https://gcc.gnu.org/g:f3b1216cc6b8f1341ca635f679e7987c454e263d
commit f3b1216cc6b8f1341ca635f679e7987c454e263d
Author: Jason Merrill <ja...@redhat.com>
Date: Tue Sep 17 17:38:35 2024 -0400
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:
* configure.ac: Update requirement to C++14.
* configure: Regenerate.
Diff:
---
configure | 832 +++++++++++++++++++++++++++++++++++++++++++++++----
configure.ac | 12 +-
gcc/doc/install.texi | 27 +-
3 files changed, 795 insertions(+), 76 deletions(-)
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<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
@@ -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<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
@@ -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<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 $cachevar=yes
@@ -6846,41 +7206,41 @@ ac_compile='$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<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
@@ -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<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
@@ -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<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
@@ -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
