From de0af7b7b32fab845bfdd54c965a28efee89468d Mon Sep 17 00:00:00 2001 From: Kittywhiskers Van Gogh <6098974-kittywhiskers@users.noreply.gitlab.com> Date: Fri, 10 Apr 2020 22:17:04 -0700 Subject: [PATCH] Merge #18591: Add C++17 build to Travis https://github.com/bitcoin/bitcoin/pull/18591/commits/7cbfebbf3df0d26f518811e0bfb7abf270c83e37 https://github.com/bitcoin/bitcoin/pull/18591/commits/0fbde488b24f62b4bbbde216647941dcac65c81a https://github.com/bitcoin/bitcoin/pull/18591/commits/7829685e27aae25efb32e07368175c8f664b2218 --- build-aux/m4/ax_cxx_compile_stdcxx.m4 | 455 ++++++++++++++++++++++++-- configure.ac | 16 +- src/span.h | 19 ++ 3 files changed, 452 insertions(+), 38 deletions(-) diff --git a/build-aux/m4/ax_cxx_compile_stdcxx.m4 b/build-aux/m4/ax_cxx_compile_stdcxx.m4 index f147cee3b1..43087b2e68 100644 --- a/build-aux/m4/ax_cxx_compile_stdcxx.m4 +++ b/build-aux/m4/ax_cxx_compile_stdcxx.m4 @@ -1,5 +1,5 @@ # =========================================================================== -# http://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html +# https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html # =========================================================================== # # SYNOPSIS @@ -33,21 +33,23 @@ # Copyright (c) 2014, 2015 Google Inc.; contributed by Alexey Sokolov # Copyright (c) 2015 Paul Norman # Copyright (c) 2015 Moritz Klammler +# Copyright (c) 2016, 2018 Krzesimir Nowak +# Copyright (c) 2019 Enji Cooper # # Copying and distribution of this file, with or without modification, are # permitted in any medium without royalty provided the copyright notice # and this notice are preserved. This file is offered as-is, without any # warranty. -#serial 4 +#serial 11 dnl This macro is based on the code from the AX_CXX_COMPILE_STDCXX_11 macro dnl (serial version number 13). AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl - m4_if([$1], [11], [], - [$1], [14], [], - [$1], [17], [m4_fatal([support for C++17 not yet implemented in AX_CXX_COMPILE_STDCXX])], + m4_if([$1], [11], [ax_cxx_compile_alternatives="11 0x"], + [$1], [14], [ax_cxx_compile_alternatives="14 1y"], + [$1], [17], [ax_cxx_compile_alternatives="17 1z"], [m4_fatal([invalid first argument `$1' to AX_CXX_COMPILE_STDCXX])])dnl m4_if([$2], [], [], [$2], [ext], [], @@ -57,26 +59,13 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl [$3], [mandatory], [ax_cxx_compile_cxx$1_required=true], [$3], [optional], [ax_cxx_compile_cxx$1_required=false], [m4_fatal([invalid third argument `$3' to AX_CXX_COMPILE_STDCXX])]) - m4_if([$4], [], [ax_cxx_compile_cxx$1_try_default=true], - [$4], [default], [ax_cxx_compile_cxx$1_try_default=true], - [$4], [nodefault], [ax_cxx_compile_cxx$1_try_default=false], - [m4_fatal([invalid fourth argument `$4' to AX_CXX_COMPILE_STDCXX])]) AC_LANG_PUSH([C++])dnl ac_success=no - m4_if([$4], [nodefault], [], [dnl - AC_CACHE_CHECK(whether $CXX supports C++$1 features by default, - ax_cv_cxx_compile_cxx$1, - [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], - [ax_cv_cxx_compile_cxx$1=yes], - [ax_cv_cxx_compile_cxx$1=no])]) - if test x$ax_cv_cxx_compile_cxx$1 = xyes; then - ac_success=yes - fi]) - m4_if([$2], [noext], [], [dnl if test x$ac_success = xno; then - for switch in -std=gnu++$1 -std=gnu++0x; do + for alternative in ${ax_cxx_compile_alternatives}; do + switch="-std=gnu++${alternative}" cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, $cachevar, @@ -102,22 +91,27 @@ AC_DEFUN([AX_CXX_COMPILE_STDCXX], [dnl dnl HP's aCC needs +std=c++11 according to: dnl http://h21007.www2.hp.com/portal/download/files/unprot/aCxx/PDF_Release_Notes/769149-001.pdf dnl Cray's crayCC needs "-h std=c++11" - for switch in -std=c++$1 -std=c++0x +std=c++$1 "-h std=c++$1"; do - cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) - AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, - $cachevar, - [ac_save_CXX="$CXX" - CXX="$CXX $switch" - AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], - [eval $cachevar=yes], - [eval $cachevar=no]) - CXX="$ac_save_CXX"]) - if eval test x\$$cachevar = xyes; then - CXX="$CXX $switch" - if test -n "$CXXCPP" ; then - CXXCPP="$CXXCPP $switch" + for alternative in ${ax_cxx_compile_alternatives}; do + for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do + cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx$1_$switch]) + AC_CACHE_CHECK(whether $CXX supports C++$1 features with $switch, + $cachevar, + [ac_save_CXX="$CXX" + CXX="$CXX $switch" + AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXX_COMPILE_STDCXX_testbody_$1])], + [eval $cachevar=yes], + [eval $cachevar=no]) + CXX="$ac_save_CXX"]) + if eval test x\$$cachevar = xyes; then + CXX="$CXX $switch" + if test -n "$CXXCPP" ; then + CXXCPP="$CXXCPP $switch" + fi + ac_success=yes + break fi - ac_success=yes + done + if test x$ac_success = xyes; then break fi done @@ -154,6 +148,11 @@ m4_define([_AX_CXX_COMPILE_STDCXX_testbody_14], _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 ) +m4_define([_AX_CXX_COMPILE_STDCXX_testbody_17], + _AX_CXX_COMPILE_STDCXX_testbody_new_in_11 + _AX_CXX_COMPILE_STDCXX_testbody_new_in_14 + _AX_CXX_COMPILE_STDCXX_testbody_new_in_17 +) dnl Tests for new features in C++11 @@ -191,11 +190,13 @@ namespace cxx11 struct Base { + virtual ~Base() {} virtual void f() {} }; struct Derived : public Base { + virtual ~Derived() override {} virtual void f() override {} }; @@ -524,7 +525,7 @@ namespace cxx14 } - namespace test_digit_seperators + namespace test_digit_separators { constexpr auto ten_million = 100'000'000; @@ -566,3 +567,385 @@ namespace cxx14 #endif // __cplusplus >= 201402L ]]) + + +dnl Tests for new features in C++17 + +m4_define([_AX_CXX_COMPILE_STDCXX_testbody_new_in_17], [[ + +// If the compiler admits that it is not ready for C++17, why torture it? +// Hopefully, this will speed up the test. + +#ifndef __cplusplus + +#error "This is not a C++ compiler" + +#elif __cplusplus < 201703L + +#error "This is not a C++17 compiler" + +#else + +#include +#include +#include + +namespace cxx17 +{ + + namespace test_constexpr_lambdas + { + + constexpr int foo = [](){return 42;}(); + + } + + namespace test::nested_namespace::definitions + { + + } + + namespace test_fold_expression + { + + template + int multiply(Args... args) + { + return (args * ... * 1); + } + + template + bool all(Args... args) + { + return (args && ...); + } + + } + + namespace test_extended_static_assert + { + + static_assert (true); + + } + + namespace test_auto_brace_init_list + { + + auto foo = {5}; + auto bar {5}; + + static_assert(std::is_same, decltype(foo)>::value); + static_assert(std::is_same::value); + } + + namespace test_typename_in_template_template_parameter + { + + template typename X> struct D; + + } + + namespace test_fallthrough_nodiscard_maybe_unused_attributes + { + + int f1() + { + return 42; + } + + [[nodiscard]] int f2() + { + [[maybe_unused]] auto unused = f1(); + + switch (f1()) + { + case 17: + f1(); + [[fallthrough]]; + case 42: + f1(); + } + return f1(); + } + + } + + namespace test_extended_aggregate_initialization + { + + struct base1 + { + int b1, b2 = 42; + }; + + struct base2 + { + base2() { + b3 = 42; + } + int b3; + }; + + struct derived : base1, base2 + { + int d; + }; + + derived d1 {{1, 2}, {}, 4}; // full initialization + derived d2 {{}, {}, 4}; // value-initialized bases + + } + + namespace test_general_range_based_for_loop + { + + struct iter + { + int i; + + int& operator* () + { + return i; + } + + const int& operator* () const + { + return i; + } + + iter& operator++() + { + ++i; + return *this; + } + }; + + struct sentinel + { + int i; + }; + + bool operator== (const iter& i, const sentinel& s) + { + return i.i == s.i; + } + + bool operator!= (const iter& i, const sentinel& s) + { + return !(i == s); + } + + struct range + { + iter begin() const + { + return {0}; + } + + sentinel end() const + { + return {5}; + } + }; + + void f() + { + range r {}; + + for (auto i : r) + { + [[maybe_unused]] auto v = i; + } + } + + } + + namespace test_lambda_capture_asterisk_this_by_value + { + + struct t + { + int i; + int foo() + { + return [*this]() + { + return i; + }(); + } + }; + + } + + namespace test_enum_class_construction + { + + enum class byte : unsigned char + {}; + + byte foo {42}; + + } + + namespace test_constexpr_if + { + + template + int f () + { + if constexpr(cond) + { + return 13; + } + else + { + return 42; + } + } + + } + + namespace test_selection_statement_with_initializer + { + + int f() + { + return 13; + } + + int f2() + { + if (auto i = f(); i > 0) + { + return 3; + } + + switch (auto i = f(); i + 4) + { + case 17: + return 2; + + default: + return 1; + } + } + + } + + namespace test_template_argument_deduction_for_class_templates + { + + template + struct pair + { + pair (T1 p1, T2 p2) + : m1 {p1}, + m2 {p2} + {} + + T1 m1; + T2 m2; + }; + + void f() + { + [[maybe_unused]] auto p = pair{13, 42u}; + } + + } + + namespace test_non_type_auto_template_parameters + { + + template + struct B + {}; + + B<5> b1; + B<'a'> b2; + + } + + namespace test_structured_bindings + { + + int arr[2] = { 1, 2 }; + std::pair pr = { 1, 2 }; + + auto f1() -> int(&)[2] + { + return arr; + } + + auto f2() -> std::pair& + { + return pr; + } + + struct S + { + int x1 : 2; + volatile double y1; + }; + + S f3() + { + return {}; + } + + auto [ x1, y1 ] = f1(); + auto& [ xr1, yr1 ] = f1(); + auto [ x2, y2 ] = f2(); + auto& [ xr2, yr2 ] = f2(); + const auto [ x3, y3 ] = f3(); + + } + + namespace test_exception_spec_type_system + { + + struct Good {}; + struct Bad {}; + + void g1() noexcept; + void g2(); + + template + Bad + f(T*, T*); + + template + Good + f(T1*, T2*); + + static_assert (std::is_same_v); + + } + + namespace test_inline_variables + { + + template void f(T) + {} + + template inline T g(T) + { + return T{}; + } + + template<> inline void f<>(int) + {} + + template<> int g<>(int) + { + return 5; + } + + } + +} // namespace cxx17 + +#endif // __cplusplus < 201703L + +]]) diff --git a/configure.ac b/configure.ac index 5db40fc99b..7ea845e77e 100644 --- a/configure.ac +++ b/configure.ac @@ -60,8 +60,20 @@ case $host in lt_cv_deplibs_check_method="pass_all" ;; esac -dnl Require C++14 compiler (no GNU extensions) -AX_CXX_COMPILE_STDCXX([14], [noext], [mandatory], [nodefault]) + +AC_ARG_ENABLE([c++17], + [AS_HELP_STRING([--enable-c++17], + [enable compilation in c++17 mode (disabled by default)])], + [use_cxx17=$enableval], + [use_cxx17=no]) + +dnl Require C++14 or C++17 compiler (no GNU extensions) +if test "x$use_cxx17" = xyes; then + AX_CXX_COMPILE_STDCXX([17], [noext], [mandatory]) +else + AX_CXX_COMPILE_STDCXX([14], [noext], [mandatory]) +fi + dnl Check if -latomic is required for CHECK_ATOMIC diff --git a/src/span.h b/src/span.h index 77de059fa6..9f118d7a12 100644 --- a/src/span.h +++ b/src/span.h @@ -24,6 +24,23 @@ public: constexpr Span(C* data, std::ptrdiff_t size) noexcept : m_data(data), m_size(size) {} constexpr Span(C* data, C* end) noexcept : m_data(data), m_size(end - data) {} + /** Implicit conversion of spans between compatible types. + * + * Specifically, if a pointer to an array of type O can be implicitly converted to a pointer to an array of type + * C, then permit implicit conversion of Span to Span. This matches the behavior of the corresponding + * C++20 std::span constructor. + * + * For example this means that a Span can be converted into a Span. + */ + template ::value, int>::type = 0> + constexpr Span(const Span& other) noexcept : m_data(other.m_data), m_size(other.m_size) {} + + /** Default copy constructor. */ + constexpr Span(const Span&) noexcept = default; + + /** Default assignment operator. */ + Span& operator=(const Span& other) noexcept = default; + constexpr C* data() const noexcept { return m_data; } constexpr C* begin() const noexcept { return m_data; } constexpr C* end() const noexcept { return m_data + m_size; } @@ -41,6 +58,8 @@ public: friend constexpr bool operator<=(const Span& a, const Span& b) noexcept { return !(b < a); } friend constexpr bool operator>(const Span& a, const Span& b) noexcept { return (b < a); } friend constexpr bool operator>=(const Span& a, const Span& b) noexcept { return !(a < b); } + + template friend class Span; }; /** Create a span to a container exposing data() and size().