[TBDGen] Walk accessors as part of their parent storage, not the main AST.

Sometimes, inconsistently, an accessor appears as a member of a parent
DeclContext, but other times it can seemingly only be accessed through the
storage decl. Instead of trying to conditionalise on this, just use the storage
decl as the canonical source, and ignore direct visits to accessors (i.e. the
membership route to ones that are members of other things).

Fixes rdar://problem/40476839.

Author: huonw

lib/TBDGen/TBDGen.cpp

@@ -150,6 +150,22 @@ void TBDGenVisitor::visitAbstractFunctionDecl(AbstractFunctionDecl *AFD) {
   }
 }
 
+void TBDGenVisitor::visitAccessorDecl(AccessorDecl *AD) {
+  // Do nothing: accessors are always nested within the storage decl, but
+  // sometimes appear outside it too. To avoid double-walking them, we
+  // explicitly visit them as members of the storage and ignore them when we
+  // visit them as part of the main walk, here.
+}
+
+void TBDGenVisitor::visitAbstractStorageDecl(AbstractStorageDecl *ASD) {
+  // Explicitly look at each accessor here: see visitAccessorDecl.
+  SmallVector<Decl *, 8> accessors;
+  ASD->getAllAccessorFunctions(accessors);
+  for (auto accessor : accessors) {
+    visitAbstractFunctionDecl(cast<AbstractFunctionDecl>(accessor));
+  }
+}
+
 void TBDGenVisitor::visitVarDecl(VarDecl *VD) {
   // statically/globally stored variables have some special handling.
   if (VD->hasStorage() && isGlobalOrStaticVar(VD)) {
@@ -162,6 +178,8 @@ void TBDGenVisitor::visitVarDecl(VarDecl *VD) {
     if (!FileHasEntryPoint || VD->isStatic())
       addSymbol(SILDeclRef(VD, SILDeclRef::Kind::GlobalAccessor));
   }
+
+  visitAbstractStorageDecl(VD);
 }
 
 void TBDGenVisitor::visitNominalTypeDecl(NominalTypeDecl *NTD) {

lib/TBDGen/TBDGenVisitor.h

@@ -94,6 +94,8 @@ class TBDGenVisitor : public ASTVisitor<TBDGenVisitor> {
 
   void visitAbstractFunctionDecl(AbstractFunctionDecl *AFD);
 
+  void visitAccessorDecl(AccessorDecl *AD);
+
   void visitNominalTypeDecl(NominalTypeDecl *NTD);
 
   void visitClassDecl(ClassDecl *CD);
@@ -104,6 +106,8 @@ class TBDGenVisitor : public ASTVisitor<TBDGenVisitor> {
 
   void visitProtocolDecl(ProtocolDecl *PD);
 
+  void visitAbstractStorageDecl(AbstractStorageDecl *ASD);
+
   void visitVarDecl(VarDecl *VD);
 
   void visitEnumDecl(EnumDecl *ED);

test/TBD/global.swift

@@ -1,4 +1,5 @@
 // RUN: %target-swift-frontend -emit-ir -o- -parse-as-library -module-name test -validate-tbd-against-ir=missing %s
+// RUN: %target-swift-frontend -emit-ir -o- -parse-as-library -module-name test -validate-tbd-against-ir=missing -enable-resilience %s
 
 public let publicLet: Int = 0
 internal let internalLet: Int = 0

test/TBD/struct.swift

@@ -1,4 +1,5 @@
 // RUN: %target-swift-frontend -emit-ir -o- -parse-as-library -module-name test -validate-tbd-against-ir=missing %s
+// RUN: %target-swift-frontend -emit-ir -o- -parse-as-library -module-name test -validate-tbd-against-ir=missing %s -enable-resilience
 
 public struct PublicNothing {}
 
@@ -44,6 +45,25 @@ public struct PublicProperties {
     }
 }
 
+public struct PublicSubscripts {
+    public subscript(publicGet _: Int) -> Int { return 0 }
+    internal subscript(internalGet _: Int) -> Int { return 0 }
+    private subscript(privateGet _: Int) -> Int { return 0 }
+
+    public subscript(publicGetSet _: Int) -> Int {
+        get {return 0 }
+        set {}
+    }
+    internal subscript(internalGetSet _: Int) -> Int {
+        get {return 0 }
+        set {}
+    }
+    private subscript(privateGetSet _: Int) -> Int {
+        get {return 0 }
+        set {}
+    }
+}
+
 public struct PublicStatics {
     public static func publicStaticFunc() {}
     internal static func internalStaticFunc() {}
@@ -135,6 +155,20 @@ internal struct InternalProperties {
     }
 }
 
+internal struct InternalSubscripts {
+    internal subscript(internalGet _: Int) -> Int { return 0 }
+    private subscript(privateGet _: Int) -> Int { return 0 }
+
+    internal subscript(internalGetSet _: Int) -> Int {
+        get {return 0 }
+        set {}
+    }
+    private subscript(privateGetSet _: Int) -> Int {
+        get {return 0 }
+        set {}
+    }
+}
+
 internal struct InternalStatics {
     internal static func internalStaticFunc() {}
     private static func privateStaticFunc() {}
@@ -203,6 +237,15 @@ private struct PrivateProperties {
     }
 }
 
+private struct PrivateSubscripts {
+    private subscript(privateGet _: Int) -> Int { return 0 }
+
+    private subscript(privateGetSet _: Int) -> Int {
+        get {return 0 }
+        set {}
+    }
+}
+
 private struct PrivateStatics {
     private static func privateStaticFunc() {}