Typecheck ABI-only VarDecls

The decl checker was effectively not being run on these because we weren’t typechecking the PBD and typechecking the VarDecl itself is basically a no-op.

Author: beccadax

lib/AST/NameLookup.cpp

@@ -2317,6 +2317,13 @@ void NominalTypeDecl::recordObjCMethod(AbstractFunctionDecl *method,
   if (!ObjCMethodLookup && !createObjCMethodLookup())
     return;
 
+  // Only record API decls.
+  Decl *abiRoleDecl = method;
+  if (auto accessor = dyn_cast<AccessorDecl>(method))
+    abiRoleDecl = accessor->getStorage();
+  if (!ABIRoleInfo(abiRoleDecl).providesAPI())
+    return;
+
   // Record the method.
   bool isInstanceMethod = method->isObjCInstanceMethod();
   auto &vec = (*ObjCMethodLookup)[{selector, isInstanceMethod}].Methods;

lib/Sema/TypeCheckAttrABI.cpp

@@ -1152,6 +1152,7 @@ void checkABIAttrPBD(PatternBindingDecl *APBD, VarDecl *VD) {
   }
 
   // Check that each pattern has the same number of variables.
+  bool didDiagnose = false;
   for (auto i : range(PBD->getNumPatternEntries())) {
     SmallVector<VarDecl *, 8> VDs;
     SmallVector<VarDecl *, 8> AVDs;
@@ -1161,18 +1162,24 @@ void checkABIAttrPBD(PatternBindingDecl *APBD, VarDecl *VD) {
 
     if (VDs.size() < AVDs.size()) {
       for (auto AVD : drop_begin(AVDs, VDs.size())) {
-        AVD->diagnose(diag::attr_abi_mismatched_var,
-                      AVD, /*isABI=*/true);
+        AVD->diagnose(diag::attr_abi_mismatched_var, AVD, /*isABI=*/true);
+        didDiagnose = true;
       }
     }
     else if (VDs.size() > AVDs.size()) {
       for (auto VD : drop_begin(VDs, AVDs.size())) {
-        VD->diagnose(diag::attr_abi_mismatched_var,
-                     VD, /*isABI=*/false);
+        VD->diagnose(diag::attr_abi_mismatched_var, VD, /*isABI=*/false);
+        didDiagnose = true;
       }
     }
   }
+  if (didDiagnose)
+    return;
+
+  // Check the ABI PBD--this is what checks the underlying vars.
+  TypeChecker::typeCheckDecl(APBD);
 }
+
 } // end anonymous namespace
 
 void TypeChecker::checkDeclABIAttribute(Decl *D, ABIAttr *attr) {

lib/Sema/TypeCheckStorage.cpp

@@ -3845,6 +3845,10 @@ void HasStorageRequest::cacheResult(bool hasStorage) const {
 StorageImplInfo
 StorageImplInfoRequest::evaluate(Evaluator &evaluator,
                                  AbstractStorageDecl *storage) const {
+  auto abiRole = ABIRoleInfo(storage);
+  if (!abiRole.providesAPI() && abiRole.getCounterpart())
+    return abiRole.getCounterpart()->getImplInfo();
+
   if (auto *param = dyn_cast<ParamDecl>(storage)) {
     return StorageImplInfo::getSimpleStored(
       param->isImmutableInFunctionBody()