Author: Viktoriia Bakalova Date: 2025-01-17T09:10:58+01:00 New Revision: c3ba6f378ef80d750e2278560c6f95a300114412
URL: https://github.com/llvm/llvm-project/commit/c3ba6f378ef80d750e2278560c6f95a300114412 DIFF: https://github.com/llvm/llvm-project/commit/c3ba6f378ef80d750e2278560c6f95a300114412.diff LOG: [Modules] Delay deserialization of preferred_name attribute at r… (#122726) …ecord level. This fixes the incorrect diagnostic emitted when compiling the following snippet ``` // string_view.h template<class _CharT> class basic_string_view; typedef basic_string_view<char> string_view; template<class _CharT> class __attribute__((__preferred_name__(string_view))) basic_string_view { public: basic_string_view() { } }; inline basic_string_view<char> foo() { return basic_string_view<char>(); } // A.cppm module; #include "string_view.h" export module A; // Use.cppm module; #include "string_view.h" export module Use; import A; ``` The diagnostic is ``` string_view.h:11:5: error: 'basic_string_view<char>::basic_string_view' from module 'A.<global>' is not present in definition of 'string_view' provided earlier ``` The underlying issue is that deserialization of the `preferred_name` attribute triggers deserialization of `basic_string_view<char>`, which triggers the deserialization of the `preferred_name` attribute again (since it's attached to the `basic_string_view` template). The deserialization logic is implemented in a way that prevents it from going on a loop in a literal sense (it detects early on that it has already seen the `string_view` typedef when trying to start its deserialization for the second time), but leaves the typedef deserialization in an unfinished state. Subsequently, the `string_view` typedef from the deserialized module cannot be merged with the same typedef from `string_view.h`, resulting in the above diagnostic. This PR resolves the problem by delaying the deserialization of the `preferred_name` attribute until the deserialization of the `basic_string_view` template is completed. As a result of deferring, the deserialization of the `preferred_name` attribute doesn't need to go on a loop since the type of the `string_view` typedef is already known when it's deserialized. Added: Modified: clang/include/clang/AST/Attr.h clang/include/clang/Basic/Attr.td clang/include/clang/Serialization/ASTReader.h clang/include/clang/Serialization/ASTRecordReader.h clang/lib/Serialization/ASTReader.cpp clang/lib/Serialization/ASTReaderDecl.cpp clang/lib/Serialization/ASTWriter.cpp clang/test/Modules/preferred_name.cppm clang/utils/TableGen/ClangAttrEmitter.cpp Removed: ################################################################################ diff --git a/clang/include/clang/AST/Attr.h b/clang/include/clang/AST/Attr.h index 3365ebe4d9012b..bed532a84a1bde 100644 --- a/clang/include/clang/AST/Attr.h +++ b/clang/include/clang/AST/Attr.h @@ -60,6 +60,8 @@ class Attr : public AttributeCommonInfo { unsigned IsLateParsed : 1; LLVM_PREFERRED_TYPE(bool) unsigned InheritEvenIfAlreadyPresent : 1; + LLVM_PREFERRED_TYPE(bool) + unsigned DeferDeserialization : 1; void *operator new(size_t bytes) noexcept { llvm_unreachable("Attrs cannot be allocated with regular 'new'."); @@ -80,10 +82,11 @@ class Attr : public AttributeCommonInfo { protected: Attr(ASTContext &Context, const AttributeCommonInfo &CommonInfo, - attr::Kind AK, bool IsLateParsed) + attr::Kind AK, bool IsLateParsed, bool DeferDeserialization = false) : AttributeCommonInfo(CommonInfo), AttrKind(AK), Inherited(false), IsPackExpansion(false), Implicit(false), IsLateParsed(IsLateParsed), - InheritEvenIfAlreadyPresent(false) {} + InheritEvenIfAlreadyPresent(false), + DeferDeserialization(DeferDeserialization) {} public: attr::Kind getKind() const { return static_cast<attr::Kind>(AttrKind); } @@ -105,6 +108,8 @@ class Attr : public AttributeCommonInfo { void setPackExpansion(bool PE) { IsPackExpansion = PE; } bool isPackExpansion() const { return IsPackExpansion; } + bool shouldDeferDeserialization() const { return DeferDeserialization; } + // Clone this attribute. Attr *clone(ASTContext &C) const; @@ -146,8 +151,9 @@ class InheritableAttr : public Attr { protected: InheritableAttr(ASTContext &Context, const AttributeCommonInfo &CommonInfo, attr::Kind AK, bool IsLateParsed, - bool InheritEvenIfAlreadyPresent) - : Attr(Context, CommonInfo, AK, IsLateParsed) { + bool InheritEvenIfAlreadyPresent, + bool DeferDeserialization = false) + : Attr(Context, CommonInfo, AK, IsLateParsed, DeferDeserialization) { this->InheritEvenIfAlreadyPresent = InheritEvenIfAlreadyPresent; } diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td index 408d3adf370c85..3969dd8af5dfae 100644 --- a/clang/include/clang/Basic/Attr.td +++ b/clang/include/clang/Basic/Attr.td @@ -713,6 +713,12 @@ class Attr { // attribute may be documented under multiple categories, more than one // Documentation entry may be listed. list<Documentation> Documentation; + // Set to true if deserialization of this attribute must be deferred until + // the parent Decl is fully deserialized (during header module file + // deserialization). E.g., this is the case for the preferred_name attribute, + // since its type deserialization depends on its target Decl type. + // (See https://github.com/llvm/llvm-project/issues/56490 for details). + bit DeferDeserialization = 0; } /// Used to define a set of mutually exclusive attributes. @@ -3254,6 +3260,11 @@ def PreferredName : InheritableAttr { let InheritEvenIfAlreadyPresent = 1; let MeaningfulToClassTemplateDefinition = 1; let TemplateDependent = 1; + // Type of this attribute depends on the target Decl type. + // Therefore, its deserialization must be deferred until + // deserialization of the target Decl is complete + // (for header modules). + let DeferDeserialization = 1; } def PreserveMost : DeclOrTypeAttr { diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h index d77bb01c5aa596..c839215dc40778 100644 --- a/clang/include/clang/Serialization/ASTReader.h +++ b/clang/include/clang/Serialization/ASTReader.h @@ -1221,6 +1221,24 @@ class ASTReader /// been completed. std::deque<PendingDeclContextInfo> PendingDeclContextInfos; + /// Deserialization of some attributes must be deferred since they refer + /// to themselves in their type (e.g., preferred_name attribute refers to the + /// typedef that refers back to the template specialization of the template + /// that the attribute is attached to). + /// More attributes that store TypeSourceInfo might be potentially affected, + /// see https://github.com/llvm/llvm-project/issues/56490 for details. + struct DeferredAttribute { + // Index of the deferred attribute in the Record of the TargetedDecl. + uint64_t RecordIdx; + // Decl to attach a deferred attribute to. + Decl *TargetedDecl; + }; + + /// The collection of Decls that have been loaded but some of their attributes + /// have been deferred, paired with the index inside the record pointing + /// at the skipped attribute. + SmallVector<DeferredAttribute> PendingDeferredAttributes; + template <typename DeclTy> using DuplicateObjCDecls = std::pair<DeclTy *, DeclTy *>; @@ -1570,6 +1588,7 @@ class ASTReader void loadPendingDeclChain(Decl *D, uint64_t LocalOffset); void loadObjCCategories(GlobalDeclID ID, ObjCInterfaceDecl *D, unsigned PreviousGeneration = 0); + void loadDeferredAttribute(const DeferredAttribute &DA); RecordLocation getLocalBitOffset(uint64_t GlobalOffset); uint64_t getGlobalBitOffset(ModuleFile &M, uint64_t LocalOffset); diff --git a/clang/include/clang/Serialization/ASTRecordReader.h b/clang/include/clang/Serialization/ASTRecordReader.h index 2561418b78ca7f..a29972fcf73a8d 100644 --- a/clang/include/clang/Serialization/ASTRecordReader.h +++ b/clang/include/clang/Serialization/ASTRecordReader.h @@ -83,6 +83,12 @@ class ASTRecordReader /// Returns the current value in this record, without advancing. uint64_t peekInt() { return Record[Idx]; } + /// Returns the next N values in this record, without advancing. + uint64_t peekInts(unsigned N) { return Record[Idx + N]; } + + /// Skips the current value. + void skipInt() { Idx += 1; } + /// Skips the specified number of values. void skipInts(unsigned N) { Idx += N; } @@ -335,7 +341,12 @@ class ASTRecordReader Attr *readAttr(); /// Reads attributes from the current stream position, advancing Idx. - void readAttributes(AttrVec &Attrs); + /// For some attributes (where type depends on itself recursively), defer + /// reading the attribute until the type has been read. + void readAttributes(AttrVec &Attrs, Decl *D = nullptr); + + /// Reads one attribute from the current stream position, advancing Idx. + Attr *readOrDeferAttrFor(Decl *D); /// Read an BTFTypeTagAttr object. BTFTypeTagAttr *readBTFTypeTagAttr() { diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp index 202227b1955855..d08dc6b1b4d938 100644 --- a/clang/lib/Serialization/ASTReader.cpp +++ b/clang/lib/Serialization/ASTReader.cpp @@ -10180,6 +10180,11 @@ void ASTReader::finishPendingActions() { } PendingDeducedVarTypes.clear(); + // Load the delayed preferred name attributes. + for (unsigned I = 0; I != PendingDeferredAttributes.size(); ++I) + loadDeferredAttribute(PendingDeferredAttributes[I]); + PendingDeferredAttributes.clear(); + // For each decl chain that we wanted to complete while deserializing, mark // it as "still needs to be completed". for (unsigned I = 0; I != PendingIncompleteDeclChains.size(); ++I) { diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp index 1c51a7b5e460f6..06dff02ac61280 100644 --- a/clang/lib/Serialization/ASTReaderDecl.cpp +++ b/clang/lib/Serialization/ASTReaderDecl.cpp @@ -612,7 +612,7 @@ void ASTDeclReader::VisitDecl(Decl *D) { if (HasAttrs) { AttrVec Attrs; - Record.readAttributes(Attrs); + Record.readAttributes(Attrs, D); // Avoid calling setAttrs() directly because it uses Decl::getASTContext() // internally which is unsafe during derialization. D->setAttrsImpl(Attrs, Reader.getContext()); @@ -3093,6 +3093,8 @@ class AttrReader { return Reader.readInt(); } + uint64_t peekInts(unsigned N) { return Reader.peekInts(N); } + bool readBool() { return Reader.readBool(); } SourceRange readSourceRange() { @@ -3123,18 +3125,29 @@ class AttrReader { return Reader.readVersionTuple(); } + void skipInt() { Reader.skipInts(1); } + + void skipInts(unsigned N) { Reader.skipInts(N); } + + unsigned getCurrentIdx() { return Reader.getIdx(); } + OMPTraitInfo *readOMPTraitInfo() { return Reader.readOMPTraitInfo(); } template <typename T> T *readDeclAs() { return Reader.readDeclAs<T>(); } }; } +/// Reads one attribute from the current stream position, advancing Idx. Attr *ASTRecordReader::readAttr() { AttrReader Record(*this); auto V = Record.readInt(); if (!V) return nullptr; + // Read and ignore the skip count, since attribute deserialization is not + // deferred on this pass. + Record.skipInt(); + Attr *New = nullptr; // Kind is stored as a 1-based integer because 0 is used to indicate a null // Attr pointer. @@ -3164,13 +3177,28 @@ Attr *ASTRecordReader::readAttr() { return New; } -/// Reads attributes from the current stream position. -void ASTRecordReader::readAttributes(AttrVec &Attrs) { +/// Reads attributes from the current stream position, advancing Idx. +/// For some attributes (where type depends on itself recursively), defer +/// reading the attribute until the type has been read. +void ASTRecordReader::readAttributes(AttrVec &Attrs, Decl *D) { for (unsigned I = 0, E = readInt(); I != E; ++I) - if (auto *A = readAttr()) + if (auto *A = readOrDeferAttrFor(D)) Attrs.push_back(A); } +/// Reads one attribute from the current stream position, advancing Idx. +/// For some attributes (where type depends on itself recursively), defer +/// reading the attribute until the type has been read. +Attr *ASTRecordReader::readOrDeferAttrFor(Decl *D) { + AttrReader Record(*this); + unsigned SkipCount = Record.peekInts(1); + if (!SkipCount) + return readAttr(); + Reader->PendingDeferredAttributes.push_back({Record.getCurrentIdx(), D}); + Record.skipInts(SkipCount); + return nullptr; +} + //===----------------------------------------------------------------------===// // ASTReader Implementation //===----------------------------------------------------------------------===// @@ -4459,6 +4487,49 @@ void ASTReader::loadPendingDeclChain(Decl *FirstLocal, uint64_t LocalOffset) { ASTDeclReader::attachLatestDecl(CanonDecl, MostRecent); } +void ASTReader::loadDeferredAttribute(const DeferredAttribute &DA) { + Decl *D = DA.TargetedDecl; + ModuleFile *M = getOwningModuleFile(D); + + unsigned LocalDeclIndex = D->getGlobalID().getLocalDeclIndex(); + const DeclOffset &DOffs = M->DeclOffsets[LocalDeclIndex]; + RecordLocation Loc(M, DOffs.getBitOffset(M->DeclsBlockStartOffset)); + + llvm::BitstreamCursor &Cursor = Loc.F->DeclsCursor; + SavedStreamPosition SavedPosition(Cursor); + if (llvm::Error Err = Cursor.JumpToBit(Loc.Offset)) { + Error(std::move(Err)); + } + + Expected<unsigned> MaybeCode = Cursor.ReadCode(); + if (!MaybeCode) { + llvm::report_fatal_error( + Twine("ASTReader::loadPreferredNameAttribute failed reading code: ") + + toString(MaybeCode.takeError())); + } + unsigned Code = MaybeCode.get(); + + ASTRecordReader Record(*this, *Loc.F); + Expected<unsigned> MaybeRecCode = Record.readRecord(Cursor, Code); + if (!MaybeRecCode) { + llvm::report_fatal_error( + Twine( + "ASTReader::loadPreferredNameAttribute failed reading rec code: ") + + toString(MaybeCode.takeError())); + } + unsigned RecCode = MaybeRecCode.get(); + if (RecCode < DECL_TYPEDEF || RecCode > DECL_LAST) { + llvm::report_fatal_error( + Twine("ASTReader::loadPreferredNameAttribute failed reading rec code: " + "expected valid DeclCode") + + toString(MaybeCode.takeError())); + } + + Record.skipInts(DA.RecordIdx); + Attr *A = Record.readAttr(); + getContext().getDeclAttrs(D).push_back(A); +} + namespace { /// Given an ObjC interface, goes through the modules and links to the diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp index 55d3c2bb56f2c5..1c4f5730df312b 100644 --- a/clang/lib/Serialization/ASTWriter.cpp +++ b/clang/lib/Serialization/ASTWriter.cpp @@ -37,6 +37,7 @@ #include "clang/AST/Type.h" #include "clang/AST/TypeLoc.h" #include "clang/AST/TypeLocVisitor.h" +#include "clang/Basic/AttrKinds.h" #include "clang/Basic/Diagnostic.h" #include "clang/Basic/DiagnosticOptions.h" #include "clang/Basic/FileEntry.h" @@ -5067,15 +5068,14 @@ void ASTWriter::WriteModuleFileExtension(Sema &SemaRef, void ASTRecordWriter::AddAttr(const Attr *A) { auto &Record = *this; - // FIXME: Clang can't handle the serialization/deserialization of - // preferred_name properly now. See - // https://github.com/llvm/llvm-project/issues/56490 for example. - if (!A || (isa<PreferredNameAttr>(A) && - Writer->isWritingStdCXXNamedModules())) + if (!A) return Record.push_back(0); Record.push_back(A->getKind() + 1); // FIXME: stable encoding, target attrs + auto SkipIdx = Record.size(); + // Add placeholder for the size of deferred attribute. + Record.push_back(0); Record.AddIdentifierRef(A->getAttrName()); Record.AddIdentifierRef(A->getScopeName()); Record.AddSourceRange(A->getRange()); @@ -5086,6 +5086,12 @@ void ASTRecordWriter::AddAttr(const Attr *A) { Record.push_back(A->isRegularKeywordAttribute()); #include "clang/Serialization/AttrPCHWrite.inc" + + if (A->shouldDeferDeserialization()) { + // Record the actual size of deferred attribute (+ 1 to count the attribute + // kind). + Record[SkipIdx] = Record.size() - SkipIdx + 1; + } } /// Emit the list of attributes to the specified record. diff --git a/clang/test/Modules/preferred_name.cppm b/clang/test/Modules/preferred_name.cppm index 806781a81c5ca7..86ba6ae96db998 100644 --- a/clang/test/Modules/preferred_name.cppm +++ b/clang/test/Modules/preferred_name.cppm @@ -53,10 +53,16 @@ import A; export using ::foo_templ; //--- Use1.cpp -import A; // expected-warning@foo.h:8 {{attribute declaration must precede definition}} -#include "foo.h" // expected-note@foo.h:9 {{previous definition is here}} - +// expected-no-diagnostics +import A; +#include "foo.h" //--- Use2.cpp // expected-no-diagnostics #include "foo.h" import A; + +//--- Use3.cpp +#include "foo.h" +import A; +foo test; +int size = test.size(); // expected-error {{no member named 'size' in 'foo'}} diff --git a/clang/utils/TableGen/ClangAttrEmitter.cpp b/clang/utils/TableGen/ClangAttrEmitter.cpp index cc6a8eaebd44ec..41730eba32ce27 100644 --- a/clang/utils/TableGen/ClangAttrEmitter.cpp +++ b/clang/utils/TableGen/ClangAttrEmitter.cpp @@ -3043,6 +3043,10 @@ static void emitAttributes(const RecordKeeper &Records, raw_ostream &OS, << (R.getValueAsBit("InheritEvenIfAlreadyPresent") ? "true" : "false"); } + if (R.getValueAsBit("DeferDeserialization")) { + OS << ", " + << "/*DeferDeserialization=*/true"; + } OS << ")\n"; for (auto const &ai : Args) { _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
