Replace double negation of !FileID.isInvalid() with FileID.isValid().
+couple more of double-negated !SourceLocation.isInvalid() unfixed in r249228.

llvm-svn: 249235
diff --git a/clang/lib/Basic/SourceManager.cpp b/clang/lib/Basic/SourceManager.cpp
index 5e408c9..536ae7f 100644
--- a/clang/lib/Basic/SourceManager.cpp
+++ b/clang/lib/Basic/SourceManager.cpp
@@ -1408,7 +1408,7 @@
 /// considered to be from a system header.
 SrcMgr::CharacteristicKind
 SourceManager::getFileCharacteristic(SourceLocation Loc) const {
-  assert(!Loc.isInvalid() && "Can't get file characteristic of invalid loc!");
+  assert(Loc.isValid() && "Can't get file characteristic of invalid loc!");
   std::pair<FileID, unsigned> LocInfo = getDecomposedExpansionLoc(Loc);
   bool Invalid = false;
   const SLocEntry &SEntry = getSLocEntry(LocInfo.first, &Invalid);
@@ -1613,7 +1613,7 @@
   // location in the main file.
   Optional<llvm::sys::fs::UniqueID> SourceFileUID;
   Optional<StringRef> SourceFileName;
-  if (!MainFileID.isInvalid()) {
+  if (MainFileID.isValid()) {
     bool Invalid = false;
     const SLocEntry &MainSLoc = getSLocEntry(MainFileID, &Invalid);
     if (Invalid)
@@ -1786,7 +1786,7 @@
 ///     110 -> SourceLocation()
 void SourceManager::computeMacroArgsCache(MacroArgsMap *&CachePtr,
                                           FileID FID) const {
-  assert(!FID.isInvalid());
+  assert(FID.isValid());
   assert(!CachePtr);
 
   CachePtr = new MacroArgsMap();