[clang] Use *Map::try_emplace (NFC)

[kazutakahirata]

• try_emplace(Key) is shorter than insert({Key, nullptr}).
• try_emplace performs value initialization without value parameters.
• We overwrite values on successful insertion anyway.

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-codegen

Author: Kazu Hirata (kazutakahirata)

Changes

• try_emplace(Key) is shorter than insert({Key, nullptr}).
• try_emplace performs value initialization without value parameters.
• We overwrite values on successful insertion anyway.

---

Full diff: https://github.com/llvm/llvm-project/pull/143563.diff

4 Files Affected:

• (modified) clang/include/clang/Basic/IdentifierTable.h (+1-1)
• (modified) clang/include/clang/ExtractAPI/API.h (+1-1)
• (modified) clang/lib/CodeGen/CodeGenTypes.cpp (+1-1)
• (modified) clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp (+1-1)

diff --git a/clang/include/clang/Basic/IdentifierTable.h b/clang/include/clang/Basic/IdentifierTable.h
index 54540193cfcc0..e4044bcdfcc60 100644
--- a/clang/include/clang/Basic/IdentifierTable.h
+++ b/clang/include/clang/Basic/IdentifierTable.h
@@ -731,7 +731,7 @@ class IdentifierTable {
   /// introduce or modify an identifier. If they called get(), they would
   /// likely end up in a recursion.
   IdentifierInfo &getOwn(StringRef Name) {
-    auto &Entry = *HashTable.insert(std::make_pair(Name, nullptr)).first;
+    auto &Entry = *HashTable.try_emplace(Name).first;
 
     IdentifierInfo *&II = Entry.second;
     if (II)
diff --git a/clang/include/clang/ExtractAPI/API.h b/clang/include/clang/ExtractAPI/API.h
index c30e6fac66d6b..1ace535686a3e 100644
--- a/clang/include/clang/ExtractAPI/API.h
+++ b/clang/include/clang/ExtractAPI/API.h
@@ -1499,7 +1499,7 @@ APISet::createRecord(StringRef USR, StringRef Name,
                      CtorArgsContTy &&...CtorArgs) {
   // Ensure USR refers to a String stored in the allocator.
   auto USRString = copyString(USR);
-  auto Result = USRBasedLookupTable.insert({USRString, nullptr});
+  auto Result = USRBasedLookupTable.try_emplace(USRString);
   RecordTy *Record;
 
   // Create the record if it does not already exist
diff --git a/clang/lib/CodeGen/CodeGenTypes.cpp b/clang/lib/CodeGen/CodeGenTypes.cpp
index 09f6b20f53ec2..c98503e4bbd26 100644
--- a/clang/lib/CodeGen/CodeGenTypes.cpp
+++ b/clang/lib/CodeGen/CodeGenTypes.cpp
@@ -726,7 +726,7 @@ llvm::Type *CodeGenTypes::ConvertType(QualType T) {
     auto *MPTy = cast<MemberPointerType>(Ty);
     if (!getCXXABI().isMemberPointerConvertible(MPTy)) {
       auto *C = MPTy->getMostRecentCXXRecordDecl()->getTypeForDecl();
-      auto Insertion = RecordsWithOpaqueMemberPointers.insert({C, nullptr});
+      auto Insertion = RecordsWithOpaqueMemberPointers.try_emplace(C);
       if (Insertion.second)
         Insertion.first->second = llvm::StructType::create(getLLVMContext());
       ResultType = Insertion.first->second;
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
index 4316b584a2f32..140833050f4e9 100644
--- a/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
+++ b/clang/lib/Tooling/DependencyScanning/DependencyScanningFilesystem.cpp
@@ -173,7 +173,7 @@ DependencyScanningFilesystemSharedCache::CacheShard::getOrEmplaceEntryForUID(
     llvm::sys::fs::UniqueID UID, llvm::vfs::Status Stat,
     std::unique_ptr<llvm::MemoryBuffer> Contents) {
   std::lock_guard<std::mutex> LockGuard(CacheLock);
-  auto [It, Inserted] = EntriesByUID.insert({UID, nullptr});
+  auto [It, Inserted] = EntriesByUID.try_emplace(UID);
   auto &CachedEntry = It->getSecond();
   if (Inserted) {
     CachedFileContents *StoredContents = nullptr;