From dc440108b9ecc72bb77574afe1f1eb29ba4774ca Mon Sep 17 00:00:00 2001 From: Jason Merrill Date: Tue, 17 Sep 2024 17:38:35 -0400 Subject: [PATCH] build: update bootstrap req to C++14 We moved to a bootstrap requirement of C++11 in GCC 11, 8 years after support was stable in GCC 4.8. It is now 8 years since C++14 was the default mode in GCC 6 (and 9 years since support was complete in GCC 5), and we have a few bits of optional C++14 code in the compiler, so it seems a good time to update the bootstrap requirement again. The big benefit of the change is the greater constexpr power, but C++14 also added variable templates, generic lambdas, lambda init-capture, binary literals, and numeric literal digit separators. C++14 was feature-complete in GCC 5, and became the default in GCC 6. 5.4.0 bootstraps trunk correctly; trunk stage1 built with 5.3.0 breaks in eh_data_format_name due to PR69995. gcc/ChangeLog: * doc/install.texi (Prerequisites): Update to C++14. ChangeLog: * .github/log_expected_warnings: Update. * configure.ac: Update requirement to C++14. * configure: Regenerate. --- .../glibcxx_ubuntu64b_log_expected_warnings | 2 +- .github/log_expected_warnings | 2 +- configure | 832 ++++++++++++++++-- configure.ac | 12 +- gcc/doc/install.texi | 27 +- 5 files changed, 797 insertions(+), 78 deletions(-) diff --git a/.github/glibcxx_ubuntu64b_log_expected_warnings b/.github/glibcxx_ubuntu64b_log_expected_warnings index b1f400a065dc..214a64aadcae 100644 --- a/.github/glibcxx_ubuntu64b_log_expected_warnings +++ b/.github/glibcxx_ubuntu64b_log_expected_warnings @@ -128,5 +128,5 @@ gengtype-lex.cc:357:15: warning: this statement may fall through [-Wimplicit-fal gengtype-lex.cc:357:15: warning: this statement may fall through [-Wimplicit-fallthrough=] gengtype-lex.cc:357:15: warning: this statement may fall through [-Wimplicit-fallthrough=] gengtype-lex.cc:357:15: warning: this statement may fall through [-Wimplicit-fallthrough=] -install.texi:2231: warning: `.' or `,' must follow @xref, not f +install.texi:2230: warning: `.' or `,' must follow @xref, not f libtool: install: warning: remember to run `libtool --finish /usr/local/libexec/gcc/x86_64-pc-linux-gnu/14.0.1' diff --git a/.github/log_expected_warnings b/.github/log_expected_warnings index 989829d685f4..9829eb2709cf 100644 --- a/.github/log_expected_warnings +++ b/.github/log_expected_warnings @@ -150,5 +150,5 @@ gengtype-lex.cc:357:15: warning: this statement may fall through [-Wimplicit-fal gengtype-lex.cc:357:15: warning: this statement may fall through [-Wimplicit-fallthrough=] gengtype-lex.cc:357:15: warning: this statement may fall through [-Wimplicit-fallthrough=] gengtype-lex.cc:357:15: warning: this statement may fall through [-Wimplicit-fallthrough=] -install.texi:2231: warning: `.' or `,' must follow @xref, not f +install.texi:2230: warning: `.' or `,' must follow @xref, not f libtool: install: warning: remember to run `libtool --finish /usr/local/libexec/gcc/x86_64-pc-linux-gnu/14.0.1' diff --git a/configure b/configure index d3374ba2229a..d18ce9f4d8ad 100755 --- a/configure +++ b/configure @@ -712,8 +712,8 @@ gmplibs PGO_BUILD_LTO_CFLAGS PGO_BUILD_USE_CFLAGS PGO_BUILD_GEN_CFLAGS -HAVE_CXX11_FOR_BUILD -HAVE_CXX11 +HAVE_CXX14_FOR_BUILD +HAVE_CXX14 do_compare GDC GNATMAKE @@ -5865,13 +5865,13 @@ $as_echo "$as_me: WARNING: trying to bootstrap a cross compiler" >&2;} ;; esac -# When bootstrapping with GCC, build stage 1 in C++11 mode to ensure that a -# C++11 compiler can still start the bootstrap. Otherwise, if building GCC, -# require C++11 (or higher). +# When bootstrapping with GCC, build stage 1 in C++14 mode to ensure that a +# C++14 compiler can still start the bootstrap. Otherwise, if building GCC, +# require C++14 (or higher). if test "$enable_bootstrap:$GXX" = "yes:yes"; then - CXX="$CXX -std=c++11" + CXX="$CXX -std=c++14" elif test "$have_compiler" = yes; then - ax_cxx_compile_alternatives="11 0x" ax_cxx_compile_cxx11_required=true + ax_cxx_compile_alternatives="14 1y" ax_cxx_compile_cxx14_required=true ac_ext=cpp ac_cpp='$CXXCPP $CPPFLAGS' ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5' @@ -5879,9 +5879,9 @@ ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ex ac_compiler_gnu=$ac_cv_cxx_compiler_gnu ac_success=no - { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5 -$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; } -if ${ax_cv_cxx_compile_cxx11+:} false; then : + { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++14 features by default" >&5 +$as_echo_n "checking whether $CXX supports C++14 features by default... " >&6; } +if ${ax_cv_cxx_compile_cxx14+:} false; then : $as_echo_n "(cached) " >&6 else cat confdefs.h - <<_ACEOF >conftest.$ac_ext @@ -6174,26 +6174,146 @@ namespace cxx11 + +// If the compiler admits that it is not ready for C++14, why torture it? +// Hopefully, this will speed up the test. + +#ifndef __cplusplus + +#error "This is not a C++ compiler" + +#elif __cplusplus < 201402L + +#error "This is not a C++14 compiler" + +#else + +namespace cxx14 +{ + + namespace test_polymorphic_lambdas + { + + int + test() + { + const auto lambda = [](auto&&... args){ + const auto istiny = [](auto x){ + return (sizeof(x) == 1UL) ? 1 : 0; + }; + const int aretiny[] = { istiny(args)... }; + return aretiny[0]; + }; + return lambda(1, 1L, 1.0f, '1'); + } + + } + + namespace test_binary_literals + { + + constexpr auto ivii = 0b0000000000101010; + static_assert(ivii == 42, "wrong value"); + + } + + namespace test_generalized_constexpr + { + + template < typename CharT > + constexpr unsigned long + strlen_c(const CharT *const s) noexcept + { + auto length = 0UL; + for (auto p = s; *p; ++p) + ++length; + return length; + } + + static_assert(strlen_c("") == 0UL, ""); + static_assert(strlen_c("x") == 1UL, ""); + static_assert(strlen_c("test") == 4UL, ""); + static_assert(strlen_c("another\0test") == 7UL, ""); + + } + + namespace test_lambda_init_capture + { + + int + test() + { + auto x = 0; + const auto lambda1 = [a = x](int b){ return a + b; }; + const auto lambda2 = [a = lambda1(x)](){ return a; }; + return lambda2(); + } + + } + + namespace test_digit_separators + { + + constexpr auto ten_million = 100'000'000; + static_assert(ten_million == 100000000, ""); + + } + + namespace test_return_type_deduction + { + + auto f(int& x) { return x; } + decltype(auto) g(int& x) { return x; } + + template < typename T1, typename T2 > + struct is_same + { + static constexpr auto value = false; + }; + + template < typename T > + struct is_same + { + static constexpr auto value = true; + }; + + int + test() + { + auto x = 0; + static_assert(is_same::value, ""); + static_assert(is_same::value, ""); + return x; + } + + } + +} // namespace cxx14 + +#endif // __cplusplus >= 201402L + + + _ACEOF if ac_fn_cxx_try_compile "$LINENO"; then : - ax_cv_cxx_compile_cxx11=yes + ax_cv_cxx_compile_cxx14=yes else - ax_cv_cxx_compile_cxx11=no + ax_cv_cxx_compile_cxx14=no fi rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext fi -{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11" >&5 -$as_echo "$ax_cv_cxx_compile_cxx11" >&6; } - if test x$ax_cv_cxx_compile_cxx11 = xyes; then +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx14" >&5 +$as_echo "$ax_cv_cxx_compile_cxx14" >&6; } + if test x$ax_cv_cxx_compile_cxx14 = xyes; then ac_success=yes fi if test x$ac_success = xno; then for alternative in ${ax_cxx_compile_alternatives}; do switch="-std=gnu++${alternative}" - cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh` - { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5 -$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; } + cachevar=`$as_echo "ax_cv_cxx_compile_cxx14_$switch" | $as_tr_sh` + { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++14 features with $switch" >&5 +$as_echo_n "checking whether $CXX supports C++14 features with $switch... " >&6; } if eval \${$cachevar+:} false; then : $as_echo_n "(cached) " >&6 else @@ -6489,6 +6609,126 @@ namespace cxx11 + +// If the compiler admits that it is not ready for C++14, why torture it? +// Hopefully, this will speed up the test. + +#ifndef __cplusplus + +#error "This is not a C++ compiler" + +#elif __cplusplus < 201402L + +#error "This is not a C++14 compiler" + +#else + +namespace cxx14 +{ + + namespace test_polymorphic_lambdas + { + + int + test() + { + const auto lambda = [](auto&&... args){ + const auto istiny = [](auto x){ + return (sizeof(x) == 1UL) ? 1 : 0; + }; + const int aretiny[] = { istiny(args)... }; + return aretiny[0]; + }; + return lambda(1, 1L, 1.0f, '1'); + } + + } + + namespace test_binary_literals + { + + constexpr auto ivii = 0b0000000000101010; + static_assert(ivii == 42, "wrong value"); + + } + + namespace test_generalized_constexpr + { + + template < typename CharT > + constexpr unsigned long + strlen_c(const CharT *const s) noexcept + { + auto length = 0UL; + for (auto p = s; *p; ++p) + ++length; + return length; + } + + static_assert(strlen_c("") == 0UL, ""); + static_assert(strlen_c("x") == 1UL, ""); + static_assert(strlen_c("test") == 4UL, ""); + static_assert(strlen_c("another\0test") == 7UL, ""); + + } + + namespace test_lambda_init_capture + { + + int + test() + { + auto x = 0; + const auto lambda1 = [a = x](int b){ return a + b; }; + const auto lambda2 = [a = lambda1(x)](){ return a; }; + return lambda2(); + } + + } + + namespace test_digit_separators + { + + constexpr auto ten_million = 100'000'000; + static_assert(ten_million == 100000000, ""); + + } + + namespace test_return_type_deduction + { + + auto f(int& x) { return x; } + decltype(auto) g(int& x) { return x; } + + template < typename T1, typename T2 > + struct is_same + { + static constexpr auto value = false; + }; + + template < typename T > + struct is_same + { + static constexpr auto value = true; + }; + + int + test() + { + auto x = 0; + static_assert(is_same::value, ""); + static_assert(is_same::value, ""); + return x; + } + + } + +} // namespace cxx14 + +#endif // __cplusplus >= 201402L + + + _ACEOF if ac_fn_cxx_try_compile "$LINENO"; then : eval $cachevar=yes @@ -6515,9 +6755,9 @@ $as_echo "$ac_res" >&6; } if test x$ac_success = xno; then for alternative in ${ax_cxx_compile_alternatives}; do for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do - cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh` - { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5 -$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; } + cachevar=`$as_echo "ax_cv_cxx_compile_cxx14_$switch" | $as_tr_sh` + { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++14 features with $switch" >&5 +$as_echo_n "checking whether $CXX supports C++14 features with $switch... " >&6; } if eval \${$cachevar+:} false; then : $as_echo_n "(cached) " >&6 else @@ -6813,6 +7053,126 @@ namespace cxx11 + +// If the compiler admits that it is not ready for C++14, why torture it? +// Hopefully, this will speed up the test. + +#ifndef __cplusplus + +#error "This is not a C++ compiler" + +#elif __cplusplus < 201402L + +#error "This is not a C++14 compiler" + +#else + +namespace cxx14 +{ + + namespace test_polymorphic_lambdas + { + + int + test() + { + const auto lambda = [](auto&&... args){ + const auto istiny = [](auto x){ + return (sizeof(x) == 1UL) ? 1 : 0; + }; + const int aretiny[] = { istiny(args)... }; + return aretiny[0]; + }; + return lambda(1, 1L, 1.0f, '1'); + } + + } + + namespace test_binary_literals + { + + constexpr auto ivii = 0b0000000000101010; + static_assert(ivii == 42, "wrong value"); + + } + + namespace test_generalized_constexpr + { + + template < typename CharT > + constexpr unsigned long + strlen_c(const CharT *const s) noexcept + { + auto length = 0UL; + for (auto p = s; *p; ++p) + ++length; + return length; + } + + static_assert(strlen_c("") == 0UL, ""); + static_assert(strlen_c("x") == 1UL, ""); + static_assert(strlen_c("test") == 4UL, ""); + static_assert(strlen_c("another\0test") == 7UL, ""); + + } + + namespace test_lambda_init_capture + { + + int + test() + { + auto x = 0; + const auto lambda1 = [a = x](int b){ return a + b; }; + const auto lambda2 = [a = lambda1(x)](){ return a; }; + return lambda2(); + } + + } + + namespace test_digit_separators + { + + constexpr auto ten_million = 100'000'000; + static_assert(ten_million == 100000000, ""); + + } + + namespace test_return_type_deduction + { + + auto f(int& x) { return x; } + decltype(auto) g(int& x) { return x; } + + template < typename T1, typename T2 > + struct is_same + { + static constexpr auto value = false; + }; + + template < typename T > + struct is_same + { + static constexpr auto value = true; + }; + + int + test() + { + auto x = 0; + static_assert(is_same::value, ""); + static_assert(is_same::value, ""); + return x; + } + + } + +} // namespace cxx14 + +#endif // __cplusplus >= 201402L + + + _ACEOF if ac_fn_cxx_try_compile "$LINENO"; then : eval $cachevar=yes @@ -6846,41 +7206,41 @@ ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5' ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5' ac_compiler_gnu=$ac_cv_c_compiler_gnu - if test x$ax_cxx_compile_cxx11_required = xtrue; then + if test x$ax_cxx_compile_cxx14_required = xtrue; then if test x$ac_success = xno; then - as_fn_error $? "*** A compiler with support for C++11 language features is required." "$LINENO" 5 + as_fn_error $? "*** A compiler with support for C++14 language features is required." "$LINENO" 5 fi fi if test x$ac_success = xno; then - HAVE_CXX11=0 - { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++11 support was found" >&5 -$as_echo "$as_me: No compiler with C++11 support was found" >&6;} + HAVE_CXX14=0 + { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++14 support was found" >&5 +$as_echo "$as_me: No compiler with C++14 support was found" >&6;} else - HAVE_CXX11=1 + HAVE_CXX14=1 -$as_echo "#define HAVE_CXX11 1" >>confdefs.h +$as_echo "#define HAVE_CXX14 1" >>confdefs.h fi if test "${build}" != "${host}"; then - ax_cxx_compile_alternatives="11 0x" ax_cxx_compile_cxx11_required=true + ax_cxx_compile_alternatives="14 1y" ax_cxx_compile_cxx14_required=true ac_ext=cpp ac_cpp='$CXXCPP $CPPFLAGS' ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5' ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5' ac_compiler_gnu=$ac_cv_cxx_compiler_gnu ac_success=no - ax_cv_cxx_compile_cxx11_orig_cxx="$CXX" - ax_cv_cxx_compile_cxx11_orig_cxxflags="$CXXFLAGS" - ax_cv_cxx_compile_cxx11_orig_cppflags="$CPPFLAGS" + ax_cv_cxx_compile_cxx14_orig_cxx="$CXX" + ax_cv_cxx_compile_cxx14_orig_cxxflags="$CXXFLAGS" + ax_cv_cxx_compile_cxx14_orig_cppflags="$CPPFLAGS" CXX="$CXX_FOR_BUILD" CXXFLAGS="$CXXFLAGS_FOR_BUILD" CPPFLAGS="$CPPFLAGS_FOR_BUILD" - { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5 -$as_echo_n "checking whether $CXX supports C++11 features by default... " >&6; } -if ${ax_cv_cxx_compile_cxx11_FOR_BUILD+:} false; then : + { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++14 features by default" >&5 +$as_echo_n "checking whether $CXX supports C++14 features by default... " >&6; } +if ${ax_cv_cxx_compile_cxx14_FOR_BUILD+:} false; then : $as_echo_n "(cached) " >&6 else cat confdefs.h - <<_ACEOF >conftest.$ac_ext @@ -7173,26 +7533,146 @@ namespace cxx11 + +// If the compiler admits that it is not ready for C++14, why torture it? +// Hopefully, this will speed up the test. + +#ifndef __cplusplus + +#error "This is not a C++ compiler" + +#elif __cplusplus < 201402L + +#error "This is not a C++14 compiler" + +#else + +namespace cxx14 +{ + + namespace test_polymorphic_lambdas + { + + int + test() + { + const auto lambda = [](auto&&... args){ + const auto istiny = [](auto x){ + return (sizeof(x) == 1UL) ? 1 : 0; + }; + const int aretiny[] = { istiny(args)... }; + return aretiny[0]; + }; + return lambda(1, 1L, 1.0f, '1'); + } + + } + + namespace test_binary_literals + { + + constexpr auto ivii = 0b0000000000101010; + static_assert(ivii == 42, "wrong value"); + + } + + namespace test_generalized_constexpr + { + + template < typename CharT > + constexpr unsigned long + strlen_c(const CharT *const s) noexcept + { + auto length = 0UL; + for (auto p = s; *p; ++p) + ++length; + return length; + } + + static_assert(strlen_c("") == 0UL, ""); + static_assert(strlen_c("x") == 1UL, ""); + static_assert(strlen_c("test") == 4UL, ""); + static_assert(strlen_c("another\0test") == 7UL, ""); + + } + + namespace test_lambda_init_capture + { + + int + test() + { + auto x = 0; + const auto lambda1 = [a = x](int b){ return a + b; }; + const auto lambda2 = [a = lambda1(x)](){ return a; }; + return lambda2(); + } + + } + + namespace test_digit_separators + { + + constexpr auto ten_million = 100'000'000; + static_assert(ten_million == 100000000, ""); + + } + + namespace test_return_type_deduction + { + + auto f(int& x) { return x; } + decltype(auto) g(int& x) { return x; } + + template < typename T1, typename T2 > + struct is_same + { + static constexpr auto value = false; + }; + + template < typename T > + struct is_same + { + static constexpr auto value = true; + }; + + int + test() + { + auto x = 0; + static_assert(is_same::value, ""); + static_assert(is_same::value, ""); + return x; + } + + } + +} // namespace cxx14 + +#endif // __cplusplus >= 201402L + + + _ACEOF if ac_fn_cxx_try_compile "$LINENO"; then : - ax_cv_cxx_compile_cxx11_FOR_BUILD=yes + ax_cv_cxx_compile_cxx14_FOR_BUILD=yes else - ax_cv_cxx_compile_cxx11_FOR_BUILD=no + ax_cv_cxx_compile_cxx14_FOR_BUILD=no fi rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext fi -{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx11_FOR_BUILD" >&5 -$as_echo "$ax_cv_cxx_compile_cxx11_FOR_BUILD" >&6; } - if test x$ax_cv_cxx_compile_cxx11_FOR_BUILD = xyes; then +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ax_cv_cxx_compile_cxx14_FOR_BUILD" >&5 +$as_echo "$ax_cv_cxx_compile_cxx14_FOR_BUILD" >&6; } + if test x$ax_cv_cxx_compile_cxx14_FOR_BUILD = xyes; then ac_success=yes fi if test x$ac_success = xno; then for alternative in ${ax_cxx_compile_alternatives}; do switch="-std=gnu++${alternative}" - cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_FOR_BUILD_$switch" | $as_tr_sh` - { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5 -$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; } + cachevar=`$as_echo "ax_cv_cxx_compile_cxx14_FOR_BUILD_$switch" | $as_tr_sh` + { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++14 features with $switch" >&5 +$as_echo_n "checking whether $CXX supports C++14 features with $switch... " >&6; } if eval \${$cachevar+:} false; then : $as_echo_n "(cached) " >&6 else @@ -7488,6 +7968,126 @@ namespace cxx11 + +// If the compiler admits that it is not ready for C++14, why torture it? +// Hopefully, this will speed up the test. + +#ifndef __cplusplus + +#error "This is not a C++ compiler" + +#elif __cplusplus < 201402L + +#error "This is not a C++14 compiler" + +#else + +namespace cxx14 +{ + + namespace test_polymorphic_lambdas + { + + int + test() + { + const auto lambda = [](auto&&... args){ + const auto istiny = [](auto x){ + return (sizeof(x) == 1UL) ? 1 : 0; + }; + const int aretiny[] = { istiny(args)... }; + return aretiny[0]; + }; + return lambda(1, 1L, 1.0f, '1'); + } + + } + + namespace test_binary_literals + { + + constexpr auto ivii = 0b0000000000101010; + static_assert(ivii == 42, "wrong value"); + + } + + namespace test_generalized_constexpr + { + + template < typename CharT > + constexpr unsigned long + strlen_c(const CharT *const s) noexcept + { + auto length = 0UL; + for (auto p = s; *p; ++p) + ++length; + return length; + } + + static_assert(strlen_c("") == 0UL, ""); + static_assert(strlen_c("x") == 1UL, ""); + static_assert(strlen_c("test") == 4UL, ""); + static_assert(strlen_c("another\0test") == 7UL, ""); + + } + + namespace test_lambda_init_capture + { + + int + test() + { + auto x = 0; + const auto lambda1 = [a = x](int b){ return a + b; }; + const auto lambda2 = [a = lambda1(x)](){ return a; }; + return lambda2(); + } + + } + + namespace test_digit_separators + { + + constexpr auto ten_million = 100'000'000; + static_assert(ten_million == 100000000, ""); + + } + + namespace test_return_type_deduction + { + + auto f(int& x) { return x; } + decltype(auto) g(int& x) { return x; } + + template < typename T1, typename T2 > + struct is_same + { + static constexpr auto value = false; + }; + + template < typename T > + struct is_same + { + static constexpr auto value = true; + }; + + int + test() + { + auto x = 0; + static_assert(is_same::value, ""); + static_assert(is_same::value, ""); + return x; + } + + } + +} // namespace cxx14 + +#endif // __cplusplus >= 201402L + + + _ACEOF if ac_fn_cxx_try_compile "$LINENO"; then : eval $cachevar=yes @@ -7514,9 +8114,9 @@ $as_echo "$ac_res" >&6; } if test x$ac_success = xno; then for alternative in ${ax_cxx_compile_alternatives}; do for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}"; do - cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_FOR_BUILD_$switch" | $as_tr_sh` - { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features with $switch" >&5 -$as_echo_n "checking whether $CXX supports C++11 features with $switch... " >&6; } + cachevar=`$as_echo "ax_cv_cxx_compile_cxx14_FOR_BUILD_$switch" | $as_tr_sh` + { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++14 features with $switch" >&5 +$as_echo_n "checking whether $CXX supports C++14 features with $switch... " >&6; } if eval \${$cachevar+:} false; then : $as_echo_n "(cached) " >&6 else @@ -7812,6 +8412,126 @@ namespace cxx11 + +// If the compiler admits that it is not ready for C++14, why torture it? +// Hopefully, this will speed up the test. + +#ifndef __cplusplus + +#error "This is not a C++ compiler" + +#elif __cplusplus < 201402L + +#error "This is not a C++14 compiler" + +#else + +namespace cxx14 +{ + + namespace test_polymorphic_lambdas + { + + int + test() + { + const auto lambda = [](auto&&... args){ + const auto istiny = [](auto x){ + return (sizeof(x) == 1UL) ? 1 : 0; + }; + const int aretiny[] = { istiny(args)... }; + return aretiny[0]; + }; + return lambda(1, 1L, 1.0f, '1'); + } + + } + + namespace test_binary_literals + { + + constexpr auto ivii = 0b0000000000101010; + static_assert(ivii == 42, "wrong value"); + + } + + namespace test_generalized_constexpr + { + + template < typename CharT > + constexpr unsigned long + strlen_c(const CharT *const s) noexcept + { + auto length = 0UL; + for (auto p = s; *p; ++p) + ++length; + return length; + } + + static_assert(strlen_c("") == 0UL, ""); + static_assert(strlen_c("x") == 1UL, ""); + static_assert(strlen_c("test") == 4UL, ""); + static_assert(strlen_c("another\0test") == 7UL, ""); + + } + + namespace test_lambda_init_capture + { + + int + test() + { + auto x = 0; + const auto lambda1 = [a = x](int b){ return a + b; }; + const auto lambda2 = [a = lambda1(x)](){ return a; }; + return lambda2(); + } + + } + + namespace test_digit_separators + { + + constexpr auto ten_million = 100'000'000; + static_assert(ten_million == 100000000, ""); + + } + + namespace test_return_type_deduction + { + + auto f(int& x) { return x; } + decltype(auto) g(int& x) { return x; } + + template < typename T1, typename T2 > + struct is_same + { + static constexpr auto value = false; + }; + + template < typename T > + struct is_same + { + static constexpr auto value = true; + }; + + int + test() + { + auto x = 0; + static_assert(is_same::value, ""); + static_assert(is_same::value, ""); + return x; + } + + } + +} // namespace cxx14 + +#endif // __cplusplus >= 201402L + + + _ACEOF if ac_fn_cxx_try_compile "$LINENO"; then : eval $cachevar=yes @@ -7841,28 +8561,28 @@ $as_echo "$ac_res" >&6; } CXX_FOR_BUILD="$CXX" CXXFLAGS_FOR_BUILD="$CXXFLAGS" CPPFLAGS_FOR_BUILD="$CPPFLAGS" - CXX="$ax_cv_cxx_compile_cxx11_orig_cxx" - CXXFLAGS="$ax_cv_cxx_compile_cxx11_orig_cxxflags" - CPPFLAGS="$ax_cv_cxx_compile_cxx11_orig_cppflags" + CXX="$ax_cv_cxx_compile_cxx14_orig_cxx" + CXXFLAGS="$ax_cv_cxx_compile_cxx14_orig_cxxflags" + CPPFLAGS="$ax_cv_cxx_compile_cxx14_orig_cppflags" ac_ext=c ac_cpp='$CPP $CPPFLAGS' ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5' ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $LIBS >&5' ac_compiler_gnu=$ac_cv_c_compiler_gnu - if test x$ax_cxx_compile_cxx11_required = xtrue; then + if test x$ax_cxx_compile_cxx14_required = xtrue; then if test x$ac_success = xno; then - as_fn_error $? "*** A compiler with support for C++11 language features is required." "$LINENO" 5 + as_fn_error $? "*** A compiler with support for C++14 language features is required." "$LINENO" 5 fi fi if test x$ac_success = xno; then - HAVE_CXX11_FOR_BUILD=0 - { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++11 support was found" >&5 -$as_echo "$as_me: No compiler with C++11 support was found" >&6;} + HAVE_CXX14_FOR_BUILD=0 + { $as_echo "$as_me:${as_lineno-$LINENO}: No compiler with C++14 support was found" >&5 +$as_echo "$as_me: No compiler with C++14 support was found" >&6;} else - HAVE_CXX11_FOR_BUILD=1 + HAVE_CXX14_FOR_BUILD=1 -$as_echo "#define HAVE_CXX11_FOR_BUILD 1" >>confdefs.h +$as_echo "#define HAVE_CXX14_FOR_BUILD 1" >>confdefs.h fi diff --git a/configure.ac b/configure.ac index 52db66cc48c5..ea988ecd5d50 100644 --- a/configure.ac +++ b/configure.ac @@ -1456,16 +1456,16 @@ case "$have_compiler:$host:$target:$enable_bootstrap" in ;; esac -# When bootstrapping with GCC, build stage 1 in C++11 mode to ensure that a -# C++11 compiler can still start the bootstrap. Otherwise, if building GCC, -# require C++11 (or higher). +# When bootstrapping with GCC, build stage 1 in C++14 mode to ensure that a +# C++14 compiler can still start the bootstrap. Otherwise, if building GCC, +# require C++14 (or higher). if test "$enable_bootstrap:$GXX" = "yes:yes"; then - CXX="$CXX -std=c++11" + CXX="$CXX -std=c++14" elif test "$have_compiler" = yes; then - AX_CXX_COMPILE_STDCXX(11) + AX_CXX_COMPILE_STDCXX(14) if test "${build}" != "${host}"; then - AX_CXX_COMPILE_STDCXX(11, [], [], [_FOR_BUILD]) + AX_CXX_COMPILE_STDCXX(14, [], [], [_FOR_BUILD]) fi fi diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi index 173233096d19..d8414fdbdc94 100644 --- a/gcc/doc/install.texi +++ b/gcc/doc/install.texi @@ -222,20 +222,19 @@ described below. @heading Tools/packages necessary for building GCC @table @asis -@item ISO C++11 compiler -Necessary to bootstrap GCC. GCC 4.8.3 or newer has sufficient -support for used C++11 features, with earlier GCC versions you -might run into implementation bugs. - -Versions of GCC prior to 11 also allow bootstrapping with an ISO C++98 -compiler, versions of GCC prior to 4.8 also allow bootstrapping with a -ISO C89 compiler, and versions of GCC prior to 3.4 also allow -bootstrapping with a traditional (K&R) C compiler. - -To build all languages in a cross-compiler or other configuration where -3-stage bootstrap is not performed, you need to start with an existing -GCC binary (version 4.8.3 or later) because source code for language -frontends other than C might use GCC extensions. +@item ISO C++14 compiler +Necessary to bootstrap GCC. GCC 5.4 or newer has sufficient support +for used C++14 features. + +Versions of GCC prior to 15 allow bootstrapping with an ISO C++11 +compiler, versions prior to 11 allow bootstrapping with an ISO C++98 +compiler, and versions prior to 4.8 allow bootstrapping with an ISO +C89 compiler. + +If you need to build an intermediate version of GCC in order to +bootstrap current GCC, consider GCC 9.5: it can build the current Ada +and D compilers, and was also the version that declared C++17 support +stable. @item C standard library and headers