swift-module-digester: diagnose fixed-order property changes to computed property and vice versa as ABI breakage.

Author: nkcsgexi

include/swift/AST/DiagnosticsModuleDiffer.def

@@ -58,6 +58,8 @@ ERROR(decl_reorder,none,"%0 in a non-resilient type changes position from %1 to
 
 ERROR(decl_added,none,"%0 is added to a non-resilient type", (StringRef))
 
+ERROR(decl_has_fixed_order_change,none,"%0 is %select{now|no longer}1 a property with fixed layout order", (StringRef, bool))
+
 ERROR(default_arg_removed,none,"%0 has removed default argument from %1", (StringRef, StringRef))
 
 ERROR(conformance_removed,none,"%0 has removed %select{conformance to|inherited protocol}2 %1", (StringRef, StringRef, bool))

test/api-digester/Inputs/cake1.swift

@@ -55,6 +55,12 @@ public struct fixedLayoutStruct {
   public var a = 1
 }
 
+@_fixed_layout
+public struct fixedLayoutStruct2 {
+  public private(set) var NoLongerWithFixedBinaryOrder = 1
+  public var BecomeFixedBinaryOrder: Int { return 1 }
+}
+
 @_frozen
 public enum FrozenKind {
   case Unchanged

test/api-digester/Inputs/cake2.swift

@@ -59,6 +59,12 @@ public struct fixedLayoutStruct {
   private lazy var lazy_d = 4
 }
 
+@_fixed_layout
+public struct fixedLayoutStruct2 {
+  public var NoLongerWithFixedBinaryOrder: Int { return 1 }
+  public var BecomeFixedBinaryOrder = 1
+}
+
 @_frozen
 public enum FrozenKind {
   case Unchanged

test/api-digester/Outputs/Cake-abi.txt

@@ -10,6 +10,7 @@ cake1: AssociatedType RequiementChanges.removedType has been removed
 cake1: Class C3 has been removed
 cake1: Constructor Somestruct2.init(_:) has been removed
 cake1: Constructor fixedLayoutStruct.init(b:a:) has been removed
+cake1: Constructor fixedLayoutStruct2.init(NoLongerWithFixedBinaryOrder:) has been removed
 cake1: Func C4.foo() has been removed
 cake1: Func RequiementChanges.removedFunc() has been removed
 cake1: Subscript RemoveSetters.subscript(_:) has removed its setter
@@ -53,6 +54,8 @@ cake1: EnumElement FrozenKind.Fixed in a non-resilient type changes position fro
 cake1: EnumElement FrozenKind.Rigid in a non-resilient type changes position from 2 to 1
 cake1: Var fixedLayoutStruct.a in a non-resilient type changes position from 1 to 0
 cake1: Var fixedLayoutStruct.b in a non-resilient type changes position from 0 to 1
+cake1: Var fixedLayoutStruct2.BecomeFixedBinaryOrder is now a property with fixed layout order
+cake1: Var fixedLayoutStruct2.NoLongerWithFixedBinaryOrder is no longer a property with fixed layout order
 cake2: EnumElement FrozenKind.AddedCase is added to a non-resilient type
 cake2: Var fixedLayoutStruct.c is added to a non-resilient type
 cake2: Var fixedLayoutStruct.lazy_d.storage is added to a non-resilient type

test/api-digester/Outputs/Cake.txt

@@ -9,6 +9,7 @@ cake1: Protocol P3 has generic signature change from <Self : P1, Self : P2> to <
 cake1: AssociatedType RequiementChanges.removedType has been removed
 cake1: Constructor Somestruct2.init(_:) has been removed
 cake1: Constructor fixedLayoutStruct.init(b:a:) has been removed
+cake1: Constructor fixedLayoutStruct2.init(NoLongerWithFixedBinaryOrder:) has been removed
 cake1: Func C4.foo() has been removed
 cake1: Func RequiementChanges.removedFunc() has been removed
 cake1: Subscript RemoveSetters.subscript(_:) has removed its setter

tools/swift-api-digester/ModuleAnalyzerNodes.cpp

@@ -693,7 +693,9 @@ bool static isSDKNodeEqual(SDKContext &Ctx, const SDKNode &L, const SDKNode &R)
         // them equal because we need to check definition orders.
         if (auto *LV = dyn_cast<SDKNodeDeclVar>(&L)) {
           if (auto *RV = dyn_cast<SDKNodeDeclVar>(&R)) {
-            if (LV->hasFixedBinaryOrder() && RV->hasFixedBinaryOrder()) {
+            if (LV->hasFixedBinaryOrder() != RV->hasFixedBinaryOrder())
+              return false;
+            if (LV->hasFixedBinaryOrder()) {
               if (LV->getFixedBinaryOrder() != RV->getFixedBinaryOrder())
                 return false;
             }

tools/swift-api-digester/ModuleDiagsConsumer.cpp

@@ -54,6 +54,7 @@ static StringRef getCategoryName(uint32_t ID) {
     return "/* Generic Signature Changes */";
   case LocalDiagID::decl_added:
   case LocalDiagID::decl_reorder:
+  case LocalDiagID::decl_has_fixed_order_change:
     return "/* Fixed-layout Type Changes */";
   case LocalDiagID::conformance_added:
   case LocalDiagID::conformance_removed:

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

@@ -808,6 +808,10 @@ void swift::ide::api::SDKNodeDeclVar::diagnose(SDKNode *Right) {
                             getScreenInfo());
   }
   if (Ctx.checkingABI()) {
+    if (hasFixedBinaryOrder() != RV->hasFixedBinaryOrder()) {
+      Ctx.getDiags().diagnose(SourceLoc(), diag::decl_has_fixed_order_change,
+                              getScreenInfo(), hasFixedBinaryOrder());
+    }
     if (hasFixedBinaryOrder() && RV->hasFixedBinaryOrder() &&
         getFixedBinaryOrder() != RV->getFixedBinaryOrder()) {
       Ctx.getDiags().diagnose(SourceLoc(), diag::decl_reorder,