[PATCH RFC] build: update bootstrap req to C++14
Jason Merrill
jason@redhat.com
Wed Sep 18 16:18:00 GMT 2024
Tested x86_64-pc-linux-gnu with 5.5.0 bootstrap compiler. Thoughts?
-- 8< --
This implements my proposal to update our bootstrap requirement to C++14.
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.
I'm not sure which GCC version to mention here. C++14 was feature-complete
in GCC 5, and became the default in GCC 6. 5.5.0 builds trunk with no
trouble, but of course trunk also doesn't use any C++14 features. Looking
at bugzilla, I see only one C++14 fix (PR71630) in 5.5, and it doesn't seem
important. In 5.4, PR69995 seems potentially significant, so shall we
recommend 5.4 or later? Or just say 5.5 because people are unlikely to be
stuck on an earlier minor release?
gcc/ChangeLog:
* doc/install.texi (Prerequisites): Update to C++14.
ChangeLog:
* configure.ac: Update requirement to C++14.
* configure: Regenerate.
---
gcc/doc/install.texi | 15 +-
configure.ac | 12 +-
configure | 832 ++++++++++++++++++++++++++++++++++++++++---
3 files changed, 790 insertions(+), 69 deletions(-)
diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
index e339d736969..87add0b6572 100644
--- a/gcc/doc/install.texi
+++ b/gcc/doc/install.texi
@@ -222,17 +222,18 @@ 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.
+@item ISO C++14 compiler
+Necessary to bootstrap GCC. GCC 5.5 or newer has sufficient
+support for used C++14 features.
-Versions of GCC prior to 11 also allow bootstrapping with an ISO C++98
-compiler, and versions of GCC prior to 4.8 also allow bootstrapping with
-an ISO C89 compiler.
+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.
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
+GCC binary (version 5.5 or later) because source code for language
frontends other than C might use GCC extensions.
@item C standard library and headers
diff --git a/configure.ac b/configure.ac
index f61dbe64a94..91635d5368a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1457,16 +1457,16 @@ 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/configure b/configure
index e9583f2ba0c..ab9719c6e93 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
CARGO
GDC
@@ -5914,13 +5914,13 @@ $as_echo "$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'
@@ -5928,9 +5928,9 @@ 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
@@ -6223,26 +6223,146 @@ 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<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::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
@@ -6538,6 +6658,126 @@ 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<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
eval $cachevar=yes
@@ -6564,9 +6804,9 @@ $as_echo "$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
@@ -6862,6 +7102,126 @@ 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<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
eval $cachevar=yes
@@ -6895,41 +7255,41 @@ ac_compile='$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
@@ -7222,26 +7582,146 @@ 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<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::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
@@ -7537,6 +8017,126 @@ 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<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
eval $cachevar=yes
@@ -7563,9 +8163,9 @@ $as_echo "$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
@@ -7861,6 +8461,126 @@ 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<T, T>
+ {
+ static constexpr auto value = true;
+ };
+
+ int
+ test()
+ {
+ auto x = 0;
+ static_assert(is_same<int, decltype(f(x))>::value, "");
+ static_assert(is_same<int&, decltype(g(x))>::value, "");
+ return x;
+ }
+
+ }
+
+} // namespace cxx14
+
+#endif // __cplusplus >= 201402L
+
+
+
_ACEOF
if ac_fn_cxx_try_compile "$LINENO"; then :
eval $cachevar=yes
@@ -7890,28 +8610,28 @@ $as_echo "$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
base-commit: 5c8f9f4d4cebabf85e68c5bdbe2d4ee6646edc7c
--
2.46.0
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