Disallow implicit conversions from None to integer types

This fixes an error introduced in r228934 where None was converted to
an int instead of the int being converted to an Optional as intended.
We make that sort of mistake a compile error by changing NoneType into
a scoped enum.

Finally, provide a static NoneType called None to avoid forcing all
users to spell it NoneType::None.

llvm-svn: 229980

diff --git a/llvm/include/llvm/ADT/None.h b/llvm/include/llvm/ADT/None.h
index 5793bd2..c78db78 100644 (file)
--- a/llvm/include/llvm/ADT/None.h
+++ b/llvm/include/llvm/ADT/None.h
@@ -19,9 +19,8 @@
 namespace llvm {
 /// \brief A simple null object to allow implicit construction of Optional<T>
 /// and similar types without having to spell out the specialization's name.
-enum NoneType {
-  None
-};
+enum class NoneType { None };
+static NoneType None;
 }
 
 #endif

diff --git a/llvm/lib/ProfileData/CoverageMapping.cpp b/llvm/lib/ProfileData/CoverageMapping.cpp
index a124d79..da619e1 100644 (file)
--- a/llvm/lib/ProfileData/CoverageMapping.cpp
+++ b/llvm/lib/ProfileData/CoverageMapping.cpp
@@ -361,7 +361,9 @@ static Optional<unsigned> findMainViewFileID(StringRef SourceFile,
       IsNotExpandedFile[CR.ExpandedFileID] = false;
   IsNotExpandedFile &= FilenameEquivalence;
   int I = IsNotExpandedFile.find_first();
-  return I != -1 ? I : None;
+  if (I == -1)
+    return None;
+  return I;
 }
 
 static Optional<unsigned> findMainViewFileID(const FunctionRecord &Function) {
@@ -370,7 +372,9 @@ static Optional<unsigned> findMainViewFileID(const FunctionRecord &Function) {
     if (CR.Kind == CounterMappingRegion::ExpansionRegion)
       IsNotExpandedFile[CR.ExpandedFileID] = false;
   int I = IsNotExpandedFile.find_first();
-  return I != -1 ? I : None;
+  if (I == -1)
+    return None;
+  return I;
 }
 
 /// Sort a nested sequence of regions from a single file.