diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp index 132245e671c5..9c8de6bf9c8f 100644 --- a/clang/lib/AST/Expr.cpp +++ b/clang/lib/AST/Expr.cpp @@ -837,19 +837,22 @@ bool Expr::isUnusedResultAWarning(SourceLocation &Loc, SourceRange &R1, } case BinaryOperatorClass: { const BinaryOperator *BO = cast(this); - // Consider comma to have side effects if the LHS or RHS does. - if (BO->getOpcode() == BinaryOperator::Comma) { - // ((foo = ), 0) is an idiom for hiding the result (and - // lvalue-ness) of an assignment written in a macro. - if (IntegerLiteral *IE = - dyn_cast(BO->getRHS()->IgnoreParens())) - if (IE->getValue() == 0) - return false; - - return (BO->getLHS()->isUnusedResultAWarning(Loc, R1, R2, Ctx) || - BO->getRHS()->isUnusedResultAWarning(Loc, R1, R2, Ctx)); + switch (BO->getOpcode()) { + default: + break; + // Consider ',', '||', '&&' to have side effects if the LHS or RHS does. + case BinaryOperator::Comma: + // ((foo = ), 0) is an idiom for hiding the result (and + // lvalue-ness) of an assignment written in a macro. + if (IntegerLiteral *IE = + dyn_cast(BO->getRHS()->IgnoreParens())) + if (IE->getValue() == 0) + return false; + case BinaryOperator::LAnd: + case BinaryOperator::LOr: + return (BO->getLHS()->isUnusedResultAWarning(Loc, R1, R2, Ctx) || + BO->getRHS()->isUnusedResultAWarning(Loc, R1, R2, Ctx)); } - if (BO->isAssignmentOp()) return false; Loc = BO->getOperatorLoc(); diff --git a/clang/test/Sema/warn-unused-value.c b/clang/test/Sema/warn-unused-value.c index 2e0fa54effbf..cc8a848bbe21 100644 --- a/clang/test/Sema/warn-unused-value.c +++ b/clang/test/Sema/warn-unused-value.c @@ -51,3 +51,16 @@ void pr4806() { *pi; // expected-warning {{expression result unused}} *pj; } + +// Don't warn about unused '||', '&&' expressions that contain assignments. +int test_logical_foo1(); +int test_logical_foo2(); +int test_logical_foo3(); +int test_logical_bar() { + int x = 0; + (x = test_logical_foo1()) || // no-warning + (x = test_logical_foo2()) || // no-warning + (x = test_logical_foo3()); // no-warning + return x; +} +