[clang] [PATCH 1/4] [clang] Improve nested name specifier AST representation (PR #147835)

[via cfe-commits]

================
@@ -6,534 +6,266 @@
 //
 //===----------------------------------------------------------------------===//
 //
-//  This file defines the NestedNameSpecifier class, which represents
-//  a C++ nested-name-specifier.
+//  This file completes the definition of the NestedNameSpecifier class.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CLANG_AST_NESTEDNAMESPECIFIER_H
 #define LLVM_CLANG_AST_NESTEDNAMESPECIFIER_H
 
-#include "clang/AST/DependenceFlags.h"
-#include "clang/Basic/Diagnostic.h"
-#include "clang/Basic/SourceLocation.h"
+#include "clang/AST/Decl.h"
+#include "clang/AST/NestedNameSpecifierBase.h"
+#include "clang/AST/Type.h"
+#include "clang/AST/TypeLoc.h"
 #include "llvm/ADT/DenseMapInfo.h"
-#include "llvm/ADT/FoldingSet.h"
-#include "llvm/ADT/PointerIntPair.h"
-#include "llvm/Support/Compiler.h"
-#include <cstdint>
-#include <cstdlib>
-#include <utility>
 
 namespace clang {
 
-class ASTContext;
-class CXXRecordDecl;
-class IdentifierInfo;
-class LangOptions;
-class NamespaceAliasDecl;
-class NamespaceDecl;
-struct PrintingPolicy;
-class Type;
-class TypeLoc;
-
-/// Represents a C++ nested name specifier, such as
-/// "\::std::vector<int>::".
-///
-/// C++ nested name specifiers are the prefixes to qualified
-/// names. For example, "foo::" in "foo::x" is a nested name
-/// specifier. Nested name specifiers are made up of a sequence of
-/// specifiers, each of which can be a namespace, type, identifier
-/// (for dependent names), decltype specifier, or the global specifier ('::').
-/// The last two specifiers can only appear at the start of a
-/// nested-namespace-specifier.
-class NestedNameSpecifier : public llvm::FoldingSetNode {
-  /// Enumeration describing
-  enum StoredSpecifierKind {
-    StoredIdentifier = 0,
-    StoredDecl = 1,
-    StoredTypeSpec = 2
-  };
-
-  /// The nested name specifier that precedes this nested name
-  /// specifier.
-  ///
-  /// The pointer is the nested-name-specifier that precedes this
-  /// one. The integer stores one of the first four values of type
-  /// SpecifierKind.
-  llvm::PointerIntPair<NestedNameSpecifier *, 2, StoredSpecifierKind> Prefix;
-
-  /// The last component in the nested name specifier, which
-  /// can be an identifier, a declaration, or a type.
-  ///
-  /// When the pointer is NULL, this specifier represents the global
-  /// specifier '::'. Otherwise, the pointer is one of
-  /// IdentifierInfo*, Namespace*, or Type*, depending on the kind of
-  /// specifier as encoded within the prefix.
-  void* Specifier = nullptr;
-
-public:
-  /// The kind of specifier that completes this nested name
-  /// specifier.
-  enum SpecifierKind {
-    /// An identifier, stored as an IdentifierInfo*.
-    Identifier,
-
-    /// A namespace, stored as a NamespaceDecl*.
-    Namespace,
-
-    /// A namespace alias, stored as a NamespaceAliasDecl*.
-    NamespaceAlias,
-
-    /// A type, stored as a Type*.
-    TypeSpec,
-
-    /// The global specifier '::'. There is no stored value.
-    Global,
-
-    /// Microsoft's '__super' specifier, stored as a CXXRecordDecl* of
-    /// the class it appeared in.
-    Super
-  };
-
-private:
-  /// Builds the global specifier.
-  NestedNameSpecifier() : Prefix(nullptr, StoredIdentifier) {}
-
-  /// Copy constructor used internally to clone nested name
-  /// specifiers.
-  NestedNameSpecifier(const NestedNameSpecifier &Other) = default;
-
-  /// Either find or insert the given nested name specifier
-  /// mockup in the given context.
-  static NestedNameSpecifier *FindOrInsert(const ASTContext &Context,
-                                           const NestedNameSpecifier &Mockup);
-
-public:
-  NestedNameSpecifier &operator=(const NestedNameSpecifier &) = delete;
-
-  /// Builds a specifier combining a prefix and an identifier.
-  ///
-  /// The prefix must be dependent, since nested name specifiers
-  /// referencing an identifier are only permitted when the identifier
-  /// cannot be resolved.
-  static NestedNameSpecifier *Create(const ASTContext &Context,
-                                     NestedNameSpecifier *Prefix,
-                                     const IdentifierInfo *II);
-
-  /// Builds a nested name specifier that names a namespace.
-  static NestedNameSpecifier *Create(const ASTContext &Context,
-                                     NestedNameSpecifier *Prefix,
-                                     const NamespaceDecl *NS);
-
-  /// Builds a nested name specifier that names a namespace alias.
-  static NestedNameSpecifier *Create(const ASTContext &Context,
-                                     NestedNameSpecifier *Prefix,
-                                     const NamespaceAliasDecl *Alias);
-
-  /// Builds a nested name specifier that names a type.
-  static NestedNameSpecifier *
-  Create(const ASTContext &Context, NestedNameSpecifier *Prefix, const Type *T);
-
-  /// Builds a specifier that consists of just an identifier.
-  ///
-  /// The nested-name-specifier is assumed to be dependent, but has no
-  /// prefix because the prefix is implied by something outside of the
-  /// nested name specifier, e.g., in "x->Base::f", the "x" has a dependent
-  /// type.
-  static NestedNameSpecifier *Create(const ASTContext &Context,
-                                     const IdentifierInfo *II);
-
-  /// Returns the nested name specifier representing the global
-  /// scope.
-  static NestedNameSpecifier *GlobalSpecifier(const ASTContext &Context);
-
-  /// Returns the nested name specifier representing the __super scope
-  /// for the given CXXRecordDecl.
-  static NestedNameSpecifier *SuperSpecifier(const ASTContext &Context,
-                                             CXXRecordDecl *RD);
-
-  /// Return the prefix of this nested name specifier.
-  ///
-  /// The prefix contains all of the parts of the nested name
-  /// specifier that precede this current specifier. For example, for a
-  /// nested name specifier that represents "foo::bar::", the current
-  /// specifier will contain "bar::" and the prefix will contain
-  /// "foo::".
-  NestedNameSpecifier *getPrefix() const { return Prefix.getPointer(); }
-
-  /// Determine what kind of nested name specifier is stored.
-  SpecifierKind getKind() const;
-
-  /// Retrieve the identifier stored in this nested name
-  /// specifier.
-  IdentifierInfo *getAsIdentifier() const {
-    if (Prefix.getInt() == StoredIdentifier)
-      return (IdentifierInfo *)Specifier;
-
-    return nullptr;
+auto NestedNameSpecifier::getKind() const -> Kind {
----------------
Sirraide wrote:

Is there a reason all of these functions are defined in a header rather than a .cpp file? Does inlining them actually have that big of a performance impact?

https://github.com/llvm/llvm-project/pull/147835