================ @@ -0,0 +1,357 @@ +//===----------------------------------------------------------------------===// +// +// 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 +// +//===----------------------------------------------------------------------===// + +#include "MacroConditionCheck.h" +#include "clang/Lex/Lexer.h" +#include "clang/Lex/MacroInfo.h" +#include "clang/Lex/PPCallbacks.h" +#include "clang/Lex/Preprocessor.h" +#include "llvm/ADT/DenseSet.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/ADT/StringSet.h" +#include <memory> +#include <string> +#include <utility> + +namespace clang::tidy::bugprone { + +namespace { +class MacroConditionCallbacks : public PPCallbacks { +public: + MacroConditionCallbacks(MacroConditionCheck *Check, const SourceManager &SM, + Preprocessor &PP) + : Check(Check), SM(SM), PP(PP) {} + + void If(SourceLocation Loc, SourceRange ConditionRange, + ConditionValueKind ConditionValue) override; + void Ifdef(SourceLocation Loc, const Token &MacroNameTok, + const MacroDefinition &MD) override; + void Ifndef(SourceLocation Loc, const Token &MacroNameTok, + const MacroDefinition &MD) override; + void Elif(SourceLocation Loc, SourceRange ConditionRange, + ConditionValueKind ConditionValue, SourceLocation IfLoc) override; + void Elifdef(SourceLocation Loc, const Token &MacroNameTok, + const MacroDefinition &MD) override; + void Elifdef(SourceLocation Loc, SourceRange ConditionRange, + SourceLocation IfLoc) override; + void Elifndef(SourceLocation Loc, const Token &MacroNameTok, + const MacroDefinition &MD) override; + void Elifndef(SourceLocation Loc, SourceRange ConditionRange, + SourceLocation IfLoc) override; + void Else(SourceLocation Loc, SourceLocation IfLoc) override; + void Endif(SourceLocation Loc, SourceLocation IfLoc) override; + +private: + struct MacroReference { + std::string Name; + SourceLocation Loc; + }; + + struct ConditionReferences { + SmallVector<MacroReference, 2> Definition; + SmallVector<MacroReference, 2> Value; + }; + + struct DefinitionCheck { + std::string Name; + SourceLocation DefinitionLoc; + SourceLocation CheckLoc; + bool ValueTested = false; + }; + + struct ConditionalBranch { + SmallVector<DefinitionCheck, 2> Checks; + llvm::StringSet<> DefinitionTests; + }; + + ConditionReferences referencesInCondition(SourceRange ConditionRange) const; + MacroReference referenceFromRange(SourceRange Range, + SourceLocation Loc) const; + bool isIgnoredIdentifier(StringRef Name) const; + void startCondition(const ConditionReferences &References); + void startDefinitionCondition(StringRef Name, SourceLocation Loc); + void nextBranch(const ConditionReferences &References = {}); + void processReferences(const ConditionReferences &References); + void finishBranch(ConditionalBranch &Branch); + void checkDefinitionReference(const MacroReference &Reference, + ConditionalBranch &Branch); + void checkValueReference(const MacroReference &Reference); + bool isDefinitionTestActive(StringRef Name) const; + + SmallVector<ConditionalBranch, 8> Conditions; + llvm::DenseSet<unsigned> DiagnosedDefinitions; + MacroConditionCheck *Check; + const SourceManager &SM; + Preprocessor &PP; +}; + +} // namespace + +static StringRef getTokenName(const Token &Tok) { + if (Tok.is(tok::raw_identifier)) + return Tok.getRawIdentifier(); + if (const IdentifierInfo *Info = Tok.getIdentifierInfo()) + return Info->getName(); + return {}; +} + +MacroConditionCallbacks::ConditionReferences +MacroConditionCallbacks::referencesInCondition( + SourceRange ConditionRange) const { + ConditionReferences References; + const SourceLocation BeginLoc = SM.getExpansionLoc(ConditionRange.getBegin()); + if (BeginLoc.isInvalid()) + return References; + + const std::pair<FileID, unsigned> Decomposed = SM.getDecomposedLoc(BeginLoc); + bool Invalid = false; + StringRef Buffer = SM.getBufferData(Decomposed.first, &Invalid); + if (Invalid || Decomposed.second >= Buffer.size()) + return References; + + size_t End = Decomposed.second; + while (End < Buffer.size()) { + if (Buffer[End] != '\r' && Buffer[End] != '\n') { + ++End; + continue; + } + + const size_t Newline = End; + if (Newline > Decomposed.second && Buffer[Newline - 1] == '\\') { + if (Buffer[End] == '\r' && End + 1 < Buffer.size() && + Buffer[End + 1] == '\n') + ++End; + ++End; + continue; + } + break; + } + + std::string Text = Buffer.slice(Decomposed.second, End).str(); + Lexer Lex(BeginLoc, PP.getLangOpts(), Text.data(), Text.data(), + Text.data() + Text.size()); + SmallVector<Token, 16> Tokens; + Token Tok; + bool AtEnd = false; + do { + AtEnd = Lex.LexFromRawLexer(Tok); + if (Tok.isNot(tok::eof)) + Tokens.push_back(Tok); + } while (!AtEnd); + + for (size_t Index = 0; Index < Tokens.size(); ++Index) { ---------------- zeyi2 wrote:
I ran the check on some real world projects: | Project | Status | Warnings | Errors | Crash | | :--- | :--- | :--- | :--- | :--- | | **abseil-cpp** | Warnings | 418 | 0 | - | | **cppcheck** | Warnings | 40 | 0 | - | | **curl** | Warnings | 1102 | 0 | - | | **doxygen** | Warnings | 331 | 0 | - | | **llvm-project** | Warnings | 204 | 0 | - | | **poco** | Warnings | 989 | 0 | - | | **stdexec** | Warnings | 53 | 0 | - | The majority of these warnings appear to be FPs caused by the same underlying issue: `referencesInCondition()` appears to treat every raw identifier in a preprocessor condition as a macro value reference. For example, it would diagnose the identifiers shown below: ``` #if __has_include(<vector>) // diagnoses `vector` #if __has_builtin(__builtin_trap) // diagnoses `__builtin_trap` #if __has_cpp_attribute(gnu::always_inline) // diagnoses `gnu` and `always_inline` #define ALWAYS_TRUE(x) 1 #if ALWAYS_TRUE(not_a_macro) // diagnoses `not_a_macro` ``` Given the warning volume across these projects, this is not an isolated edge case. It appears to be the primary source of false positives in the current implementation. https://github.com/llvm/llvm-project/pull/210768 _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
