[Clang] Make the SizeType, SignedSizeType and PtrdiffType be named sugar types instead of built-in types

clang-tools-extra/clangd/unittests/HoverTests.cpp

@@ -2794,7 +2794,7 @@ TEST(Hover, All) {
           })cpp",
           [](HoverInfo &HI) {
             HI.Name = "expression";
-            HI.Type = "unsigned long";
+            HI.Type = {"__size_t", "unsigned long"};
             HI.Value = "1";
           }},
       {
@@ -2804,7 +2804,7 @@ TEST(Hover, All) {
           })cpp",
           [](HoverInfo &HI) {
             HI.Name = "expression";
-            HI.Type = "unsigned long";
+            HI.Type = {"__size_t", "unsigned long"};
             HI.Value = "1";
           }},
       {

clang/include/clang/AST/ASTContext.h

@@ -277,6 +277,11 @@ class ASTContext : public RefCountedBase<ASTContext> {
   mutable llvm::ContextualFoldingSet<ArrayParameterType, ASTContext &>
       ArrayParameterTypes;
 
+  /// Store the unique Type corresponding to each Kind.
+  mutable std::array<Type *,
+                     llvm::to_underlying(PredefinedSugarType::Kind::Max)>
+      PredefinedSugarTypes{};
+
   /// The set of nested name specifiers.
   ///
   /// This set is managed by the NestedNameSpecifier class.
@@ -1567,6 +1572,8 @@ class ASTContext : public RefCountedBase<ASTContext> {
   /// and bit count.
   QualType getDependentBitIntType(bool Unsigned, Expr *BitsExpr) const;
 
+  QualType getPredefinedSugarType(PredefinedSugarType::Kind KD) const;
+
   /// Gets the struct used to keep track of the extended descriptor for
   /// pointer to blocks.
   QualType getBlockDescriptorExtendedType() const;
@@ -1999,11 +2006,13 @@ class ASTContext : public RefCountedBase<ASTContext> {
   /// <stddef.h>.
   ///
   /// The sizeof operator requires this (C99 6.5.3.4p4).
-  CanQualType getSizeType() const;
+  QualType getSizeType() const;
+
+  CanQualType getCanonicalSizeType() const;
 
   /// Return the unique signed counterpart of
   /// the integer type corresponding to size_t.
-  CanQualType getSignedSizeType() const;
+  QualType getSignedSizeType() const;
 
   /// Return the unique type for "intmax_t" (C99 7.18.1.5), defined in
   /// <stdint.h>.

clang/include/clang/AST/FormatString.h

@@ -489,7 +489,8 @@ class FormatSpecifier {
 
   /// For a TypedefType QT, if it is a named integer type such as size_t,
   /// assign the appropriate value to LM and return true.
-  static bool namedTypeToLengthModifier(QualType QT, LengthModifier &LM);
+  static bool namedTypeToLengthModifier(ASTContext &Ctx, QualType QT,
+                                        LengthModifier &LM);
 };
 
 } // end analyze_format_string namespace

clang/include/clang/AST/RecursiveASTVisitor.h

@@ -1210,6 +1210,8 @@ DEF_TRAVERSE_TYPE(BitIntType, {})
 DEF_TRAVERSE_TYPE(DependentBitIntType,
                   { TRY_TO(TraverseStmt(T->getNumBitsExpr())); })
 
+DEF_TRAVERSE_TYPE(PredefinedSugarType, {})
+
 #undef DEF_TRAVERSE_TYPE
 
 // ----------------- TypeLoc traversal -----------------
@@ -1526,6 +1528,8 @@ DEF_TRAVERSE_TYPELOC(DependentBitIntType, {
   TRY_TO(TraverseStmt(TL.getTypePtr()->getNumBitsExpr()));
 })
 
+DEF_TRAVERSE_TYPELOC(PredefinedSugarType, {})
+
 #undef DEF_TRAVERSE_TYPELOC
 
 // ----------------- Decl traversal -----------------

clang/include/clang/AST/Type.h

@@ -2258,6 +2258,30 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
     unsigned NumExpansions;
   };
 
+  enum class PredefinedSugarKind {
+    /// The "size_t" type.
+    SizeT,
+
+    /// The signed integer type corresponding to "size_t".
+    SignedSizeT,
+
+    /// The "ptrdiff_t" type.
+    PtrdiffT,
+
+    // Indicates how many items the enum has.
+    Max
+  };
+
+  class PresefinedSugarTypeBitfields {
+    friend class PredefinedSugarType;
+
+    LLVM_PREFERRED_TYPE(TypeBitfields)
+    unsigned : NumTypeBits;
+
+    LLVM_PREFERRED_TYPE(PredefinedSugarKind)
+    unsigned Kind : 8;
+  };
+
   class CountAttributedTypeBitfields {
     friend class CountAttributedType;
 
@@ -2297,6 +2321,7 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
       DependentTemplateSpecializationTypeBits;
     PackExpansionTypeBitfields PackExpansionTypeBits;
     CountAttributedTypeBitfields CountAttributedTypeBits;
+    PresefinedSugarTypeBitfields PredefinedSugarTypeBits;
   };
 
 private:
@@ -8038,6 +8063,37 @@ class DependentBitIntType final : public Type, public llvm::FoldingSetNode {
   }
 };
 
+class PredefinedSugarType final : public Type {
+public:
+  friend class ASTContext;
+  using Kind = PredefinedSugarKind;
+
+private:
+  PredefinedSugarType(Kind KD, const IdentifierInfo *IdentName,
+                      QualType CanonicalType)
+      : Type(PredefinedSugar, CanonicalType, TypeDependence::None),
+        Name(IdentName) {
+    PredefinedSugarTypeBits.Kind = llvm::to_underlying(KD);
+  }
+
+  static StringRef getName(Kind KD);
+
+  const IdentifierInfo *Name;
+
+public:
+  bool isSugared() const { return true; }
+
+  QualType desugar() const { return getCanonicalTypeInternal(); }
+
+  Kind getKind() const { return Kind(PredefinedSugarTypeBits.Kind); }
+
+  const IdentifierInfo *getIdentifier() const { return Name; }
+
+  static bool classof(const Type *T) {
+    return T->getTypeClass() == PredefinedSugar;
+  }
+};
+
 /// A qualifier set is used to build a set of qualifiers.
 class QualifierCollector : public Qualifiers {
 public:

clang/include/clang/AST/TypeLoc.h

@@ -2767,6 +2767,10 @@ class DependentBitIntTypeLoc final
     : public InheritingConcreteTypeLoc<TypeSpecTypeLoc, DependentBitIntTypeLoc,
                                        DependentBitIntType> {};
 
+class PredefinedSugarTypeLoc final
+    : public InheritingConcreteTypeLoc<TypeSpecTypeLoc, PredefinedSugarTypeLoc,
+                                       PredefinedSugarType> {};
+
 class ObjCProtocolLoc {
   ObjCProtocolDecl *Protocol = nullptr;
   SourceLocation Loc = SourceLocation();

clang/include/clang/AST/TypeProperties.td

@@ -1028,3 +1028,12 @@ let Class = DependentBitIntType in {
     return ctx.getDependentBitIntType(isUnsigned, numBitsExpr);
   }]>;
 }
+
+let Class = PredefinedSugarType in {
+  def : Property<"kind", UInt32> {
+    let Read = [{ static_cast<uint32_t>(node->getKind()) }];
+  }
+  def : Creator<[{
+    return ctx.getPredefinedSugarType(static_cast<PredefinedSugarType::Kind>(kind));
+  }]>;
+}

clang/include/clang/Basic/TypeNodes.td

@@ -117,3 +117,4 @@ def PipeType : TypeNode<Type>;
 def AtomicType : TypeNode<Type>;
 def BitIntType : TypeNode<Type>;
 def DependentBitIntType : TypeNode<Type>, AlwaysDependent;
+def PredefinedSugarType : TypeNode<Type>, NeverCanonical;

clang/include/clang/Serialization/TypeBitCodes.def

@@ -69,5 +69,6 @@ TYPE_BIT_CODE(CountAttributed, COUNT_ATTRIBUTED, 57)
 TYPE_BIT_CODE(ArrayParameter, ARRAY_PARAMETER, 58)
 TYPE_BIT_CODE(HLSLAttributedResource, HLSLRESOURCE_ATTRIBUTED, 59)
 TYPE_BIT_CODE(HLSLInlineSpirv, HLSL_INLINE_SPIRV, 60)
+TYPE_BIT_CODE(PredefinedSugar, PREDEFINED_SUGAR, 61)
 
 #undef TYPE_BIT_CODE

clang/lib/AST/ASTContext.cpp

@@ -2595,8 +2595,12 @@ TypeInfo ASTContext::getTypeInfoImpl(const Type *T) const {
       Align = static_cast<unsigned>(Width);
     }
   }
+
   break;
 
+  case Type::PredefinedSugar:
+    return getTypeInfo(cast<PredefinedSugarType>(T)->desugar().getTypePtr());
+
   case Type::Pipe:
     Width = Target->getPointerWidth(LangAS::opencl_global);
     Align = Target->getPointerAlign(LangAS::opencl_global);
@@ -5216,6 +5220,42 @@ QualType ASTContext::getDependentBitIntType(bool IsUnsigned,
   return QualType(New, 0);
 }
 
+QualType
+ASTContext::getPredefinedSugarType(PredefinedSugarType::Kind KD) const {
+  using Kind = PredefinedSugarType::Kind;
+
+  assert(KD != Kind::Max);
+
+  if (auto *Target = PredefinedSugarTypes[llvm::to_underlying(KD)];
+      Target != nullptr)
+    return QualType(Target, 0);
+
+  auto getCanonicalType = [](const ASTContext &Ctx, Kind KDI) -> QualType {
+    switch (KDI) {
+      // size_t (C99TC3 6.5.3.4), signed size_t (C++23 5.13.2) and
+      // ptrdiff_t (C99TC3 6.5.6) Although these types are not built-in, they
+      // are part of the core language and are widely used. Using
+      // PredefinedSugarType makes these types as named sugar types rather than
+      // standard integer types, enabling better hints and diagnostics.
+    case Kind::SizeT:
+      return Ctx.getFromTargetType(Ctx.Target->getSizeType());
+    case Kind::SignedSizeT:
+      return Ctx.getFromTargetType(Ctx.Target->getSignedSizeType());
+    case Kind::PtrdiffT:
+      return Ctx.getFromTargetType(Ctx.Target->getPtrDiffType(LangAS::Default));
+    case Kind::Max:;
+    }
+    llvm_unreachable("unexpected kind");
+  };
+
+  auto *New = new (*this, alignof(PredefinedSugarType))
+      PredefinedSugarType(KD, &Idents.get(PredefinedSugarType::getName(KD)),
+                          getCanonicalType(*this, static_cast<Kind>(KD)));
+  Types.push_back(New);
+  PredefinedSugarTypes[llvm::to_underlying(KD)] = New;
+  return QualType(New, 0);
+}
+
 #ifndef NDEBUG
 static bool NeedsInjectedClassNameType(const RecordDecl *D) {
   if (!isa<CXXRecordDecl>(D)) return false;
@@ -6796,14 +6836,31 @@ QualType ASTContext::getTagDeclType(const TagDecl *Decl) const {
 /// getSizeType - Return the unique type for "size_t" (C99 7.17), the result
 /// of the sizeof operator (C99 6.5.3.4p4). The value is target dependent and
 /// needs to agree with the definition in <stddef.h>.
-CanQualType ASTContext::getSizeType() const {
+QualType ASTContext::getSizeType() const {
+  return getPredefinedSugarType(PredefinedSugarType::Kind::SizeT);
+}
+
+CanQualType ASTContext::getCanonicalSizeType() const {
   return getFromTargetType(Target->getSizeType());
 }
 
 /// Return the unique signed counterpart of the integer type
 /// corresponding to size_t.
-CanQualType ASTContext::getSignedSizeType() const {
-  return getFromTargetType(Target->getSignedSizeType());
+QualType ASTContext::getSignedSizeType() const {
+  return getPredefinedSugarType(PredefinedSugarType::Kind::SignedSizeT);
+}
+
+/// getPointerDiffType - Return the unique type for "ptrdiff_t" (C99 7.17)
+/// defined in <stddef.h>. Pointer - pointer requires this (C99 6.5.6p9).
+QualType ASTContext::getPointerDiffType() const {
+  return getPredefinedSugarType(PredefinedSugarType::Kind::PtrdiffT);
+}
+
+/// Return the unique unsigned counterpart of "ptrdiff_t"
+/// integer type. The standard (C11 7.21.6.1p7) refers to this type
+/// in the definition of %tu format specifier.
+QualType ASTContext::getUnsignedPointerDiffType() const {
+  return getFromTargetType(Target->getUnsignedPtrDiffType(LangAS::Default));
 }
 
 /// getIntMaxType - Return the unique type for "intmax_t" (C99 7.18.1.5).
@@ -6838,19 +6895,6 @@ QualType ASTContext::getUIntPtrType() const {
   return getCorrespondingUnsignedType(getIntPtrType());
 }
 
-/// getPointerDiffType - Return the unique type for "ptrdiff_t" (C99 7.17)
-/// defined in <stddef.h>. Pointer - pointer requires this (C99 6.5.6p9).
-QualType ASTContext::getPointerDiffType() const {
-  return getFromTargetType(Target->getPtrDiffType(LangAS::Default));
-}
-
-/// Return the unique unsigned counterpart of "ptrdiff_t"
-/// integer type. The standard (C11 7.21.6.1p7) refers to this type
-/// in the definition of %tu format specifier.
-QualType ASTContext::getUnsignedPointerDiffType() const {
-  return getFromTargetType(Target->getUnsignedPtrDiffType(LangAS::Default));
-}
-
 /// Return the unique type for "pid_t" defined in
 /// <sys/types.h>. We need this to compute the correct type for vfork().
 QualType ASTContext::getProcessIDType() const {
@@ -14526,6 +14570,10 @@ static QualType getCommonSugarTypeNode(ASTContext &Ctx, const Type *X,
                                       DX->isCountInBytes(), DX->isOrNull(),
                                       CDX);
   }
+  case Type::PredefinedSugar:
+    assert(cast<PredefinedSugarType>(X)->getKind() !=
+           cast<PredefinedSugarType>(Y)->getKind());
+    return QualType();
   }
   llvm_unreachable("Unhandled Type Class");
 }

clang/lib/AST/ASTImporter.cpp

@@ -1893,6 +1893,11 @@ ExpectedType clang::ASTNodeImporter::VisitDependentBitIntType(
                                                         *ToNumBitsExprOrErr);
 }
 
+ExpectedType clang::ASTNodeImporter::VisitPredefinedSugarType(
+    const clang::PredefinedSugarType *T) {
+  return Importer.getToContext().getPredefinedSugarType(T->getKind());
+}
+
 ExpectedType clang::ASTNodeImporter::VisitDependentSizedMatrixType(
     const clang::DependentSizedMatrixType *T) {
   Error Err = Error::success();

clang/lib/AST/ASTStructuralEquivalence.cpp

@@ -1480,6 +1480,13 @@ static bool IsStructurallyEquivalent(StructuralEquivalenceContext &Context,
       return false;
     break;
   }
+  case Type::PredefinedSugar: {
+    const auto *TP1 = cast<PredefinedSugarType>(T1);
+    const auto *TP2 = cast<PredefinedSugarType>(T2);
+    if (TP1->getKind() != TP2->getKind())
+      return false;
+    break;
+  }
   } // end switch
 
   return true;