//===- ASTImporter.h - Importing ASTs from other Contexts -------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines the ASTImporter class which imports AST nodes from one
// context into another context.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CLANG_AST_ASTIMPORTER_H
#define LLVM_CLANG_AST_ASTIMPORTER_H
#include "clang/AST/ASTImportError.h"
#include "clang/AST/DeclBase.h"
#include "clang/AST/DeclarationName.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/NestedNameSpecifier.h"
#include "clang/AST/TemplateName.h"
#include "clang/AST/Type.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/IdentifierTable.h"
#include "clang/Basic/LLVM.h"
#include "clang/Basic/SourceLocation.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/SmallVector.h"
#include <optional>
#include <utility>
namespace clang {
class ASTContext;
class ASTImporterSharedState;
class Attr;
class CXXBaseSpecifier;
class CXXCtorInitializer;
class Decl;
class DeclContext;
class Expr;
class FileManager;
class NamedDecl;
class Stmt;
class TagDecl;
class TranslationUnitDecl;
class TypeSourceInfo;
// \brief Returns with a list of declarations started from the canonical decl
// then followed by subsequent decls in the translation unit.
// This gives a canonical list for each entry in the redecl chain.
// `Decl::redecls()` gives a list of decls which always start from the
// previous decl and the next item is actually the previous item in the order
// of source locations. Thus, `Decl::redecls()` gives different lists for
// the different entries in a given redecl chain.
llvm::SmallVector<Decl*, 2> getCanonicalForwardRedeclChain(Decl* D);
/// Imports selected nodes from one AST context into another context,
/// merging AST nodes where appropriate.
class ASTImporter {
friend class ASTNodeImporter;
public:
using NonEquivalentDeclSet = llvm::DenseSet<std::pair<Decl *, Decl *>>;
using ImportedCXXBaseSpecifierMap =
llvm::DenseMap<const CXXBaseSpecifier *, CXXBaseSpecifier *>;
enum class ODRHandlingType { Conservative, Liberal };
// An ImportPath is the list of the AST nodes which we visit during an
// Import call.
// If node `A` depends on node `B` then the path contains an `A`->`B` edge.
// From the call stack of the import functions we can read the very same
// path.
//
// Now imagine the following AST, where the `->` represents dependency in
// therms of the import.
// ```
// A->B->C->D
// `->E
// ```
// We would like to import A.
// The import behaves like a DFS, so we will visit the nodes in this order:
// ABCDE.
// During the visitation we will have the following ImportPaths:
// ```
// A
// AB
// ABC
// ABCD
// ABC
// AB
// ABE
// AB
// A
// ```
// If during the visit of E there is an error then we set an error for E,
// then as the call stack shrinks for B, then for A:
// ```
// A
// AB
// ABC
// ABCD
// ABC
// AB
// ABE // Error! Set an error to E
// AB // Set an error to B
// A // Set an error to A
// ```
// However, during the import we could import C and D without any error and
// they are independent from A,B and E.
// We must not set up an error for C and D.
// So, at the end of the import we have an entry in `ImportDeclErrors` for
// A,B,E but not for C,D.
//
// Now what happens if there is a cycle in the import path?
// Let's consider this AST:
// ```
// A->B->C->A
// `->E
// ```
// During the visitation we will have the below ImportPaths and if during
// the visit of E there is an error then we will set up an error for E,B,A.
// But what's up with C?
// ```
// A
// AB
// ABC
// ABCA
// ABC
// AB
// ABE // Error! Set an error to E
// AB // Set an error to B
// A // Set an error to A
// ```
// This time we know that both B and C are dependent on A.
// This means we must set up an error for C too.
// As the call stack reverses back we get to A and we must set up an error
// to all nodes which depend on A (this includes C).
// But C is no longer on the import path, it just had been previously.
// Such situation can happen only if during the visitation we had a cycle.
// If we didn't have any cycle, then the normal way of passing an Error
// object through the call stack could handle the situation.
// This is why we must track cycles during the import process for each
// visited declaration.
class ImportPathTy {
public:
using VecTy = llvm::SmallVector<Decl *, 32>;
void push(Decl *D) {
Nodes.push_back(D);
++Aux[D];
}
void pop() {
if (Nodes.empty())
return;
--Aux[Nodes.back()];
Nodes.pop_back();
}
/// Returns true if the last element can be found earlier in the path.
bool hasCycleAtBack() const {
auto Pos = Aux.find(Nodes.back());
return Pos != Aux.end() && Pos->second > 1;
}
using Cycle = llvm::iterator_range<VecTy::const_reverse_iterator>;
Cycle getCycleAtBack() const {
assert(Nodes.size() >= 2);
return Cycle(Nodes.rbegin(),
std::find(Nodes.rbegin() + 1, Nodes.rend(), Nodes.back()) +
1);
}
/// Returns the copy of the cycle.
VecTy copyCycleAtBack() const {
auto R = getCycleAtBack();
return VecTy(R.begin(), R.end());
}
private:
// All nodes of the path.
VecTy Nodes;
// Auxiliary container to be able to answer "Do we have a cycle ending
// at last element?" as fast as possible.
// We count each Decl's occurrence over the path.
llvm::SmallDenseMap<Decl *, int, 32> Aux;
};
private:
std::shared_ptr<ASTImporterSharedState> SharedState = nullptr;
/// The path which we go through during the import of a given AST node.
ImportPathTy ImportPath;
/// Sometimes we have to save some part of an import path, so later we can
/// set up properties to the saved nodes.
/// We may have several of these import paths associated to one Decl.
using SavedImportPathsForOneDecl =
llvm::SmallVector<ImportPathTy::VecTy, 32>;
using SavedImportPathsTy =
llvm::SmallDenseMap<Decl *, SavedImportPathsForOneDecl, 32>;
SavedImportPathsTy SavedImportPaths;
/// The contexts we're importing to and from.
ASTContext &ToContext, &FromContext;
/// The file managers we're importing to and from.
FileManager &ToFileManager, &FromFileManager;
/// Whether to perform a minimal import.
bool Minimal;
ODRHandlingType ODRHandling;
/// Whether the last diagnostic came from the "from" context.
bool LastDiagFromFrom = false;
/// Mapping from the already-imported types in the "from" context
/// to the corresponding types in the "to" context.
llvm::DenseMap<const Type *, const Type *> ImportedTypes;
/// Mapping from the already-imported declarations in the "from"
/// context to the corresponding declarations in the "to" context.
llvm::DenseMap<Decl *, Decl *> ImportedDecls;
/// Mapping from the already-imported declarations in the "from"
/// context to the error status of the import of that declaration.
/// This map contains only the declarations that were not correctly
/// imported. The same declaration may or may not be included in
/// ImportedDecls. This map is updated continuously during imports and never
/// cleared (like ImportedDecls).
llvm::DenseMap<Decl *, ASTImportError> ImportDeclErrors;
/// Mapping from the already-imported declarations in the "to"
/// context to the corresponding declarations in the "from" context.
llvm::DenseMap<Decl *, Decl *> ImportedFromDecls;
/// Mapping from the already-imported statements in the "from"
/// context to the corresponding statements in the "to" context.
llvm::DenseMap<Stmt *, Stmt *> ImportedStmts;
/// Mapping from the already-imported FileIDs in the "from" source
/// manager to the corresponding FileIDs in the "to" source manager.
llvm::DenseMap<FileID, FileID> ImportedFileIDs;
/// Mapping from the already-imported CXXBasesSpecifier in
/// the "from" source manager to the corresponding CXXBasesSpecifier
/// in the "to" source manager.
ImportedCXXBaseSpecifierMap ImportedCXXBaseSpecifiers;
/// Declaration (from, to) pairs that are known not to be equivalent
/// (which we have already complained about).
NonEquivalentDeclSet NonEquivalentDecls;
using FoundDeclsTy = SmallVector<NamedDecl *, 2>;
FoundDeclsTy findDeclsInToCtx(DeclContext *DC, DeclarationName Name);
void AddToLookupTable(Decl *ToD);
protected:
/// Can be overwritten by subclasses to implement their own import logic.
/// The overwritten method should call this method if it didn't import the
/// decl on its own.
virtual Expected<Decl *> ImportImpl(Decl *From);
/// Used only in unittests to verify the behaviour of the error handling.
virtual bool returnWithErrorInTest() { return false; };
public:
/// \param ToContext The context we'll be importing into.
///
/// \param ToFileManager The file manager we'll be importing into.
///
/// \param FromContext The context we'll be importing from.
///
/// \param FromFileManager The file manager we'll be importing into.
///
/// \param MinimalImport If true, the importer will attempt to import
/// as little as it can, e.g., by importing declarations as forward
/// declarations that can be completed at a later point.
///
/// \param SharedState The importer specific lookup table which may be
/// shared amongst several ASTImporter objects.
/// If not set then the original C/C++ lookup is used.
ASTImporter(ASTContext &ToContext, FileManager &ToFileManager,
ASTContext &FromContext, FileManager &FromFileManager,
bool MinimalImport,
std::shared_ptr<ASTImporterSharedState> SharedState = nullptr);
virtual ~ASTImporter();
/// Whether the importer will perform a minimal import, creating
/// to-be-completed forward declarations when possible.
bool isMinimalImport() const { return Minimal; }
void setODRHandling(ODRHandlingType T) { ODRHandling = T; }
/// \brief Import the given object, returns the result.
///
/// \param To Import the object into this variable.
/// \param From Object to import.
/// \return Error information (success or error).
template <typename ImportT>
[[nodiscard]] llvm::Error importInto(ImportT &To, const ImportT &From) {
auto ToOrErr = Import(From);
if (ToOrErr)
To = *ToOrErr;
return ToOrErr.takeError();
}
/// Import cleanup objects owned by ExprWithCleanup.
llvm::Expected<ExprWithCleanups::CleanupObject>
Import(ExprWithCleanups::CleanupObject From);
/// Import the given type from the "from" context into the "to"
/// context.
///
/// \returns The equivalent type in the "to" context, or the import error.
llvm::Expected<const Type *> Import(const Type *FromT);
/// Import the given qualified type from the "from" context into the "to"
/// context. A null type is imported as a null type (no error).
///
/// \returns The equivalent type in the "to" context, or the import error.
llvm::Expected<QualType> Import(QualType FromT);
/// Import the given type source information from the
/// "from" context into the "to" context.
///
/// \returns The equivalent type source information in the "to"
/// context, or the import error.
llvm::Expected<TypeSourceInfo *> Import(TypeSourceInfo *FromTSI);
/// Import the given attribute from the "from" context into the
/// "to" context.
///
/// \returns The equivalent attribute in the "to" context, or the import
/// error.
llvm::Expected<Attr *> Import(const Attr *FromAttr);
/// Import the given declaration from the "from" context into the
/// "to" context.
///
/// \returns The equivalent declaration in the "to" context, or the import
/// error.
llvm::Expected<Decl *> Import(Decl *FromD);
llvm::Expected<const Decl *> Import(const Decl *FromD) {
return Import(const_cast<Decl *>(FromD));
}
llvm::Expected<InheritedConstructor>
Import(const InheritedConstructor &From);
/// Return the copy of the given declaration in the "to" context if
/// it has already been imported from the "from" context. Otherwise return
/// nullptr.
Decl *GetAlreadyImportedOrNull(const Decl *FromD) const;
/// Return the translation unit from where the declaration was
/// imported. If it does not exist nullptr is returned.
TranslationUnitDecl *GetFromTU(Decl *ToD);
/// Return the declaration in the "from" context from which the declaration
/// in the "to" context was imported. If it was not imported or of the wrong
/// type a null value is returned.
template <typename DeclT>
std::optional<DeclT *> getImportedFromDecl(const DeclT *ToD) const {
auto FromI = ImportedFromDecls.find(ToD);
if (FromI == ImportedFromDecls.end())
return {};
auto *FromD = dyn_cast<DeclT>(FromI->second);
if (!FromD)
return {};
return FromD;
}
/// Import the given declaration context from the "from"
/// AST context into the "to" AST context.
///
/// \returns the equivalent declaration context in the "to"
/// context, or error value.
llvm::Expected<DeclContext *> ImportContext(DeclContext *FromDC);
/// Import the given expression from the "from" context into the
/// "to" context.
///
/// \returns The equivalent expression in the "to" context, or the import
/// error.
llvm::Expected<Expr *> Import(Expr *FromE);
/// Import the given statement from the "from" context into the
/// "to" context.
///
/// \returns The equivalent statement in the "to" context, or the import
/// error.
llvm::Expected<Stmt *> Import(Stmt *FromS);
/// Import the given nested-name-specifier from the "from"
/// context into the "to" context.
///
/// \returns The equivalent nested-name-specifier in the "to"
/// context, or the import error.
llvm::Expected<NestedNameSpecifier *> Import(NestedNameSpecifier *FromNNS);
/// Import the given nested-name-specifier-loc from the "from"
/// context into the "to" context.
///
/// \returns The equivalent nested-name-specifier-loc in the "to"
/// context, or the import error.
llvm::Expected<NestedNameSpecifierLoc>
Import(NestedNameSpecifierLoc FromNNS);
/// Import the given template name from the "from" context into the
/// "to" context, or the import error.
llvm::Expected<TemplateName> Import(TemplateName From);
/// Import the given source location from the "from" context into
/// the "to" context.
///
/// \returns The equivalent source location in the "to" context, or the
/// import error.
llvm::Expected<SourceLocation> Import(SourceLocation FromLoc);
/// Import the given source range from the "from" context into
/// the "to" context.
///
/// \returns The equivalent source range in the "to" context, or the import
/// error.
llvm::Expected<SourceRange> Import(SourceRange FromRange);
/// Import the given declaration name from the "from"
/// context into the "to" context.
///
/// \returns The equivalent declaration name in the "to" context, or the
/// import error.
llvm::Expected<DeclarationName> Import(DeclarationName FromName);
/// Import the given identifier from the "from" context
/// into the "to" context.
///
/// \returns The equivalent identifier in the "to" context. Note: It
/// returns nullptr only if the FromId was nullptr.
IdentifierInfo *Import(const IdentifierInfo *FromId);
/// Import the given Objective-C selector from the "from"
/// context into the "to" context.
///
/// \returns The equivalent selector in the "to" context, or the import
/// error.
llvm::Expected<Selector> Import(Selector FromSel);
/// Import the given file ID from the "from" context into the
/// "to" context.
///
/// \returns The equivalent file ID in the source manager of the "to"
/// context, or the import error.
llvm::Expected<FileID> Import(FileID, bool IsBuiltin = false);
/// Import the given C++ constructor initializer from the "from"
/// context into the "to" context.
///
/// \returns The equivalent initializer in the "to" context, or the import
/// error.
llvm::Expected<CXXCtorInitializer *> Import(CXXCtorInitializer *FromInit);
/// Import the given CXXBaseSpecifier from the "from" context into
/// the "to" context.
///
/// \returns The equivalent CXXBaseSpecifier in the source manager of the
/// "to" context, or the import error.
llvm::Expected<CXXBaseSpecifier *> Import(const CXXBaseSpecifier *FromSpec);
/// Import the given APValue from the "from" context into
/// the "to" context.
///
/// \return the equivalent APValue in the "to" context or the import
/// error.
llvm::Expected<APValue> Import(const APValue &FromValue);
/// Import the definition of the given declaration, including all of
/// the declarations it contains.
[[nodiscard]] llvm::Error ImportDefinition(Decl *From);
/// Cope with a name conflict when importing a declaration into the
/// given context.
///
/// This routine is invoked whenever there is a name conflict while
/// importing a declaration. The returned name will become the name of the
/// imported declaration. By default, the returned name is the same as the
/// original name, leaving the conflict unresolve such that name lookup
/// for this name is likely to find an ambiguity later.
///
/// Subclasses may override this routine to resolve the conflict, e.g., by
/// renaming the declaration being imported.
///
/// \param Name the name of the declaration being imported, which conflicts
/// with other declarations.
///
/// \param DC the declaration context (in the "to" AST context) in which
/// the name is being imported.
///
/// \param IDNS the identifier namespace in which the name will be found.
///
/// \param Decls the set of declarations with the same name as the
/// declaration being imported.
///
/// \param NumDecls the number of conflicting declarations in \p Decls.
///
/// \returns the name that the newly-imported declaration should have. Or
/// an error if we can't handle the name conflict.
virtual Expected<DeclarationName>
HandleNameConflict(DeclarationName Name, DeclContext *DC, unsigned IDNS,
NamedDecl **Decls, unsigned NumDecls);
/// Retrieve the context that AST nodes are being imported into.
ASTContext &getToContext() const { return ToContext; }
/// Retrieve the context that AST nodes are being imported from.
ASTContext &getFromContext() const { return FromContext; }
/// Retrieve the file manager that AST nodes are being imported into.
FileManager &getToFileManager() const { return ToFileManager; }
/// Retrieve the file manager that AST nodes are being imported from.
FileManager &getFromFileManager() const { return FromFileManager; }
/// Report a diagnostic in the "to" context.
DiagnosticBuilder ToDiag(SourceLocation Loc, unsigned DiagID);
/// Report a diagnostic in the "from" context.
DiagnosticBuilder FromDiag(SourceLocation Loc, unsigned DiagID);
/// Return the set of declarations that we know are not equivalent.
NonEquivalentDeclSet &getNonEquivalentDecls() { return NonEquivalentDecls; }
/// Called for ObjCInterfaceDecl, ObjCProtocolDecl, and TagDecl.
/// Mark the Decl as complete, filling it in as much as possible.
///
/// \param D A declaration in the "to" context.
virtual void CompleteDecl(Decl* D);
/// Subclasses can override this function to observe all of the \c From ->
/// \c To declaration mappings as they are imported.
virtual void Imported(Decl *From, Decl *To) {}
void RegisterImportedDecl(Decl *FromD, Decl *ToD);
/// Store and assign the imported declaration to its counterpart.
/// It may happen that several decls from the 'from' context are mapped to
/// the same decl in the 'to' context.
Decl *MapImported(Decl *From, Decl *To);
/// Called by StructuralEquivalenceContext. If a RecordDecl is
/// being compared to another RecordDecl as part of import, completing the
/// other RecordDecl may trigger importation of the first RecordDecl. This
/// happens especially for anonymous structs. If the original of the second
/// RecordDecl can be found, we can complete it without the need for
/// importation, eliminating this loop.
virtual Decl *GetOriginalDecl(Decl *To) { return nullptr; }
/// Return if import of the given declaration has failed and if yes
/// the kind of the problem. This gives the first error encountered with
/// the node.
std::optional<ASTImportError> getImportDeclErrorIfAny(Decl *FromD) const;
/// Mark (newly) imported declaration with error.
void setImportDeclError(Decl *From, ASTImportError Error);
/// Determine whether the given types are structurally
/// equivalent.
bool IsStructurallyEquivalent(QualType From, QualType To,
bool Complain = true);
/// Determine the index of a field in its parent record.
/// F should be a field (or indirect field) declaration.
/// \returns The index of the field in its parent context (starting from 0).
/// On error `std::nullopt` is returned (parent context is non-record).
static std::optional<unsigned> getFieldIndex(Decl *F);
};
} // namespace clang
#endif // LLVM_CLANG_AST_ASTIMPORTER_H