[Sema] InitAccessors: Implement validation of @storageRestrictions attribute

Author: xedin

include/swift/AST/Attr.h

@@ -1646,6 +1646,9 @@ class StorageRestrictionsAttr final
     return {getTrailingObjects<Identifier>() + NumInitializes, NumAccesses};
   }
 
+  ArrayRef<VarDecl *> getInitializesProperties(AccessorDecl *attachedTo) const;
+  ArrayRef<VarDecl *> getAccessesProperties(AccessorDecl *attachedTo) const;
+
   static StorageRestrictionsAttr *create(ASTContext &ctx, SourceLoc atLoc,
                                          SourceRange range,
                                          ArrayRef<Identifier> initializes,

lib/AST/Attr.cpp

@@ -2608,6 +2608,26 @@ AccessesAttr::getPropertyDecls(AccessorDecl *attachedTo) const {
       {});
 }
 
+ArrayRef<VarDecl *> StorageRestrictionsAttr::getInitializesProperties(
+    AccessorDecl *attachedTo) const {
+  auto &ctx = attachedTo->getASTContext();
+  return evaluateOrDefault(ctx.evaluator,
+                           InitAccessorReferencedVariablesRequest{
+                               const_cast<StorageRestrictionsAttr *>(this),
+                               attachedTo, getInitializesNames()},
+                           {});
+}
+
+ArrayRef<VarDecl *>
+StorageRestrictionsAttr::getAccessesProperties(AccessorDecl *attachedTo) const {
+  auto &ctx = attachedTo->getASTContext();
+  return evaluateOrDefault(ctx.evaluator,
+                           InitAccessorReferencedVariablesRequest{
+                               const_cast<StorageRestrictionsAttr *>(this),
+                               attachedTo, getAccessesNames()},
+                           {});
+}
+
 void swift::simple_display(llvm::raw_ostream &out, const DeclAttribute *attr) {
   if (attr)
     attr->print(out);

lib/Sema/TypeCheckAttr.cpp

@@ -3591,6 +3591,21 @@ void AttributeChecker::visitAccessesAttr(AccessesAttr *attr) {
 }
 
 void AttributeChecker::visitStorageRestrictionsAttr(StorageRestrictionsAttr *attr) {
+  auto *accessor = dyn_cast<AccessorDecl>(D);
+  if (!accessor || accessor->getAccessorKind() != AccessorKind::Init) {
+    diagnose(attr->getLocation(),
+             diag::storage_restrictions_attribute_not_on_init_accessor);
+    return;
+  }
+
+  auto initializesProperties = attr->getInitializesProperties(accessor);
+  for (auto *property : attr->getAccessesProperties(accessor)) {
+    if (llvm::is_contained(initializesProperties, property)) {
+      diagnose(attr->getLocation(),
+               diag::init_accessor_property_both_init_and_accessed,
+               property->getName());
+    }
+  }
 }
 
 void AttributeChecker::visitImplementsAttr(ImplementsAttr *attr) {

test/decl/var/init_accessors.swift

@@ -524,6 +524,9 @@ do {
 
 func test_invalid_storage_restrictions() {
   struct Test {
+    var _a: Int
+    var _b: Int
+
     var a: Int {
       @storageRestrictions()
       // expected-error@-1 {{missing label in @storageRestrictions attribute}}
@@ -553,5 +556,17 @@ func test_invalid_storage_restrictions() {
       // expected-error@-1 {{unexpected label 'initialize' in @storageRestrictions attribute}}
       init {}
     }
+
+    var f: Int {
+      @storageRestrictions(initializes: _a, accesses: _b, _a)
+      // expected-error@-1 {{property '_a' cannot be both initialized and accessed}}
+      init {}
+    }
+
+    var g: Int {
+      @storageRestrictions(initializes: _a)
+      // expected-error@-1 {{@storageRestrictions attribute could only be used with init accessors}}
+      get { 0 }
+    }
   }
 }