[ASTGen] Lower @abi in ASTGen

Author: beccadax

include/swift/AST/ASTBridging.h

@@ -581,6 +581,11 @@ BridgedDeclAttribute BridgedDeclAttribute_createSimple(
     BridgedASTContext cContext, BridgedDeclAttrKind cKind,
     BridgedSourceLoc cAtLoc, BridgedSourceLoc cNameLoc);
 
+SWIFT_NAME("BridgedABIAttr.createParsed(_:atLoc:range:abiDecl:)")
+BridgedABIAttr BridgedABIAttr_createParsed(
+    BridgedASTContext cContext, BridgedSourceLoc atLoc,
+    BridgedSourceRange range, BridgedNullableDecl abiDecl);
+
 enum ENUM_EXTENSIBILITY_ATTR(closed) BridgedAccessLevel {
   BridgedAccessLevelPrivate,
   BridgedAccessLevelFilePrivate,

include/swift/AST/ASTBridgingWrappers.def

@@ -68,7 +68,7 @@
 
 // Some of the base classes need to be nullable to allow them to be used as
 // optional parameters.
-AST_BRIDGING_WRAPPER_NONNULL(Decl)
+AST_BRIDGING_WRAPPER_NULLABLE(Decl)
 AST_BRIDGING_WRAPPER_NONNULL(DeclContext)
 AST_BRIDGING_WRAPPER_NONNULL(SourceFile)
 AST_BRIDGING_WRAPPER_NULLABLE(Stmt)

lib/AST/Bridging/DeclAttributeBridging.cpp

@@ -93,6 +93,16 @@ static std::optional<AccessLevel> unbridge(BridgedAccessLevel level) {
   llvm_unreachable("unhandled BridgedAccessLevel");
 }
 
+BridgedABIAttr BridgedABIAttr_createParsed(BridgedASTContext cContext,
+                                           BridgedSourceLoc atLoc,
+                                           BridgedSourceRange range,
+                                           BridgedNullableDecl abiDecl) {
+  return new (cContext.unbridged()) ABIAttr(abiDecl.unbridged(),
+                                            atLoc.unbridged(),
+                                            range.unbridged(),
+                                            /*isImplicit=*/false);
+}
+
 BridgedAccessControlAttr
 BridgedAccessControlAttr_createParsed(BridgedASTContext cContext,
                                       BridgedSourceRange cRange,

lib/ASTGen/Sources/ASTGen/Bridge.swift

@@ -26,6 +26,7 @@ extension BridgedNullable {
 
 extension BridgedSourceLoc: /*@retroactive*/ swiftASTGen.BridgedNullable {}
 extension BridgedIdentifier: /*@retroactive*/ swiftASTGen.BridgedNullable {}
+extension BridgedNullableDecl: /*@retroactive*/ swiftASTGen.BridgedNullable {}
 extension BridgedNullableExpr: /*@retroactive*/ swiftASTGen.BridgedNullable {}
 extension BridgedNullableStmt: /*@retroactive*/ swiftASTGen.BridgedNullable {}
 extension BridgedNullableTypeRepr: /*@retroactive*/ swiftASTGen.BridgedNullable {}
@@ -60,6 +61,9 @@ extension Optional where Wrapped: BridgedHasNullable {
 extension BridgedStmt: BridgedHasNullable {
   typealias Nullable = BridgedNullableStmt
 }
+extension BridgedDecl: BridgedHasNullable {
+  typealias Nullable = BridgedNullableDecl
+}
 extension BridgedExpr: BridgedHasNullable {
   typealias Nullable = BridgedNullableExpr
 }

lib/ASTGen/Sources/ASTGen/DeclAttrs.swift

@@ -112,7 +112,7 @@ extension ASTGenVisitor {
       let attrKind = BridgedDeclAttrKind(from: attrName.bridged)
       switch attrKind {
       case .ABI:
-        return self.generateABIAttr(attribute: node)?.asDeclAttribute
+        return handle(self.generateABIAttr(attribute: node)?.asDeclAttribute)
       case .alignment:
         return handle(self.generateAlignmentAttr(attribute: node)?.asDeclAttribute)
       case .allowFeatureSuppression:
@@ -333,8 +333,45 @@ extension ASTGenVisitor {
   ///   @abi(func fn())
   ///   ```
   func generateABIAttr(attribute node: AttributeSyntax) -> BridgedABIAttr? {
-    #warning("TODO: implement generateABIAttr")
-    fatalError("TODO: implement generateABIAttr")
+    guard
+      let arg = node.arguments?.as(ABIAttributeArgumentsSyntax.self)
+    else {
+      // TODO: diagnose
+      return nil
+    }
+
+    let abiDecl: BridgedDecl?
+    switch arg.provider {
+    case .associatedType(let assocTyDecl):
+      abiDecl = self.generate(associatedTypeDecl: assocTyDecl)?.asDecl
+    case .deinitializer(let deinitDecl):
+      abiDecl = self.generate(deinitializerDecl: deinitDecl).asDecl
+    case .enumCase(let caseDecl):
+      abiDecl = self.generate(enumCaseDecl: caseDecl).asDecl
+    case .function(let funcDecl):
+      abiDecl = self.generate(functionDecl: funcDecl)?.asDecl
+    case .initializer(let initDecl):
+      abiDecl = self.generate(initializerDecl: initDecl).asDecl
+    case .`subscript`(let subscriptDecl):
+      abiDecl = self.generate(subscriptDecl: subscriptDecl).asDecl
+    case .typeAlias(let typealiasDecl):
+      abiDecl = self.generate(typeAliasDecl: typealiasDecl)?.asDecl
+    case .variable(let varDecl):
+      abiDecl = self.generate(variableDecl: varDecl).asDecl
+    case .missing(_):
+      // This error condition will have been diagnosed in SwiftSyntax.
+      abiDecl = nil
+    }
+
+    // TODO: Diagnose if `abiDecl` has a body/initial value/etc.
+    // The C++ parser considers it syntactically invalid but SwiftSyntax does not.
+
+    return .createParsed(
+      self.ctx,
+      atLoc: self.generateSourceLoc(node.atSign),
+      range: self.generateAttrSourceRange(node),
+      abiDecl: abiDecl.asNullable
+    )
   }
 
   /// E.g.:

lib/ASTGen/Sources/ASTGen/SourceFile.swift

@@ -76,6 +76,7 @@ extension Parser.ExperimentalFeatures {
     mapFeature(.TrailingComma, to: .trailingComma)
     mapFeature(.CoroutineAccessors, to: .coroutineAccessors)
     mapFeature(.ValueGenerics, to: .valueGenerics)
+    mapFeature(.ABIAttribute, to: .abiAttribute)
   }
 }
 

test/ASTGen/attrs.swift

@@ -1,20 +1,21 @@
 // RUN: %empty-directory(%t)
-// RUN: %target-swift-frontend %s -dump-parse -disable-availability-checking -enable-experimental-feature SymbolLinkageMarkers -enable-experimental-feature Extern -enable-experimental-move-only -enable-experimental-feature ParserASTGen > %t/astgen.ast.raw
-// RUN: %target-swift-frontend %s -dump-parse -disable-availability-checking -enable-experimental-feature SymbolLinkageMarkers -enable-experimental-feature Extern -enable-experimental-move-only > %t/cpp-parser.ast.raw
+// RUN: %target-swift-frontend %s -dump-parse -disable-availability-checking -enable-experimental-feature SymbolLinkageMarkers -enable-experimental-feature ABIAttribute -enable-experimental-feature Extern -enable-experimental-move-only -enable-experimental-feature ParserASTGen > %t/astgen.ast.raw
+// RUN: %target-swift-frontend %s -dump-parse -disable-availability-checking -enable-experimental-feature SymbolLinkageMarkers -enable-experimental-feature ABIAttribute -enable-experimental-feature Extern -enable-experimental-move-only > %t/cpp-parser.ast.raw
 
 // Filter out any addresses in the dump, since they can differ.
 // RUN: sed -E 's#0x[0-9a-fA-F]+##g' %t/cpp-parser.ast.raw > %t/cpp-parser.ast
 // RUN: sed -E 's#0x[0-9a-fA-F]+##g' %t/astgen.ast.raw > %t/astgen.ast
 
 // RUN: %diff -u %t/astgen.ast %t/cpp-parser.ast
 
-// RUN: %target-typecheck-verify-swift -enable-experimental-feature SymbolLinkageMarkers -enable-experimental-feature Extern -enable-experimental-move-only -enable-experimental-feature ParserASTGen 
+// RUN: %target-typecheck-verify-swift -enable-experimental-feature SymbolLinkageMarkers -enable-experimental-feature ABIAttribute -enable-experimental-feature Extern -enable-experimental-move-only -enable-experimental-feature ParserASTGen
 
 // REQUIRES: executable_test
 // REQUIRES: swift_swift_parser
 // REQUIRES: swift_feature_SymbolLinkageMarkers
 // REQUIRES: swift_feature_Extern
 // REQUIRES: swift_feature_ParserASTGen
+// REQUIRES: swift_feature_ABIAttribute
 
 // rdar://116686158
 // UNSUPPORTED: asan
@@ -62,7 +63,10 @@ struct S4 {}
 @implementation extension ObjCClass1 {} // expected-error {{cannot find type 'ObjCClass1' in scope}}
 @implementation(Category) extension ObjCClass1 {} // expected-error {{cannot find type 'ObjCClass1' in scope}}
 
-@_alignment(8) struct AnyAlignment {} 
+@abi(func fn_abi()) // expected-error {{cannot give global function 'fn' the ABI of a global function with a different number of low-level parameters}}
+func fn(_: Int) {}
+
+@_alignment(8) struct AnyAlignment {}
 
 @_allowFeatureSuppression(IsolatedAny) public func testFeatureSuppression(fn: @isolated(any) @Sendable () -> ()) {}
 

test/attr/feature_requirement.swift

@@ -1,4 +1,4 @@
-// RUN: %target-typecheck-verify-swift -parse-as-library -verify-additional-prefix disabled-
+// RUN: %target-typecheck-verify-swift -parse-as-library -disable-experimental-parser-round-trip -verify-additional-prefix disabled-
 // RUN: %target-typecheck-verify-swift -parse-as-library -verify-additional-prefix enabled- -enable-experimental-feature ABIAttribute
 
 // REQUIRES: asserts