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-rw-r--r--clang-tidy/misc/RedundantExpressionCheck.cpp287
1 files changed, 213 insertions, 74 deletions
diff --git a/clang-tidy/misc/RedundantExpressionCheck.cpp b/clang-tidy/misc/RedundantExpressionCheck.cpp
index 901b54cb..265cb385 100644
--- a/clang-tidy/misc/RedundantExpressionCheck.cpp
+++ b/clang-tidy/misc/RedundantExpressionCheck.cpp
@@ -23,7 +23,6 @@
#include <algorithm>
#include <cassert>
#include <cstdint>
-#include <set>
#include <string>
#include <vector>
@@ -38,8 +37,8 @@ namespace {
using llvm::APSInt;
} // namespace
-static const char KnownBannedMacroNames[] =
- "EAGAIN;EWOULDBLOCK;SIGCLD;SIGCHLD;";
+static const llvm::StringSet<> KnownBannedMacroNames = {"EAGAIN", "EWOULDBLOCK",
+ "SIGCLD", "SIGCHLD"};
static bool incrementWithoutOverflow(const APSInt &Value, APSInt &Result) {
Result = Value;
@@ -99,7 +98,6 @@ static bool areEquivalentExpr(const Expr *Left, const Expr *Right) {
case Stmt::StringLiteralClass:
return cast<StringLiteral>(Left)->getBytes() ==
cast<StringLiteral>(Right)->getBytes();
-
case Stmt::DependentScopeDeclRefExprClass:
if (cast<DependentScopeDeclRefExpr>(Left)->getDeclName() !=
cast<DependentScopeDeclRefExpr>(Right)->getDeclName())
@@ -113,16 +111,14 @@ static bool areEquivalentExpr(const Expr *Left, const Expr *Right) {
case Stmt::MemberExprClass:
return cast<MemberExpr>(Left)->getMemberDecl() ==
cast<MemberExpr>(Right)->getMemberDecl();
-
+ case Stmt::CXXFunctionalCastExprClass:
case Stmt::CStyleCastExprClass:
- return cast<CStyleCastExpr>(Left)->getTypeAsWritten() ==
- cast<CStyleCastExpr>(Right)->getTypeAsWritten();
-
+ return cast<ExplicitCastExpr>(Left)->getTypeAsWritten() ==
+ cast<ExplicitCastExpr>(Right)->getTypeAsWritten();
case Stmt::CallExprClass:
case Stmt::ImplicitCastExprClass:
case Stmt::ArraySubscriptExprClass:
return true;
-
case Stmt::UnaryOperatorClass:
if (cast<UnaryOperator>(Left)->isIncrementDecrementOp())
return false;
@@ -282,7 +278,8 @@ static bool rangeSubsumesRange(BinaryOperatorKind OpcodeLHS,
}
}
-static void canonicalNegateExpr(BinaryOperatorKind &Opcode, APSInt &Value) {
+static void transformSubToCanonicalAddExpr(BinaryOperatorKind &Opcode,
+ APSInt &Value) {
if (Opcode == BO_Sub) {
Opcode = BO_Add;
Value = -Value;
@@ -295,32 +292,77 @@ AST_MATCHER(Expr, isIntegerConstantExpr) {
return Node.isIntegerConstantExpr(Finder->getASTContext());
}
-// Returns a matcher for integer constant expression.
+AST_MATCHER(BinaryOperator, operandsAreEquivalent) {
+ return areEquivalentExpr(Node.getLHS(), Node.getRHS());
+}
+
+AST_MATCHER(ConditionalOperator, expressionsAreEquivalent) {
+ return areEquivalentExpr(Node.getTrueExpr(), Node.getFalseExpr());
+}
+
+AST_MATCHER(CallExpr, parametersAreEquivalent) {
+ return Node.getNumArgs() == 2 &&
+ areEquivalentExpr(Node.getArg(0), Node.getArg(1));
+}
+
+AST_MATCHER(BinaryOperator, binaryOperatorIsInMacro) {
+ return Node.getOperatorLoc().isMacroID();
+}
+
+AST_MATCHER(ConditionalOperator, conditionalOperatorIsInMacro) {
+ return Node.getQuestionLoc().isMacroID() || Node.getColonLoc().isMacroID();
+}
+
+AST_MATCHER(Expr, isMacro) { return Node.getExprLoc().isMacroID(); }
+
+AST_MATCHER_P(Expr, expandedByMacro, llvm::StringSet<>, Names) {
+ const SourceManager &SM = Finder->getASTContext().getSourceManager();
+ const LangOptions &LO = Finder->getASTContext().getLangOpts();
+ SourceLocation Loc = Node.getExprLoc();
+ while (Loc.isMacroID()) {
+ StringRef MacroName = Lexer::getImmediateMacroName(Loc, SM, LO);
+ if (Names.count(MacroName))
+ return true;
+ Loc = SM.getImmediateMacroCallerLoc(Loc);
+ }
+ return false;
+}
+
+// Returns a matcher for integer constant expressions.
static ast_matchers::internal::Matcher<Expr>
matchIntegerConstantExpr(StringRef Id) {
std::string CstId = (Id + "-const").str();
return expr(isIntegerConstantExpr()).bind(CstId);
}
-// Retrieve the integer value matched by 'matchIntegerConstantExpr' with name
-// 'Id' and store it into 'Value'.
+// Retrieves the integer expression matched by 'matchIntegerConstantExpr' with
+// name 'Id' and stores it into 'ConstExpr', the value of the expression is
+// stored into `Value`.
static bool retrieveIntegerConstantExpr(const MatchFinder::MatchResult &Result,
- StringRef Id, APSInt &Value) {
+ StringRef Id, APSInt &Value,
+ const Expr *&ConstExpr) {
std::string CstId = (Id + "-const").str();
- const auto *CstExpr = Result.Nodes.getNodeAs<Expr>(CstId);
- return CstExpr && CstExpr->isIntegerConstantExpr(Value, *Result.Context);
+ ConstExpr = Result.Nodes.getNodeAs<Expr>(CstId);
+ return ConstExpr && ConstExpr->isIntegerConstantExpr(Value, *Result.Context);
+}
+
+// Overloaded `retrieveIntegerConstantExpr` for compatibility.
+static bool retrieveIntegerConstantExpr(const MatchFinder::MatchResult &Result,
+ StringRef Id, APSInt &Value) {
+ const Expr *ConstExpr = nullptr;
+ return retrieveIntegerConstantExpr(Result, Id, Value, ConstExpr);
}
-// Returns a matcher for a symbolic expression (any expression except ingeter
-// constant expression).
+// Returns a matcher for symbolic expressions (matches every expression except
+// ingeter constant expressions).
static ast_matchers::internal::Matcher<Expr> matchSymbolicExpr(StringRef Id) {
std::string SymId = (Id + "-sym").str();
return ignoringParenImpCasts(
expr(unless(isIntegerConstantExpr())).bind(SymId));
}
-// Retrieve the expression matched by 'matchSymbolicExpr' with name 'Id' and
-// store it into 'SymExpr'.
+// Retrieves the expression matched by 'matchSymbolicExpr' with name 'Id' and
+// stores it into 'SymExpr'.
static bool retrieveSymbolicExpr(const MatchFinder::MatchResult &Result,
StringRef Id, const Expr *&SymExpr) {
std::string SymId = (Id + "-sym").str();
@@ -348,7 +390,7 @@ matchBinOpIntegerConstantExpr(StringRef Id) {
return ignoringParenImpCasts(BinOpCstExpr);
}
-// Retrieve sub-expressions matched by 'matchBinOpIntegerConstantExpr' with
+// Retrieves sub-expressions matched by 'matchBinOpIntegerConstantExpr' with
// name 'Id'.
static bool
retrieveBinOpIntegerConstantExpr(const MatchFinder::MatchResult &Result,
@@ -362,7 +404,7 @@ retrieveBinOpIntegerConstantExpr(const MatchFinder::MatchResult &Result,
return false;
}
-// Matches relational expression: 'Expr <op> k' (i.e. x < 2, x != 3, 12 <= x).
+// Matches relational expressions: 'Expr <op> k' (i.e. x < 2, x != 3, 12 <= x).
static ast_matchers::internal::Matcher<Expr>
matchRelationalIntegerConstantExpr(StringRef Id) {
std::string CastId = (Id + "-cast").str();
@@ -388,6 +430,7 @@ matchRelationalIntegerConstantExpr(StringRef Id) {
hasUnaryOperand(anyOf(CastExpr, RelationalExpr)))
.bind(NegateId);
+ // Do not bind to double negation.
const auto NegateNegateRelationalExpr =
unaryOperator(hasOperatorName("!"),
hasUnaryOperand(unaryOperator(
@@ -398,13 +441,12 @@ matchRelationalIntegerConstantExpr(StringRef Id) {
NegateNegateRelationalExpr);
}
-// Retrieve sub-expressions matched by 'matchRelationalIntegerConstantExpr' with
+// Retrieves sub-expressions matched by 'matchRelationalIntegerConstantExpr' with
// name 'Id'.
-static bool
-retrieveRelationalIntegerConstantExpr(const MatchFinder::MatchResult &Result,
- StringRef Id, const Expr *&OperandExpr,
- BinaryOperatorKind &Opcode,
- const Expr *&Symbol, APSInt &Value) {
+static bool retrieveRelationalIntegerConstantExpr(
+ const MatchFinder::MatchResult &Result, StringRef Id,
+ const Expr *&OperandExpr, BinaryOperatorKind &Opcode, const Expr *&Symbol,
+ APSInt &Value, const Expr *&ConstExpr) {
std::string CastId = (Id + "-cast").str();
std::string SwapId = (Id + "-swap").str();
std::string NegateId = (Id + "-negate").str();
@@ -413,8 +455,10 @@ retrieveRelationalIntegerConstantExpr(const MatchFinder::MatchResult &Result,
// Operand received with explicit comparator.
Opcode = Bin->getOpcode();
OperandExpr = Bin;
- if (!retrieveIntegerConstantExpr(Result, Id, Value))
+
+ if (!retrieveIntegerConstantExpr(Result, Id, Value, ConstExpr))
return false;
+
} else if (const auto *Cast = Result.Nodes.getNodeAs<CastExpr>(CastId)) {
// Operand received with implicit comparator (cast).
Opcode = BO_NE;
@@ -431,56 +475,96 @@ retrieveRelationalIntegerConstantExpr(const MatchFinder::MatchResult &Result,
Opcode = BinaryOperator::reverseComparisonOp(Opcode);
if (Result.Nodes.getNodeAs<Expr>(NegateId))
Opcode = BinaryOperator::negateComparisonOp(Opcode);
-
return true;
}
-AST_MATCHER(BinaryOperator, operandsAreEquivalent) {
- return areEquivalentExpr(Node.getLHS(), Node.getRHS());
-}
+// Checks for expressions like (X == 4) && (Y != 9)
+static bool areSidesBinaryConstExpressions(const BinaryOperator *&BinOp, const ASTContext *AstCtx) {
+ const auto *LhsBinOp = dyn_cast<BinaryOperator>(BinOp->getLHS());
+ const auto *RhsBinOp = dyn_cast<BinaryOperator>(BinOp->getRHS());
-AST_MATCHER(ConditionalOperator, expressionsAreEquivalent) {
- return areEquivalentExpr(Node.getTrueExpr(), Node.getFalseExpr());
-}
+ if (!LhsBinOp || !RhsBinOp)
+ return false;
-AST_MATCHER(CallExpr, parametersAreEquivalent) {
- return Node.getNumArgs() == 2 &&
- areEquivalentExpr(Node.getArg(0), Node.getArg(1));
+ if ((LhsBinOp->getLHS()->isIntegerConstantExpr(*AstCtx) ||
+ LhsBinOp->getRHS()->isIntegerConstantExpr(*AstCtx)) &&
+ (RhsBinOp->getLHS()->isIntegerConstantExpr(*AstCtx) ||
+ RhsBinOp->getRHS()->isIntegerConstantExpr(*AstCtx)))
+ return true;
+ return false;
}
-AST_MATCHER(BinaryOperator, binaryOperatorIsInMacro) {
- return Node.getOperatorLoc().isMacroID();
+// Retrieves integer constant subexpressions from binary operator expressions
+// that have two equivalent sides
+// E.g.: from (X == 5) && (X == 5) retrieves 5 and 5.
+static bool retrieveConstExprFromBothSides(const BinaryOperator *&BinOp,
+ BinaryOperatorKind &MainOpcode,
+ BinaryOperatorKind &SideOpcode,
+ const Expr *&LhsConst,
+ const Expr *&RhsConst,
+ const ASTContext *AstCtx) {
+ assert(areSidesBinaryConstExpressions(BinOp, AstCtx) &&
+ "Both sides of binary operator must be constant expressions!");
+
+ MainOpcode = BinOp->getOpcode();
+
+ const auto *BinOpLhs = cast<BinaryOperator>(BinOp->getLHS());
+ const auto *BinOpRhs = cast<BinaryOperator>(BinOp->getRHS());
+
+ LhsConst = BinOpLhs->getLHS()->isIntegerConstantExpr(*AstCtx)
+ ? BinOpLhs->getLHS()
+ : BinOpLhs->getRHS();
+ RhsConst = BinOpRhs->getLHS()->isIntegerConstantExpr(*AstCtx)
+ ? BinOpRhs->getLHS()
+ : BinOpRhs->getRHS();
+
+ if (!LhsConst || !RhsConst)
+ return false;
+
+ assert(BinOpLhs->getOpcode() == BinOpRhs->getOpcode() &&
+ "Sides of the binary operator must be equivalent expressions!");
+
+ SideOpcode = BinOpLhs->getOpcode();
+
+ return true;
}
-AST_MATCHER(ConditionalOperator, conditionalOperatorIsInMacro) {
- return Node.getQuestionLoc().isMacroID() || Node.getColonLoc().isMacroID();
+static bool areExprsFromDifferentMacros(const Expr *LhsExpr,
+ const Expr *RhsExpr,
+ const ASTContext *AstCtx) {
+ if (!LhsExpr || !RhsExpr)
+ return false;
+
+ SourceLocation LhsLoc = LhsExpr->getExprLoc();
+ SourceLocation RhsLoc = RhsExpr->getExprLoc();
+
+ if (!LhsLoc.isMacroID() || !RhsLoc.isMacroID())
+ return false;
+
+ const SourceManager &SM = AstCtx->getSourceManager();
+ const LangOptions &LO = AstCtx->getLangOpts();
+
+ return !(Lexer::getImmediateMacroName(LhsLoc, SM, LO) ==
+ Lexer::getImmediateMacroName(RhsLoc, SM, LO));
}
-AST_MATCHER(Expr, isMacro) { return Node.getExprLoc().isMacroID(); }
+static bool areExprsMacroAndNonMacro(const Expr *&LhsExpr, const Expr *&RhsExpr) {
+ if (!LhsExpr || !RhsExpr)
+ return false;
-AST_MATCHER_P(Expr, expandedByMacro, std::set<std::string>, Names) {
- const SourceManager &SM = Finder->getASTContext().getSourceManager();
- const LangOptions &LO = Finder->getASTContext().getLangOpts();
- SourceLocation Loc = Node.getExprLoc();
- while (Loc.isMacroID()) {
- std::string MacroName = Lexer::getImmediateMacroName(Loc, SM, LO);
- if (Names.find(MacroName) != Names.end())
- return true;
- Loc = SM.getImmediateMacroCallerLoc(Loc);
- }
- return false;
+ SourceLocation LhsLoc = LhsExpr->getExprLoc();
+ SourceLocation RhsLoc = RhsExpr->getExprLoc();
+
+ return LhsLoc.isMacroID() != RhsLoc.isMacroID();
}
void RedundantExpressionCheck::registerMatchers(MatchFinder *Finder) {
const auto AnyLiteralExpr = ignoringParenImpCasts(
anyOf(cxxBoolLiteral(), characterLiteral(), integerLiteral()));
- std::vector<std::string> MacroNames =
- utils::options::parseStringList(KnownBannedMacroNames);
- std::set<std::string> Names(MacroNames.begin(), MacroNames.end());
-
- const auto BannedIntegerLiteral = integerLiteral(expandedByMacro(Names));
+ const auto BannedIntegerLiteral = integerLiteral(expandedByMacro(KnownBannedMacroNames));
+ // Binary with equivalent operands, like (X != 2 && X != 2).
Finder->addMatcher(
binaryOperator(anyOf(hasOperatorName("-"), hasOperatorName("/"),
hasOperatorName("%"), hasOperatorName("|"),
@@ -499,15 +583,16 @@ void RedundantExpressionCheck::registerMatchers(MatchFinder *Finder) {
.bind("binary"),
this);
+ // Conditional (trenary) operator with equivalent operands, like (Y ? X : X).
Finder->addMatcher(
conditionalOperator(expressionsAreEquivalent(),
// Filter noisy false positives.
unless(conditionalOperatorIsInMacro()),
- unless(hasTrueExpression(AnyLiteralExpr)),
unless(isInTemplateInstantiation()))
.bind("cond"),
this);
+ // Overloaded operators with equivalent operands.
Finder->addMatcher(
cxxOperatorCallExpr(
anyOf(
@@ -613,8 +698,8 @@ void RedundantExpressionCheck::checkArithmeticExpr(
!areEquivalentExpr(LhsSymbol, RhsSymbol))
return;
- canonicalNegateExpr(LhsOpcode, LhsValue);
- canonicalNegateExpr(RhsOpcode, RhsValue);
+ transformSubToCanonicalAddExpr(LhsOpcode, LhsValue);
+ transformSubToCanonicalAddExpr(RhsOpcode, RhsValue);
// Check expressions: x + 1 == x + 2 or x + 1 != x + 2.
if (LhsOpcode == BO_Add && RhsOpcode == BO_Add) {
@@ -674,20 +759,23 @@ void RedundantExpressionCheck::checkRelationalExpr(
if (const auto *ComparisonOperator = Result.Nodes.getNodeAs<BinaryOperator>(
"comparisons-of-symbol-and-const")) {
// Matched expressions are: (x <op> k1) <REL> (x <op> k2).
+ // E.g.: (X < 2) && (X > 4)
BinaryOperatorKind Opcode = ComparisonOperator->getOpcode();
const Expr *LhsExpr = nullptr, *RhsExpr = nullptr;
- APSInt LhsValue, RhsValue;
const Expr *LhsSymbol = nullptr, *RhsSymbol = nullptr;
+ const Expr *LhsConst = nullptr, *RhsConst = nullptr;
BinaryOperatorKind LhsOpcode, RhsOpcode;
+ APSInt LhsValue, RhsValue;
+
if (!retrieveRelationalIntegerConstantExpr(
- Result, "lhs", LhsExpr, LhsOpcode, LhsSymbol, LhsValue) ||
+ Result, "lhs", LhsExpr, LhsOpcode, LhsSymbol, LhsValue, LhsConst) ||
!retrieveRelationalIntegerConstantExpr(
- Result, "rhs", RhsExpr, RhsOpcode, RhsSymbol, RhsValue) ||
+ Result, "rhs", RhsExpr, RhsOpcode, RhsSymbol, RhsValue, RhsConst) ||
!areEquivalentExpr(LhsSymbol, RhsSymbol))
return;
- // Bring to a canonical form: smallest constant must be on the left side.
+ // Bring expr to a canonical form: smallest constant must be on the left.
if (APSInt::compareValues(LhsValue, RhsValue) > 0) {
std::swap(LhsExpr, RhsExpr);
std::swap(LhsValue, RhsValue);
@@ -695,10 +783,15 @@ void RedundantExpressionCheck::checkRelationalExpr(
std::swap(LhsOpcode, RhsOpcode);
}
+ // Constants come from two different macros, or one of them is a macro.
+ if (areExprsFromDifferentMacros(LhsConst, RhsConst, Result.Context) ||
+ areExprsMacroAndNonMacro(LhsConst, RhsConst))
+ return;
+
if ((Opcode == BO_LAnd || Opcode == BO_LOr) &&
areEquivalentRanges(LhsOpcode, LhsValue, RhsOpcode, RhsValue)) {
diag(ComparisonOperator->getOperatorLoc(),
- "equivalent expression on both side of logical operator");
+ "equivalent expression on both sides of logical operator");
return;
}
@@ -727,16 +820,62 @@ void RedundantExpressionCheck::checkRelationalExpr(
}
void RedundantExpressionCheck::check(const MatchFinder::MatchResult &Result) {
- if (const auto *BinOp = Result.Nodes.getNodeAs<BinaryOperator>("binary"))
- diag(BinOp->getOperatorLoc(), "both side of operator are equivalent");
- if (const auto *CondOp = Result.Nodes.getNodeAs<ConditionalOperator>("cond"))
- diag(CondOp->getColonLoc(), "'true' and 'false' expression are equivalent");
- if (const auto *Call = Result.Nodes.getNodeAs<CXXOperatorCallExpr>("call"))
+ if (const auto *BinOp = Result.Nodes.getNodeAs<BinaryOperator>("binary")) {
+
+ // If the expression's constants are macros, check whether they are
+ // intentional.
+ if (areSidesBinaryConstExpressions(BinOp, Result.Context)) {
+ const Expr *LhsConst = nullptr, *RhsConst = nullptr;
+ BinaryOperatorKind MainOpcode, SideOpcode;
+
+ if(!retrieveConstExprFromBothSides(BinOp, MainOpcode, SideOpcode, LhsConst,
+ RhsConst, Result.Context))
+ return;
+
+ if (areExprsFromDifferentMacros(LhsConst, RhsConst, Result.Context) ||
+ areExprsMacroAndNonMacro(LhsConst, RhsConst))
+ return;
+ }
+
+ diag(BinOp->getOperatorLoc(), "both sides of operator are equivalent");
+ }
+
+ if (const auto *CondOp =
+ Result.Nodes.getNodeAs<ConditionalOperator>("cond")) {
+ const Expr *TrueExpr = CondOp->getTrueExpr();
+ const Expr *FalseExpr = CondOp->getFalseExpr();
+
+ if (areExprsFromDifferentMacros(TrueExpr, FalseExpr, Result.Context) ||
+ areExprsMacroAndNonMacro(TrueExpr, FalseExpr))
+ return;
+ diag(CondOp->getColonLoc(),
+ "'true' and 'false' expressions are equivalent");
+ }
+
+ if (const auto *Call = Result.Nodes.getNodeAs<CXXOperatorCallExpr>("call")) {
diag(Call->getOperatorLoc(),
- "both side of overloaded operator are equivalent");
+ "both sides of overloaded operator are equivalent");
+ }
+ // Check for the following bound expressions:
+ // - "binop-const-compare-to-sym",
+ // - "binop-const-compare-to-binop-const",
+ // Produced message:
+ // -> "logical expression is always false/true"
checkArithmeticExpr(Result);
+
+ // Check for the following bound expression:
+ // - "binop-const-compare-to-const",
+ // Produced message:
+ // -> "logical expression is always false/true"
checkBitwiseExpr(Result);
+
+ // Check for te following bound expression:
+ // - "comparisons-of-symbol-and-const",
+ // Produced messages:
+ // -> "equivalent expression on both sides of logical operator",
+ // -> "logical expression is always false/true"
+ // -> "expression is redundant"
checkRelationalExpr(Result);
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-02 00:06:25 +0000