AST: promote API/ABI impact bit of decl attributes to AST, NFC

ABI/API checker used to hard-code whether adding or removing of a
decl attribute could break the existing ABI/API. This is not ideal because
new attributes may be added to AST without updating the checker. After this
change, new decl attribute could be specified whether it has ABI/API
impact and the checker could pick up the knowledge instantly.

Author: nkcsgexi

include/swift/AST/Attr.def

@@ -121,11 +121,12 @@ DECL_ATTR(available, Available,
   1)
 CONTEXTUAL_SIMPLE_DECL_ATTR(final, Final,
   OnClass | OnFunc | OnAccessor | OnVar | OnSubscript |
-  DeclModifier,
+  DeclModifier | ABIBreakingToAdd | ABIBreakingToRemove |
+  APIBreakingToAdd,
   2)
 DECL_ATTR(objc, ObjC,
   OnAbstractFunction | OnClass | OnProtocol | OnExtension | OnVar |
-  OnSubscript | OnEnum | OnEnumElement,
+  OnSubscript | OnEnum | OnEnumElement | ABIBreakingToAdd | ABIBreakingToRemove,
   3)
 CONTEXTUAL_SIMPLE_DECL_ATTR(required, Required,
   OnConstructor |
@@ -187,7 +188,7 @@ DECL_ATTR(_semantics, Semantics,
   21)
 CONTEXTUAL_SIMPLE_DECL_ATTR(dynamic, Dynamic,
   OnFunc | OnAccessor | OnVar | OnSubscript | OnConstructor |
-  DeclModifier,
+  DeclModifier | ABIBreakingToAdd | ABIBreakingToRemove,
   22)
 CONTEXTUAL_SIMPLE_DECL_ATTR(infix, Infix,
   OnFunc | OnOperator |
@@ -212,7 +213,7 @@ SIMPLE_DECL_ATTR(nonobjc, NonObjC,
   30)
 SIMPLE_DECL_ATTR(_fixed_layout, FixedLayout,
   OnVar | OnClass | OnStruct |
-  UserInaccessible,
+  UserInaccessible | ABIBreakingToAdd | ABIBreakingToRemove,
   31)
 SIMPLE_DECL_ATTR(inlinable, Inlinable,
   OnVar | OnSubscript | OnAbstractFunction,
@@ -362,7 +363,7 @@ SIMPLE_DECL_ATTR(_weakLinked, WeakLinked,
   OnSubscript | OnConstructor | OnEnumElement | OnExtension | UserInaccessible,
   75)
 SIMPLE_DECL_ATTR(frozen, Frozen,
-  OnEnum | OnStruct,
+  OnEnum | OnStruct | ABIBreakingToAdd | ABIBreakingToRemove | APIBreakingToRemove,
   76)
 DECL_ATTR_ALIAS(_frozen, Frozen)
 SIMPLE_DECL_ATTR(_forbidSerializingReference, ForbidSerializingReference,

include/swift/AST/Attr.h

@@ -353,6 +353,18 @@ class DeclAttribute : public AttributeBase {
 
     /// Whether client code cannot use the attribute.
     UserInaccessible = 1ull << (unsigned(DeclKindIndex::Last_Decl) + 7),
+
+    /// Whether adding this attribute can break API
+    APIBreakingToAdd = 1ull << (unsigned(DeclKindIndex::Last_Decl) + 8),
+
+    /// Whether removing this attribute can break API
+    APIBreakingToRemove = 1ull << (unsigned(DeclKindIndex::Last_Decl) + 9),
+
+    /// Whether adding this attribute can break ABI
+    ABIBreakingToAdd = 1ull << (unsigned(DeclKindIndex::Last_Decl) + 10),
+
+    /// Whether removing this attribute can break ABI
+    ABIBreakingToRemove = 1ull << (unsigned(DeclKindIndex::Last_Decl) + 11),
   };
 
   LLVM_READNONE
@@ -435,6 +447,21 @@ class DeclAttribute : public AttributeBase {
     return getOptions(DK) & UserInaccessible;
   }
 
+  static bool isAddingBreakingABI(DeclAttrKind DK) {
+    return getOptions(DK) & ABIBreakingToAdd;
+  }
+
+  static bool isAddingBreakingAPI(DeclAttrKind DK) {
+    return getOptions(DK) & APIBreakingToAdd;
+  }
+
+  static bool isRemovingBreakingABI(DeclAttrKind DK) {
+    return getOptions(DK) & ABIBreakingToRemove;
+  }
+  static bool isRemovingBreakingAPI(DeclAttrKind DK) {
+    return getOptions(DK) & APIBreakingToRemove;
+  }
+
   bool isDeclModifier() const {
     return isDeclModifier(getKind());
   }

test/api-digester/Outputs/Cake.txt

@@ -38,9 +38,9 @@ cake: Func ownershipChange(_:_:) has parameter 1 changing from Shared to Owned
 cake: TypeAlias TChangesFromIntToString.T has underlying type change from Swift.Int to Swift.String
 
 /* Decl Attribute changes */
+cake: Enum IceKind is now without @frozen
 cake: Func C1.foo1() is now not static
 cake: Func FinalFuncContainer.NewFinalFunc() is now with final
-cake: Func FinalFuncContainer.NoLongerFinalFunc() is now without final
 cake: Func HasMutatingMethodClone.foo() has self access kind changing from Mutating to NonMutating
 cake: Func S1.foo1() has self access kind changing from NonMutating to Mutating
 cake: Func S1.foo3() is now static

tools/swift-api-digester/ModuleAnalyzerNodes.cpp

@@ -11,18 +11,6 @@ namespace fs = llvm::sys::fs;
 namespace path = llvm::sys::path;
 
 namespace {
-static StringRef getAttrName(DeclAttrKind Kind) {
-  switch (Kind) {
-#define DECL_ATTR(NAME, CLASS, ...)                                           \
-  case DAK_##CLASS:                                                           \
-      return DeclAttribute::isDeclModifier(DAK_##CLASS) ? #NAME : "@"#NAME;
-#include "swift/AST/Attr.def"
-  case DAK_Count:
-    llvm_unreachable("unrecognized attribute kind.");
-  }
-  llvm_unreachable("covered switch");
-}
-
 static PrintOptions getTypePrintOpts(CheckerOptions CheckerOpts) {
   PrintOptions Opts;
   Opts.SynthesizeSugarOnTypes = true;
@@ -33,7 +21,6 @@ static PrintOptions getTypePrintOpts(CheckerOptions CheckerOpts) {
   }
   return Opts;
 }
-
 } // End of anonymous namespace.
 
 struct swift::ide::api::SDKNodeInitInfo {
@@ -63,20 +50,7 @@ struct swift::ide::api::SDKNodeInitInfo {
   SDKNode* createSDKNode(SDKNodeKind Kind);
 };
 
-SDKContext::SDKContext(CheckerOptions Opts): Diags(SourceMgr), Opts(Opts) {
-#define ADD(NAME) BreakingAttrs.push_back({DeclAttrKind::DAK_##NAME, \
-      getAttrName(DeclAttrKind::DAK_##NAME)});
-  // Add attributes that both break ABI and API.
-  ADD(Final)
-  if (checkingABI()) {
-    // Add ABI-breaking-specific attributes.
-    ADD(ObjC)
-    ADD(FixedLayout)
-    ADD(Frozen)
-    ADD(Dynamic)
-  }
-#undef ADD
-}
+SDKContext::SDKContext(CheckerOptions Opts): Diags(SourceMgr), Opts(Opts) {}
 
 void SDKNodeRoot::registerDescendant(SDKNode *D) {
   // Operator doesn't have usr

tools/swift-api-digester/swift-api-digester.cpp

@@ -824,6 +824,26 @@ void swift::ide::api::SDKNodeDeclFunction::diagnose(SDKNode *Right) {
   }
 }
 
+static StringRef getAttrName(DeclAttrKind Kind) {
+  switch (Kind) {
+#define DECL_ATTR(NAME, CLASS, ...)                                           \
+  case DAK_##CLASS:                                                           \
+      return DeclAttribute::isDeclModifier(DAK_##CLASS) ? #NAME : "@"#NAME;
+#include "swift/AST/Attr.def"
+  case DAK_Count:
+    llvm_unreachable("unrecognized attribute kind.");
+  }
+  llvm_unreachable("covered switch");
+}
+
+static bool shouldDiagnoseAddingAttribute(SDKNodeDecl *D, DeclAttrKind Kind) {
+  return true;
+}
+
+static bool shouldDiagnoseRemovingAttribute(SDKNodeDecl *D, DeclAttrKind Kind) {
+  return true;
+}
+
 void swift::ide::api::SDKNodeDecl::diagnose(SDKNode *Right) {
   SDKNode::diagnose(Right);
   auto *RD = dyn_cast<SDKNodeDecl>(Right);
@@ -882,13 +902,27 @@ void swift::ide::api::SDKNodeDecl::diagnose(SDKNode *Right) {
     }
   }
 
-  // Check if some attributes with ABI/API-impact have been added/removed.
-  for (auto &Info: Ctx.getBreakingAttributeInfo()) {
-    if (hasDeclAttribute(Info.Kind) != RD->hasDeclAttribute(Info.Kind)) {
-      auto Desc = hasDeclAttribute(Info.Kind) ?
-      Ctx.buffer((llvm::Twine("without ") + Info.Content).str()):
-      Ctx.buffer((llvm::Twine("with ") + Info.Content).str());
-      emitDiag(diag::decl_new_attr, Desc);
+  // Diagnose removing attributes.
+  for (auto Kind: getDeclAttributes()) {
+    if (!RD->hasDeclAttribute(Kind)) {
+      if ((Ctx.checkingABI() ? DeclAttribute::isRemovingBreakingABI(Kind) :
+                               DeclAttribute::isRemovingBreakingAPI(Kind)) &&
+          shouldDiagnoseRemovingAttribute(this, Kind)) {
+        emitDiag(diag::decl_new_attr,
+                Ctx.buffer((llvm::Twine("without ") + getAttrName(Kind)).str()));
+      }
+    }
+  }
+
+  // Diagnose adding attributes.
+  for (auto Kind: RD->getDeclAttributes()) {
+    if (!hasDeclAttribute(Kind)) {
+      if ((Ctx.checkingABI() ? DeclAttribute::isAddingBreakingABI(Kind) :
+                               DeclAttribute::isAddingBreakingAPI(Kind)) &&
+          shouldDiagnoseAddingAttribute(this, Kind)) {
+        emitDiag(diag::decl_new_attr,
+                Ctx.buffer((llvm::Twine("with ") + getAttrName(Kind)).str()));
+      }
     }
   }