diff --git a/include/llvm/ADT/ArrayRef.h b/include/llvm/ADT/ArrayRef.h index bfe851485f3..41a54c390bc 100644 --- a/include/llvm/ADT/ArrayRef.h +++ b/include/llvm/ADT/ArrayRef.h @@ -203,6 +203,22 @@ namespace llvm { return Data[Index]; } + /// Disallow accidental assignment from a temporary. + /// + /// The declaration here is extra complicated so that "arrayRef = {}" + /// continues to select the move assignment operator. + template + typename std::enable_if::value, ArrayRef>::type & + operator=(U &&Temporary) = delete; + + /// Disallow accidental assignment from a temporary. + /// + /// The declaration here is extra complicated so that "arrayRef = {}" + /// continues to select the move assignment operator. + template + typename std::enable_if::value, ArrayRef>::type & + operator=(std::initializer_list) = delete; + /// @} /// @name Expensive Operations /// @{ diff --git a/unittests/ADT/ArrayRefTest.cpp b/unittests/ADT/ArrayRefTest.cpp index b5b71f06f65..f8d679444b6 100644 --- a/unittests/ADT/ArrayRefTest.cpp +++ b/unittests/ADT/ArrayRefTest.cpp @@ -31,6 +31,26 @@ static_assert( !std::is_convertible, ArrayRef>::value, "Removing volatile"); +// Check that we can't accidentally assign a temporary location to an ArrayRef. +// (Unfortunately we can't make use of the same thing with constructors.) +// +// Disable this check under MSVC; even MSVC 2015 isn't inconsistent between +// std::is_assignable and actually writing such an assignment. +#if !defined(_MSC_VER) +static_assert( + !std::is_assignable, int *>::value, + "Assigning from single prvalue element"); +static_assert( + !std::is_assignable, int * &&>::value, + "Assigning from single xvalue element"); +static_assert( + std::is_assignable, int * &>::value, + "Assigning from single lvalue element"); +static_assert( + !std::is_assignable, std::initializer_list>::value, + "Assigning from an initializer list"); +#endif + namespace { TEST(ArrayRefTest, AllocatorCopy) { @@ -146,6 +166,14 @@ TEST(ArrayRefTest, InitializerList) { ArgTest12({1, 2}); } +TEST(ArrayRefTest, EmptyInitializerList) { + ArrayRef A = {}; + EXPECT_TRUE(A.empty()); + + A = {}; + EXPECT_TRUE(A.empty()); +} + // Test that makeArrayRef works on ArrayRef (no-op) TEST(ArrayRefTest, makeArrayRef) { static const int A1[] = {1, 2, 3, 4, 5, 6, 7, 8};