[ASTGen] Gnerate PlaceholderTypeRepr

Author: rintaro

include/swift/AST/ASTBridging.h

@@ -2696,6 +2696,11 @@ BridgedOwnershipTypeRepr BridgedOwnershipTypeRepr_createParsed(
     BridgedASTContext cContext, BridgedTypeRepr base,
     BridgedParamSpecifier cSpecifier, BridgedSourceLoc cSpecifierLoc);
 
+SWIFT_NAME("BridgedPlaceholderTypeRepr.createParsed(_:loc:)")
+BridgedPlaceholderTypeRepr
+BridgedPlaceholderTypeRepr_createParsed(BridgedASTContext cContext,
+                                        BridgedSourceLoc cLoc);
+
 SWIFT_NAME("BridgedProtocolTypeRepr.createParsed(_:base:protocolKeywordLoc:)")
 BridgedProtocolTypeRepr
 BridgedProtocolTypeRepr_createParsed(BridgedASTContext cContext,

lib/AST/Bridging/TypeReprBridging.cpp

@@ -141,6 +141,12 @@ BridgedOwnershipTypeRepr BridgedOwnershipTypeRepr_createParsed(
       base.unbridged(), unbridge(cSpecifier), cSpecifierLoc.unbridged());
 }
 
+BridgedPlaceholderTypeRepr
+BridgedPlaceholderTypeRepr_createParsed(BridgedASTContext cContext,
+                                        BridgedSourceLoc cLoc) {
+  return new (cContext.unbridged()) PlaceholderTypeRepr(cLoc.unbridged());
+}
+
 BridgedProtocolTypeRepr
 BridgedProtocolTypeRepr_createParsed(BridgedASTContext cContext,
                                      BridgedTypeRepr baseType,

lib/ASTGen/Sources/ASTGen/Types.swift

@@ -70,6 +70,17 @@ extension ASTGenVisitor {
     if node.name.keywordKind == .Any && node.genericArgumentClause == nil {
       return BridgedCompositionTypeRepr.createEmpty(self.ctx, anyKeywordLoc: loc).asTypeRepr
     }
+    if node.name.rawText == "_" {
+      guard node.genericArgumentClause == nil else {
+        // TODO: Diagnose.
+        fatalError()
+        // return BridgedErrorTypeRepr.create()
+      }
+      return BridgedPlaceholderTypeRepr.createParsed(
+        self.ctx,
+        loc: loc
+      ).asTypeRepr
+    }
 
     let id = self.generateIdentifier(node.name)
 

test/ASTGen/types.swift

@@ -70,3 +70,6 @@ struct SomeGlobalActor {
 typealias SomeGlobalActorIsolated = @SomeGlobalActor () -> Void
 typealias TestSpecifiers<Value, Result, E> = (inout sending Value) throws(E) -> sending Result where Value: ~Copyable, Result: ~Copyable, E: Error
 typealias TestSpecifierAndAttr<T> = (__owned @Sendable @escaping () async -> T) -> T
+
+let globalOptionalInt: _? = 42
+let optionalIntArray: Array<_> = [42]