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martongmartong
committedDec 17, 2018
[ASTImporter] Add importer specific lookup
Summary: There are certain cases when normal C/C++ lookup (localUncachedLookup) does not find AST nodes. E.g.: Example 1: template <class T> struct X { friend void foo(); // this is never found in the DC of the TU. }; Example 2: // The fwd decl to Foo is not found in the lookupPtr of the DC of the // translation unit decl. struct A { struct Foo *p; }; In these cases we create a new node instead of returning with the old one. To fix it we create a new lookup table which holds every node and we are not interested in any C++ specific visibility considerations. Simply, we must know if there is an existing Decl in a given DC. Reviewers: a_sidorin, a.sidorin Subscribers: mgorny, rnkovacs, dkrupp, Szelethus, cfe-commits Differential Revision: https://reviews.llvm.org/D53708 llvm-svn: 349351
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Diff for: ‎clang/include/clang/AST/ASTImporter.h

+22-3
Original file line numberDiff line numberDiff line change
@@ -33,6 +33,7 @@
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namespace clang {
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class ASTContext;
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class ASTImporterLookupTable;
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class CXXBaseSpecifier;
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class CXXCtorInitializer;
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class Decl;
@@ -80,12 +81,21 @@ class Attr;
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/// Imports selected nodes from one AST context into another context,
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/// merging AST nodes where appropriate.
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class ASTImporter {
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friend class ASTNodeImporter;
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public:
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using NonEquivalentDeclSet = llvm::DenseSet<std::pair<Decl *, Decl *>>;
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using ImportedCXXBaseSpecifierMap =
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llvm::DenseMap<const CXXBaseSpecifier *, CXXBaseSpecifier *>;
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private:
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/// Pointer to the import specific lookup table, which may be shared
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/// amongst several ASTImporter objects.
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/// This is an externally managed resource (and should exist during the
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/// lifetime of the ASTImporter object)
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/// If not set then the original C/C++ lookup is used.
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ASTImporterLookupTable *LookupTable = nullptr;
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/// The contexts we're importing to and from.
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ASTContext &ToContext, &FromContext;
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@@ -123,9 +133,13 @@ class Attr;
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/// (which we have already complained about).
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NonEquivalentDeclSet NonEquivalentDecls;
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using FoundDeclsTy = SmallVector<NamedDecl *, 2>;
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FoundDeclsTy findDeclsInToCtx(DeclContext *DC, DeclarationName Name);
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void AddToLookupTable(Decl *ToD);
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public:
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/// Create a new AST importer.
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///
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/// \param ToContext The context we'll be importing into.
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///
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/// \param ToFileManager The file manager we'll be importing into.
@@ -137,9 +151,14 @@ class Attr;
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/// \param MinimalImport If true, the importer will attempt to import
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/// as little as it can, e.g., by importing declarations as forward
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/// declarations that can be completed at a later point.
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///
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/// \param LookupTable The importer specific lookup table which may be
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/// shared amongst several ASTImporter objects.
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/// If not set then the original C/C++ lookup is used.
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ASTImporter(ASTContext &ToContext, FileManager &ToFileManager,
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ASTContext &FromContext, FileManager &FromFileManager,
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bool MinimalImport);
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bool MinimalImport,
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ASTImporterLookupTable *LookupTable = nullptr);
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virtual ~ASTImporter();
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Diff for: ‎clang/include/clang/AST/ASTImporterLookupTable.h

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@@ -0,0 +1,75 @@
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//===- ASTImporterLookupTable.h - ASTImporter specific lookup--*- C++ -*---===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines the ASTImporterLookupTable class which implements a
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// lookup procedure for the import mechanism.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H
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#define LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H
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#include "clang/AST/DeclBase.h" // lookup_result
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#include "clang/AST/DeclarationName.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SetVector.h"
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namespace clang {
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class ASTContext;
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class NamedDecl;
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class DeclContext;
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// There are certain cases when normal C/C++ lookup (localUncachedLookup)
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// does not find AST nodes. E.g.:
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// Example 1:
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// template <class T>
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// struct X {
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// friend void foo(); // this is never found in the DC of the TU.
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// };
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// Example 2:
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// // The fwd decl to Foo is not found in the lookupPtr of the DC of the
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// // translation unit decl.
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// // Here we could find the node by doing a traverse throught the list of
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// // the Decls in the DC, but that would not scale.
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// struct A { struct Foo *p; };
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// This is a severe problem because the importer decides if it has to create a
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// new Decl or not based on the lookup results.
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// To overcome these cases we need an importer specific lookup table which
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// holds every node and we are not interested in any C/C++ specific visibility
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// considerations. Simply, we must know if there is an existing Decl in a
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// given DC. Once we found it then we can handle any visibility related tasks.
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class ASTImporterLookupTable {
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// We store a list of declarations for each name.
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// And we collect these lists for each DeclContext.
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// We could have a flat map with (DeclContext, Name) tuple as key, but a two
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// level map seems easier to handle.
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using DeclList = llvm::SmallSetVector<NamedDecl *, 2>;
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using NameMap = llvm::SmallDenseMap<DeclarationName, DeclList, 4>;
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using DCMap = llvm::DenseMap<DeclContext *, NameMap>;
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void add(DeclContext *DC, NamedDecl *ND);
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void remove(DeclContext *DC, NamedDecl *ND);
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DCMap LookupTable;
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public:
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ASTImporterLookupTable(TranslationUnitDecl &TU);
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void add(NamedDecl *ND);
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void remove(NamedDecl *ND);
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using LookupResult = DeclList;
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LookupResult lookup(DeclContext *DC, DeclarationName Name) const;
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void dump(DeclContext *DC) const;
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void dump() const;
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};
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} // namespace clang
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#endif // LLVM_CLANG_AST_ASTIMPORTERLOOKUPTABLE_H

Diff for: ‎clang/include/clang/CrossTU/CrossTranslationUnit.h

+3
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@@ -15,6 +15,7 @@
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#ifndef LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H
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#define LLVM_CLANG_CROSSTU_CROSSTRANSLATIONUNIT_H
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#include "clang/AST/ASTImporterLookupTable.h"
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#include "clang/Basic/LLVM.h"
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallPtrSet.h"
@@ -152,6 +153,7 @@ class CrossTranslationUnitContext {
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void emitCrossTUDiagnostics(const IndexError &IE);
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private:
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void lazyInitLookupTable(TranslationUnitDecl *ToTU);
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ASTImporter &getOrCreateASTImporter(ASTContext &From);
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const FunctionDecl *findFunctionInDeclContext(const DeclContext *DC,
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StringRef LookupFnName);
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ASTUnitImporterMap;
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CompilerInstance &CI;
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ASTContext &Context;
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std::unique_ptr<ASTImporterLookupTable> LookupTable;
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};
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} // namespace cross_tu

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