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[clang] SequenceChecker: C++17 sequencing rule for overloaded operators.
In C++17 the operand(s) of an overloaded operator are sequenced as for the corresponding built-in operator when the overloaded operator is called with the operator notation ([over.match.oper]p2). Reported in PR35340. Differential Revision: https://reviews.llvm.org/D81330 Reviewed By: rsmith
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Bruno Ricci
@@ -13031,6 +13031,130 @@ public:
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});
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}
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void VisitCXXOperatorCallExpr(const CXXOperatorCallExpr *CXXOCE) {
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// C++17 [over.match.oper]p2:
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// [...] the operator notation is first transformed to the equivalent
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// function-call notation as summarized in Table 12 (where @ denotes one
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// of the operators covered in the specified subclause). However, the
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// operands are sequenced in the order prescribed for the built-in
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// operator (Clause 8).
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//
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// From the above only overloaded binary operators and overloaded call
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// operators have sequencing rules in C++17 that we need to handle
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// separately.
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if (!SemaRef.getLangOpts().CPlusPlus17 ||
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(CXXOCE->getNumArgs() != 2 && CXXOCE->getOperator() != OO_Call))
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return VisitCallExpr(CXXOCE);
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enum {
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NoSequencing,
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LHSBeforeRHS,
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RHSBeforeLHS,
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LHSBeforeRest
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} SequencingKind;
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switch (CXXOCE->getOperator()) {
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case OO_Equal:
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case OO_PlusEqual:
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case OO_MinusEqual:
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case OO_StarEqual:
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case OO_SlashEqual:
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case OO_PercentEqual:
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case OO_CaretEqual:
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case OO_AmpEqual:
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case OO_PipeEqual:
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case OO_LessLessEqual:
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case OO_GreaterGreaterEqual:
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SequencingKind = RHSBeforeLHS;
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break;
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case OO_LessLess:
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case OO_GreaterGreater:
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case OO_AmpAmp:
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case OO_PipePipe:
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case OO_Comma:
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case OO_ArrowStar:
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case OO_Subscript:
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SequencingKind = LHSBeforeRHS;
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break;
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case OO_Call:
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SequencingKind = LHSBeforeRest;
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break;
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default:
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SequencingKind = NoSequencing;
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break;
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}
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if (SequencingKind == NoSequencing)
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return VisitCallExpr(CXXOCE);
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// This is a call, so all subexpressions are sequenced before the result.
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SequencedSubexpression Sequenced(*this);
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SemaRef.runWithSufficientStackSpace(CXXOCE->getExprLoc(), [&] {
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assert(SemaRef.getLangOpts().CPlusPlus17 &&
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"Should only get there with C++17 and above!");
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assert((CXXOCE->getNumArgs() == 2 || CXXOCE->getOperator() == OO_Call) &&
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"Should only get there with an overloaded binary operator"
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" or an overloaded call operator!");
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if (SequencingKind == LHSBeforeRest) {
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assert(CXXOCE->getOperator() == OO_Call &&
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"We should only have an overloaded call operator here!");
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// This is very similar to VisitCallExpr, except that we only have the
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// C++17 case. The postfix-expression is the first argument of the
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// CXXOperatorCallExpr. The expressions in the expression-list, if any,
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// are in the following arguments.
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//
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// Note that we intentionally do not visit the callee expression since
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// it is just a decayed reference to a function.
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SequenceTree::Seq PostfixExprRegion = Tree.allocate(Region);
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SequenceTree::Seq ArgsRegion = Tree.allocate(Region);
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SequenceTree::Seq OldRegion = Region;
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assert(CXXOCE->getNumArgs() >= 1 &&
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"An overloaded call operator must have at least one argument"
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" for the postfix-expression!");
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const Expr *PostfixExpr = CXXOCE->getArgs()[0];
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llvm::ArrayRef<const Expr *> Args(CXXOCE->getArgs() + 1,
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CXXOCE->getNumArgs() - 1);
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// Visit the postfix-expression first.
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{
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Region = PostfixExprRegion;
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SequencedSubexpression Sequenced(*this);
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Visit(PostfixExpr);
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}
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// Then visit the argument expressions.
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Region = ArgsRegion;
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for (const Expr *Arg : Args)
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Visit(Arg);
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Region = OldRegion;
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Tree.merge(PostfixExprRegion);
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Tree.merge(ArgsRegion);
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} else {
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assert(CXXOCE->getNumArgs() == 2 &&
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"Should only have two arguments here!");
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assert((SequencingKind == LHSBeforeRHS ||
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SequencingKind == RHSBeforeLHS) &&
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"Unexpected sequencing kind!");
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// We do not visit the callee expression since it is just a decayed
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// reference to a function.
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const Expr *E1 = CXXOCE->getArg(0);
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const Expr *E2 = CXXOCE->getArg(1);
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if (SequencingKind == RHSBeforeLHS)
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std::swap(E1, E2);
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return VisitSequencedExpressions(E1, E2);
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}
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});
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}
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void VisitCXXConstructExpr(const CXXConstructExpr *CCE) {
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// This is a call, so all subexpressions are sequenced before the result.
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SequencedSubexpression Sequenced(*this);
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@@ -278,6 +278,174 @@ namespace PR20819 {
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}
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}
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namespace overloaded_operators {
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struct E {
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E &operator=(E &);
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E operator()(E);
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E operator()(E, E);
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E operator[](E);
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} e;
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// Binary operators with unsequenced operands.
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E operator+(E,E);
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E operator-(E,E);
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E operator*(E,E);
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E operator/(E,E);
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E operator%(E,E);
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E operator^(E,E);
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E operator&(E,E);
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E operator|(E,E);
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E operator<(E,E);
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E operator>(E,E);
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E operator==(E,E);
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E operator!=(E,E);
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E operator>=(E,E);
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E operator<=(E,E);
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// Binary operators where the RHS is sequenced before the LHS in C++17.
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E operator+=(E,E);
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E operator-=(E,E);
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E operator*=(E,E);
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E operator/=(E,E);
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E operator%=(E,E);
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E operator^=(E,E);
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E operator&=(E,E);
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E operator|=(E,E);
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E operator<<=(E,E);
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E operator>>=(E,E);
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// Binary operators where the LHS is sequenced before the RHS in C++17.
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E operator<<(E,E);
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E operator>>(E,E);
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E operator&&(E,E);
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E operator||(E,E);
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E operator,(E,E);
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E operator->*(E,E);
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void test() {
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int i = 0;
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// Binary operators with unsequenced operands.
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((void)i++,e) + ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) - ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) * ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) / ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) % ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) ^ ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) & ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) | ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) < ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) > ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) == ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) != ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) <= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) >= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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// Binary operators where the RHS is sequenced before the LHS in C++17.
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((void)i++,e) = ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) += ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) -= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) *= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) /= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) %= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) ^= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) &= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) |= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) <<= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) >>= ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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operator+=(((void)i++,e), ((void)i++,e));
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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// Binary operators where the LHS is sequenced before the RHS in C++17.
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((void)i++,e) << ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) >> ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) || ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) && ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e) , ((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e)->*((void)i++,e);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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operator<<(((void)i++,e), ((void)i++,e));
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e)[((void)i++,e)];
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e)(((void)i++,e));
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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e(((void)i++,e), ((void)i++,e));
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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((void)i++,e).operator()(((void)i++,e));
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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}
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}
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namespace PR35340 {
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struct S {};
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S &operator<<(S &, int);
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void test() {
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S s;
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int i = 0;
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s << i++ << i++;
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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operator<<(operator<<(s, i++), i++);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'i'}}
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// cxx17-warning@-2 {{multiple unsequenced modifications to 'i'}}
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}
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}
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namespace members {
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struct S1 {
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@@ -612,7 +780,6 @@ int Foo<X>::Run() {
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if (static_cast<E>((num = bar.get()) < 5) && static_cast<E>(num < 10)) { }
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// cxx11-warning@-1 {{unsequenced modification and access to 'num'}}
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// cxx17-warning@-2 {{unsequenced modification and access to 'num'}}
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foo(num++, num++);
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// cxx11-warning@-1 {{multiple unsequenced modifications to 'num'}}
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@@ -630,13 +797,11 @@ int Run2() {
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T t = static_cast<T>(0);
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return (t = static_cast<T>(1)) && t;
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// cxx11-warning@-1 {{unsequenced modification and access to 't'}}
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// cxx17-warning@-2 {{unsequenced modification and access to 't'}}
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}
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int y = Run2<bool>();
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int z = Run2<E>();
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// cxx11-note@-1{{in instantiation of function template specialization 'templates::Run2<templates::E>' requested here}}
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// cxx17-note@-2{{in instantiation of function template specialization 'templates::Run2<templates::E>' requested here}}
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template <typename T> int var = sizeof(T);
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void test_var() {
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