From 1b3f84f967daf9a668a5b1f5337d5d3d96e9112b Mon Sep 17 00:00:00 2001
From: Jay Berkenbilt <ejb@ql.org>
Date: Wed, 10 Feb 2021 14:26:54 -0500
Subject: Require C++14 instead of C++11

---
 configure | 144 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
 1 file changed, 132 insertions(+), 12 deletions(-)

(limited to 'configure')

diff --git a/configure b/configure
index e1111989..5a043128 100755
--- a/configure
+++ b/configure
@@ -710,7 +710,7 @@ AS
 EGREP
 GREP
 CPP
-HAVE_CXX11
+HAVE_CXX14
 ac_ct_CXX
 CXXFLAGS
 CXX
@@ -4055,7 +4055,7 @@ ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext $
 ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
-  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'
@@ -4068,9 +4068,9 @@ ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
     if test x$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
@@ -4366,6 +4366,126 @@ 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 && ! defined(_MSC_VER)
+
+#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 $cachevar=yes
@@ -4398,19 +4518,19 @@ ac_compile='$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
 
-- 
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