[clang] 03dcd57 - [clang] add a new `swift_attr` attribute

[Alex Lorenz via cfe-commits]

Author: Alex Lorenz
Date: 2020-12-04T15:53:24-08:00
New Revision: 03dcd57ecf99b31021644b868cae422897d520f8

URL: https://github.com/llvm/llvm-project/commit/03dcd57ecf99b31021644b868cae422897d520f8
DIFF: https://github.com/llvm/llvm-project/commit/03dcd57ecf99b31021644b868cae422897d520f8.diff

LOG: [clang] add a new `swift_attr` attribute

The swift_attr attribute is a generic annotation attribute that's not used by clang,
but is used by the Swift compiler. The Swift compiler can use these annotations to provide
various syntactic and semantic sugars for the imported Objective-C API declarations.

Differential Revision: https://reviews.llvm.org/D92354

Added: 
    clang/test/AST/attr-swift_attr.m
    clang/test/SemaObjC/validate-attr-swift_attr.m

Modified: 
    clang/include/clang/Basic/Attr.td
    clang/include/clang/Basic/AttrDocs.td
    clang/lib/Sema/SemaDeclAttr.cpp

Removed: 
    


################################################################################
diff  --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index 8555bd351747..3beef7b89243 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -2149,6 +2149,12 @@ def Regparm : TypeAttr {
   let ASTNode = 0;
 }
 
+def SwiftAttr : InheritableAttr {
+  let Spellings = [GNU<"swift_attr">];
+  let Args = [StringArgument<"Attribute">];
+  let Documentation = [SwiftAttrDocs];
+}
+
 def SwiftBridge : InheritableAttr {
   let Spellings = [GNU<"swift_bridge">];
   let Args = [StringArgument<"SwiftType">];

diff  --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index 1781543cc4f3..673c9553c83d 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -3628,6 +3628,19 @@ Swift.
   }];
 }
 
+def SwiftAttrDocs : Documentation {
+  let Category = SwiftDocs;
+  let Heading = "swift_attr";
+  let Content = [{
+The ``swift_attr`` provides a Swift-specific annotation for the declaration
+to which the attribute appertains to. It can be used on any declaration
+in Clang. This kind of annotation is ignored by Clang as it doesn't have any
+semantic meaning in languages supported by Clang. The Swift compiler can
+interpret these annotations according to its own rules when importing C or
+Objective-C declarations.
+}];
+}
+
 def SwiftBridgeDocs : Documentation {
   let Category = SwiftDocs;
   let Heading = "swift_bridge";

diff  --git a/clang/lib/Sema/SemaDeclAttr.cpp b/clang/lib/Sema/SemaDeclAttr.cpp
index d31d18eac474..e0aa6d1f119c 100644
--- a/clang/lib/Sema/SemaDeclAttr.cpp
+++ b/clang/lib/Sema/SemaDeclAttr.cpp
@@ -5607,6 +5607,16 @@ static void handleObjCPreciseLifetimeAttr(Sema &S, Decl *D,
   D->addAttr(::new (S.Context) ObjCPreciseLifetimeAttr(S.Context, AL));
 }
 
+static void handleSwiftAttrAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
+  // Make sure that there is a string literal as the annotation's single
+  // argument.
+  StringRef Str;
+  if (!S.checkStringLiteralArgumentAttr(AL, 0, Str))
+    return;
+
+  D->addAttr(::new (S.Context) SwiftAttrAttr(S.Context, AL, Str));
+}
+
 static void handleSwiftBridge(Sema &S, Decl *D, const ParsedAttr &AL) {
   // Make sure that there is a string literal as the annotation's single
   // argument.
@@ -7941,6 +7951,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
     break;
 
   // Swift attributes.
+  case ParsedAttr::AT_SwiftAttr:
+    handleSwiftAttrAttr(S, D, AL);
+    break;
   case ParsedAttr::AT_SwiftBridge:
     handleSwiftBridge(S, D, AL);
     break;

diff  --git a/clang/test/AST/attr-swift_attr.m b/clang/test/AST/attr-swift_attr.m
new file mode 100644
index 000000000000..3cd51b81e349
--- /dev/null
+++ b/clang/test/AST/attr-swift_attr.m
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -fsyntax-only -ast-dump %s | FileCheck %s
+
+__attribute__((swift_attr("@actor")))
+ at interface View
+ at end
+
+// CHECK: InterfaceDecl {{.*}} View
+// CHECK-NEXT: SwiftAttrAttr {{.*}} "@actor"

diff  --git a/clang/test/SemaObjC/validate-attr-swift_attr.m b/clang/test/SemaObjC/validate-attr-swift_attr.m
new file mode 100644
index 000000000000..4ff434d17972
--- /dev/null
+++ b/clang/test/SemaObjC/validate-attr-swift_attr.m
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -verify -fsyntax-only %s
+
+// expected-error at +1 {{'swift_attr' attribute takes one argument}}
+__attribute__((swift_attr))
+ at interface I
+ at end
+
+// expected-error at +1 {{'swift_attr' attribute requires a string}}
+__attribute__((swift_attr(1)))
+ at interface J
+ at end