diff --git a/.github/workflows/pull_request.yml b/.github/workflows/pull_request.yml
index 5a1eedb8ec8..fd8e6f14272 100644
--- a/.github/workflows/pull_request.yml
+++ b/.github/workflows/pull_request.yml
@@ -2,7 +2,7 @@ name: Pull request
 
 on:
   pull_request:
-    types: [opened, reopened, synchronize]
+    types: [opened, reopened, synchronize, ready_for_review]
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
@@ -11,15 +11,20 @@ concurrency:
 jobs:
   tests:
     name: Test
+    # PRs created by GitHub Actions don't kick off further actions (https://github.com/peter-evans/create-pull-request/blob/d57e551ebc1a16dee0b8c9ea6d24dba7627a6e35/docs/concepts-guidelines.md#triggering-further-workflow-runs).
+    # As a workaround, we mark automerge PRs that are created by GitHub actions as draft and trigger the GitHub actions by marking the PR as ready for review. But we don't want to re-trigger testing this when a normal user's PR is marked as ready for review.
+    if: (github.event.action != 'ready_for_review') || (github.event.action == 'ready_for_review' && github.event.pull_request.user.login == 'github-actions[bot]')
     uses: swiftlang/github-workflows/.github/workflows/swift_package_test.yml@main
   soundness:
     name: Soundness
+    if: (github.event.action != 'ready_for_review') || (github.event.action == 'ready_for_review' && github.event.pull_request.user.login == 'github-actions[bot]')
     uses: swiftlang/github-workflows/.github/workflows/soundness.yml@main
     with:
       api_breakage_check_enabled: false  # https://github.com/swiftlang/swift-syntax/issues/3010
       docs_check_additional_arguments: "--disable-parameters-and-returns-validation"
   verify_source_code:
     name: Validate generated code
+    if: (github.event.action != 'ready_for_review') || (github.event.action == 'ready_for_review' && github.event.pull_request.user.login == 'github-actions[bot]')
     runs-on: ubuntu-latest
     container:
       image: swift:latest
@@ -32,6 +37,7 @@ jobs:
         run: "./swift-syntax-dev-utils verify-source-code --toolchain /usr"
   test_using_swift_syntax_dev_utils_linux:
     name: Run tests using swift-syntax-dev-utils (Linux)
+    if: (github.event.action != 'ready_for_review') || (github.event.action == 'ready_for_review' && github.event.pull_request.user.login == 'github-actions[bot]')
     runs-on: ubuntu-latest
     container:
       image: swift:latest
@@ -44,6 +50,7 @@ jobs:
         run: "./swift-syntax-dev-utils test --enable-rawsyntax-validation --enable-test-fuzzing --toolchain /usr"
   test_using_swift_syntax_dev_utils_windows:
     name: Run tests using swift-syntax-dev-utils (Windows)
+    if: (github.event.action != 'ready_for_review') || (github.event.action == 'ready_for_review' && github.event.pull_request.user.login == 'github-actions[bot]')
     runs-on: windows-2022
     steps:
       - name: Pull Docker image
diff --git a/Sources/SwiftParser/Attributes.swift b/Sources/SwiftParser/Attributes.swift
index 2f066fd6c39..3cfc6ae801d 100644
--- a/Sources/SwiftParser/Attributes.swift
+++ b/Sources/SwiftParser/Attributes.swift
@@ -66,7 +66,7 @@ extension Parser {
       case TokenSpec(._specialize): self = ._specialize
       case TokenSpec(._spi_available): self = ._spi_available
       case TokenSpec(.`rethrows`): self = .rethrows
-      case TokenSpec(.abi) where experimentalFeatures.contains(.abiAttribute): self = .abi
+      case TokenSpec(.abi): self = .abi
       case TokenSpec(.attached): self = .attached
       case TokenSpec(.available): self = .available
       case TokenSpec(.backDeployed): self = .backDeployed
@@ -139,8 +139,12 @@ extension Parser {
   ///   - parseMissingArguments: If provided, called instead of `parseArgument` when an argument list was required but no opening parenthesis was present.
   mutating func parseAttribute(
     argumentMode: AttributeArgumentMode,
-    parseArguments: (inout Parser) -> RawAttributeSyntax.Arguments,
-    parseMissingArguments: ((inout Parser) -> RawAttributeSyntax.Arguments)? = nil
+    parseArguments: (inout Parser) -> (
+      unexpectedBefore: RawUnexpectedNodesSyntax?, arguments: RawAttributeSyntax.Arguments
+    ),
+    parseMissingArguments: (
+      (inout Parser) -> (unexpectedBefore: RawUnexpectedNodesSyntax?, arguments: RawAttributeSyntax.Arguments)
+    )? = nil
   ) -> RawAttributeListSyntax.Element {
     var (unexpectedBeforeAtSign, atSign) = self.expect(.atSign)
     if atSign.trailingTriviaByteLength > 0 || self.currentToken.leadingTriviaByteLength > 0 {
@@ -175,11 +179,12 @@ extension Parser {
         )
         leftParen = leftParen.tokenView.withTokenDiagnostic(tokenDiagnostic: diagnostic, arena: self.arena)
       }
+      let unexpectedBeforeArguments: RawUnexpectedNodesSyntax?
       let argument: RawAttributeSyntax.Arguments
       if let parseMissingArguments, leftParen.presence == .missing {
-        argument = parseMissingArguments(&self)
+        (unexpectedBeforeArguments, argument) = parseMissingArguments(&self)
       } else {
-        argument = parseArguments(&self)
+        (unexpectedBeforeArguments, argument) = parseArguments(&self)
       }
       let (unexpectedBeforeRightParen, rightParen) = self.expect(.rightParen)
       return .attribute(
@@ -189,6 +194,7 @@ extension Parser {
           attributeName: attributeName,
           unexpectedBeforeLeftParen,
           leftParen: leftParen,
+          unexpectedBeforeArguments,
           arguments: argument,
           unexpectedBeforeRightParen,
           rightParen: rightParen,
@@ -224,41 +230,41 @@ extension Parser {
     switch peek(isAtAnyIn: DeclarationAttributeWithSpecialSyntax.self) {
     case .abi:
       return parseAttribute(argumentMode: .required) { parser in
-        return .abiArguments(parser.parseABIAttributeArguments())
+        return parser.parseABIAttributeArguments()
       } parseMissingArguments: { parser in
-        return .abiArguments(parser.parseABIAttributeArguments(missingLParen: true))
+        return parser.parseABIAttributeArguments(missingLParen: true)
       }
     case .available, ._spi_available:
       return parseAttribute(argumentMode: .required) { parser in
-        return .availability(parser.parseAvailabilityArgumentSpecList())
+        return (nil, .availability(parser.parseAvailabilityArgumentSpecList()))
       }
     case .backDeployed, ._backDeploy:
       return parseAttribute(argumentMode: .required) { parser in
-        return .backDeployedArguments(parser.parseBackDeployedAttributeArguments())
+        return (nil, .backDeployedArguments(parser.parseBackDeployedAttributeArguments()))
       }
     case .differentiable:
       return parseAttribute(argumentMode: .required) { parser in
-        return .differentiableArguments(parser.parseDifferentiableAttributeArguments())
+        return (nil, .differentiableArguments(parser.parseDifferentiableAttributeArguments()))
       }
     case .derivative, .transpose:
       return parseAttribute(argumentMode: .required) { parser in
-        return .derivativeRegistrationArguments(parser.parseDerivativeAttributeArguments())
+        return (nil, .derivativeRegistrationArguments(parser.parseDerivativeAttributeArguments()))
       }
     case .objc:
       return parseAttribute(argumentMode: .optional) { parser in
-        return .objCName(parser.parseObjectiveCSelector())
+        return (nil, .objCName(parser.parseObjectiveCSelector()))
       }
     case ._specialize:
       return parseAttribute(argumentMode: .required) { parser in
-        return .specializeArguments(parser.parseSpecializeAttributeArgumentList())
+        return (nil, .specializeArguments(parser.parseSpecializeAttributeArgumentList()))
       }
     case ._dynamicReplacement:
       return parseAttribute(argumentMode: .required) { parser in
-        return .dynamicReplacementArguments(parser.parseDynamicReplacementAttributeArguments())
+        return (nil, .dynamicReplacementArguments(parser.parseDynamicReplacementAttributeArguments()))
       }
     case ._documentation:
       return parseAttribute(argumentMode: .required) { parser in
-        return .documentationArguments(parser.parseDocumentationAttributeArguments())
+        return (nil, .documentationArguments(parser.parseDocumentationAttributeArguments()))
       }
     case ._effects:
       return parseAttribute(argumentMode: .required) { parser in
@@ -268,20 +274,20 @@ extension Parser {
         while !parser.at(.rightParen, .endOfFile) {
           tokens.append(parser.consumeAnyToken())
         }
-        return .effectsArguments(RawEffectsAttributeArgumentListSyntax(elements: tokens, arena: parser.arena))
+        return (nil, .effectsArguments(RawEffectsAttributeArgumentListSyntax(elements: tokens, arena: parser.arena)))
       }
     case ._implements:
       return parseAttribute(argumentMode: .required) { parser in
-        return .implementsArguments(parser.parseImplementsAttributeArguments())
+        return (nil, .implementsArguments(parser.parseImplementsAttributeArguments()))
       }
     case ._originallyDefinedIn:
       return parseAttribute(argumentMode: .required) { parser in
-        return .originallyDefinedInArguments(parser.parseOriginallyDefinedInAttributeArguments())
+        return (nil, .originallyDefinedInArguments(parser.parseOriginallyDefinedInAttributeArguments()))
       }
     case .attached, .freestanding:
       return parseAttribute(argumentMode: .customAttribute) { parser in
         let arguments = parser.parseMacroRoleArguments()
-        return .argumentList(RawLabeledExprListSyntax(elements: arguments, arena: parser.arena))
+        return (nil, .argumentList(RawLabeledExprListSyntax(elements: arguments, arena: parser.arena)))
       }
     case .rethrows:
       let (unexpectedBeforeAtSign, atSign) = self.expect(.atSign)
@@ -308,7 +314,7 @@ extension Parser {
           pattern: .none,
           allowTrailingComma: true
         )
-        return .argumentList(RawLabeledExprListSyntax(elements: arguments, arena: parser.arena))
+        return (nil, .argumentList(RawLabeledExprListSyntax(elements: arguments, arena: parser.arena)))
       }
     }
   }
@@ -786,9 +792,11 @@ extension Parser {
   /// Parse the arguments inside an `@abi(...)` attribute.
   ///
   /// - Parameter missingLParen: `true` if the opening paren for the argument list was missing.
-  mutating func parseABIAttributeArguments(missingLParen: Bool = false) -> RawABIAttributeArgumentsSyntax {
-    func makeMissingProviderArguments(unexpectedBefore: [RawSyntax]) -> RawABIAttributeArgumentsSyntax {
-      return RawABIAttributeArgumentsSyntax(
+  mutating func parseABIAttributeArguments(
+    missingLParen: Bool = false
+  ) -> (RawUnexpectedNodesSyntax?, RawAttributeSyntax.Arguments) {
+    func makeMissingProviderArguments(unexpectedBefore: [RawSyntax]) -> RawAttributeSyntax.Arguments {
+      let args = RawABIAttributeArgumentsSyntax(
         provider: .missing(
           RawMissingDeclSyntax(
             unexpectedBefore.isEmpty ? nil : RawUnexpectedNodesSyntax(elements: unexpectedBefore, arena: self.arena),
@@ -800,6 +808,7 @@ extension Parser {
         ),
         arena: self.arena
       )
+      return .abiArguments(args)
     }
 
     // Consider the three kinds of mistakes we might see here:
@@ -815,16 +824,23 @@ extension Parser {
     // In lieu of that, we judge that recovering gracefully from #3 is more important than #2 and therefore do not even
     // attempt to parse the argument unless we've seen a left paren.
     guard !missingLParen && !self.at(.rightParen) else {
-      return makeMissingProviderArguments(unexpectedBefore: [])
+      return (nil, makeMissingProviderArguments(unexpectedBefore: []))
     }
 
     let decl = parseDeclaration(in: .argumentList)
 
+    guard experimentalFeatures.contains(.abiAttribute) else {
+      return (
+        RawUnexpectedNodesSyntax([decl], arena: self.arena),
+        .argumentList(RawLabeledExprListSyntax(elements: [], arena: self.arena))
+      )
+    }
+
     guard let provider = RawABIAttributeArgumentsSyntax.Provider(decl) else {
-      return makeMissingProviderArguments(unexpectedBefore: [decl.raw])
+      return (nil, makeMissingProviderArguments(unexpectedBefore: [decl.raw]))
     }
 
-    return RawABIAttributeArgumentsSyntax(provider: provider, arena: self.arena)
+    return (nil, .abiArguments(RawABIAttributeArgumentsSyntax(provider: provider, arena: self.arena)))
   }
 }
 
diff --git a/Sources/SwiftParser/Types.swift b/Sources/SwiftParser/Types.swift
index 416f06ddc1f..67c7604ce0f 100644
--- a/Sources/SwiftParser/Types.swift
+++ b/Sources/SwiftParser/Types.swift
@@ -1291,7 +1291,7 @@ extension Parser {
 
     case .isolated:
       return parseAttribute(argumentMode: .required) { parser in
-        return .argumentList(parser.parseIsolatedAttributeArguments())
+        return (nil, .argumentList(parser.parseIsolatedAttributeArguments()))
       }
     case .convention, ._opaqueReturnTypeOf, nil:  // Custom attribute
       return parseAttribute(argumentMode: .customAttribute) { parser in
@@ -1299,7 +1299,7 @@ extension Parser {
           pattern: .none,
           allowTrailingComma: true
         )
-        return .argumentList(RawLabeledExprListSyntax(elements: arguments, arena: parser.arena))
+        return (nil, .argumentList(RawLabeledExprListSyntax(elements: arguments, arena: parser.arena)))
       }
 
     }
diff --git a/Tests/SwiftParserTest/AttributeTests.swift b/Tests/SwiftParserTest/AttributeTests.swift
index 6415986681d..1bc34070d1b 100644
--- a/Tests/SwiftParserTest/AttributeTests.swift
+++ b/Tests/SwiftParserTest/AttributeTests.swift
@@ -1283,6 +1283,49 @@ final class AttributeTests: ParserTestCase {
     )
   }
 
+  func testABIAttributeWithoutFeature() throws {
+    assertParse(
+      """
+      @abi(1️⃣func fn() -> Int2️⃣)
+      func fn1() -> Int { }
+      """,
+      substructure: FunctionDeclSyntax(
+        attributes: [
+          .attribute(
+            AttributeSyntax(
+              attributeName: TypeSyntax("abi"),
+              leftParen: .leftParenToken(),
+              [Syntax(try FunctionDeclSyntax("func fn() -> Int"))],
+              arguments: .argumentList([]),
+              rightParen: .rightParenToken()
+            )
+          )
+        ],
+        name: "fn1",
+        signature: FunctionSignatureSyntax(
+          parameterClause: FunctionParameterClauseSyntax {},
+          returnClause: ReturnClauseSyntax(type: TypeSyntax("Int"))
+        )
+      ) {},
+      diagnostics: [
+        DiagnosticSpec(
+          locationMarker: "1️⃣",
+          message: "unexpected code 'func fn() -> Int' in attribute"
+        ),
+        DiagnosticSpec(
+          locationMarker: "2️⃣",
+          message: "expected argument for '@abi' attribute",
+          fixIts: ["insert attribute argument"]
+        ),
+      ],
+      fixedSource: """
+        @abi(func fn() -> Int)
+        func fn1() -> Int { }
+        """,
+      experimentalFeatures: []
+    )
+  }
+
   func testSpaceBetweenAtAndAttribute() {
     assertParse(
       "@1️⃣ custom func foo() {}",