[AST] Use DenseMapBase::lookup (NFC)

clang/lib/AST/ASTContext.cpp

@@ -499,10 +499,7 @@ const RawComment *ASTContext::getRawCommentForAnyRedecl(
   // Any redeclarations of D that we haven't checked for comments yet?
   // We can't use DenseMap::iterator directly since it'd get invalid.
   auto LastCheckedRedecl = [this, CanonicalD]() -> const Decl * {
-    auto LookupRes = CommentlessRedeclChains.find(CanonicalD);
-    if (LookupRes != CommentlessRedeclChains.end())
-      return LookupRes->second;
-    return nullptr;
+    return CommentlessRedeclChains.lookup(CanonicalD);
   }();
 
   for (const auto Redecl : D->redecls()) {
@@ -1523,11 +1520,7 @@ ASTContext::setTemplateOrSpecializationInfo(VarDecl *Inst,
 
 NamedDecl *
 ASTContext::getInstantiatedFromUsingDecl(NamedDecl *UUD) {
-  auto Pos = InstantiatedFromUsingDecl.find(UUD);
-  if (Pos == InstantiatedFromUsingDecl.end())
-    return nullptr;
-
-  return Pos->second;
+  return InstantiatedFromUsingDecl.lookup(UUD);
 }
 
 void
@@ -1546,11 +1539,7 @@ ASTContext::setInstantiatedFromUsingDecl(NamedDecl *Inst, NamedDecl *Pattern) {
 
 UsingEnumDecl *
 ASTContext::getInstantiatedFromUsingEnumDecl(UsingEnumDecl *UUD) {
-  auto Pos = InstantiatedFromUsingEnumDecl.find(UUD);
-  if (Pos == InstantiatedFromUsingEnumDecl.end())
-    return nullptr;
-
-  return Pos->second;
+  return InstantiatedFromUsingEnumDecl.lookup(UUD);
 }
 
 void ASTContext::setInstantiatedFromUsingEnumDecl(UsingEnumDecl *Inst,
@@ -1561,12 +1550,7 @@ void ASTContext::setInstantiatedFromUsingEnumDecl(UsingEnumDecl *Inst,
 
 UsingShadowDecl *
 ASTContext::getInstantiatedFromUsingShadowDecl(UsingShadowDecl *Inst) {
-  llvm::DenseMap<UsingShadowDecl*, UsingShadowDecl*>::const_iterator Pos
-    = InstantiatedFromUsingShadowDecl.find(Inst);
-  if (Pos == InstantiatedFromUsingShadowDecl.end())
-    return nullptr;
-
-  return Pos->second;
+  return InstantiatedFromUsingShadowDecl.lookup(Inst);
 }
 
 void
@@ -1577,12 +1561,7 @@ ASTContext::setInstantiatedFromUsingShadowDecl(UsingShadowDecl *Inst,
 }
 
 FieldDecl *ASTContext::getInstantiatedFromUnnamedFieldDecl(FieldDecl *Field) {
-  llvm::DenseMap<FieldDecl *, FieldDecl *>::iterator Pos
-    = InstantiatedFromUnnamedFieldDecl.find(Field);
-  if (Pos == InstantiatedFromUnnamedFieldDecl.end())
-    return nullptr;
-
-  return Pos->second;
+  return InstantiatedFromUnnamedFieldDecl.lookup(Field);
 }
 
 void ASTContext::setInstantiatedFromUnnamedFieldDecl(FieldDecl *Inst,

clang/lib/AST/ASTImporter.cpp

@@ -8994,11 +8994,7 @@ Expected<Attr *> ASTImporter::Import(const Attr *FromAttr) {
 }
 
 Decl *ASTImporter::GetAlreadyImportedOrNull(const Decl *FromD) const {
-  auto Pos = ImportedDecls.find(FromD);
-  if (Pos != ImportedDecls.end())
-    return Pos->second;
-  else
-    return nullptr;
+  return ImportedDecls.lookup(FromD);
 }
 
 TranslationUnitDecl *ASTImporter::GetFromTU(Decl *ToD) {

clang/lib/AST/ExternalASTMerger.cpp

@@ -187,10 +187,7 @@ public:
   /// Implements the ASTImporter interface for tracking back a declaration
   /// to its original declaration it came from.
   Decl *GetOriginalDecl(Decl *To) override {
-    auto It = ToOrigin.find(To);
-    if (It != ToOrigin.end())
-      return It->second;
-    return nullptr;
+    return ToOrigin.lookup(To);
   }
 
   /// Whenever a DeclContext is imported, ensure that ExternalASTSource's origin
@@ -541,4 +538,3 @@ void ExternalASTMerger::FindExternalLexicalDecls(
     return false;
   });
 }
-

clang/lib/AST/Interp/Record.cpp

@@ -44,9 +44,7 @@ const Record::Base *Record::getBase(QualType T) const {
     return nullptr;
 
   const RecordDecl *RD = T->getAs<RecordType>()->getDecl();
-  if (auto It = BaseMap.find(RD); It != BaseMap.end())
-    return It->second;
-  return nullptr;
+  return BaseMap.lookup(RD);
 }
 
 const Record::Base *Record::getVirtualBase(const RecordDecl *FD) const {