gdb/ax_cxx_compile_stdcxx.m4: upgrade

This patch upgrades gdb/ax_cxx_compile_stdcxx.m4 to follow changes
available in [1] and regenerates the configure script.

[1] https://www.gnu.org/software/autoconf-archive/ax_cxx_compile_stdcxx.html

Change-Id: I5b16adc65c9e48a13ad65202d58ab7a9d487214e
Approved-By: Tom Tromey <tom@tromey.com>
Approved-By: Pedro Alves <pedro@palves.net>

1 files changed, 34 insertions, 10 deletions

diff --git a/gdb/configure b/gdb/configure
index 5361bf4..408d8a5 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -16501,7 +16501,8 @@ ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ex
 ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
   CXX_DIALECT=""
   ac_success=no
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether $CXX supports C++11 features by default" >&5
+
+      { $as_echo "$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_n "(cached) " >&6
@@ -16517,7 +16518,11 @@ else
 
 #error "This is not a C++ compiler"
 
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
 
 #error "This is not a C++11 compiler"
 
@@ -16542,11 +16547,13 @@ namespace cxx11
 
     struct Base
     {
+      virtual ~Base() {}
       virtual void f() {}
     };
 
     struct Derived : public Base
     {
+      virtual ~Derived() override {}
       virtual void f() override {}
     };
 
@@ -16804,9 +16811,9 @@ 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$ax_cv_cxx_compile_cxx11 = xyes; then
-    ac_success=yes
-  fi
+    if test x$ax_cv_cxx_compile_cxx11 = xyes; then
+      ac_success=yes
+    fi
 
     if test x$ac_success = xno; then
     for alternative in ${ax_cxx_compile_alternatives}; do
@@ -16830,7 +16837,11 @@ else
 
 #error "This is not a C++ compiler"
 
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
 
 #error "This is not a C++11 compiler"
 
@@ -16855,11 +16866,13 @@ namespace cxx11
 
     struct Base
     {
+      virtual ~Base() {}
       virtual void f() {}
     };
 
     struct Derived : public Base
     {
+      virtual ~Derived() override {}
       virtual void f() override {}
     };
 
@@ -17132,9 +17145,14 @@ $as_echo "$ac_res" >&6; }
   fi
 
     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`
+                    for alternative in ${ax_cxx_compile_alternatives}; do
+      for switch in -std=c++${alternative} +std=c++${alternative} "-h std=c++${alternative}" MSVC; do
+        if test x"$switch" = xMSVC; then
+                                        switch=-std:c++${alternative}
+          cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_${switch}_MSVC" | $as_tr_sh`
+        else
+          cachevar=`$as_echo "ax_cv_cxx_compile_cxx11_$switch" | $as_tr_sh`
+        fi
         { $as_echo "$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 $switch... " >&6; }
 if eval \${$cachevar+:} false; then :
@@ -17153,7 +17171,11 @@ else
 
 #error "This is not a C++ compiler"
 
-#elif __cplusplus < 201103L
+// MSVC always sets __cplusplus to 199711L in older versions; newer versions
+// only set it correctly if /Zc:__cplusplus is specified as well as a
+// /std:c++NN switch:
+// https://devblogs.microsoft.com/cppblog/msvc-now-correctly-reports-__cplusplus/
+#elif __cplusplus < 201103L && !defined _MSC_VER
 
 #error "This is not a C++11 compiler"
 
@@ -17178,11 +17200,13 @@ namespace cxx11
 
     struct Base
     {
+      virtual ~Base() {}
       virtual void f() {}
     };
 
     struct Derived : public Base
     {
+      virtual ~Derived() override {}
       virtual void f() override {}
     };