=?utf-8?b?R8OhYm9yIFTDs3RodsOhcmk=?= <tigbrc...@protonmail.com>, =?utf-8?b?R8OhYm9yIFTDs3RodsOhcmk=?= <tigbrc...@protonmail.com>, =?utf-8?b?R8OhYm9yIFTDs3RodsOhcmk=?= <tigbrc...@protonmail.com> Message-ID: In-Reply-To: <llvm.org/llvm/llvm-project/pull/89...@github.com>
================ @@ -0,0 +1,125 @@ +//===--- TaggedUnionMemberCountCheck.cpp - clang-tidy ---------------------===// +// +// 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 "TaggedUnionMemberCountCheck.h" +#include "clang/AST/ASTContext.h" +#include "clang/AST/Expr.h" +#include "clang/ASTMatchers/ASTMatchFinder.h" + +#include "clang/AST/PrettyPrinter.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/Support/Casting.h" +#include <limits> + +using namespace clang::ast_matchers; + +namespace clang::tidy::bugprone { + +void TaggedUnionMemberCountCheck::registerMatchers(MatchFinder *Finder) { + Finder->addMatcher( + recordDecl( + allOf(isStruct(), + has(fieldDecl(hasType(recordDecl(isUnion()).bind("union")))), + has(fieldDecl(hasType(enumDecl().bind("tags")))))) + .bind("root"), + this); +} + +static bool hasMultipleUnionsOrEnums(const RecordDecl *rec) { + int tags = 0; + int unions = 0; + for (const FieldDecl *r : rec->fields()) { + TypeSourceInfo *info = r->getTypeSourceInfo(); + QualType qualtype = info->getType(); + const Type *type = qualtype.getTypePtr(); + if (type->isUnionType()) + unions += 1; + else if (type->isEnumeralType()) + tags += 1; + if (tags > 1 || unions > 1) + return true; + } + return false; +} + +static int64_t getNumberOfValidEnumValues(const EnumDecl *ed) { + int64_t maxTagValue = std::numeric_limits<int64_t>::min(); + int64_t minTagValue = std::numeric_limits<int64_t>::max(); + + // Heuristic for counter enum constants. + // + // enum tag_with_counter { + // tag1, + // tag2, + // tag_count, <-- Searching for these enum constants + // }; + // + // The 'ce' prefix is used to abbreviate counterEnum. + // The final tag count is decreased by 1 if and only if: + // 1. The number of counting enum constants = 1, + int ceCount = 0; + // 2. The counting enum constant is the last enum constant that is defined, + int ceFirstIndex = 0; + // 3. The value of the counting enum constant is the largest out of every enum constant. + int64_t ceValue = 0; + + int64_t enumConstantsCount = 0; + for (auto En : llvm::enumerate(ed->enumerators())) { + enumConstantsCount += 1; + + int64_t enumValue = En.value()->getInitVal().getExtValue(); + StringRef enumName = En.value()->getName(); + + if (enumValue > maxTagValue) + maxTagValue = enumValue; + if (enumValue < minTagValue) + minTagValue = enumValue; + + if (enumName.ends_with_insensitive("count")) { + if (ceCount == 0) { + ceFirstIndex = En.index(); + } + ceValue = enumValue; + ceCount += 1; + } + } + + int64_t validValuesCount = maxTagValue - minTagValue + 1; + if (ceCount == 1 && + ceFirstIndex == enumConstantsCount - 1 && + ceValue == maxTagValue) { + validValuesCount -= 1; + } + return validValuesCount; +} + +void TaggedUnionMemberCountCheck::check( + const MatchFinder::MatchResult &Result) { + const auto *root = Result.Nodes.getNodeAs<RecordDecl>("root"); + const auto *unionMatch = Result.Nodes.getNodeAs<RecordDecl>("union"); + const auto *tagMatch = Result.Nodes.getNodeAs<EnumDecl>("tags"); + + if (hasMultipleUnionsOrEnums(root)) + return; + + int64_t unionMemberCount = llvm::range_size(unionMatch->fields()); + int64_t tagCount = getNumberOfValidEnumValues(tagMatch); + + // FIXME: Maybe a emit a note when a counter enum constant was found. + if (unionMemberCount > tagCount) { + diag(root->getLocation(), "Tagged union has more data members than tags! " + "Data members: %0 Tags: %1") + << unionMemberCount << tagCount; + } else if (unionMemberCount < tagCount) { ---------------- tigbr wrote: This diagnostic is emitted only when the `StrictMode` option to `true`, which is disabled by default precisely because of these cases. https://github.com/llvm/llvm-project/pull/89925 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
