Sema: Catch invalid stored properties in the StorageImplInfoRequest

Previously we were only checking in declarations in primary files, which
is insufficient since SILGen crashes if presented with an invalid stored
property.

Fixes <rdar://problem/54471229>, <https://bugs.swift.org/browse/SR-11322>.

Author: slavapestov

lib/Sema/TypeCheckDecl.cpp

@@ -2159,24 +2159,9 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
     // Reject cases where this is a variable that has storage but it isn't
     // allowed.
     if (VD->hasStorage()) {
-      // Note: Stored properties in protocols are diagnosed in
-      // finishProtocolStorageImplInfo().
-
-      // Enums and extensions cannot have stored instance properties.
-      // Static stored properties are allowed, with restrictions
-      // enforced below.
-      if (isa<EnumDecl>(VD->getDeclContext()) &&
-          !VD->isStatic() && !VD->isInvalid()) {
-        // Enums can only have computed properties.
-        TC.diagnose(VD->getLoc(), diag::enum_stored_property);
-        VD->markInvalid();
-      } else if (isa<ExtensionDecl>(VD->getDeclContext()) &&
-                 !VD->isStatic() && !VD->isInvalid() &&
-                 !VD->getAttrs().getAttribute<DynamicReplacementAttr>()) {
-        TC.diagnose(VD->getLoc(), diag::extension_stored_property);
-        VD->markInvalid();
-      }
-      
+      // Note: Stored properties in protocols, enums, etc are diagnosed in
+      // finishStorageImplInfo().
+
       // We haven't implemented type-level storage in some contexts.
       if (VD->isStatic()) {
         auto PBD = VD->getParentPatternBinding();
@@ -2197,13 +2182,9 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
 
         auto DC = VD->getDeclContext();
 
-        // Non-stored properties are fine.
-        if (!PBD->hasStorage()) {
-          // do nothing
-
         // Stored type variables in a generic context need to logically
         // occur once per instantiation, which we don't yet handle.
-        } else if (DC->getExtendedProtocolDecl()) {
+        if (DC->getExtendedProtocolDecl()) {
           unimplementedStatic(ProtocolExtensions);
         } else if (DC->isGenericContext()
                && !DC->getGenericSignatureOfContext()->areAllParamsConcrete()) {

lib/Sema/TypeCheckStorage.cpp

@@ -2567,6 +2567,8 @@ static void finishNSManagedImplInfo(VarDecl *var,
 
 static void finishStorageImplInfo(AbstractStorageDecl *storage,
                                   StorageImplInfo &info) {
+  auto dc = storage->getDeclContext();
+
   if (auto var = dyn_cast<VarDecl>(storage)) {
     if (!info.hasStorage()) {
       if (auto *init = var->getParentInitializer()) {
@@ -2585,8 +2587,28 @@ static void finishStorageImplInfo(AbstractStorageDecl *storage,
     }
   }
 
-  if (isa<ProtocolDecl>(storage->getDeclContext()))
+  if (isa<ProtocolDecl>(dc))
     finishProtocolStorageImplInfo(storage, info);
+
+  // If we have a stored property in an unsupported context, diagnose
+  // and change it to computed to avoid confusing SILGen.
+
+  // Note: Stored properties in protocols are diagnosed in
+  // finishProtocolStorageImplInfo().
+
+  if (info.hasStorage() && !storage->isStatic()) {
+    if (isa<EnumDecl>(dc)) {
+      storage->diagnose(diag::enum_stored_property);
+      info = StorageImplInfo::getMutableComputed();
+    } else if (isa<ExtensionDecl>(dc) &&
+              !storage->getAttrs().getAttribute<DynamicReplacementAttr>()) {
+      storage->diagnose(diag::extension_stored_property);
+
+      info = (info.supportsMutation()
+              ? StorageImplInfo::getMutableComputed()
+              : StorageImplInfo::getImmutableComputed());
+    }
+  }
 }
 
 /// Gets the storage info of the provided storage decl if it has the
@@ -2634,6 +2656,13 @@ static StorageImplInfo classifyWithHasStorageAttr(VarDecl *var) {
 llvm::Expected<StorageImplInfo>
 StorageImplInfoRequest::evaluate(Evaluator &evaluator,
                                  AbstractStorageDecl *storage) const {
+  if (auto *param = dyn_cast<ParamDecl>(storage)) {
+    return StorageImplInfo::getSimpleStored(
+      param->isInOut()
+      ? StorageIsMutable
+      : StorageIsNotMutable);
+  }
+
   if (auto *var = dyn_cast<VarDecl>(storage)) {
     // Allow the @_hasStorage attribute to override all the accessors we parsed
     // when making the final classification.

test/NameBinding/name_lookup.swift

@@ -239,7 +239,7 @@ class ThisDerived1 : ThisBase1 {
 
     self.baseExtProp = 42 // expected-error {{member 'baseExtProp' cannot be used on type 'ThisDerived1'}}
     self.baseExtFunc0() // expected-error {{instance member 'baseExtFunc0' cannot be used on type 'ThisDerived1'}}
-    self.baseExtStaticVar = 42
+    self.baseExtStaticVar = 42 // expected-error {{instance member 'baseExtStaticVar' cannot be used on type 'ThisDerived1'}}
     self.baseExtStaticProp = 42 // expected-error {{member 'baseExtStaticProp' cannot be used on type 'ThisDerived1'}}
     self.baseExtStaticFunc0()
 
@@ -264,7 +264,7 @@ class ThisDerived1 : ThisBase1 {
 
     self.derivedExtProp = 42 // expected-error {{member 'derivedExtProp' cannot be used on type 'ThisDerived1'}}
     self.derivedExtFunc0() // expected-error {{instance member 'derivedExtFunc0' cannot be used on type 'ThisDerived1'}}
-    self.derivedExtStaticVar = 42
+    self.derivedExtStaticVar = 42 // expected-error {{instance member 'derivedExtStaticVar' cannot be used on type 'ThisDerived1'}}
     self.derivedExtStaticProp = 42 // expected-error {{member 'derivedExtStaticProp' cannot be used on type 'ThisDerived1'}}
     self.derivedExtStaticFunc0()
 
@@ -305,7 +305,7 @@ class ThisDerived1 : ThisBase1 {
 
     super.baseExtProp = 42 // expected-error {{member 'baseExtProp' cannot be used on type 'ThisBase1'}}
     super.baseExtFunc0() // expected-error {{instance member 'baseExtFunc0' cannot be used on type 'ThisBase1'}}
-    super.baseExtStaticVar = 42 
+    super.baseExtStaticVar = 42 // expected-error {{instance member 'baseExtStaticVar' cannot be used on type 'ThisBase1'}}
     super.baseExtStaticProp = 42 // expected-error {{member 'baseExtStaticProp' cannot be used on type 'ThisBase1'}}
     super.baseExtStaticFunc0()