| 1 | From d0f929a5db87cb34d03afb0d8e8bfc95b8f786e3 Mon Sep 17 00:00:00 2001 |
| 2 | From: Victor Costan <costan@gmail.com> |
| 3 | Date: Mon, 11 Sep 2017 13:18:27 -0700 |
| 4 | Subject: [PATCH] More conservative check for <string_view> availability. (#4) |
| 5 | |
| 6 | has_include(<string_view>) does not imply that the header can be |
| 7 | included and will work. The assumption fails on MSVC and libc++ [1, 2]. |
| 8 | Conversely, checking that __cplusplus > 201402L is not sufficient on its |
| 9 | own either, as the toolchain on Mac OS 10.12 passes that check but does |
| 10 | not contain a <string_view> header. |
| 11 | |
| 12 | [1] https://crbug.com/759349 |
| 13 | [2] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79433 |
| 14 | --- |
| 15 | include/crc32c/crc32c.h | 10 +++------- |
| 16 | src/crc32c_unittest.cc | 6 ++---- |
| 17 | 2 files changed, 5 insertions(+), 11 deletions(-) |
| 18 | |
| 19 | diff --git a/include/crc32c/crc32c.h b/include/crc32c/crc32c.h |
| 20 | index 9f1973a..8ecab0d 100644 |
| 21 | --- a/include/crc32c/crc32c.h |
| 22 | +++ b/include/crc32c/crc32c.h |
| 23 | @@ -33,22 +33,18 @@ inline uint32_t Crc32c(const std::string& string) { |
| 24 | string.size()); |
| 25 | } |
| 26 | |
| 27 | -#if defined(__has_include) |
| 28 | +#if __cplusplus > 201402L |
| 29 | #if __has_include(<string_view>) |
| 30 | -// Visual Studio provides a <string_view> header even in C++11 mode. When |
| 31 | -// included, the header issues an #error. (C1189) |
| 32 | -#if !defined(_MSC_VER) || __cplusplus >= 201703L |
| 33 | #include <string_view> |
| 34 | |
| 35 | -// Comptues the CRC32C of the bytes in the string_view. |
| 36 | +// Computes the CRC32C of the bytes in the string_view. |
| 37 | inline uint32_t Crc32c(const std::string_view& string_view) { |
| 38 | return Crc32c(reinterpret_cast<const uint8_t*>(string_view.data()), |
| 39 | string_view.size()); |
| 40 | } |
| 41 | |
| 42 | -#endif // !defined(_MSC_VER) || __cplusplus >= 201703L |
| 43 | #endif // __has_include(<string_view>) |
| 44 | -#endif // defined(__has_include) |
| 45 | +#endif // __cplusplus > 201402L |
| 46 | |
| 47 | } // namespace crc32c |
| 48 | |
| 49 | diff --git a/src/crc32c_unittest.cc b/src/crc32c_unittest.cc |
| 50 | index 7a9c765..69babb3 100644 |
| 51 | --- a/src/crc32c_unittest.cc |
| 52 | +++ b/src/crc32c_unittest.cc |
| 53 | @@ -95,9 +95,8 @@ TEST(CRC32CTest, Crc32cStdString) { |
| 54 | EXPECT_EQ(static_cast<uint32_t>(0x113fdb5c), crc32c::Crc32c(buf)); |
| 55 | } |
| 56 | |
| 57 | -#if defined(__has_include) |
| 58 | +#if __cplusplus > 201402L |
| 59 | #if __has_include(<string_view>) |
| 60 | -#if !defined(_MSC_VER) || __cplusplus >= 201703L |
| 61 | |
| 62 | TEST(CRC32CTest, Crc32cStdStringView) { |
| 63 | uint8_t buf[32]; |
| 64 | @@ -118,9 +117,8 @@ TEST(CRC32CTest, Crc32cStdStringView) { |
| 65 | EXPECT_EQ(static_cast<uint32_t>(0x113fdb5c), crc32c::Crc32c(view)); |
| 66 | } |
| 67 | |
| 68 | -#endif // !defined(_MSC_VER) || __cplusplus >= 201703L |
| 69 | #endif // __has_include(<string_view>) |
| 70 | -#endif // defined(__has_include) |
| 71 | +#endif // __cplusplus > 201402L |
| 72 | |
| 73 | #define TESTED_EXTEND Extend |
| 74 | #include "./crc32c_extend_unittests.h" |