clang: Fix variable spelling

[urnathan]

Summary

In looking at how TrailingObject worked, I came across this use to crib from. But it spells 'trailing' as 'trailling'. Let's fix that.

Aaron acked this on IRC, so going to commit

[aaron.ballman]

LGTM! Btw, for these sort of "it's a typo" kind of obvious non-functional changes, feel free to commit without posting a phab review if you'd like.

clang/include/clang/AST/DeclCXX.h

ExplicitSpecifier getExplicitSpecifierInternal() const {
     if (CXXConstructorDeclBits.HasTrailingExplicitSpecifier)
       return *getTrailingObjects<ExplicitSpecifier>();
     return ExplicitSpecifier(
         nullptr, CXXConstructorDeclBits.IsSimpleExplicit
                      ? ExplicitSpecKind::ResolvedTrue
                      : ExplicitSpecKind::ResolvedFalse);
   }
 
-  enum TraillingAllocKind {
+  enum TrailingAllocKind {
     TAKInheritsConstructor = 1,
     TAKHasTailExplicit = 1 << 1,
   };
 
-  uint64_t getTraillingAllocKind() const {
+  uint64_t getTrailingAllocKind() const {
     return numTrailingObjects(OverloadToken<InheritedConstructor>()) |
            (numTrailingObjects(OverloadToken<ExplicitSpecifier>()) << 1);
   }
 
 public:
   friend class ASTDeclReader;
   friend class ASTDeclWriter;
   friend TrailingObjects;

clang/lib/AST/DeclCXX.cpp

CXXConstructorDecl::CXXConstructorDecl(
   setExplicitSpecifier(ES);
 }
 
 void CXXConstructorDecl::anchor() {}
 
 CXXConstructorDecl *CXXConstructorDecl::CreateDeserialized(ASTContext &C,
                                                            unsigned ID,
                                                            uint64_t AllocKind) {
-  bool hasTraillingExplicit = static_cast<bool>(AllocKind & TAKHasTailExplicit);
+  bool hasTrailingExplicit = static_cast<bool>(AllocKind & TAKHasTailExplicit);
   bool isInheritingConstructor =
       static_cast<bool>(AllocKind & TAKInheritsConstructor);
   unsigned Extra =
       additionalSizeToAlloc<InheritedConstructor, ExplicitSpecifier>(
-          isInheritingConstructor, hasTraillingExplicit);
+          isInheritingConstructor, hasTrailingExplicit);
   auto *Result = new (C, ID, Extra) CXXConstructorDecl(
       C, nullptr, SourceLocation(), DeclarationNameInfo(), QualType(), nullptr,
       ExplicitSpecifier(), false, false, ConstexprSpecKind::Unspecified,
       InheritedConstructor(), nullptr);
   Result->setInheritingConstructor(isInheritingConstructor);
   Result->CXXConstructorDeclBits.HasTrailingExplicitSpecifier =
-      hasTraillingExplicit;
+      hasTrailingExplicit;
   Result->setExplicitSpecifier(ExplicitSpecifier());
   return Result;
 }
 
 CXXConstructorDecl *CXXConstructorDecl::Create(
     ASTContext &C, CXXRecordDecl *RD, SourceLocation StartLoc,
     const DeclarationNameInfo &NameInfo, QualType T, TypeSourceInfo *TInfo,
     ExplicitSpecifier ES, bool isInline, bool isImplicitlyDeclared,

clang/lib/Serialization/ASTWriterDecl.cpp

if (D->getDeclContext() == D->getLexicalDeclContext() &&
       !D->hasInheritedPrototype() &&
       D->hasWrittenPrototype())
     AbbrevToUse = Writer.getDeclCXXMethodAbbrev();
 
   Code = serialization::DECL_CXX_METHOD;
 }
 
 void ASTDeclWriter::VisitCXXConstructorDecl(CXXConstructorDecl *D) {
-  Record.push_back(D->getTraillingAllocKind());
+  Record.push_back(D->getTrailingAllocKind());
   addExplicitSpecifier(D->getExplicitSpecifier(), Record);
   if (auto Inherited = D->getInheritedConstructor()) {
     Record.AddDeclRef(Inherited.getShadowDecl());
     Record.AddDeclRef(Inherited.getConstructor());
   }
 
   VisitCXXMethodDecl(D);
   Code = serialization::DECL_CXX_CONSTRUCTOR;

clang/test/SemaCXX/cxx2a-explicit-bool.cpp

 };
 
 E<void> e = 1;
 // expected-error@-1 {{no viable conversion}}
 // expected-note@-2 {{in instantiation of}}
 
 }
 
-namespace trailling_object {
+namespace trailing_object {
 
 template<bool b>
 struct B {
   explicit(b) B(int) {}
 };
 
 template<bool b>
 struct A : B<b> {