Add diagnostics for missing modifier in operator declaration

CodeGeneration/Sources/SyntaxSupport/AttributeKinds.swift

@@ -676,10 +676,57 @@ public let DECL_ATTR_KINDS: [Attribute] = [
 ///
 /// If you're adding a new kind of attribute that is spelled with a leading
 /// '@' symbol, add an entry to the `DECL_ATTR_KINDS` array instead.
-public let DECL_MODIFIER_KINDS: [Attribute] = [
-  // These are not really attributes or modifiers in the C++ AST and they are
-  // serialized directly into the ASTs they are attached to rather than using
-  // the generic attribute serialization infrastructure.
+
+// These are not really attributes or modifiers in the C++ AST and they are
+// serialized directly into the ASTs they are attached to rather than using
+// the generic attribute serialization infrastructure.
+public let DECL_MODIFIER_KINDS: [Attribute] = CONTEXTUAL_DECL_MODIFIER_KINDS + NONCONTEXTUAL_DECL_MODIFIER_KINDS
+
+// Modifiers that not exclusively used for declarations
+public let CONTEXTUAL_DECL_MODIFIER_KINDS: [Attribute] = [
+  ContextualDeclAttribute(
+    name: "weak",
+    className: "ReferenceOwnership"
+  ),
+  ContextualDeclAttributeAlias(
+    name: "unowned",
+    className: "ReferenceOwnership",
+    swiftName: "unowned"
+  ),
+  SimpleDeclAttribute(
+    name: "rethrows",
+    className: "Rethrows",
+    swiftName: "`rethrows`"
+  ),
+  ContextualSimpleDeclAttribute(
+    name: "isolated",
+    className: "Isolated"
+  ),
+  ContextualSimpleDeclAttribute(
+    name: "async",
+    className: "Async"
+  ),
+  SimpleDeclAttribute(
+    name: "reasync",
+    className: "Reasync",
+    swiftName: "reasync"
+  ),
+  ContextualSimpleDeclAttribute(
+    name: "consuming",
+    className: "Consuming"
+  ),
+  ContextualSimpleDeclAttribute(
+    name: "borrowing",
+    className: "Borrowing"
+  ),
+  ContextualSimpleDeclAttribute(
+    name: "_const",
+    className: "CompileTimeConst"
+  ),
+]
+
+// Modifiers that exclusively used for declarations
+public let NONCONTEXTUAL_DECL_MODIFIER_KINDS: [Attribute] = [
   BuiltinDeclModifier(
     name: "static",
     swiftName: "`static`"
@@ -775,37 +822,10 @@ public let DECL_MODIFIER_KINDS: [Attribute] = [
     className: "SetterAccess",
     swiftName: "__setter_access"
   ),
-  ContextualDeclAttribute(
-    name: "weak",
-    className: "ReferenceOwnership"
-  ),
-  ContextualDeclAttributeAlias(
-    name: "unowned",
-    className: "ReferenceOwnership",
-    swiftName: "unowned"
-  ),
-  SimpleDeclAttribute(
-    name: "rethrows",
-    className: "Rethrows",
-    swiftName: "`rethrows`"
-  ),
   ContextualSimpleDeclAttribute(
     name: "indirect",
     className: "Indirect"
   ),
-  ContextualSimpleDeclAttribute(
-    name: "isolated",
-    className: "Isolated"
-  ),
-  ContextualSimpleDeclAttribute(
-    name: "async",
-    className: "Async"
-  ),
-  SimpleDeclAttribute(
-    name: "reasync",
-    className: "Reasync",
-    swiftName: "reasync"
-  ),
   ContextualSimpleDeclAttribute(
     name: "nonisolated",
     className: "Nonisolated"
@@ -814,22 +834,10 @@ public let DECL_MODIFIER_KINDS: [Attribute] = [
     name: "distributed",
     className: "DistributedActor"
   ),
-  ContextualSimpleDeclAttribute(
-    name: "_const",
-    className: "CompileTimeConst"
-  ),
   ContextualSimpleDeclAttribute(
     name: "_local",
     className: "KnownToBeLocal"
   ),
-  ContextualSimpleDeclAttribute(
-    name: "consuming",
-    className: "Consuming"
-  ),
-  ContextualSimpleDeclAttribute(
-    name: "borrowing",
-    className: "Borrowing"
-  ),
 ]
 
 public let DEPRECATED_MODIFIER_KINDS: [Attribute] = [

CodeGeneration/Sources/SyntaxSupport/DeclNodes.swift

@@ -1422,25 +1422,14 @@ public let DECL_NODES: [Node] = [
     nameForDiagnostics: "operator declaration",
     documentation: "A Swift `operator` declaration.",
     traits: [
-      "IdentifiedDecl",
-      "WithAttributes",
-      "WithModifiers",
+      "IdentifiedDecl"
     ],
     children: [
       Child(
-        name: "Attributes",
-        kind: .collection(kind: .attributeList, collectionElementName: "Attribute"),
-        nameForDiagnostics: "attributes",
-        documentation: "The attributes applied to the 'operator' declaration.",
-        isOptional: true
-      ),
-      Child(
-        name: "Modifiers",
-        kind: .collection(kind: .modifierList, collectionElementName: "Modifier"),
-        nameForDiagnostics: "modifiers",
-        documentation: "The declaration modifiers applied to the 'operator' declaration.",
-        isOptional: true,
-        classification: "Attribute"
+        name: "Fixity",
+        kind: .token(choices: [.keyword(text: "prefix"), .keyword(text: "postfix"), .keyword(text: "infix")]),
+        nameForDiagnostics: "fixity",
+        documentation: "The fixity applied to the 'operator' declaration."
       ),
       Child(
         name: "OperatorKeyword",

CodeGeneration/Sources/generate-swiftsyntax/templates/swiftparser/DeclarationModifierFile.swift

@@ -38,13 +38,14 @@ let declarationModifierFile = SourceFileSyntax(leadingTrivia: copyrightHeader) {
 
     try VariableDeclSyntax("var spec: TokenSpec") {
       try SwitchExprSyntax("switch self") {
-        for attribute in DECL_MODIFIER_KINDS {
+        for attribute in NONCONTEXTUAL_DECL_MODIFIER_KINDS {
+          SwitchCaseSyntax("case .\(raw: attribute.swiftName):") {
+            StmtSyntax("return .keyword(.\(raw: attribute.swiftName))")
+          }
+        }
+        for attribute in CONTEXTUAL_DECL_MODIFIER_KINDS {
           SwitchCaseSyntax("case .\(raw: attribute.swiftName):") {
-            if attribute.swiftName.hasSuffix("Keyword") {
-              StmtSyntax("return .\(raw: attribute.swiftName)")
-            } else {
-              StmtSyntax("return .keyword(.\(raw: attribute.swiftName))")
-            }
+            StmtSyntax("return TokenSpec(.\(raw: attribute.swiftName), recoveryPrecedence: .declKeyword)")
           }
         }
       }

Sources/SwiftIDEUtils/generated/SyntaxClassification.swift

@@ -87,8 +87,6 @@ extension SyntaxClassification {
       return (.buildConfigId, false)
     case \MemberTypeIdentifierSyntax.name:
       return (.typeIdentifier, false)
-    case \OperatorDeclSyntax.modifiers:
-      return (.attribute, false)
     case \OperatorDeclSyntax.identifier:
       return (.operatorIdentifier, false)
     case \PrecedenceGroupAssociativitySyntax.associativityKeyword:

Sources/SwiftOperators/OperatorTable+Semantics.swift

@@ -68,11 +68,7 @@ extension Operator {
   /// TODO: This ignores all semantic errors.
   init(from syntax: OperatorDeclSyntax) {
     self.syntax = syntax
-
-    kind =
-      syntax.modifiers?.compactMap {
-        OperatorKind(rawValue: $0.name.text)
-      }.first ?? .infix
+    kind = OperatorKind(rawValue: syntax.fixity.text) ?? .infix
 
     name = syntax.identifier.text
 

Sources/SwiftOperators/SyntaxSynthesis.swift

@@ -26,9 +26,7 @@ extension Operator {
   /// Synthesize a syntactic representation of this operator based on its
   /// semantic definition.
   public func synthesizedSyntax() -> OperatorDeclSyntax {
-    let modifiers = ModifierListSyntax(
-      [DeclModifierSyntax(name: .keyword(kind.keyword))]
-    )
+    let fixity = TokenSyntax.keyword(kind.keyword)
     let operatorKeyword = TokenSyntax.keyword(.operator, leadingTrivia: .space)
     let identifierSyntax =
       TokenSyntax.binaryOperator(name, leadingTrivia: .space)
@@ -41,7 +39,7 @@ extension Operator {
     }
 
     return OperatorDeclSyntax(
-      modifiers: modifiers,
+      fixity: fixity,
       operatorKeyword: operatorKeyword,
       identifier: identifierSyntax,
       operatorPrecedenceAndTypes: precedenceGroupSyntax

Sources/SwiftParser/Declarations.swift

@@ -89,15 +89,15 @@ extension TokenConsumer {
       return attrLookahead.consumeIfConfigOfAttributes()
     }
 
-    let declStartKeyword: DeclarationStart?
+    let declStartKeyword: DeclarationKeyword?
     if allowRecovery {
       declStartKeyword =
         subparser.canRecoverTo(
-          anyIn: DeclarationStart.self,
+          anyIn: DeclarationKeyword.self,
           overrideRecoveryPrecedence: isAtTopLevel ? nil : .closingBrace
         )?.0
     } else {
-      declStartKeyword = subparser.at(anyIn: DeclarationStart.self)?.0
+      declStartKeyword = subparser.at(anyIn: DeclarationKeyword.self)?.0
     }
     switch declStartKeyword {
     case .actor:
@@ -233,7 +233,7 @@ extension Parser {
     // while recoverying to the declaration start.
     let recoveryPrecedence = inMemberDeclList ? TokenPrecedence.closingBrace : nil
 
-    switch self.canRecoverTo(anyIn: DeclarationStart.self, overrideRecoveryPrecedence: recoveryPrecedence) {
+    switch self.canRecoverTo(anyIn: DeclarationKeyword.self, overrideRecoveryPrecedence: recoveryPrecedence) {
     case (.import, let handle)?:
       return RawDeclSyntax(self.parseImportDeclaration(attrs, handle))
     case (.class, let handle)?:
@@ -1694,11 +1694,69 @@ extension Parser {
   ///     postfix-operator-declaration → 'postfix' 'operator' operator
   ///     infix-operator-declaration → 'infix' 'operator' operator infix-operator-group?
   ///     infix-operator-group → ':' precedence-group-name
+
+  struct OperatorDeclIntroducer {
+    var unexpectedBeforeFixity: RawUnexpectedNodesSyntax?
+    var fixity: RawTokenSyntax
+    var unexpectedBeforeOperatorKeyword: RawUnexpectedNodesSyntax?
+    var operatorKeyword: RawTokenSyntax
+  }
+
+  mutating func parseOperatorDeclIntroducer(_ attrs: DeclAttributes, _ handle: RecoveryConsumptionHandle) -> OperatorDeclIntroducer {
+    func isFixity(_ modifier: RawDeclModifierSyntax) -> Bool {
+      switch modifier.name {
+      case .keyword(.prefix),
+        .keyword(.infix),
+        .keyword(.postfix):
+        return true
+      default:
+        return false
+      }
+    }
+
+    var unexpectedBeforeFixity = RawUnexpectedNodesSyntax(attrs.attributes?.elements ?? [], arena: self.arena)
+
+    var fixity: RawTokenSyntax?
+    var unexpectedAfterFixity: RawUnexpectedNodesSyntax?
+
+    if let modifiers = attrs.modifiers?.elements {
+      if let firstFixityIndex = modifiers.firstIndex(where: { isFixity($0) }) {
+        let fixityModifier = modifiers[firstFixityIndex]
+        fixity = fixityModifier.name
+
+        unexpectedBeforeFixity = RawUnexpectedNodesSyntax(combining: unexpectedBeforeFixity, RawUnexpectedNodesSyntax(Array(modifiers[0..<firstFixityIndex]), arena: self.arena), fixityModifier.unexpectedBeforeName, arena: self.arena)
+
+        unexpectedAfterFixity = RawUnexpectedNodesSyntax(
+          combining: fixityModifier.unexpectedBetweenNameAndDetail,
+          RawUnexpectedNodesSyntax([fixityModifier.detail], arena: self.arena),
+          fixityModifier.unexpectedAfterDetail,
+          RawUnexpectedNodesSyntax(Array(modifiers[modifiers.index(after: firstFixityIndex)...]), arena: self.arena),
+          arena: self.arena
+        )
+
+      } else {
+        unexpectedBeforeFixity = RawUnexpectedNodesSyntax(combining: unexpectedBeforeFixity, RawUnexpectedNodesSyntax(modifiers, arena: self.arena), arena: self.arena)
+      }
+    }
+
+    var (unexpectedBeforeOperatorKeyword, operatorKeyword) = self.expect(.keyword(.operator))
+
+    unexpectedBeforeOperatorKeyword = RawUnexpectedNodesSyntax(combining: unexpectedAfterFixity, unexpectedBeforeOperatorKeyword, arena: self.arena)
+
+    return OperatorDeclIntroducer(
+      unexpectedBeforeFixity: unexpectedBeforeFixity,
+      fixity: fixity ?? self.missingToken(.prefix),
+      unexpectedBeforeOperatorKeyword: unexpectedBeforeOperatorKeyword,
+      operatorKeyword: operatorKeyword
+    )
+  }
+
   mutating func parseOperatorDeclaration(
     _ attrs: DeclAttributes,
     _ handle: RecoveryConsumptionHandle
   ) -> RawOperatorDeclSyntax {
-    let (unexpectedBeforeOperatorKeyword, operatorKeyword) = self.eat(handle)
+    let introducer = parseOperatorDeclIntroducer(attrs, handle)
+
     let unexpectedBeforeName: RawUnexpectedNodesSyntax?
     let name: RawTokenSyntax
     switch self.canRecoverTo(anyIn: OperatorLike.self) {
@@ -1775,10 +1833,10 @@ extension Parser {
       unexpectedAtEnd = nil
     }
     return RawOperatorDeclSyntax(
-      attributes: attrs.attributes,
-      modifiers: attrs.modifiers,
-      unexpectedBeforeOperatorKeyword,
-      operatorKeyword: operatorKeyword,
+      introducer.unexpectedBeforeFixity,
+      fixity: introducer.fixity,
+      introducer.unexpectedBeforeOperatorKeyword,
+      operatorKeyword: introducer.operatorKeyword,
       unexpectedBeforeName,
       identifier: name,
       RawUnexpectedNodesSyntax(identifiersAfterOperatorName, arena: self.arena),