }
 }
@@ -79,14 +68,6 @@ extension Tag: Equatable, Hashable, Comparable {
     switch (lhs.kind, rhs.kind) {
     case let (.staticMember(lhs), .staticMember(rhs)):
       lhs < rhs
-    case let (.stringLiteral(lhs), .stringLiteral(rhs)):
-      lhs < rhs
-
-    // (Arbitrarily) sort static members before string literals.
-    case (.staticMember, .stringLiteral):
-      true
-    case (.stringLiteral, .staticMember):
-      false
     }
   }
 }
@@ -102,10 +83,8 @@ extension Tag: Codable, CodingKeyRepresentable {
   private init(_codableStringValue stringValue: String) {
     if stringValue.first == "." {
       self.init(kind: .staticMember(String(stringValue.dropFirst())))
-    } else if stringValue.first == #"\"# {
-      self.init(kind: .stringLiteral(String(stringValue.dropFirst())))
     } else {
-      self.init(kind: .stringLiteral(stringValue))
+      self.init(kind: .staticMember(stringValue))
     }
   }
 
@@ -119,12 +98,6 @@ extension Tag: Codable, CodingKeyRepresentable {
     switch kind {
     case let .staticMember(name):
       ".\(name)"
-    case let .stringLiteral(stringLiteral):
-      if stringLiteral.first == "." || stringLiteral.first == #"\"# {
-        #"\\#(stringLiteral)"#
-      } else {
-        stringLiteral
-      }
     }
   }
 
@@ -165,10 +138,7 @@ extension Tag: Codable, CodingKeyRepresentable {
 extension Test {
   /// The complete, unique set of tags associated with this test.
   ///
-  /// Tags are associated with tests using one of the following functions:
-  ///
-  /// - ``Trait/tags(_:)-505n9``
-  /// - ``Trait/tags(_:)-yg0i``
+  /// Tags are associated with tests using the ``Trait/tags(_:)`` function.
   public var tags: Set<Tag> {
     traits.lazy
       .compactMap { $0 as? Tag.List }

Tests/TestingTests/MiscellaneousTests.swift

@@ -35,7 +35,7 @@
 }
 
 @`Suite`(.hidden) struct `SuiteWithBackticks` {
-  @`Test`(.hidden, .`tags`("tag")) func `testWithBackticks`() {
+  @`Test`(.hidden, .`tags`(.namedConstant)) func `testWithBackticks`() {
     #`expect`(Bool(true))
   }
 }
@@ -78,9 +78,9 @@ struct SendableTests: Sendable {
   @Test(.hidden, arguments: FixtureData.zeroUpTo100)
   static func `reserved1`(`reserved2`: Int) async throws {}
 
-  @Suite(.hidden, .tags("tag-1"))
+  @Suite(.hidden, .tags(.namedConstant))
   struct NestedSendableTests: Sendable {
-    @Test(.hidden, .tags("tag-2"))
+    @Test(.hidden, .tags(.anotherConstant))
     func succeeds() throws {}
 
     @Test(.hidden)

Tests/TestingTests/PlanTests.swift

@@ -116,7 +116,7 @@ struct PlanTests {
     ]
 
     var configuration = Configuration()
-    var filter = Configuration.TestFilter(includingAnyOf: [Tag("tag-1"), Tag("tag-2")])
+    var filter = Configuration.TestFilter(includingAnyOf: [.namedConstant, .anotherConstant])
     filter.includeHiddenTests = true
     configuration.testFilter = filter
 
@@ -146,7 +146,7 @@ struct PlanTests {
     ]
 
     var configuration = Configuration()
-    var filter = Configuration.TestFilter(includingAllOf: [Tag("tag-1"), Tag("tag-2")])
+    var filter = Configuration.TestFilter(includingAllOf: [.namedConstant, .anotherConstant])
     filter.includeHiddenTests = true
     configuration.testFilter = filter
 
@@ -176,7 +176,7 @@ struct PlanTests {
     ]
 
     var configuration = Configuration()
-    var filter = Configuration.TestFilter(excludingAnyOf: [Tag("tag-1"), Tag("tag-2")])
+    var filter = Configuration.TestFilter(excludingAnyOf: [.namedConstant, .anotherConstant])
     filter.includeHiddenTests = true
     configuration.testFilter = filter
 
@@ -206,7 +206,7 @@ struct PlanTests {
     ]
 
     var configuration = Configuration()
-    var filter = Configuration.TestFilter(excludingAllOf: [Tag("tag-1"), Tag("tag-2")])
+    var filter = Configuration.TestFilter(excludingAllOf: [.namedConstant, .anotherConstant])
     filter.includeHiddenTests = true
     configuration.testFilter = filter
 
@@ -356,7 +356,7 @@ struct PlanTests {
     var configuration = Configuration()
     let selection = [testA.id]
     var testFilter = Configuration.TestFilter(including: selection)
-    testFilter.combine(with: .init(includingAnyOf: [Tag("tag-2")]), using: .or)
+    testFilter.combine(with: .init(includingAnyOf: [.anotherConstant]), using: .or)
     testFilter.includeHiddenTests = true
     configuration.testFilter = testFilter
 

Tests/TestingTests/Traits/ParallelizationTraitTests.swift

@@ -10,7 +10,7 @@
 
 @testable @_spi(Experimental) @_spi(ForToolsIntegrationOnly) import Testing
 
-@Suite("Parallelization Trait Tests", .tags("trait"))
+@Suite("Parallelization Trait Tests", .tags(.traitRelated))
 struct ParallelizationTraitTests {
   @Test(".serialized trait is recursively applied")
   func serializedTrait() async {