pw_polyfill: Update to support detecting C++20

- Expand PW_CXX_STANDARD_IS_SUPPORTED() for C++20. - Remove redundant inline. Change-Id: I1f56226d30342bdf9e202522fcb6b66fea2072bc Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/95461 Pigweed-Auto-Submit: Wyatt Hepler <[email protected]> Reviewed-by: Ted Pudlik <[email protected]> Commit-Queue: Auto-Submit <[email protected]>
google · May 31, 2022 · e8f3e42 · e8f3e42
1 parent bb5fb4e
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Showing 4 changed files with 25 additions and 7 deletions.
diff --git a/pw_polyfill/docs.rst b/pw_polyfill/docs.rst
@@ -50,15 +50,26 @@ Header              Feature                           Level of support
 ----------------------------------------------------
 Adapt code to compile with different versions of C++
 ----------------------------------------------------
- ``pw_polyfill`` provides features for adapting to different C++ standards when
- ``pw_polyfill:overrides``'s automatic backporting is insufficient:
+``pw_polyfill`` provides features for adapting to different C++ standards when
+``pw_polyfill:overrides``'s automatic backporting is insufficient.
+
+C++ standard macro
+==================
+``pw_polyfill/standard.h`` provides a macro for checking if a C++ standard is
+supported.
+
+.. c:macro:: PW_CXX_STANDARD_IS_SUPPORTED(standard)
+
+   Evaluates true if the provided C++ standard (98, 11, 14, 17, 20) is supported
+   by the compiler. This is a simpler, cleaner alternative to checking the value
+   of the ``__cplusplus`` macro.
 
-  - ``pw_polyfill/standard.h`` -- provides a macro for checking the C++ standard
-  - ``pw_polyfill/language_feature_macros.h`` -- provides macros for adapting
-    code to work with or without newer language features
 
 Language feature macros
 =======================
+``pw_polyfill/language_feature_macros.h`` provides macros for adapting code to
+work with or without newer language features
+
 ======================  ================================  ========================================  ==========================
 Macro                   Feature                           Description                               Feature test macro
 ======================  ================================  ========================================  ==========================

diff --git a/pw_polyfill/public/pw_polyfill/standard.h b/pw_polyfill/public/pw_polyfill/standard.h
@@ -24,3 +24,4 @@
 #define _PW_CXX_STANDARD_11() 201103L
 #define _PW_CXX_STANDARD_14() 201402L
 #define _PW_CXX_STANDARD_17() 201703L
+#define _PW_CXX_STANDARD_20() 202002L
diff --git a/pw_polyfill/standard_library_public/pw_polyfill/standard_library/cstddef.h b/pw_polyfill/standard_library_public/pw_polyfill/standard_library/cstddef.h
@@ -61,12 +61,12 @@ constexpr byte& operator&=(byte& l, byte r) noexcept { return l = l & r; }
 constexpr byte& operator^=(byte& l, byte r) noexcept { return l = l ^ r; }
 
 template <typename I>
-constexpr inline byte& operator<<=(byte& b, I shift) noexcept {
+constexpr byte& operator<<=(byte& b, I shift) noexcept {
   return b = b << shift;
 }
 
 template <typename I>
-constexpr inline byte& operator>>=(byte& b, I shift) noexcept {
+constexpr byte& operator>>=(byte& b, I shift) noexcept {
   return b = b >> shift;
 }
 

diff --git a/pw_polyfill/test.cc b/pw_polyfill/test.cc
@@ -40,6 +40,12 @@ static_assert(PW_CXX_STANDARD_IS_SUPPORTED(17), "C++17 must be not supported");
 static_assert(!PW_CXX_STANDARD_IS_SUPPORTED(17), "C++17 must be supported");
 #endif  // __cplusplus >= 201703L
 
+#if __cplusplus >= 202002L
+static_assert(PW_CXX_STANDARD_IS_SUPPORTED(20), "C++20 must be supported");
+#else
+static_assert(!PW_CXX_STANDARD_IS_SUPPORTED(20), "C++20 must not be supported");
+#endif  // __cplusplus >= 202002L
+
 TEST(Bit, Endian) {
   if (__BYTE_ORDER__ == __ORDER_BIG_ENDIAN__) {
     EXPECT_EQ(std::endian::native, std::endian::big);