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//===--- EnumInitialValueCheck.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 "EnumInitialValueCheck.h"
#include "../utils/LexerUtils.h"
#include "clang/AST/Decl.h"
#include "clang/ASTMatchers/ASTMatchFinder.h"
#include "clang/ASTMatchers/ASTMatchers.h"
#include "clang/Basic/Diagnostic.h"
#include "clang/Basic/SourceLocation.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallString.h"
using namespace clang::ast_matchers;
namespace clang::tidy::readability {
static bool isNoneEnumeratorsInitialized(const EnumDecl &Node) {
return llvm::all_of(Node.enumerators(), [](const EnumConstantDecl *ECD) {
return ECD->getInitExpr() == nullptr;
});
}
static bool isOnlyFirstEnumeratorInitialized(const EnumDecl &Node) {
bool IsFirst = true;
for (const EnumConstantDecl *ECD : Node.enumerators()) {
if ((IsFirst && ECD->getInitExpr() == nullptr) ||
(!IsFirst && ECD->getInitExpr() != nullptr))
return false;
IsFirst = false;
}
return !IsFirst;
}
static bool areAllEnumeratorsInitialized(const EnumDecl &Node) {
return llvm::all_of(Node.enumerators(), [](const EnumConstantDecl *ECD) {
return ECD->getInitExpr() != nullptr;
});
}
/// Check if \p Enumerator is initialized with a (potentially negated) \c
/// IntegerLiteral.
static bool isInitializedByLiteral(const EnumConstantDecl *Enumerator) {
const Expr *const Init = Enumerator->getInitExpr();
if (!Init)
return false;
return Init->isIntegerConstantExpr(Enumerator->getASTContext());
}
static void cleanInitialValue(DiagnosticBuilder &Diag,
const EnumConstantDecl *ECD,
const SourceManager &SM,
const LangOptions &LangOpts) {
const SourceRange InitExprRange = ECD->getInitExpr()->getSourceRange();
if (InitExprRange.isInvalid() || InitExprRange.getBegin().isMacroID() ||
InitExprRange.getEnd().isMacroID())
return;
std::optional<Token> EqualToken = utils::lexer::findNextTokenSkippingComments(
ECD->getLocation(), SM, LangOpts);
if (!EqualToken.has_value() ||
EqualToken.value().getKind() != tok::TokenKind::equal)
return;
const SourceLocation EqualLoc{EqualToken->getLocation()};
if (EqualLoc.isInvalid() || EqualLoc.isMacroID())
return;
Diag << FixItHint::CreateRemoval(EqualLoc)
<< FixItHint::CreateRemoval(InitExprRange);
}
namespace {
AST_MATCHER(EnumDecl, isMacro) {
SourceLocation Loc = Node.getBeginLoc();
return Loc.isMacroID();
}
AST_MATCHER(EnumDecl, hasConsistentInitialValues) {
return isNoneEnumeratorsInitialized(Node) ||
isOnlyFirstEnumeratorInitialized(Node) ||
areAllEnumeratorsInitialized(Node);
}
AST_MATCHER(EnumDecl, hasZeroInitialValueForFirstEnumerator) {
const EnumDecl::enumerator_range Enumerators = Node.enumerators();
if (Enumerators.empty())
return false;
const EnumConstantDecl *ECD = *Enumerators.begin();
return isOnlyFirstEnumeratorInitialized(Node) &&
isInitializedByLiteral(ECD) && ECD->getInitVal().isZero();
}
/// Excludes bitfields because enumerators initialized with the result of a
/// bitwise operator on enumeration values or any other expr that is not a
/// potentially negative integer literal.
/// Enumerations where it is not directly clear if they are used with
/// bitmask, evident when enumerators are only initialized with (potentially
/// negative) integer literals, are ignored. This is also the case when all
/// enumerators are powers of two (e.g., 0, 1, 2).
AST_MATCHER(EnumDecl, hasSequentialInitialValues) {
const EnumDecl::enumerator_range Enumerators = Node.enumerators();
if (Enumerators.empty())
return false;
const EnumConstantDecl *const FirstEnumerator = *Node.enumerator_begin();
llvm::APSInt PrevValue = FirstEnumerator->getInitVal();
if (!isInitializedByLiteral(FirstEnumerator))
return false;
bool AllEnumeratorsArePowersOfTwo = true;
for (const EnumConstantDecl *Enumerator : llvm::drop_begin(Enumerators)) {
const llvm::APSInt NewValue = Enumerator->getInitVal();
if (NewValue != ++PrevValue)
return false;
if (!isInitializedByLiteral(Enumerator))
return false;
PrevValue = NewValue;
AllEnumeratorsArePowersOfTwo &= NewValue.isPowerOf2();
}
return !AllEnumeratorsArePowersOfTwo;
}
std::string getName(const EnumDecl *Decl) {
if (!Decl->getDeclName())
return "<unnamed>";
return Decl->getQualifiedNameAsString();
}
} // namespace
EnumInitialValueCheck::EnumInitialValueCheck(StringRef Name,
ClangTidyContext *Context)
: ClangTidyCheck(Name, Context),
AllowExplicitZeroFirstInitialValue(
Options.get("AllowExplicitZeroFirstInitialValue", true)),
AllowExplicitSequentialInitialValues(
Options.get("AllowExplicitSequentialInitialValues", true)) {}
void EnumInitialValueCheck::storeOptions(ClangTidyOptions::OptionMap &Opts) {
Options.store(Opts, "AllowExplicitZeroFirstInitialValue",
AllowExplicitZeroFirstInitialValue);
Options.store(Opts, "AllowExplicitSequentialInitialValues",
AllowExplicitSequentialInitialValues);
}
void EnumInitialValueCheck::registerMatchers(MatchFinder *Finder) {
Finder->addMatcher(enumDecl(isDefinition(), unless(isMacro()),
unless(hasConsistentInitialValues()))
.bind("inconsistent"),
this);
if (!AllowExplicitZeroFirstInitialValue)
Finder->addMatcher(
enumDecl(isDefinition(), hasZeroInitialValueForFirstEnumerator())
.bind("zero_first"),
this);
if (!AllowExplicitSequentialInitialValues)
Finder->addMatcher(enumDecl(isDefinition(), unless(isMacro()),
hasSequentialInitialValues())
.bind("sequential"),
this);
}
void EnumInitialValueCheck::check(const MatchFinder::MatchResult &Result) {
if (const auto *Enum = Result.Nodes.getNodeAs<EnumDecl>("inconsistent")) {
DiagnosticBuilder Diag =
diag(
Enum->getBeginLoc(),
"initial values in enum '%0' are not consistent, consider explicit "
"initialization of all, none or only the first enumerator")
<< getName(Enum);
for (const EnumConstantDecl *ECD : Enum->enumerators())
if (ECD->getInitExpr() == nullptr) {
const SourceLocation EndLoc = Lexer::getLocForEndOfToken(
ECD->getLocation(), 0, *Result.SourceManager, getLangOpts());
if (EndLoc.isMacroID())
continue;
llvm::SmallString<8> Str{" = "};
ECD->getInitVal().toString(Str);
Diag << FixItHint::CreateInsertion(EndLoc, Str);
}
return;
}
if (const auto *Enum = Result.Nodes.getNodeAs<EnumDecl>("zero_first")) {
const EnumConstantDecl *ECD = *Enum->enumerator_begin();
const SourceLocation Loc = ECD->getLocation();
if (Loc.isInvalid() || Loc.isMacroID())
return;
DiagnosticBuilder Diag = diag(Loc, "zero initial value for the first "
"enumerator in '%0' can be disregarded")
<< getName(Enum);
cleanInitialValue(Diag, ECD, *Result.SourceManager, getLangOpts());
return;
}
if (const auto *Enum = Result.Nodes.getNodeAs<EnumDecl>("sequential")) {
DiagnosticBuilder Diag =
diag(Enum->getBeginLoc(),
"sequential initial value in '%0' can be ignored")
<< getName(Enum);
for (const EnumConstantDecl *ECD : llvm::drop_begin(Enum->enumerators()))
cleanInitialValue(Diag, ECD, *Result.SourceManager, getLangOpts());
return;
}
}
} // namespace clang::tidy::readability
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