Handle access note I/O and parse errors

include/swift/AST/DiagnosticsFrontend.def

@@ -405,5 +405,10 @@ WARNING(module_incompatible_with_skip_function_bodies,none,
         "-experimental-skip-*-function-bodies* flags; they have "
         "been automatically disabled", (StringRef))
 
+WARNING(invalid_access_notes_file,none,
+        "access notes at '%0' will be ignored due to an error while loading "
+        "them: %1",
+        (StringRef, StringRef))
+
 #define UNDEFINE_DIAGNOSTIC_MACROS
 #include "DefineDiagnosticMacros.h"

lib/AST/AccessNotes.cpp

@@ -215,15 +215,30 @@ template <> struct llvm::yaml::MappingTraits<swift::AccessNote> {
 };
 
 namespace swift {
+
+static void
+convertToErrorAndJoin(const llvm::SMDiagnostic &diag, void *Context) {
+  auto newError = llvm::createStringError(std::errc::invalid_argument,
+                                          "%s at line %d, column %d",
+                                          diag.getMessage().bytes_begin(),
+                                          diag.getLineNo(), diag.getColumnNo());
+
+  auto &errors = *(llvm::Error*)Context;
+  errors = llvm::joinErrors(std::move(errors), std::move(newError));
+}
+
 llvm::Expected<AccessNotes>
 AccessNotes::load(ASTContext &ctx, llvm::MemoryBuffer *buffer) {
-  llvm::yaml::Input yamlIn(buffer->getBuffer(), (void *)&ctx);
+  llvm::Error errors = llvm::Error::success();
+
+  llvm::yaml::Input yamlIn(buffer->getBuffer(), (void *)&ctx,
+                           convertToErrorAndJoin, &errors);
 
   AccessNotes notes;
   yamlIn >> notes;
 
   if (yamlIn.error())
-    return llvm::errorCodeToError(yamlIn.error());
+    return llvm::Expected<AccessNotes>(std::move(errors));
 
   return notes;
 }

lib/Frontend/Frontend.cpp

@@ -902,6 +902,16 @@ bool CompilerInstance::createFilesForMainModule(
   return false;
 }
 
+template<typename ExpectedOut, typename ExpectedIn>
+static llvm::Expected<ExpectedOut>
+flatMap(llvm::Expected<ExpectedIn> &&in,
+        llvm::function_ref<llvm::Expected<ExpectedOut>(ExpectedIn &&)> transform) {
+  if (!in)
+    return llvm::Expected<ExpectedOut>(in.takeError());
+
+  return transform(std::move(in.get()));
+}
+
 ModuleDecl *CompilerInstance::getMainModule() const {
   if (!MainModule) {
     Identifier ID = Context->getIdentifier(Invocation.getModuleName());
@@ -935,18 +945,26 @@ ModuleDecl *CompilerInstance::getMainModule() const {
     }
 
     if (!Invocation.getFrontendOptions().AccessNotesPath.empty()) {
-      auto bufferOrError =
-          swift::vfs::getFileOrSTDIN(getFileSystem(),
-                               Invocation.getFrontendOptions().AccessNotesPath);
-      // FIXME: Diagnose properly
-      auto buffer = cantFail(llvm::errorOrToExpected(std::move(bufferOrError)),
-                             "can't open access notes file");
+      auto accessNotesPath = Invocation.getFrontendOptions().AccessNotesPath;
 
-      auto expectedAccessNotes = AccessNotes::load(*Context, buffer.get());
-      // FIXME: Diagnose properly
-      MainModule->getAccessNotes() = cantFail(std::move(expectedAccessNotes),
-                                              "invalid access notes:");
+      auto expectedBuffer = llvm::errorOrToExpected(
+          swift::vfs::getFileOrSTDIN(getFileSystem(), accessNotesPath));
 
+      auto expectedAccessNotes =
+          flatMap<AccessNotes, std::unique_ptr<llvm::MemoryBuffer>>(
+              std::move(expectedBuffer),
+              [&](auto &&buffer) -> auto {
+                return AccessNotes::load(*Context, buffer.get());
+              });
+
+      if (expectedAccessNotes)
+        MainModule->getAccessNotes() = std::move(expectedAccessNotes).get();
+      else
+        llvm::handleAllErrors(expectedAccessNotes.takeError(),
+                              [&](const llvm::ErrorInfoBase &error) {
+          Context->Diags.diagnose(SourceLoc(), diag::invalid_access_notes_file,
+                                  accessNotesPath, error.message());
+        });
     }
   }
   return MainModule;

test/Sema/Inputs/bad.accessnotes

@@ -0,0 +1 @@
+Colourless green ideas sleep furiously.

test/Sema/access-notes-invalid.swift

@@ -0,0 +1,5 @@
+// RUN: %target-swift-frontend -typecheck -primary-file %s -access-notes-path %S/Inputs/missing.accessnotes 2>&1 | %FileCheck --check-prefix=CHECK-MISSING %s
+// CHECK-MISSING: <unknown>:0: warning: access notes at 'SOURCE_DIR/test/Sema/Inputs/missing.accessnotes' will be ignored due to an error while loading them: No such file or directory{{$}}
+
+// RUN: %target-swift-frontend -typecheck -primary-file %s -access-notes-path %S/Inputs/bad.accessnotes 2>&1 | %FileCheck --check-prefix=CHECK-BAD %s
+// CHECK-BAD: <unknown>:0: warning: access notes at 'SOURCE_DIR/test/Sema/Inputs/bad.accessnotes' will be ignored due to an error while loading them: not a mapping at line 1, column 0{{$}}