7 files changed, 54 insertions, 40 deletions
diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
index 4d4b2482d046..a92bbde113fc 100644
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -150,11 +150,19 @@ bool Sema::CheckConstraintExpression(const Expr *ConstraintExpression,
 namespace {
 struct SatisfactionStackRAII {
   Sema &SemaRef;
-  SatisfactionStackRAII(Sema &SemaRef, llvm::FoldingSetNodeID FSNID)
+  bool Inserted = false;
+  SatisfactionStackRAII(Sema &SemaRef, const NamedDecl *ND,
+                        llvm::FoldingSetNodeID FSNID)
       : SemaRef(SemaRef) {
-      SemaRef.PushSatisfactionStackEntry(FSNID);
+      if (ND) {
+      SemaRef.PushSatisfactionStackEntry(ND, FSNID);
+      Inserted = true;
+      }
+  }
+  ~SatisfactionStackRAII() {
+        if (Inserted)
+          SemaRef.PopSatisfactionStackEntry();
   }
-  ~SatisfactionStackRAII() { SemaRef.PopSatisfactionStackEntry(); }
 };
 } // namespace
 
@@ -273,7 +281,8 @@ calculateConstraintSatisfaction(Sema &S, const Expr *ConstraintExpr,
 }
 
 static bool
-DiagRecursiveConstraintEval(Sema &S, llvm::FoldingSetNodeID &ID, const Expr *E,
+DiagRecursiveConstraintEval(Sema &S, llvm::FoldingSetNodeID &ID,
+                            const NamedDecl *Templ, const Expr *E,
                             const MultiLevelTemplateArgumentList &MLTAL) {
   E->Profile(ID, S.Context, /*Canonical=*/true);
   for (const auto &List : MLTAL)
@@ -286,7 +295,7 @@ DiagRecursiveConstraintEval(Sema &S, llvm::FoldingSetNodeID &ID, const Expr *E,
   // expression, or when trying to determine the constexpr-ness of special
   // members. Otherwise we could just use the
   // Sema::InstantiatingTemplate::isAlreadyBeingInstantiated function.
-  if (S.SatisfactionStackContains(ID)) {
+  if (S.SatisfactionStackContains(Templ, ID)) {
     S.Diag(E->getExprLoc(), diag::err_constraint_depends_on_self)
         << const_cast<Expr *>(E) << E->getSourceRange();
     return true;
@@ -317,13 +326,14 @@ static ExprResult calculateConstraintSatisfaction(
             return ExprError();
 
           llvm::FoldingSetNodeID ID;
-          if (DiagRecursiveConstraintEval(S, ID, AtomicExpr, MLTAL)) {
+          if (Template &&
+              DiagRecursiveConstraintEval(S, ID, Template, AtomicExpr, MLTAL)) {
             Satisfaction.IsSatisfied = false;
             Satisfaction.ContainsErrors = true;
             return ExprEmpty();
           }
 
-          SatisfactionStackRAII StackRAII(S, ID);
+          SatisfactionStackRAII StackRAII(S, Template, ID);
 
           // We do not want error diagnostics escaping here.
           Sema::SFINAETrap Trap(S);
@@ -1132,8 +1142,7 @@ substituteParameterMappings(Sema &S, NormalizedConstraint &N,
   Sema::InstantiatingTemplate Inst(
       S, ArgsAsWritten->arguments().front().getSourceRange().getBegin(),
       Sema::InstantiatingTemplate::ParameterMappingSubstitution{}, Concept,
-      SourceRange(ArgsAsWritten->arguments()[0].getSourceRange().getBegin(),
-                  ArgsAsWritten->arguments().back().getSourceRange().getEnd()));
+      ArgsAsWritten->arguments().front().getSourceRange());
   if (S.SubstTemplateArguments(*Atomic.ParameterMapping, MLTAL, SubstArgs))
     return true;
 
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index e2b921bfe78f..051fad04219f 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -13088,9 +13088,10 @@ void Sema::AddInitializerToDecl(Decl *RealDecl, Expr *Init, bool DirectInit) {
   // C++ [module.import/6] external definitions are not permitted in header
   // units.
   if (getLangOpts().CPlusPlusModules && currentModuleIsHeaderUnit() &&
-      VDecl->isThisDeclarationADefinition() &&
+      !VDecl->isInvalidDecl() && VDecl->isThisDeclarationADefinition() &&
       VDecl->getFormalLinkage() == Linkage::ExternalLinkage &&
-      !VDecl->isInline()) {
+      !VDecl->isInline() && !VDecl->isTemplated() &&
+      !isa<VarTemplateSpecializationDecl>(VDecl)) {
     Diag(VDecl->getLocation(), diag::err_extern_def_in_header_unit);
     VDecl->setInvalidDecl();
   }
@@ -15259,9 +15260,10 @@ Decl *Sema::ActOnStartOfFunctionDef(Scope *FnBodyScope, Decl *D,
   // FIXME: Consider an alternate location for the test where the inlined()
   // state is complete.
   if (getLangOpts().CPlusPlusModules && currentModuleIsHeaderUnit() &&
+      !FD->isInvalidDecl() && !FD->isInlined() &&
+      BodyKind != FnBodyKind::Delete && BodyKind != FnBodyKind::Default &&
       FD->getFormalLinkage() == Linkage::ExternalLinkage &&
-      !FD->isInvalidDecl() && BodyKind != FnBodyKind::Delete &&
-      BodyKind != FnBodyKind::Default && !FD->isInlined()) {
+      !FD->isTemplated() && !FD->isTemplateInstantiation()) {
     assert(FD->isThisDeclarationADefinition());
     Diag(FD->getLocation(), diag::err_extern_def_in_header_unit);
     FD->setInvalidDecl();
@@ -16616,8 +16618,7 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
                bool &IsDependent, SourceLocation ScopedEnumKWLoc,
                bool ScopedEnumUsesClassTag, TypeResult UnderlyingType,
                bool IsTypeSpecifier, bool IsTemplateParamOrArg,
-               OffsetOfKind OOK, UsingShadowDecl *&FoundUsingShadow,
-               SkipBodyInfo *SkipBody) {
+               OffsetOfKind OOK, SkipBodyInfo *SkipBody) {
   // If this is not a definition, it must have a name.
   IdentifierInfo *OrigName = Name;
   assert((Name != nullptr || TUK == TUK_Definition) &&
@@ -17052,7 +17053,6 @@ Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK, SourceLocation KWLoc,
     // redefinition if either context is within the other.
     if (auto *Shadow = dyn_cast<UsingShadowDecl>(DirectPrevDecl)) {
       auto *OldTag = dyn_cast<TagDecl>(PrevDecl);
-      FoundUsingShadow = Shadow;
       if (SS.isEmpty() && TUK != TUK_Reference && TUK != TUK_Friend &&
           isDeclInScope(Shadow, SearchDC, S, isMemberSpecialization) &&
           !(OldTag && isAcceptableTagRedeclContext(
@@ -18871,10 +18871,24 @@ void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
     ProcessDeclAttributeList(S, Record, Attrs);
 
     // Check to see if a FieldDecl is a pointer to a function.
-    auto IsFunctionPointer = [&](const Decl *D) {
+    auto IsFunctionPointerOrForwardDecl = [&](const Decl *D) {
       const FieldDecl *FD = dyn_cast<FieldDecl>(D);
-      if (!FD)
+      if (!FD) {
+        // Check whether this is a forward declaration that was inserted by
+        // Clang. This happens when a non-forward declared / defined type is
+        // used, e.g.:
+        //
+        //   struct foo {
+        //     struct bar *(*f)();
+        //     struct bar *(*g)();
+        //   };
+        //
+        // "struct bar" shows up in the decl AST as a "RecordDecl" with an
+        // incomplete definition.
+        if (const auto *TD = dyn_cast<TagDecl>(D))
+          return !TD->isCompleteDefinition();
         return false;
+      }
       QualType FieldType = FD->getType().getDesugaredType(Context);
       if (isa<PointerType>(FieldType)) {
         QualType PointeeType = cast<PointerType>(FieldType)->getPointeeType();
@@ -18888,7 +18902,7 @@ void Sema::ActOnFields(Scope *S, SourceLocation RecLoc, Decl *EnclosingDecl,
     if (!getLangOpts().CPlusPlus &&
         (Record->hasAttr<RandomizeLayoutAttr>() ||
          (!Record->hasAttr<NoRandomizeLayoutAttr>() &&
-          llvm::all_of(Record->decls(), IsFunctionPointer))) &&
+          llvm::all_of(Record->decls(), IsFunctionPointerOrForwardDecl))) &&
         !Record->isUnion() && !getLangOpts().RandstructSeed.empty() &&
         !Record->isRandomized()) {
       SmallVector<Decl *, 32> NewDeclOrdering;
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 348092fc62e8..df83442a8cd1 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -16977,7 +16977,6 @@ DeclResult Sema::ActOnTemplatedFriendTag(
     if (SS.isEmpty()) {
       bool Owned = false;
       bool IsDependent = false;
-      UsingShadowDecl* FoundUsing = nullptr;
       return ActOnTag(S, TagSpec, TUK_Friend, TagLoc, SS, Name, NameLoc, Attr,
                       AS_public,
                       /*ModulePrivateLoc=*/SourceLocation(),
@@ -16986,7 +16985,7 @@ DeclResult Sema::ActOnTemplatedFriendTag(
                       /*ScopedEnumUsesClassTag=*/false,
                       /*UnderlyingType=*/TypeResult(),
                       /*IsTypeSpecifier=*/false,
-                      /*IsTemplateParamOrArg=*/false, /*OOK=*/OOK_Outside, FoundUsing);
+                      /*IsTemplateParamOrArg=*/false, /*OOK=*/OOK_Outside);
     }
 
     NestedNameSpecifierLoc QualifierLoc = SS.getWithLocInContext(Context);
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index e3eef9323b2f..abf5a72e7308 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -1483,13 +1483,14 @@ Sema::BuildCXXTypeConstructExpr(TypeSourceInfo *TInfo,
   //   Otherwise, if the type contains a placeholder type, it is replaced by the
   //   type determined by placeholder type deduction.
   DeducedType *Deduced = Ty->getContainedDeducedType();
-  if (Deduced && isa<DeducedTemplateSpecializationType>(Deduced)) {
+  if (Deduced && !Deduced->isDeduced() &&
+      isa<DeducedTemplateSpecializationType>(Deduced)) {
     Ty = DeduceTemplateSpecializationFromInitializer(TInfo, Entity,
                                                      Kind, Exprs);
     if (Ty.isNull())
       return ExprError();
     Entity = InitializedEntity::InitializeTemporary(TInfo, Ty);
-  } else if (Deduced) {
+  } else if (Deduced && !Deduced->isDeduced()) {
     MultiExprArg Inits = Exprs;
     if (ListInitialization) {
       auto *ILE = cast<InitListExpr>(Exprs[0]);
@@ -2016,7 +2017,8 @@ ExprResult Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
 
   // C++11 [dcl.spec.auto]p6. Deduce the type which 'auto' stands in for.
   auto *Deduced = AllocType->getContainedDeducedType();
-  if (Deduced && isa<DeducedTemplateSpecializationType>(Deduced)) {
+  if (Deduced && !Deduced->isDeduced() &&
+      isa<DeducedTemplateSpecializationType>(Deduced)) {
     if (ArraySize)
       return ExprError(
           Diag(*ArraySize ? (*ArraySize)->getExprLoc() : TypeRange.getBegin(),
@@ -2030,7 +2032,7 @@ ExprResult Sema::BuildCXXNew(SourceRange Range, bool UseGlobal,
         AllocTypeInfo, Entity, Kind, Exprs);
     if (AllocType.isNull())
       return ExprError();
-  } else if (Deduced) {
+  } else if (Deduced && !Deduced->isDeduced()) {
     MultiExprArg Inits = Exprs;
     bool Braced = (initStyle == CXXNewExpr::ListInit);
     if (Braced) {
diff --git a/clang/lib/Sema/SemaRISCVVectorLookup.cpp b/clang/lib/Sema/SemaRISCVVectorLookup.cpp
index 7716dfb15458..fedc314f2965 100644
--- a/clang/lib/Sema/SemaRISCVVectorLookup.cpp
+++ b/clang/lib/Sema/SemaRISCVVectorLookup.cpp
@@ -192,7 +192,7 @@ void RISCVIntrinsicManagerImpl::InitIntrinsicList() {
     PolicyScheme MaskedPolicyScheme =
         static_cast<PolicyScheme>(Record.MaskedPolicyScheme);
 
-    const Policy DefaultPolicy(Record.HasTailPolicy, Record.HasMaskPolicy);
+    const Policy DefaultPolicy;
 
     llvm::SmallVector<PrototypeDescriptor> ProtoSeq =
         RVVIntrinsic::computeBuiltinTypes(BasicProtoSeq, /*IsMasked=*/false,
@@ -208,8 +208,7 @@ void RISCVIntrinsicManagerImpl::InitIntrinsicList() {
     bool UnMaskedHasPolicy = UnMaskedPolicyScheme != PolicyScheme::SchemeNone;
     bool MaskedHasPolicy = MaskedPolicyScheme != PolicyScheme::SchemeNone;
     SmallVector<Policy> SupportedUnMaskedPolicies =
-        RVVIntrinsic::getSupportedUnMaskedPolicies(Record.HasTailPolicy,
-                                                   Record.HasMaskPolicy);
+        RVVIntrinsic::getSupportedUnMaskedPolicies();
     SmallVector<Policy> SupportedMaskedPolicies =
         RVVIntrinsic::getSupportedMaskedPolicies(Record.HasTailPolicy,
                                                  Record.HasMaskPolicy);
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 4b144c239fa4..b40bd0978a8a 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -10181,14 +10181,11 @@ Sema::ActOnExplicitInstantiation(Scope *S, SourceLocation ExternLoc,
 
   bool Owned = false;
   bool IsDependent = false;
-  UsingShadowDecl* FoundUsing = nullptr;
-  Decl *TagD =
-      ActOnTag(S, TagSpec, Sema::TUK_Reference, KWLoc, SS, Name, NameLoc, Attr,
-               AS_none, /*ModulePrivateLoc=*/SourceLocation(),
+  Decl *TagD = ActOnTag(S, TagSpec, Sema::TUK_Reference, KWLoc, SS, Name,
+               NameLoc, Attr, AS_none, /*ModulePrivateLoc=*/SourceLocation(),
                MultiTemplateParamsArg(), Owned, IsDependent, SourceLocation(),
                false, TypeResult(), /*IsTypeSpecifier*/ false,
-               /*IsTemplateParamOrArg*/ false, /*OOK=*/OOK_Outside, FoundUsing)
-          .get();
+               /*IsTemplateParamOrArg*/ false, /*OOK=*/OOK_Outside).get();
   assert(!IsDependent && "explicit instantiation of dependent name not yet handled");
 
   if (!TagD)
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
index 89d819a77dcb..8cb1ed28fe3e 100644
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -1588,9 +1588,6 @@ static QualType ConvertDeclSpecToType(TypeProcessingState &state) {
 
     // TypeQuals handled by caller.
     Result = Context.getTypeDeclType(D);
-    if (const auto *Using =
-            dyn_cast_or_null<UsingShadowDecl>(DS.getRepAsFoundDecl()))
-      Result = Context.getUsingType(Using, Result);
 
     // In both C and C++, make an ElaboratedType.
     ElaboratedTypeKeyword Keyword
@@ -6256,9 +6253,6 @@ namespace {
     void VisitTagTypeLoc(TagTypeLoc TL) {
       TL.setNameLoc(DS.getTypeSpecTypeNameLoc());
     }
-    void VisitUsingTypeLoc(UsingTypeLoc TL) {
-      TL.setNameLoc(DS.getTypeSpecTypeNameLoc());
-    }
     void VisitAtomicTypeLoc(AtomicTypeLoc TL) {
       // An AtomicTypeLoc can come from either an _Atomic(...) type specifier
       // or an _Atomic qualifier.