[clang] Improve stack usage to increase recursive initialization depth (PR #88546)

Aaron Ballman via cfe-commits cfe-commits at lists.llvm.org
Tue Apr 16 06:02:41 PDT 2024


https://github.com/AaronBallman updated https://github.com/llvm/llvm-project/pull/88546

>From b3c53b13181d0ae9897a79aa5dff59b90b8025fd Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Fri, 12 Apr 2024 12:48:09 -0400
Subject: [PATCH 01/10] More efficient stack usage; NFC

---
 clang/include/clang/Sema/Overload.h | 69 +++++++++--------------------
 clang/lib/Sema/SemaCodeComplete.cpp |  6 ++-
 clang/lib/Sema/SemaDecl.cpp         |  3 +-
 clang/lib/Sema/SemaDeclCXX.cpp      |  5 ++-
 clang/lib/Sema/SemaExpr.cpp         |  7 +--
 clang/lib/Sema/SemaExprCXX.cpp      |  6 +--
 clang/lib/Sema/SemaInit.cpp         | 11 +++--
 clang/lib/Sema/SemaLookup.cpp       |  2 +-
 clang/lib/Sema/SemaOverload.cpp     | 53 +++++++++++++---------
 clang/lib/Sema/SemaStmt.cpp         |  2 +-
 10 files changed, 78 insertions(+), 86 deletions(-)

diff --git a/clang/include/clang/Sema/Overload.h b/clang/include/clang/Sema/Overload.h
index 76311b00d2fc58..40800c7e1af381 100644
--- a/clang/include/clang/Sema/Overload.h
+++ b/clang/include/clang/Sema/Overload.h
@@ -874,7 +874,8 @@ class Sema;
     ConversionFixItGenerator Fix;
 
     /// Viable - True to indicate that this overload candidate is viable.
-    bool Viable : 1;
+    LLVM_PREFERRED_TYPE(bool)
+    unsigned Viable : 1;
 
     /// Whether this candidate is the best viable function, or tied for being
     /// the best viable function.
@@ -883,12 +884,14 @@ class Sema;
     /// was part of the ambiguity kernel: the minimal non-empty set of viable
     /// candidates such that all elements of the ambiguity kernel are better
     /// than all viable candidates not in the ambiguity kernel.
-    bool Best : 1;
+    LLVM_PREFERRED_TYPE(bool)
+    unsigned Best : 1;
 
     /// IsSurrogate - True to indicate that this candidate is a
     /// surrogate for a conversion to a function pointer or reference
     /// (C++ [over.call.object]).
-    bool IsSurrogate : 1;
+    LLVM_PREFERRED_TYPE(bool)
+    unsigned IsSurrogate : 1;
 
     /// IgnoreObjectArgument - True to indicate that the first
     /// argument's conversion, which for this function represents the
@@ -897,18 +900,20 @@ class Sema;
     /// implicit object argument is just a placeholder) or a
     /// non-static member function when the call doesn't have an
     /// object argument.
-    bool IgnoreObjectArgument : 1;
+    LLVM_PREFERRED_TYPE(bool)
+    unsigned IgnoreObjectArgument : 1;
 
     /// True if the candidate was found using ADL.
-    CallExpr::ADLCallKind IsADLCandidate : 1;
+    LLVM_PREFERRED_TYPE(CallExpr::ADLCallKind)
+    unsigned IsADLCandidate : 1;
 
     /// Whether this is a rewritten candidate, and if so, of what kind?
     LLVM_PREFERRED_TYPE(OverloadCandidateRewriteKind)
     unsigned RewriteKind : 2;
 
     /// FailureKind - The reason why this candidate is not viable.
-    /// Actually an OverloadFailureKind.
-    unsigned char FailureKind;
+    LLVM_PREFERRED_TYPE(OverloadFailureKind)
+    unsigned FailureKind : 5;
 
     /// The number of call arguments that were explicitly provided,
     /// to be used while performing partial ordering of function templates.
@@ -972,7 +977,9 @@ class Sema;
   private:
     friend class OverloadCandidateSet;
     OverloadCandidate()
-        : IsSurrogate(false), IsADLCandidate(CallExpr::NotADL), RewriteKind(CRK_None) {}
+        : IsSurrogate(false),
+          IsADLCandidate(static_cast<unsigned>(CallExpr::NotADL)),
+          RewriteKind(CRK_None) {}
   };
 
   /// OverloadCandidateSet - A set of overload candidates, used in C++
@@ -1070,57 +1077,25 @@ class Sema;
     };
 
   private:
-    SmallVector<OverloadCandidate, 16> Candidates;
-    llvm::SmallPtrSet<uintptr_t, 16> Functions;
-
-    // Allocator for ConversionSequenceLists. We store the first few of these
-    // inline to avoid allocation for small sets.
-    llvm::BumpPtrAllocator SlabAllocator;
+    ASTContext &Ctx;
+    SmallVector<OverloadCandidate, 4> Candidates;
+    llvm::SmallPtrSet<uintptr_t, 4> Functions;
 
     SourceLocation Loc;
     CandidateSetKind Kind;
     OperatorRewriteInfo RewriteInfo;
 
-    constexpr static unsigned NumInlineBytes =
-        24 * sizeof(ImplicitConversionSequence);
-    unsigned NumInlineBytesUsed = 0;
-    alignas(void *) char InlineSpace[NumInlineBytes];
-
     // Address space of the object being constructed.
     LangAS DestAS = LangAS::Default;
 
-    /// If we have space, allocates from inline storage. Otherwise, allocates
-    /// from the slab allocator.
-    /// FIXME: It would probably be nice to have a SmallBumpPtrAllocator
-    /// instead.
-    /// FIXME: Now that this only allocates ImplicitConversionSequences, do we
-    /// want to un-generalize this?
-    template <typename T>
-    T *slabAllocate(unsigned N) {
-      // It's simpler if this doesn't need to consider alignment.
-      static_assert(alignof(T) == alignof(void *),
-                    "Only works for pointer-aligned types.");
-      static_assert(std::is_trivial<T>::value ||
-                        std::is_same<ImplicitConversionSequence, T>::value,
-                    "Add destruction logic to OverloadCandidateSet::clear().");
-
-      unsigned NBytes = sizeof(T) * N;
-      if (NBytes > NumInlineBytes - NumInlineBytesUsed)
-        return SlabAllocator.Allocate<T>(N);
-      char *FreeSpaceStart = InlineSpace + NumInlineBytesUsed;
-      assert(uintptr_t(FreeSpaceStart) % alignof(void *) == 0 &&
-             "Misaligned storage!");
-
-      NumInlineBytesUsed += NBytes;
-      return reinterpret_cast<T *>(FreeSpaceStart);
-    }
 
     void destroyCandidates();
 
   public:
-    OverloadCandidateSet(SourceLocation Loc, CandidateSetKind CSK,
+    OverloadCandidateSet(ASTContext &Ctx, SourceLocation Loc,
+                         CandidateSetKind CSK,
                          OperatorRewriteInfo RewriteInfo = {})
-        : Loc(Loc), Kind(CSK), RewriteInfo(RewriteInfo) {}
+        : Ctx(Ctx), Loc(Loc), Kind(CSK), RewriteInfo(RewriteInfo) {}
     OverloadCandidateSet(const OverloadCandidateSet &) = delete;
     OverloadCandidateSet &operator=(const OverloadCandidateSet &) = delete;
     ~OverloadCandidateSet() { destroyCandidates(); }
@@ -1163,7 +1138,7 @@ class Sema;
     ConversionSequenceList
     allocateConversionSequences(unsigned NumConversions) {
       ImplicitConversionSequence *Conversions =
-          slabAllocate<ImplicitConversionSequence>(NumConversions);
+          Ctx.Allocate<ImplicitConversionSequence>(NumConversions);
 
       // Construct the new objects.
       for (unsigned I = 0; I != NumConversions; ++I)
diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index c335017f243eb2..c561fdc93ba00c 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -6210,7 +6210,8 @@ QualType Sema::ProduceCallSignatureHelp(Expr *Fn, ArrayRef<Expr *> Args,
   Expr *NakedFn = Fn->IgnoreParenCasts();
   // Build an overload candidate set based on the functions we find.
   SourceLocation Loc = Fn->getExprLoc();
-  OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Normal);
+  OverloadCandidateSet CandidateSet(Context, Loc,
+                                    OverloadCandidateSet::CSK_Normal);
 
   if (auto ULE = dyn_cast<UnresolvedLookupExpr>(NakedFn)) {
     AddOverloadedCallCandidates(ULE, ArgsWithoutDependentTypes, CandidateSet,
@@ -6411,7 +6412,8 @@ QualType Sema::ProduceConstructorSignatureHelp(QualType Type,
   // FIXME: Provide support for variadic template constructors.
 
   if (CRD) {
-    OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Normal);
+    OverloadCandidateSet CandidateSet(Context, Loc,
+                                      OverloadCandidateSet::CSK_Normal);
     for (NamedDecl *C : LookupConstructors(CRD)) {
       if (auto *FD = dyn_cast<FunctionDecl>(C)) {
         // FIXME: we can't yet provide correct signature help for initializer
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 720e56692359b3..de22408cd16a03 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -19073,7 +19073,8 @@ static void ComputeSelectedDestructor(Sema &S, CXXRecordDecl *Record) {
   }
 
   SourceLocation Loc = Record->getLocation();
-  OverloadCandidateSet OCS(Loc, OverloadCandidateSet::CSK_Normal);
+  OverloadCandidateSet OCS(S.getASTContext(), Loc,
+                           OverloadCandidateSet::CSK_Normal);
 
   for (auto *Decl : Record->decls()) {
     if (auto *DD = dyn_cast<CXXDestructorDecl>(Decl)) {
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 51c14443d2d8f1..df6381e2cdf3bc 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -8198,7 +8198,8 @@ class DefaultedComparisonAnalyzer
     // we've already found there is no viable 'operator<=>' candidate (and are
     // considering synthesizing a '<=>' from '==' and '<').
     OverloadCandidateSet CandidateSet(
-        FD->getLocation(), OverloadCandidateSet::CSK_Operator,
+        S.getASTContext(), FD->getLocation(),
+        OverloadCandidateSet::CSK_Operator,
         OverloadCandidateSet::OperatorRewriteInfo(
             OO, FD->getLocation(),
             /*AllowRewrittenCandidates=*/!SpaceshipCandidates));
@@ -17409,7 +17410,7 @@ bool Sema::EvaluateStaticAssertMessageAsString(Expr *Message,
     LookupResult MemberLookup(*this, DN, Loc, Sema::LookupMemberName);
     LookupQualifiedName(MemberLookup, RD);
     Empty = MemberLookup.empty();
-    OverloadCandidateSet Candidates(MemberLookup.getNameLoc(),
+    OverloadCandidateSet Candidates(Context, MemberLookup.getNameLoc(),
                                     OverloadCandidateSet::CSK_Normal);
     if (MemberLookup.empty())
       return std::nullopt;
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index b294d2bd9f53f2..c14d484378a866 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -2500,7 +2500,7 @@ bool Sema::DiagnoseEmptyLookup(Scope *S, CXXScopeSpec &SS, LookupResult &R,
 
         // If there's a best viable function among the results, only mention
         // that one in the notes.
-        OverloadCandidateSet Candidates(R.getNameLoc(),
+        OverloadCandidateSet Candidates(Context, R.getNameLoc(),
                                         OverloadCandidateSet::CSK_Normal);
         AddOverloadedCallCandidates(R, ExplicitTemplateArgs, Args, Candidates);
         OverloadCandidateSet::iterator Best;
@@ -2548,7 +2548,7 @@ bool Sema::DiagnoseEmptyLookup(Scope *S, CXXScopeSpec &SS, LookupResult &R,
     NamedDecl *ND = Corrected.getFoundDecl();
     if (ND) {
       if (Corrected.isOverloaded()) {
-        OverloadCandidateSet OCS(R.getNameLoc(),
+        OverloadCandidateSet OCS(Context, R.getNameLoc(),
                                  OverloadCandidateSet::CSK_Normal);
         OverloadCandidateSet::iterator Best;
         for (NamedDecl *CD : Corrected) {
@@ -6501,7 +6501,8 @@ static TypoCorrection TryTypoCorrectionForCall(Sema &S, Expr *Fn,
           Sema::CTK_ErrorRecovery)) {
     if (NamedDecl *ND = Corrected.getFoundDecl()) {
       if (Corrected.isOverloaded()) {
-        OverloadCandidateSet OCS(NameLoc, OverloadCandidateSet::CSK_Normal);
+        OverloadCandidateSet OCS(S.getASTContext(), NameLoc,
+                                 OverloadCandidateSet::CSK_Normal);
         OverloadCandidateSet::iterator Best;
         for (NamedDecl *CD : Corrected) {
           if (FunctionDecl *FD = dyn_cast<FunctionDecl>(CD))
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index ce9d5c26e21858..0b7bda6d5f2f25 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -2586,7 +2586,7 @@ static bool resolveAllocationOverload(
     Sema &S, LookupResult &R, SourceRange Range, SmallVectorImpl<Expr *> &Args,
     bool &PassAlignment, FunctionDecl *&Operator,
     OverloadCandidateSet *AlignedCandidates, Expr *AlignArg, bool Diagnose) {
-  OverloadCandidateSet Candidates(R.getNameLoc(),
+  OverloadCandidateSet Candidates(S.getASTContext(), R.getNameLoc(),
                                   OverloadCandidateSet::CSK_Normal);
   for (LookupResult::iterator Alloc = R.begin(), AllocEnd = R.end();
        Alloc != AllocEnd; ++Alloc) {
@@ -3919,7 +3919,7 @@ static bool resolveBuiltinNewDeleteOverload(Sema &S, CallExpr *TheCall,
   R.suppressDiagnostics();
 
   SmallVector<Expr *, 8> Args(TheCall->arguments());
-  OverloadCandidateSet Candidates(R.getNameLoc(),
+  OverloadCandidateSet Candidates(S.getASTContext(), R.getNameLoc(),
                                   OverloadCandidateSet::CSK_Normal);
   for (LookupResult::iterator FnOvl = R.begin(), FnOvlEnd = R.end();
        FnOvl != FnOvlEnd; ++FnOvl) {
@@ -6488,7 +6488,7 @@ static bool TryClassUnification(Sema &Self, Expr *From, Expr *To,
 static bool FindConditionalOverload(Sema &Self, ExprResult &LHS, ExprResult &RHS,
                                     SourceLocation QuestionLoc) {
   Expr *Args[2] = { LHS.get(), RHS.get() };
-  OverloadCandidateSet CandidateSet(QuestionLoc,
+  OverloadCandidateSet CandidateSet(Self.getASTContext(), QuestionLoc,
                                     OverloadCandidateSet::CSK_Operator);
   Self.AddBuiltinOperatorCandidates(OO_Conditional, QuestionLoc, Args,
                                     CandidateSet);
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 6b8ce0f633a3ea..86d2d4c530679a 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -6114,7 +6114,8 @@ InitializationSequence::InitializationSequence(
     Sema &S, const InitializedEntity &Entity, const InitializationKind &Kind,
     MultiExprArg Args, bool TopLevelOfInitList, bool TreatUnavailableAsInvalid)
     : FailedOverloadResult(OR_Success),
-      FailedCandidateSet(Kind.getLocation(), OverloadCandidateSet::CSK_Normal) {
+      FailedCandidateSet(S.getASTContext(), Kind.getLocation(),
+                         OverloadCandidateSet::CSK_Normal) {
   InitializeFrom(S, Entity, Kind, Args, TopLevelOfInitList,
                  TreatUnavailableAsInvalid);
 }
@@ -6808,7 +6809,8 @@ static ExprResult CopyObject(Sema &S,
   // Perform overload resolution using the class's constructors. Per
   // C++11 [dcl.init]p16, second bullet for class types, this initialization
   // is direct-initialization.
-  OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Normal);
+  OverloadCandidateSet CandidateSet(S.getASTContext(), Loc,
+                                    OverloadCandidateSet::CSK_Normal);
   DeclContext::lookup_result Ctors = S.LookupConstructors(Class);
 
   OverloadCandidateSet::iterator Best;
@@ -6949,7 +6951,8 @@ static void CheckCXX98CompatAccessibleCopy(Sema &S,
     return;
 
   // Find constructors which would have been considered.
-  OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Normal);
+  OverloadCandidateSet CandidateSet(S.getASTContext(), Loc,
+                                    OverloadCandidateSet::CSK_Normal);
   DeclContext::lookup_result Ctors =
       S.LookupConstructors(cast<CXXRecordDecl>(Record->getDecl()));
 
@@ -10818,7 +10821,7 @@ QualType Sema::DeduceTemplateSpecializationFromInitializer(
   //
   // Since we know we're initializing a class type of a type unrelated to that
   // of the initializer, this reduces to something fairly reasonable.
-  OverloadCandidateSet Candidates(Kind.getLocation(),
+  OverloadCandidateSet Candidates(Context, Kind.getLocation(),
                                   OverloadCandidateSet::CSK_Normal);
   OverloadCandidateSet::iterator Best;
 
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index d65f52b8efe81f..eedba5c1394770 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -3481,7 +3481,7 @@ Sema::LookupSpecialMember(CXXRecordDecl *RD, CXXSpecialMemberKind SM,
   // 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);
+  OverloadCandidateSet OCS(Context, LookupLoc, OverloadCandidateSet::CSK_Normal);
   DeclContext::lookup_result R = RD->lookup(Name);
 
   if (R.empty()) {
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index e1155dc2d5d285..e94db8aee144b3 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -1057,7 +1057,8 @@ bool OverloadCandidateSet::OperatorRewriteInfo::shouldAddReversed(
 void OverloadCandidateSet::destroyCandidates() {
   for (iterator i = begin(), e = end(); i != e; ++i) {
     for (auto &C : i->Conversions)
-      C.~ImplicitConversionSequence();
+      C.~ImplicitConversionSequence();    
+    Ctx.Deallocate(i->Conversions.begin());
     if (!i->Viable && i->FailureKind == ovl_fail_bad_deduction)
       i->DeductionFailure.Destroy();
   }
@@ -1065,8 +1066,6 @@ void OverloadCandidateSet::destroyCandidates() {
 
 void OverloadCandidateSet::clear(CandidateSetKind CSK) {
   destroyCandidates();
-  SlabAllocator.Reset();
-  NumInlineBytesUsed = 0;
   Candidates.clear();
   Functions.clear();
   Kind = CSK;
@@ -1603,7 +1602,7 @@ TryUserDefinedConversion(Sema &S, Expr *From, QualType ToType,
   }
 
   // Attempt user-defined conversion.
-  OverloadCandidateSet Conversions(From->getExprLoc(),
+  OverloadCandidateSet Conversions(S.getASTContext(), From->getExprLoc(),
                                    OverloadCandidateSet::CSK_Normal);
   switch (IsUserDefinedConversion(S, From, ToType, ICS.UserDefined,
                                   Conversions, AllowExplicit,
@@ -4040,7 +4039,7 @@ IsUserDefinedConversion(Sema &S, Expr *From, QualType ToType,
 bool
 Sema::DiagnoseMultipleUserDefinedConversion(Expr *From, QualType ToType) {
   ImplicitConversionSequence ICS;
-  OverloadCandidateSet CandidateSet(From->getExprLoc(),
+  OverloadCandidateSet CandidateSet(Context, From->getExprLoc(),
                                     OverloadCandidateSet::CSK_Normal);
   OverloadingResult OvResult =
     IsUserDefinedConversion(*this, From, ToType, ICS.UserDefined,
@@ -5032,7 +5031,8 @@ FindConversionForRefInit(Sema &S, ImplicitConversionSequence &ICS,
   auto *T2RecordDecl = cast<CXXRecordDecl>(T2->castAs<RecordType>()->getDecl());
 
   OverloadCandidateSet CandidateSet(
-      DeclLoc, OverloadCandidateSet::CSK_InitByUserDefinedConversion);
+      S.getASTContext(), DeclLoc,
+      OverloadCandidateSet::CSK_InitByUserDefinedConversion);
   const auto &Conversions = T2RecordDecl->getVisibleConversionFunctions();
   for (auto I = Conversions.begin(), E = Conversions.end(); I != E; ++I) {
     NamedDecl *D = *I;
@@ -6786,7 +6786,8 @@ ExprResult Sema::PerformContextualImplicitConversion(
     // If one unique T is found:
     // First, build a candidate set from the previously recorded
     // potentially viable conversions.
-    OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Normal);
+    OverloadCandidateSet CandidateSet(Context, Loc,
+                                      OverloadCandidateSet::CSK_Normal);
     collectViableConversionCandidates(*this, From, ToType, ViableConversions,
                                       CandidateSet);
 
@@ -6982,7 +6983,7 @@ void Sema::AddOverloadCandidate(
   Candidate.RewriteKind =
       CandidateSet.getRewriteInfo().getRewriteKind(Function, PO);
   Candidate.IsSurrogate = false;
-  Candidate.IsADLCandidate = IsADLCandidate;
+  Candidate.IsADLCandidate = static_cast<unsigned>(IsADLCandidate);
   Candidate.IgnoreObjectArgument = false;
   Candidate.ExplicitCallArguments = Args.size();
 
@@ -7813,7 +7814,7 @@ void Sema::AddTemplateOverloadCandidate(
     Candidate.RewriteKind =
       CandidateSet.getRewriteInfo().getRewriteKind(Candidate.Function, PO);
     Candidate.IsSurrogate = false;
-    Candidate.IsADLCandidate = IsADLCandidate;
+    Candidate.IsADLCandidate = static_cast<unsigned>(IsADLCandidate);
     // Ignore the object argument if there is one, since we don't have an object
     // type.
     Candidate.IgnoreObjectArgument =
@@ -13770,7 +13771,7 @@ static bool DiagnoseTwoPhaseLookup(
     if (!R.empty()) {
       R.suppressDiagnostics();
 
-      OverloadCandidateSet Candidates(FnLoc, CSK);
+      OverloadCandidateSet Candidates(SemaRef.getASTContext(), FnLoc, CSK);
       SemaRef.AddOverloadedCallCandidates(R, ExplicitTemplateArgs, Args,
                                           Candidates);
 
@@ -14123,7 +14124,8 @@ static ExprResult FinishOverloadedCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
       return ExprError();
     return SemaRef.BuildResolvedCallExpr(
         Res.get(), FDecl, LParenLoc, Args, RParenLoc, ExecConfig,
-        /*IsExecConfig=*/false, (*Best)->IsADLCandidate);
+        /*IsExecConfig=*/false,
+        static_cast<CallExpr::ADLCallKind>((*Best)->IsADLCandidate));
   }
 
   case OR_No_Viable_Function: {
@@ -14184,7 +14186,8 @@ static ExprResult FinishOverloadedCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
       return ExprError();
     return SemaRef.BuildResolvedCallExpr(
         Res.get(), FDecl, LParenLoc, Args, RParenLoc, ExecConfig,
-        /*IsExecConfig=*/false, (*Best)->IsADLCandidate);
+        /*IsExecConfig=*/false,
+        static_cast<CallExpr::ADLCallKind>((*Best)->IsADLCandidate));
   }
   }
 
@@ -14220,7 +14223,7 @@ ExprResult Sema::BuildOverloadedCallExpr(Scope *S, Expr *Fn,
                                          Expr *ExecConfig,
                                          bool AllowTypoCorrection,
                                          bool CalleesAddressIsTaken) {
-  OverloadCandidateSet CandidateSet(Fn->getExprLoc(),
+  OverloadCandidateSet CandidateSet(Context, Fn->getExprLoc(),
                                     OverloadCandidateSet::CSK_Normal);
   ExprResult result;
 
@@ -14411,7 +14414,8 @@ Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, UnaryOperatorKind Opc,
   }
 
   // Build an empty overload set.
-  OverloadCandidateSet CandidateSet(OpLoc, OverloadCandidateSet::CSK_Operator);
+  OverloadCandidateSet CandidateSet(Context, OpLoc,
+                                    OverloadCandidateSet::CSK_Operator);
 
   // Add the candidates from the given function set.
   AddNonMemberOperatorCandidates(Fns, ArgsArray, CandidateSet);
@@ -14484,7 +14488,8 @@ Sema::CreateOverloadedUnaryOp(SourceLocation OpLoc, UnaryOperatorKind Opc,
       Args[0] = Input;
       CallExpr *TheCall = CXXOperatorCallExpr::Create(
           Context, Op, FnExpr.get(), ArgsArray, ResultTy, VK, OpLoc,
-          CurFPFeatureOverrides(), Best->IsADLCandidate);
+          CurFPFeatureOverrides(),
+          static_cast<CallExpr::ADLCallKind>(Best->IsADLCandidate));
 
       if (CheckCallReturnType(FnDecl->getReturnType(), OpLoc, TheCall, FnDecl))
         return ExprError();
@@ -14718,7 +14723,8 @@ ExprResult Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
     return CreateBuiltinBinOp(OpLoc, Opc, Args[0], Args[1]);
 
   // Build the overload set.
-  OverloadCandidateSet CandidateSet(OpLoc, OverloadCandidateSet::CSK_Operator,
+  OverloadCandidateSet CandidateSet(Context, OpLoc,
+                                    OverloadCandidateSet::CSK_Operator,
                                     OverloadCandidateSet::OperatorRewriteInfo(
                                         Op, OpLoc, AllowRewrittenCandidates));
   if (DefaultedFn)
@@ -14898,7 +14904,8 @@ ExprResult Sema::CreateOverloadedBinOp(SourceLocation OpLoc,
         // members; CodeGen should take care not to emit the this pointer.
         TheCall = CXXOperatorCallExpr::Create(
             Context, ChosenOp, FnExpr.get(), Args, ResultTy, VK, OpLoc,
-            CurFPFeatureOverrides(), Best->IsADLCandidate);
+            CurFPFeatureOverrides(),
+            static_cast<CallExpr::ADLCallKind>(Best->IsADLCandidate));
 
         if (const auto *Method = dyn_cast<CXXMethodDecl>(FnDecl);
             Method && Method->isImplicitObjectMemberFunction()) {
@@ -15267,7 +15274,8 @@ ExprResult Sema::CreateOverloadedArraySubscriptExpr(SourceLocation LLoc,
     return ExprError();
   }
   // Build an empty overload set.
-  OverloadCandidateSet CandidateSet(LLoc, OverloadCandidateSet::CSK_Operator);
+  OverloadCandidateSet CandidateSet(Context, LLoc,
+                                    OverloadCandidateSet::CSK_Operator);
 
   // Subscript can only be overloaded as a member function.
 
@@ -15521,7 +15529,7 @@ ExprResult Sema::BuildCallToMemberFunction(Scope *S, Expr *MemExprE,
                             : UnresExpr->getBase()->Classify(Context);
 
     // Add overload candidates
-    OverloadCandidateSet CandidateSet(UnresExpr->getMemberLoc(),
+    OverloadCandidateSet CandidateSet(Context, UnresExpr->getMemberLoc(),
                                       OverloadCandidateSet::CSK_Normal);
 
     // FIXME: avoid copy.
@@ -15771,7 +15779,7 @@ Sema::BuildCallToObjectOfClassType(Scope *S, Expr *Obj,
   //  operators of T. The function call operators of T are obtained by
   //  ordinary lookup of the name operator() in the context of
   //  (E).operator().
-  OverloadCandidateSet CandidateSet(LParenLoc,
+  OverloadCandidateSet CandidateSet(Context, LParenLoc,
                                     OverloadCandidateSet::CSK_Operator);
   DeclarationName OpName = Context.DeclarationNames.getCXXOperatorName(OO_Call);
 
@@ -16038,7 +16046,8 @@ Sema::BuildOverloadedArrowExpr(Scope *S, Expr *Base, SourceLocation OpLoc,
   //   overload resolution mechanism (13.3).
   DeclarationName OpName =
     Context.DeclarationNames.getCXXOperatorName(OO_Arrow);
-  OverloadCandidateSet CandidateSet(Loc, OverloadCandidateSet::CSK_Operator);
+  OverloadCandidateSet CandidateSet(Context, Loc,
+                                    OverloadCandidateSet::CSK_Operator);
 
   if (RequireCompleteType(Loc, Base->getType(),
                           diag::err_typecheck_incomplete_tag, Base))
@@ -16154,7 +16163,7 @@ ExprResult Sema::BuildLiteralOperatorCall(LookupResult &R,
                                        TemplateArgumentListInfo *TemplateArgs) {
   SourceLocation UDSuffixLoc = SuffixInfo.getCXXLiteralOperatorNameLoc();
 
-  OverloadCandidateSet CandidateSet(UDSuffixLoc,
+  OverloadCandidateSet CandidateSet(Context, UDSuffixLoc,
                                     OverloadCandidateSet::CSK_Normal);
   AddNonMemberOperatorCandidates(R.asUnresolvedSet(), Args, CandidateSet,
                                  TemplateArgs);
diff --git a/clang/lib/Sema/SemaStmt.cpp b/clang/lib/Sema/SemaStmt.cpp
index 1c2f6120f6218b..8a6e0c58684cf4 100644
--- a/clang/lib/Sema/SemaStmt.cpp
+++ b/clang/lib/Sema/SemaStmt.cpp
@@ -2944,7 +2944,7 @@ StmtResult Sema::BuildCXXForRangeStmt(
         return StmtError();
       }
     } else {
-      OverloadCandidateSet CandidateSet(RangeLoc,
+      OverloadCandidateSet CandidateSet(Context, RangeLoc,
                                         OverloadCandidateSet::CSK_Normal);
       BeginEndFunction BEFFailure;
       ForRangeStatus RangeStatus = BuildNonArrayForRange(

>From a89ea6c2b409d41be25f52f32c8523bc06734847 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Fri, 12 Apr 2024 13:28:09 -0400
Subject: [PATCH 02/10] Further improvements to stack usage

---
 clang/include/clang/Sema/Initialization.h |  6 ++++--
 clang/lib/Sema/SemaInit.cpp               | 24 ++++++++++++-----------
 2 files changed, 17 insertions(+), 13 deletions(-)

diff --git a/clang/include/clang/Sema/Initialization.h b/clang/include/clang/Sema/Initialization.h
index 2072cd8d1c3ef8..f41ca97f030066 100644
--- a/clang/include/clang/Sema/Initialization.h
+++ b/clang/include/clang/Sema/Initialization.h
@@ -1134,7 +1134,7 @@ class InitializationSequence {
   OverloadingResult FailedOverloadResult;
 
   /// The candidate set created when initialization failed.
-  OverloadCandidateSet FailedCandidateSet;
+  OverloadCandidateSet *FailedCandidateSet;
 
   /// The incomplete type that caused a failure.
   QualType FailedIncompleteType;
@@ -1403,7 +1403,9 @@ class InitializationSequence {
   /// Retrieve a reference to the candidate set when overload
   /// resolution fails.
   OverloadCandidateSet &getFailedCandidateSet() {
-    return FailedCandidateSet;
+    assert(FailedCandidateSet &&
+           "this should have been allocated in the constructor!");
+    return *FailedCandidateSet;
   }
 
   /// Get the overloading result, for when the initialization
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 86d2d4c530679a..883bdece74daf1 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -6113,9 +6113,10 @@ static bool TryOCLZeroOpaqueTypeInitialization(Sema &S,
 InitializationSequence::InitializationSequence(
     Sema &S, const InitializedEntity &Entity, const InitializationKind &Kind,
     MultiExprArg Args, bool TopLevelOfInitList, bool TreatUnavailableAsInvalid)
-    : FailedOverloadResult(OR_Success),
-      FailedCandidateSet(S.getASTContext(), Kind.getLocation(),
-                         OverloadCandidateSet::CSK_Normal) {
+    : FailedOverloadResult(OR_Success), FailedCandidateSet(nullptr) {
+  FailedCandidateSet = S.getASTContext().Allocate<OverloadCandidateSet>();
+  FailedCandidateSet = new (FailedCandidateSet) OverloadCandidateSet(
+      S.getASTContext(), Kind.getLocation(), OverloadCandidateSet::CSK_Normal);
   InitializeFrom(S, Entity, Kind, Args, TopLevelOfInitList,
                  TreatUnavailableAsInvalid);
 }
@@ -9738,7 +9739,7 @@ bool InitializationSequence::Diagnose(Sema &S,
     switch (FailedOverloadResult) {
     case OR_Ambiguous:
 
-      FailedCandidateSet.NoteCandidates(
+      FailedCandidateSet->NoteCandidates(
           PartialDiagnosticAt(
               Kind.getLocation(),
               Failure == FK_UserConversionOverloadFailed
@@ -9752,7 +9753,8 @@ bool InitializationSequence::Diagnose(Sema &S,
       break;
 
     case OR_No_Viable_Function: {
-      auto Cands = FailedCandidateSet.CompleteCandidates(S, OCD_AllCandidates, Args);
+      auto Cands =
+          FailedCandidateSet->CompleteCandidates(S, OCD_AllCandidates, Args);
       if (!S.RequireCompleteType(Kind.getLocation(),
                                  DestType.getNonReferenceType(),
                           diag::err_typecheck_nonviable_condition_incomplete,
@@ -9762,7 +9764,7 @@ bool InitializationSequence::Diagnose(Sema &S,
           << OnlyArg->getType() << Args[0]->getSourceRange()
           << DestType.getNonReferenceType();
 
-      FailedCandidateSet.NoteCandidates(S, Args, Cands);
+      FailedCandidateSet->NoteCandidates(S, Args, Cands);
       break;
     }
     case OR_Deleted: {
@@ -9771,7 +9773,7 @@ bool InitializationSequence::Diagnose(Sema &S,
         << Args[0]->getSourceRange();
       OverloadCandidateSet::iterator Best;
       OverloadingResult Ovl
-        = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
+        = FailedCandidateSet->BestViableFunction(S, Kind.getLocation(), Best);
       if (Ovl == OR_Deleted) {
         S.NoteDeletedFunction(Best->Function);
       } else {
@@ -9949,7 +9951,7 @@ bool InitializationSequence::Diagnose(Sema &S,
     // bad.
     switch (FailedOverloadResult) {
       case OR_Ambiguous:
-        FailedCandidateSet.NoteCandidates(
+        FailedCandidateSet->NoteCandidates(
             PartialDiagnosticAt(Kind.getLocation(),
                                 S.PDiag(diag::err_ovl_ambiguous_init)
                                     << DestType << ArgsRange),
@@ -10003,7 +10005,7 @@ bool InitializationSequence::Diagnose(Sema &S,
           break;
         }
 
-        FailedCandidateSet.NoteCandidates(
+        FailedCandidateSet->NoteCandidates(
             PartialDiagnosticAt(
                 Kind.getLocation(),
                 S.PDiag(diag::err_ovl_no_viable_function_in_init)
@@ -10014,7 +10016,7 @@ bool InitializationSequence::Diagnose(Sema &S,
       case OR_Deleted: {
         OverloadCandidateSet::iterator Best;
         OverloadingResult Ovl
-          = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
+          = FailedCandidateSet->BestViableFunction(S, Kind.getLocation(), Best);
         if (Ovl != OR_Deleted) {
           S.Diag(Kind.getLocation(), diag::err_ovl_deleted_init)
               << DestType << ArgsRange;
@@ -10091,7 +10093,7 @@ bool InitializationSequence::Diagnose(Sema &S,
       << Args[0]->getSourceRange();
     OverloadCandidateSet::iterator Best;
     OverloadingResult Ovl
-      = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
+      = FailedCandidateSet->BestViableFunction(S, Kind.getLocation(), Best);
     (void)Ovl;
     assert(Ovl == OR_Success && "Inconsistent overload resolution");
     CXXConstructorDecl *CtorDecl = cast<CXXConstructorDecl>(Best->Function);

>From 09085fa2de67b5e1321b910e61d0bddb93d27ea4 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Fri, 12 Apr 2024 14:00:19 -0400
Subject: [PATCH 03/10] Add a release note

---
 clang/docs/ReleaseNotes.rst | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 45a9a79739a4eb..d61a0a327c2622 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -203,6 +203,10 @@ Non-comprehensive list of changes in this release
 - ``__typeof_unqual__`` is available in all C modes as an extension, which behaves
   like ``typeof_unqual`` from C23, similar to ``__typeof__`` and ``typeof``.
 
+- Improved stack usage with C++ initialization code. This allows significantly
+  more template instantiations before reaching stack exhaustion limits.
+  Fixes #GH88330
+
 New Compiler Flags
 ------------------
 - ``-fsanitize=implicit-bitfield-conversion`` checks implicit truncation and

>From 7b874a9eb221057a88260037584aabc0fb504fd3 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Fri, 12 Apr 2024 14:07:46 -0400
Subject: [PATCH 04/10] Fix formatting

---
 clang/include/clang/Sema/Overload.h |  1 -
 clang/lib/Sema/SemaInit.cpp         | 12 ++++++------
 clang/lib/Sema/SemaLookup.cpp       |  3 ++-
 clang/lib/Sema/SemaOverload.cpp     |  2 +-
 4 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/clang/include/clang/Sema/Overload.h b/clang/include/clang/Sema/Overload.h
index 40800c7e1af381..c356a2f03a2246 100644
--- a/clang/include/clang/Sema/Overload.h
+++ b/clang/include/clang/Sema/Overload.h
@@ -1088,7 +1088,6 @@ class Sema;
     // Address space of the object being constructed.
     LangAS DestAS = LangAS::Default;
 
-
     void destroyCandidates();
 
   public:
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 883bdece74daf1..6cbcccdb7c6b52 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -9772,8 +9772,8 @@ bool InitializationSequence::Diagnose(Sema &S,
         << OnlyArg->getType() << DestType.getNonReferenceType()
         << Args[0]->getSourceRange();
       OverloadCandidateSet::iterator Best;
-      OverloadingResult Ovl
-        = FailedCandidateSet->BestViableFunction(S, Kind.getLocation(), Best);
+      OverloadingResult Ovl =
+          FailedCandidateSet->BestViableFunction(S, Kind.getLocation(), Best);
       if (Ovl == OR_Deleted) {
         S.NoteDeletedFunction(Best->Function);
       } else {
@@ -10015,8 +10015,8 @@ bool InitializationSequence::Diagnose(Sema &S,
 
       case OR_Deleted: {
         OverloadCandidateSet::iterator Best;
-        OverloadingResult Ovl
-          = FailedCandidateSet->BestViableFunction(S, Kind.getLocation(), Best);
+        OverloadingResult Ovl =
+            FailedCandidateSet->BestViableFunction(S, Kind.getLocation(), Best);
         if (Ovl != OR_Deleted) {
           S.Diag(Kind.getLocation(), diag::err_ovl_deleted_init)
               << DestType << ArgsRange;
@@ -10092,8 +10092,8 @@ bool InitializationSequence::Diagnose(Sema &S,
     S.Diag(Kind.getLocation(), diag::err_selected_explicit_constructor)
       << Args[0]->getSourceRange();
     OverloadCandidateSet::iterator Best;
-    OverloadingResult Ovl
-      = FailedCandidateSet->BestViableFunction(S, Kind.getLocation(), Best);
+    OverloadingResult Ovl =
+        FailedCandidateSet->BestViableFunction(S, Kind.getLocation(), Best);
     (void)Ovl;
     assert(Ovl == OR_Success && "Inconsistent overload resolution");
     CXXConstructorDecl *CtorDecl = cast<CXXConstructorDecl>(Best->Function);
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index eedba5c1394770..aa50ae37b4a6b4 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -3481,7 +3481,8 @@ Sema::LookupSpecialMember(CXXRecordDecl *RD, CXXSpecialMemberKind SM,
   // 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(Context, LookupLoc, OverloadCandidateSet::CSK_Normal);
+  OverloadCandidateSet OCS(Context, LookupLoc,
+                           OverloadCandidateSet::CSK_Normal);
   DeclContext::lookup_result R = RD->lookup(Name);
 
   if (R.empty()) {
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index e94db8aee144b3..ef72c024da241d 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -1057,7 +1057,7 @@ bool OverloadCandidateSet::OperatorRewriteInfo::shouldAddReversed(
 void OverloadCandidateSet::destroyCandidates() {
   for (iterator i = begin(), e = end(); i != e; ++i) {
     for (auto &C : i->Conversions)
-      C.~ImplicitConversionSequence();    
+      C.~ImplicitConversionSequence();
     Ctx.Deallocate(i->Conversions.begin());
     if (!i->Viable && i->FailureKind == ovl_fail_bad_deduction)
       i->DeductionFailure.Destroy();

>From bb2c55cc3509b35dd464da1f5748f066b6bdf0fb Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Fri, 12 Apr 2024 14:16:13 -0400
Subject: [PATCH 05/10] Update clang/docs/ReleaseNotes.rst

Co-authored-by: Erich Keane <ekeane at nvidia.com>
---
 clang/docs/ReleaseNotes.rst | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index d61a0a327c2622..f2c1e0a8a0b268 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -204,7 +204,7 @@ Non-comprehensive list of changes in this release
   like ``typeof_unqual`` from C23, similar to ``__typeof__`` and ``typeof``.
 
 - Improved stack usage with C++ initialization code. This allows significantly
-  more template instantiations before reaching stack exhaustion limits.
+  more levels of recursive initialization before reaching stack exhaustion limits.
   Fixes #GH88330
 
 New Compiler Flags

>From be4605daeed3ccc57b4a21cead52f92acab5aacc Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Fri, 12 Apr 2024 14:17:29 -0400
Subject: [PATCH 06/10] Update clang/lib/Sema/SemaOverload.cpp

Co-authored-by: Erich Keane <ekeane at nvidia.com>
---
 clang/lib/Sema/SemaOverload.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index ef72c024da241d..13ceec1b830d3b 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -1058,7 +1058,7 @@ void OverloadCandidateSet::destroyCandidates() {
   for (iterator i = begin(), e = end(); i != e; ++i) {
     for (auto &C : i->Conversions)
       C.~ImplicitConversionSequence();
-    Ctx.Deallocate(i->Conversions.begin());
+    Ctx.Deallocate(i->Conversions.data());
     if (!i->Viable && i->FailureKind == ovl_fail_bad_deduction)
       i->DeductionFailure.Destroy();
   }

>From 39203ed904673d9e58fd1f41aeb420468d07dfc9 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Fri, 12 Apr 2024 15:00:58 -0400
Subject: [PATCH 07/10] More updates to the release notes

---
 clang/docs/ReleaseNotes.rst | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index d61a0a327c2622..b342a1f798ded4 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -204,8 +204,9 @@ Non-comprehensive list of changes in this release
   like ``typeof_unqual`` from C23, similar to ``__typeof__`` and ``typeof``.
 
 - Improved stack usage with C++ initialization code. This allows significantly
-  more template instantiations before reaching stack exhaustion limits.
-  Fixes #GH88330
+  more initializations before reaching stack exhaustion limits. This will
+  positively impact recursive template instantiation code, but should also
+  reduce memory overhead for initializations in general. Fixes #GH88330
 
 New Compiler Flags
 ------------------

>From 3bff337a5246fa3ab855aa1bd3e88d5893baf5bb Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Mon, 15 Apr 2024 16:59:53 -0400
Subject: [PATCH 08/10] Fix after merge

---
 clang/lib/Sema/SemaInit.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 4a642f08f5c76a..49dc41c36f86e5 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -9769,8 +9769,8 @@ bool InitializationSequence::Diagnose(Sema &S,
     }
     case OR_Deleted: {
       OverloadCandidateSet::iterator Best;
-      OverloadingResult Ovl
-        = FailedCandidateSet.BestViableFunction(S, Kind.getLocation(), Best);
+      OverloadingResult Ovl =
+          FailedCandidateSet->BestViableFunction(S, Kind.getLocation(), Best);
 
       StringLiteral *Msg = Best->Function->getDeletedMessage();
       S.Diag(Kind.getLocation(), diag::err_typecheck_deleted_function)

>From 4c1749532a3faf0586a070743a4003810494acba Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Tue, 16 Apr 2024 07:26:52 -0400
Subject: [PATCH 09/10] Call the destructor for the allocated object

It turns out this is important for some strange reason. ;-) Many thanks
to @ErichKeane and @cor3ntin for helping me solve this!
---
 clang/lib/Sema/SemaInit.cpp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 49dc41c36f86e5..6015b0a6315e0d 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -6600,6 +6600,7 @@ void InitializationSequence::InitializeFrom(Sema &S,
 InitializationSequence::~InitializationSequence() {
   for (auto &S : Steps)
     S.Destroy();
+  FailedCandidateSet->~OverloadCandidateSet();
 }
 
 //===----------------------------------------------------------------------===//

>From c4d47c13bbc3d263eda85844c487259bd22c65f0 Mon Sep 17 00:00:00 2001
From: Aaron Ballman <aaron at aaronballman.com>
Date: Tue, 16 Apr 2024 08:34:23 -0400
Subject: [PATCH 10/10] Use the STL rather than do work manually; NFC

---
 clang/include/clang/Sema/Overload.h | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/clang/include/clang/Sema/Overload.h b/clang/include/clang/Sema/Overload.h
index c356a2f03a2246..f98c9edea2851f 100644
--- a/clang/include/clang/Sema/Overload.h
+++ b/clang/include/clang/Sema/Overload.h
@@ -37,6 +37,7 @@
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
+#include <memory>
 #include <utility>
 
 namespace clang {
@@ -1140,9 +1141,8 @@ class Sema;
           Ctx.Allocate<ImplicitConversionSequence>(NumConversions);
 
       // Construct the new objects.
-      for (unsigned I = 0; I != NumConversions; ++I)
-        new (&Conversions[I]) ImplicitConversionSequence();
-
+      std::uninitialized_default_construct(Conversions,
+                                           Conversions + NumConversions);
       return ConversionSequenceList(Conversions, NumConversions);
     }
 



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