Simpler approach

Author: alejandro-alvarez-sonarsource

clang/include/clang/AST/DeclTemplate.h

@@ -1365,8 +1365,6 @@ class NonTypeTemplateParmDecl final
       DefaultArgStorage<NonTypeTemplateParmDecl, TemplateArgumentLoc *>;
   DefArgStorage DefaultArgument;
 
-  bool PlaceholderTypeConstraintInitialized = false;
-
   // FIXME: Collapse this into TemplateParamPosition; or, just move depth/index
   // down here to save memory.
 
@@ -1535,11 +1533,13 @@ class NonTypeTemplateParmDecl final
   /// Return the constraint introduced by the placeholder type of this non-type
   /// template parameter (if any).
   Expr *getPlaceholderTypeConstraint() const {
-    return PlaceholderTypeConstraintInitialized ? *getTrailingObjects<Expr *>()
-                                                : nullptr;
+    return hasPlaceholderTypeConstraint() ? *getTrailingObjects<Expr *>() :
+        nullptr;
   }
 
-  void setPlaceholderTypeConstraint(Expr *E);
+  void setPlaceholderTypeConstraint(Expr *E) {
+    *getTrailingObjects<Expr *>() = E;
+  }
 
   /// Determine whether this non-type template parameter's type has a
   /// placeholder with a type-constraint.

clang/lib/AST/DeclTemplate.cpp

@@ -786,12 +786,16 @@ NonTypeTemplateParmDecl *NonTypeTemplateParmDecl::Create(
     QualType T, bool ParameterPack, TypeSourceInfo *TInfo) {
   AutoType *AT =
       C.getLangOpts().CPlusPlus20 ? T->getContainedAutoType() : nullptr;
-  return new (C, DC,
-              additionalSizeToAlloc<std::pair<QualType, TypeSourceInfo *>,
-                                    Expr *>(0,
-                                            AT && AT->isConstrained() ? 1 : 0))
-      NonTypeTemplateParmDecl(DC, StartLoc, IdLoc, D, P, Id, T, ParameterPack,
-                              TInfo);
+  bool const HasConstraint = AT && AT->isConstrained();
+  auto *NTTP =
+      new (C, DC,
+           additionalSizeToAlloc<std::pair<QualType, TypeSourceInfo *>, Expr *>(
+               0, HasConstraint ? 1 : 0))
+          NonTypeTemplateParmDecl(DC, StartLoc, IdLoc, D, P, Id, T,
+                                  ParameterPack, TInfo);
+  if (HasConstraint)
+    NTTP->setPlaceholderTypeConstraint(nullptr);
+  return NTTP;
 }
 
 NonTypeTemplateParmDecl *NonTypeTemplateParmDecl::Create(
@@ -800,23 +804,30 @@ NonTypeTemplateParmDecl *NonTypeTemplateParmDecl::Create(
     QualType T, TypeSourceInfo *TInfo, ArrayRef<QualType> ExpandedTypes,
     ArrayRef<TypeSourceInfo *> ExpandedTInfos) {
   AutoType *AT = TInfo->getType()->getContainedAutoType();
-  return new (C, DC,
-              additionalSizeToAlloc<std::pair<QualType, TypeSourceInfo *>,
-                                    Expr *>(
-                  ExpandedTypes.size(), AT && AT->isConstrained() ? 1 : 0))
-      NonTypeTemplateParmDecl(DC, StartLoc, IdLoc, D, P, Id, T, TInfo,
-                              ExpandedTypes, ExpandedTInfos);
+  bool const HasConstraint = AT && AT->isConstrained();
+  auto *NTTP =
+      new (C, DC,
+           additionalSizeToAlloc<std::pair<QualType, TypeSourceInfo *>, Expr *>(
+               ExpandedTypes.size(), HasConstraint ? 1 : 0))
+          NonTypeTemplateParmDecl(DC, StartLoc, IdLoc, D, P, Id, T, TInfo,
+                                  ExpandedTypes, ExpandedTInfos);
+  if (HasConstraint)
+    NTTP->setPlaceholderTypeConstraint(nullptr);
+  return NTTP;
 }
 
 NonTypeTemplateParmDecl *
 NonTypeTemplateParmDecl::CreateDeserialized(ASTContext &C, GlobalDeclID ID,
                                             bool HasTypeConstraint) {
-  return new (C, ID, additionalSizeToAlloc<std::pair<QualType,
-                                                     TypeSourceInfo *>,
-                                           Expr *>(0,
-                                                   HasTypeConstraint ? 1 : 0))
+  auto *NTTP =
+      new (C, ID,
+           additionalSizeToAlloc<std::pair<QualType, TypeSourceInfo *>, Expr *>(
+               0, HasTypeConstraint ? 1 : 0))
           NonTypeTemplateParmDecl(nullptr, SourceLocation(), SourceLocation(),
                                   0, 0, nullptr, QualType(), false, nullptr);
+  if (HasTypeConstraint)
+    NTTP->setPlaceholderTypeConstraint(nullptr);
+  return NTTP;
 }
 
 NonTypeTemplateParmDecl *
@@ -830,6 +841,8 @@ NonTypeTemplateParmDecl::CreateDeserialized(ASTContext &C, GlobalDeclID ID,
           NonTypeTemplateParmDecl(nullptr, SourceLocation(), SourceLocation(),
                                   0, 0, nullptr, QualType(), nullptr, {}, {});
   NTTP->NumExpandedTypes = NumExpandedTypes;
+  if (HasTypeConstraint)
+    NTTP->setPlaceholderTypeConstraint(nullptr);
   return NTTP;
 }
 
@@ -853,16 +866,6 @@ void NonTypeTemplateParmDecl::setDefaultArgument(
     DefaultArgument.set(new (C) TemplateArgumentLoc(DefArg));
 }
 
-void NonTypeTemplateParmDecl::setPlaceholderTypeConstraint(Expr *E) {
-  assert(hasPlaceholderTypeConstraint() &&
-         "setPlaceholderTypeConstraint called on a NonTypeTemplateParmDecl "
-         "without constraint");
-  assert(!PlaceholderTypeConstraintInitialized && "PlaceholderTypeConstraint "
-                                                  "was already initialized!");
-  *getTrailingObjects<Expr *>() = E;
-  PlaceholderTypeConstraintInitialized = true;
-}
-
 //===----------------------------------------------------------------------===//
 // TemplateTemplateParmDecl Method Implementations
 //===----------------------------------------------------------------------===//

clang/lib/Serialization/ASTReaderDecl.cpp

@@ -2713,10 +2713,8 @@ void ASTDeclReader::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
   // TemplateParmPosition.
   D->setDepth(Record.readInt());
   D->setPosition(Record.readInt());
-  if (D->hasPlaceholderTypeConstraint()) {
-    if (Record.readBool()) // PlaceholderTypeConstraintInitialized
-      D->setPlaceholderTypeConstraint(Record.readExpr());
-  }
+  if (D->hasPlaceholderTypeConstraint())
+    D->setPlaceholderTypeConstraint(Record.readExpr());
   if (D->isExpandedParameterPack()) {
     auto TypesAndInfos =
         D->getTrailingObjects<std::pair<QualType, TypeSourceInfo *>>();

clang/lib/Serialization/ASTWriterDecl.cpp

@@ -2020,13 +2020,8 @@ void ASTDeclWriter::VisitNonTypeTemplateParmDecl(NonTypeTemplateParmDecl *D) {
   Record.push_back(D->getDepth());
   Record.push_back(D->getPosition());
 
-  if (D->hasPlaceholderTypeConstraint()) {
-    Expr *TypeConstraint = D->getPlaceholderTypeConstraint();
-    Record.push_back(/*PlaceholderTypeConstraintInitialized=*/TypeConstraint !=
-                     nullptr);
-    if (TypeConstraint)
-      Record.AddStmt(TypeConstraint);
-  }
+  if (D->hasPlaceholderTypeConstraint())
+    Record.AddStmt(D->getPlaceholderTypeConstraint());
 
   if (D->isExpandedParameterPack()) {
     for (unsigned I = 0, N = D->getNumExpansionTypes(); I != N; ++I) {