Add isFragile to VarDecl which allows visibility into the decl if

the decl is non-resilient or its defining module allows non-resilient
access. This way when package-cmo is enabled, global accessor and
other necessary symbols are added to TBD and doesn't throw linker
errors.

Resolves rdar://127321129

Author: elsh

include/swift/AST/Decl.h

@@ -5964,11 +5964,16 @@ class AbstractStorageDecl : public ValueDecl {
   /// Do we need to use resilient access patterns outside of this
   /// property's resilience domain?
   bool isResilient() const;
-
+ 
   /// Do we need to use resilient access patterns when accessing this
   /// property from the given module?
   bool isResilient(ModuleDecl *M, ResilienceExpansion expansion) const;
 
+  /// True if the decl is non-resilient, or its defining module allows non-resilient
+  /// access so its consuming modules within the same package can have
+  /// visibility into this decl.
+  bool isFragile() const;
+
   /// True if the storage can be referenced by a keypath directly.
   /// Otherwise, its override must be referenced.
   bool isValidKeyPathComponent() const;

lib/AST/Decl.cpp

@@ -3032,6 +3032,10 @@ bool Decl::isOutermostPrivateOrFilePrivateScope() const {
          !isInPrivateOrLocalContext(this);
 }
 
+bool AbstractStorageDecl::isFragile() const {
+  return !isResilient() || getModuleContext()->allowNonResilientAccess();
+}
+
 bool AbstractStorageDecl::isResilient() const {
   // Check for an explicit @_fixed_layout attribute.
   if (getAttrs().hasAttribute<FixedLayoutAttr>())

lib/SIL/IR/SILDeclRef.cpp

@@ -461,7 +461,7 @@ static LinkageLimit getLinkageLimit(SILDeclRef constant) {
     return Limit::OnDemand;
 
   case Kind::GlobalAccessor:
-    return cast<VarDecl>(d)->isResilient() ? Limit::NeverPublic : Limit::None;
+    return !cast<VarDecl>(d)->isFragile() ? Limit::NeverPublic : Limit::None;
 
   case Kind::DefaultArgGenerator:
     // If the default argument is to be serialized, only use non-ABI public

lib/SIL/IR/SILSymbolVisitor.cpp

@@ -579,7 +579,7 @@ class SILSymbolVisitorImpl : public ASTVisitor<SILSymbolVisitorImpl> {
 
   void visitVarDecl(VarDecl *VD) {
     // Variables inside non-resilient modules have some additional symbols.
-    if (!VD->isResilient()) {
+    if (VD->isFragile()) {
       // Non-global variables might have an explicit initializer symbol in
       // non-resilient modules.
       if (VD->getAttrs().hasAttribute<HasInitialValueAttr>() &&
@@ -589,25 +589,22 @@ class SILSymbolVisitorImpl : public ASTVisitor<SILSymbolVisitorImpl> {
         // Stored property initializers for public properties are public.
         addFunction(declRef);
       }
-
       // Statically/globally stored variables have some special handling.
       if (VD->hasStorage() && isGlobalOrStaticVar(VD)) {
         if (!shouldSkipVisit(getDeclLinkage(VD))) {
           Visitor.addGlobalVar(VD);
         }
-
         if (VD->isLazilyInitializedGlobal())
           addFunction(SILDeclRef(VD, SILDeclRef::Kind::GlobalAccessor));
       }
-
       // Wrapped non-static member properties may have a backing initializer.
       auto initInfo = VD->getPropertyWrapperInitializerInfo();
       if (initInfo.hasInitFromWrappedValue() && !VD->isStatic()) {
         addFunction(SILDeclRef(
             VD, SILDeclRef::Kind::PropertyWrapperBackingInitializer));
       }
     }
-
+    
     visitAbstractStorageDecl(VD);
   }
 

lib/Sema/TypeCheckStorage.cpp

@@ -2537,7 +2537,7 @@ RequiresOpaqueAccessorsRequest::evaluate(Evaluator &evaluator,
 
   } else if (dc->isModuleScopeContext()) {
     // Fixed-layout global variables don't require opaque accessors.
-    if (!var->isResilient() && !var->shouldUseNativeDynamicDispatch())
+    if (var->isFragile() && !var->shouldUseNativeDynamicDispatch())
       return false;
 
   // Stored properties imported from Clang don't require opaque accessors.

test/IRGen/package_global_accessor.swift

@@ -0,0 +1,21 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-build-swift -module-name=File -package-name Pkg -I%t -emit-sil %s | %FileCheck %s --check-prefix=CHECK-SIL
+// RUN: %target-build-swift -module-name=File -package-name Pkg -I%t -emit-sil %s -enable-library-evolution | %FileCheck %s --check-prefix=CHECK-SIL-HID
+// RUN: %target-build-swift -module-name=File -package-name Pkg -I%t -emit-sil %s -enable-library-evolution -Xfrontend -experimental-allow-non-resilient-access | %FileCheck %s --check-prefix=CHECK-SIL
+// RUN: %target-build-swift -module-name=File -package-name Pkg -I%t -emit-ir %s | %FileCheck %s --check-prefix=CHECK-IR
+// RUN: %target-build-swift -module-name=File -package-name Pkg -I%t -emit-ir %s -enable-library-evolution | %FileCheck %s --check-prefix=CHECK-IR-HID
+// RUN: %target-build-swift -module-name=File -package-name Pkg -I%t -emit-ir %s -enable-library-evolution -Xfrontend -experimental-allow-non-resilient-access | %FileCheck %s --check-prefix=CHECK-IR
+
+public struct S {
+  public static var x = "hello world"
+}
+
+// S.x.unsafeMutableAddressor
+// CHECK-SIL: sil [global_init] @$s4File1SV1xSSvau : $@convention(thin) () -> Builtin.RawPointer {
+// S.x.unsafeMutableAddressor
+// CHECK-SIL-HID: sil hidden [global_init] @$s4File1SV1xSSvau : $@convention(thin) () -> Builtin.RawPointer {
+
+// CHECK-IR: define swiftcc ptr @"$s4File1SV1xSSvau"()
+// CHECK-IR-HID: define hidden swiftcc ptr @"$s4File1SV1xSSvau"()
+