[Clang][NFC] Move the type trait logic to a separate file. (#141245)

Just to try to keep the size of SemaExprCXX.cpp in check.

As discussed in #141238

Author: cor3ntin

clang/lib/Sema/CMakeLists.txt

@@ -96,6 +96,7 @@ add_clang_library(clangSema
   SemaTemplateInstantiateDecl.cpp
   SemaTemplateVariadic.cpp
   SemaType.cpp
+  SemaTypeTraits.cpp
   SemaWasm.cpp
   SemaX86.cpp
   TypeLocBuilder.cpp

clang/lib/Sema/SemaDeclCXX.cpp

@@ -7368,279 +7368,6 @@ void Sema::CheckCompletedCXXClass(Scope *S, CXXRecordDecl *Record) {
   CheckMismatchedTypeAwareAllocators(OO_Array_New, OO_Array_Delete);
 }
 
-static CXXMethodDecl *LookupSpecialMemberFromXValue(Sema &SemaRef,
-                                                    const CXXRecordDecl *RD,
-                                                    bool Assign) {
-  RD = RD->getDefinition();
-  SourceLocation LookupLoc = RD->getLocation();
-
-  CanQualType CanTy = SemaRef.getASTContext().getCanonicalType(
-      SemaRef.getASTContext().getTagDeclType(RD));
-  DeclarationName Name;
-  Expr *Arg = nullptr;
-  unsigned NumArgs;
-
-  QualType ArgType = CanTy;
-  ExprValueKind VK = clang::VK_XValue;
-
-  if (Assign)
-    Name =
-        SemaRef.getASTContext().DeclarationNames.getCXXOperatorName(OO_Equal);
-  else
-    Name =
-        SemaRef.getASTContext().DeclarationNames.getCXXConstructorName(CanTy);
-
-  OpaqueValueExpr FakeArg(LookupLoc, ArgType, VK);
-  NumArgs = 1;
-  Arg = &FakeArg;
-
-  // Create the object argument
-  QualType ThisTy = CanTy;
-  Expr::Classification Classification =
-      OpaqueValueExpr(LookupLoc, ThisTy, VK_LValue)
-          .Classify(SemaRef.getASTContext());
-
-  // Now we perform lookup on the name we computed earlier and do overload
-  // resolution. Lookup is only performed directly into the class since there
-  // will always be a (possibly implicit) declaration to shadow any others.
-  OverloadCandidateSet OCS(LookupLoc, OverloadCandidateSet::CSK_Normal);
-  DeclContext::lookup_result R = RD->lookup(Name);
-
-  if (R.empty())
-    return nullptr;
-
-  // Copy the candidates as our processing of them may load new declarations
-  // from an external source and invalidate lookup_result.
-  SmallVector<NamedDecl *, 8> Candidates(R.begin(), R.end());
-
-  for (NamedDecl *CandDecl : Candidates) {
-    if (CandDecl->isInvalidDecl())
-      continue;
-
-    DeclAccessPair Cand = DeclAccessPair::make(CandDecl, clang::AS_none);
-    auto CtorInfo = getConstructorInfo(Cand);
-    if (CXXMethodDecl *M = dyn_cast<CXXMethodDecl>(Cand->getUnderlyingDecl())) {
-      if (Assign)
-        SemaRef.AddMethodCandidate(M, Cand, const_cast<CXXRecordDecl *>(RD),
-                                   ThisTy, Classification,
-                                   llvm::ArrayRef(&Arg, NumArgs), OCS, true);
-      else {
-        assert(CtorInfo);
-        SemaRef.AddOverloadCandidate(CtorInfo.Constructor, CtorInfo.FoundDecl,
-                                     llvm::ArrayRef(&Arg, NumArgs), OCS,
-                                     /*SuppressUserConversions*/ true);
-      }
-    } else if (FunctionTemplateDecl *Tmpl =
-                   dyn_cast<FunctionTemplateDecl>(Cand->getUnderlyingDecl())) {
-      if (Assign)
-        SemaRef.AddMethodTemplateCandidate(
-            Tmpl, Cand, const_cast<CXXRecordDecl *>(RD), nullptr, ThisTy,
-            Classification, llvm::ArrayRef(&Arg, NumArgs), OCS, true);
-      else {
-        assert(CtorInfo);
-        SemaRef.AddTemplateOverloadCandidate(
-            CtorInfo.ConstructorTmpl, CtorInfo.FoundDecl, nullptr,
-            llvm::ArrayRef(&Arg, NumArgs), OCS, true);
-      }
-    }
-  }
-
-  OverloadCandidateSet::iterator Best;
-  switch (OCS.BestViableFunction(SemaRef, LookupLoc, Best)) {
-  case OR_Success:
-    return cast<CXXMethodDecl>(Best->Function);
-  default:
-    return nullptr;
-  }
-}
-
-static bool hasSuitableConstructorForRelocation(Sema &SemaRef,
-                                                const CXXRecordDecl *D,
-                                                bool AllowUserDefined) {
-  assert(D->hasDefinition() && !D->isInvalidDecl());
-
-  if (D->hasSimpleMoveConstructor() || D->hasSimpleCopyConstructor())
-    return true;
-
-  CXXMethodDecl *Decl =
-      LookupSpecialMemberFromXValue(SemaRef, D, /*Assign=*/false);
-  return Decl && Decl->isUserProvided() == AllowUserDefined;
-}
-
-static bool hasSuitableMoveAssignmentOperatorForRelocation(
-    Sema &SemaRef, const CXXRecordDecl *D, bool AllowUserDefined) {
-  assert(D->hasDefinition() && !D->isInvalidDecl());
-
-  if (D->hasSimpleMoveAssignment() || D->hasSimpleCopyAssignment())
-    return true;
-
-  CXXMethodDecl *Decl =
-      LookupSpecialMemberFromXValue(SemaRef, D, /*Assign=*/true);
-  if (!Decl)
-    return false;
-
-  return Decl && Decl->isUserProvided() == AllowUserDefined;
-}
-
-// [C++26][class.prop]
-// A class C is default-movable if
-// - overload resolution for direct-initializing an object of type C
-// from an xvalue of type C selects a constructor that is a direct member of C
-// and is neither user-provided nor deleted,
-// - overload resolution for assigning to an lvalue of type C from an xvalue of
-// type C selects an assignment operator function that is a direct member of C
-// and is neither user-provided nor deleted, and C has a destructor that is
-// neither user-provided nor deleted.
-static bool IsDefaultMovable(Sema &SemaRef, const CXXRecordDecl *D) {
-  if (!hasSuitableConstructorForRelocation(SemaRef, D,
-                                           /*AllowUserDefined=*/false))
-    return false;
-
-  if (!hasSuitableMoveAssignmentOperatorForRelocation(
-          SemaRef, D, /*AllowUserDefined=*/false))
-    return false;
-
-  CXXDestructorDecl *Dtr = D->getDestructor();
-
-  if (!Dtr)
-    return true;
-
-  if (Dtr->isUserProvided() && (!Dtr->isDefaulted() || Dtr->isDeleted()))
-    return false;
-
-  return !Dtr->isDeleted();
-}
-
-// [C++26][class.prop]
-// A class is eligible for trivial relocation unless it...
-static bool IsEligibleForTrivialRelocation(Sema &SemaRef,
-                                           const CXXRecordDecl *D) {
-
-  for (const CXXBaseSpecifier &B : D->bases()) {
-    const auto *BaseDecl = B.getType()->getAsCXXRecordDecl();
-    if (!BaseDecl)
-      continue;
-    // ... has any virtual base classes
-    // ... has a base class that is not a trivially relocatable class
-    if (B.isVirtual() || (!BaseDecl->isDependentType() &&
-                          !SemaRef.IsCXXTriviallyRelocatableType(B.getType())))
-      return false;
-  }
-
-  for (const FieldDecl *Field : D->fields()) {
-    if (Field->getType()->isDependentType())
-      continue;
-    if (Field->getType()->isReferenceType())
-      continue;
-    // ... has a non-static data member of an object type that is not
-    // of a trivially relocatable type
-    if (!SemaRef.IsCXXTriviallyRelocatableType(Field->getType()))
-      return false;
-  }
-  return !D->hasDeletedDestructor();
-}
-
-// [C++26][class.prop]
-// A class C is eligible for replacement unless
-static bool IsEligibleForReplacement(Sema &SemaRef, const CXXRecordDecl *D) {
-
-  for (const CXXBaseSpecifier &B : D->bases()) {
-    const auto *BaseDecl = B.getType()->getAsCXXRecordDecl();
-    if (!BaseDecl)
-      continue;
-    // it has a base class that is not a replaceable class
-    if (!BaseDecl->isDependentType() &&
-        !SemaRef.IsCXXReplaceableType(B.getType()))
-      return false;
-  }
-
-  for (const FieldDecl *Field : D->fields()) {
-    if (Field->getType()->isDependentType())
-      continue;
-
-    // it has a non-static data member that is not of a replaceable type,
-    if (!SemaRef.IsCXXReplaceableType(Field->getType()))
-      return false;
-  }
-  return !D->hasDeletedDestructor();
-}
-
-ASTContext::CXXRecordDeclRelocationInfo
-Sema::CheckCXX2CRelocatableAndReplaceable(const CXXRecordDecl *D) {
-  ASTContext::CXXRecordDeclRelocationInfo Info{false, false};
-
-  if (!getLangOpts().CPlusPlus || D->isInvalidDecl())
-    return Info;
-
-  assert(D->hasDefinition());
-
-  // This is part of "eligible for replacement", however we defer it
-  // to avoid extraneous computations.
-  auto HasSuitableSMP = [&] {
-    return hasSuitableConstructorForRelocation(*this, D,
-                                               /*AllowUserDefined=*/true) &&
-           hasSuitableMoveAssignmentOperatorForRelocation(
-               *this, D, /*AllowUserDefined=*/true);
-  };
-
-  auto IsUnion = [&, Is = std::optional<bool>{}]() mutable {
-    if (!Is.has_value())
-      Is = D->isUnion() && !D->hasUserDeclaredCopyConstructor() &&
-           !D->hasUserDeclaredCopyAssignment() &&
-           !D->hasUserDeclaredMoveOperation() &&
-           !D->hasUserDeclaredDestructor();
-    return *Is;
-  };
-
-  auto IsDefaultMovable = [&, Is = std::optional<bool>{}]() mutable {
-    if (!Is.has_value())
-      Is = ::IsDefaultMovable(*this, D);
-    return *Is;
-  };
-
-  Info.IsRelocatable = [&] {
-    if (D->isDependentType())
-      return false;
-
-    // if it is eligible for trivial relocation
-    if (!IsEligibleForTrivialRelocation(*this, D))
-      return false;
-
-    // has the trivially_relocatable_if_eligible class-property-specifier,
-    if (D->hasAttr<TriviallyRelocatableAttr>())
-      return true;
-
-    // is a union with no user-declared special member functions, or
-    if (IsUnion())
-      return true;
-
-    // is default-movable.
-    return IsDefaultMovable();
-  }();
-
-  Info.IsReplaceable = [&] {
-    if (D->isDependentType())
-      return false;
-
-    // A class C is a replaceable class if it is eligible for replacement
-    if (!IsEligibleForReplacement(*this, D))
-      return false;
-
-    // has the replaceable_if_eligible class-property-specifier
-    if (D->hasAttr<ReplaceableAttr>())
-      return HasSuitableSMP();
-
-    // is a union with no user-declared special member functions, or
-    if (IsUnion())
-      return HasSuitableSMP();
-
-    // is default-movable.
-    return IsDefaultMovable();
-  }();
-
-  return Info;
-}
-
 /// Look up the special member function that would be called by a special
 /// member function for a subobject of class type.
 ///