FileManager: Use llvm::Expected in new getFileRef API

`FileManager::getFileRef` is a modern API which we expect to convert to
over time.  We should modernize the error handling as well, using
`llvm::Expected` instead of `llvm::ErrorOr`, to help clients that care
about errors to ensure nothing is missed.

However, not all clients care.  I've also added another path for those
that don't:

- `FileEntryRef` is now copy- and move-assignable (using a pointer
  instead of a reference).
- `FileManager::getOptionalFileRef` returns an `llvm::Optional` instead
  of `llvm::Expected`.
- Added an `llvm::expectedToOptional` utility in case this is useful
  elsewhere.

https://reviews.llvm.org/D66705

llvm-svn: 369943

2 files changed, 9 insertions, 13 deletions

diff --git a/clang/lib/Lex/HeaderMap.cpp b/clang/lib/Lex/HeaderMap.cpp
index 1c7fb1a..d44ef29c 100644
--- a/clang/lib/Lex/HeaderMap.cpp
+++ b/clang/lib/Lex/HeaderMap.cpp
@@ -204,9 +204,7 @@ Optional<FileEntryRef> HeaderMap::LookupFile(StringRef Filename,
   if (Dest.empty())
     return None;
 
-  if (auto File = FM.getFileRef(Dest))
-    return *File;
-  return None;
+  return FM.getOptionalFileRef(Dest);
 }
 
 StringRef HeaderMapImpl::lookupFilename(StringRef Filename,
diff --git a/clang/lib/Lex/HeaderSearch.cpp b/clang/lib/Lex/HeaderSearch.cpp
index 84af65c..0160677 100644
--- a/clang/lib/Lex/HeaderSearch.cpp
+++ b/clang/lib/Lex/HeaderSearch.cpp
@@ -314,7 +314,7 @@ Optional<FileEntryRef> HeaderSearch::getFileAndSuggestModule(
   if (!File) {
     // For rare, surprising errors (e.g. "out of file handles"), diag the EC
     // message.
-    std::error_code EC = File.getError();
+    std::error_code EC = llvm::errorToErrorCode(File.takeError());
     if (EC != llvm::errc::no_such_file_or_directory &&
         EC != llvm::errc::invalid_argument &&
         EC != llvm::errc::is_a_directory && EC != llvm::errc::not_a_directory) {
@@ -401,7 +401,7 @@ Optional<FileEntryRef> DirectoryLookup::LookupFile(
       FixupSearchPath();
       return *Result;
     }
-  } else if (auto Res = HS.getFileMgr().getFileRef(Dest)) {
+  } else if (auto Res = HS.getFileMgr().getOptionalFileRef(Dest)) {
     FixupSearchPath();
     return *Res;
   }
@@ -553,9 +553,8 @@ Optional<FileEntryRef> DirectoryLookup::DoFrameworkLookup(
 
   FrameworkName.append(Filename.begin()+SlashPos+1, Filename.end());
 
-  llvm::ErrorOr<FileEntryRef> File =
-      FileMgr.getFileRef(FrameworkName, /*OpenFile=*/!SuggestedModule);
-
+  auto File =
+      FileMgr.getOptionalFileRef(FrameworkName, /*OpenFile=*/!SuggestedModule);
   if (!File) {
     // Check "/System/Library/Frameworks/Cocoa.framework/PrivateHeaders/file.h"
     const char *Private = "Private";
@@ -565,7 +564,8 @@ Optional<FileEntryRef> DirectoryLookup::DoFrameworkLookup(
       SearchPath->insert(SearchPath->begin()+OrigSize, Private,
                          Private+strlen(Private));
 
-    File = FileMgr.getFileRef(FrameworkName, /*OpenFile=*/!SuggestedModule);
+    File = FileMgr.getOptionalFileRef(FrameworkName,
+                                      /*OpenFile=*/!SuggestedModule);
   }
 
   // If we found the header and are allowed to suggest a module, do so now.
@@ -1076,9 +1076,7 @@ Optional<FileEntryRef> HeaderSearch::LookupSubframeworkHeader(
   }
 
   HeadersFilename.append(Filename.begin()+SlashPos+1, Filename.end());
-  llvm::ErrorOr<FileEntryRef> File =
-      FileMgr.getFileRef(HeadersFilename, /*OpenFile=*/true);
-
+  auto File = FileMgr.getOptionalFileRef(HeadersFilename, /*OpenFile=*/true);
   if (!File) {
     // Check ".../Frameworks/HIToolbox.framework/PrivateHeaders/HIToolbox.h"
     HeadersFilename = FrameworkName;
@@ -1090,7 +1088,7 @@ Optional<FileEntryRef> HeaderSearch::LookupSubframeworkHeader(
     }
 
     HeadersFilename.append(Filename.begin()+SlashPos+1, Filename.end());
-    File = FileMgr.getFileRef(HeadersFilename, /*OpenFile=*/true);
+    File = FileMgr.getOptionalFileRef(HeadersFilename, /*OpenFile=*/true);
 
     if (!File)
       return None;