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[tor-commits] [stegotorus/master] Add autoconf probes for C++11 and method deletion; use the latter in crypt.h.



commit 623c1912051d4fccec3be22e98e53d9f680f6f8a
Author: Zack Weinberg <zackw@xxxxxxxxx>
Date:   Mon Mar 5 16:49:13 2012 -0800

    Add autoconf probes for C++11 and method deletion; use the latter in crypt.h.
---
 configure.ac             |    3 +
 m4/cxx_delete_method.m4  |   76 ++++++++++++++++++++++++++++++++
 m4/cxxflags_stdcxx_11.m4 |  107 ++++++++++++++++++++++++++++++++++++++++++++++
 m4/winsock.m4            |   10 ++--
 src/crypt.h              |   12 +++---
 5 files changed, 197 insertions(+), 11 deletions(-)

diff --git a/configure.ac b/configure.ac
index ca76a7a..d491479 100644
--- a/configure.ac
+++ b/configure.ac
@@ -65,6 +65,9 @@ LIBS="$LIBS $ws32_LIBS"
 
 AC_CHECK_HEADERS([execinfo.h],,, [AC_INCLUDES_DEFAULT()])
 
+AX_CXXFLAGS_STDCXX_11([ext])
+AX_CXX_DELETE_METHOD
+
 ### Output ###
 
 AC_CONFIG_FILES([Makefile])
diff --git a/m4/cxx_delete_method.m4 b/m4/cxx_delete_method.m4
new file mode 100644
index 0000000..2f7decf
--- /dev/null
+++ b/m4/cxx_delete_method.m4
@@ -0,0 +1,76 @@
+# ============================================================================
+#  http://www.gnu.org/software/autoconf-archive/ax_cxx_delete_method.m4
+# ============================================================================
+#
+# SYNOPSIS
+#
+#   AX_CXX_DELETE_METHOD
+#
+# DESCRIPTION
+#
+#   Check whether the C++11 '= delete' syntax, for suppressing undesired
+#   implicit methods, is supported.  If it is, the macro DELETE_METHOD is
+#   defined to '= delete'; otherwise it is defined to nothing.  Thus, you
+#   can write
+#
+#     class foo {
+#       ...
+#     private:
+#       foo(foo const&) DELETE_METHOD;
+#     };
+#
+#   to delete the 'foo' copy constructor or fall back to the idiom of
+#   a private undefined method if the compiler doesn't support this.
+#
+#   Does not test '= delete' on a template specialization.
+#   Does not ensure that the compiler is in C++11 mode.
+#
+# LICENSE
+#
+#   Copyright (c) 2012 Zack Weinberg <zackw@xxxxxxxxx>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+AC_DEFUN([AX_CXX_DELETE_METHOD], [dnl
+  AC_LANG_ASSERT([C++])
+  # This compilation should succeed...
+  AC_CACHE_CHECK(whether $CXX accepts method deletion,
+                 ax_cv_cxx_delete_method_syntax, [
+    AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+      struct foo {
+        foo(double);
+        foo(int) = delete;
+      };
+      extern void t(foo const&);
+      void tt(double n) { t(n); }
+   ]])],
+      [ax_cv_cxx_delete_method_syntax=yes],
+      [ax_cv_cxx_delete_method_syntax=no])])
+  # ... and this one should fail.
+  AC_CACHE_CHECK(whether $CXX enforces method deletion,
+                 ax_cv_cxx_delete_method_enforced, [
+    AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+      struct foo {
+        foo(double);
+        foo(int) = delete;
+      };
+      extern void t(foo const&);
+      void tt(int n) { t(n); }
+   ]])],
+      [ax_cv_cxx_delete_method_enforced=no],
+      [ax_cv_cxx_delete_method_enforced=yes])])
+  if test $ax_cv_cxx_delete_method_syntax = yes &&
+     test $ax_cv_cxx_delete_method_enforced = yes
+  then
+     AC_DEFINE([DELETE_METHOD], [= delete],
+               [Define as `= delete' if your compiler supports C++11 method
+                deletion, as nothing otherwise.])
+  else
+     AC_DEFINE([DELETE_METHOD], [],
+               [Define as `= delete' if your compiler supports C++11 method
+                deletion, as nothing otherwise.])
+  fi
+])
diff --git a/m4/cxxflags_stdcxx_11.m4 b/m4/cxxflags_stdcxx_11.m4
new file mode 100644
index 0000000..1c5c0f2
--- /dev/null
+++ b/m4/cxxflags_stdcxx_11.m4
@@ -0,0 +1,107 @@
+# ============================================================================
+#  http://www.gnu.org/software/autoconf-archive/ax_cxxflags_stdcxx_11.html
+# ============================================================================
+#
+# SYNOPSIS
+#
+#   AX_CXXFLAGS_STDCXX_11([ext|noext])
+#
+# DESCRIPTION
+#
+#   Check for baseline language coverage in the compiler for the C++11
+#   standard; if necessary, add switches to CXXFLAGS to enable support.
+#   Errors out if no mode that supports C++11 baseline syntax can be found.
+#   The argument, if specified, indicates whether you insist on an extended
+#   mode (e.g. -std=gnu++11) or a strict conformance mode (e.g. -std=c++11).
+#   If neither is specified, you get whatever works, with preference for an
+#   extended mode.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Benjamin Kosnik <bkoz@xxxxxxxxxx>
+#   Copyright (c) 2012 Zack Weinberg <zackw@xxxxxxxxx>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved. This file is offered as-is, without any
+#   warranty.
+
+#serial 8
+
+m4_define([_AX_CXXFLAGS_STDCXX_11_testbody], [
+  template <typename T>
+    struct check
+    {
+      static_assert(sizeof(int) <= sizeof(T), "not big enough");
+    };
+
+    typedef check<check<bool>> right_angle_brackets;
+
+    int a;
+    decltype(a) b;
+
+    typedef check<int> check_type;
+    check_type c;
+    check_type&& cr = static_cast<check_type&&>(c);
+])
+
+AC_DEFUN([AX_CXXFLAGS_STDCXX_11], [dnl
+  m4_if([$1], [], [],
+        [$1], [ext], [],
+        [$1], [noext], [],
+        [m4_fatal([invalid argument `$1' to AX_CXXFLAGS_STDCXX_11])])dnl
+  AC_LANG_ASSERT([C++])dnl
+  ac_success=no
+  AC_CACHE_CHECK(whether $CXX supports C++11 features by default,
+  ax_cv_cxx_compile_cxx11,
+  [AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXXFLAGS_STDCXX_11_testbody])],
+    [ax_cv_cxx_compile_cxx11=yes],
+    [ax_cv_cxx_compile_cxx11=no])])
+  if test x$ax_cv_cxx_compile_cxx11 = xyes; then
+    ac_success=yes
+  fi
+
+  m4_if([$1], [noext], [], [dnl
+  if test x$ac_success = xno; then
+    for switch in -std=gnu++11 -std=gnu++0x; do
+      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
+      AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
+                     $cachevar,
+        [ac_save_CXXFLAGS="$CXXFLAGS"
+         CXXFLAGS="$CXXFLAGS $switch"
+         AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXXFLAGS_STDCXX_11_testbody])],
+          [eval $cachevar=yes],
+          [eval $cachevar=no])
+         CXXFLAGS="$ac_save_CXXFLAGS"])
+      if eval test x\$$cachevar = xyes; then
+        CXXFLAGS="$CXXFLAGS $switch"
+        ac_success=yes
+        break
+      fi
+    done
+  fi])
+
+  m4_if([$1], [ext], [], [dnl
+  if test x$ac_success = xno; then
+    for switch in -std=c++11 -std=c++0x; do
+      cachevar=AS_TR_SH([ax_cv_cxx_compile_cxx11_$switch])
+      AC_CACHE_CHECK(whether $CXX supports C++11 features with $switch,
+                     $cachevar,
+        [ac_save_CXXFLAGS="$CXXFLAGS"
+         CXXFLAGS="$CXXFLAGS $switch"
+         AC_COMPILE_IFELSE([AC_LANG_SOURCE([_AX_CXXFLAGS_STDCXX_11_testbody])],
+          [eval $cachevar=yes],
+          [eval $cachevar=no])
+         CXXFLAGS="$ac_save_CXXFLAGS"])
+      if eval test x\$$cachevar = xyes; then
+        CXXFLAGS="$CXXFLAGS $switch"
+        ac_success=yes
+        break
+      fi
+    done
+  fi])
+
+  if test x$ac_success = xno; then
+    AC_MSG_ERROR([*** A compiler with support for C++11 language features is required.])
+  fi
+])
diff --git a/m4/winsock.m4 b/m4/winsock.m4
index a90cc50..fd3d8b5 100644
--- a/m4/winsock.m4
+++ b/m4/winsock.m4
@@ -47,10 +47,10 @@ AC_DEFUN([AX_LIB_WINSOCK2],
   ])
 
   ws32_LIBS=
-  if test "x$ac_cv_search_ntohl" == "xno"; then
-    AC_MSG_ERROR([could not find ntohl])
-  elif test "x$ac_cv_search_ntohl" != "xnone required"; then
-    ws32_LIBS="$ac_cv_search_ntohl"
-  fi
+  case "$ac_cv_search_ntohl" in
+    no)              AC_MSG_ERROR([could not find ntohl]) ;;
+    "none required") ;;
+    *)               ws32_LIBS="$ac_cv_search_ntohl"
+  esac
   AC_SUBST(ws32_LIBS)
 ])
diff --git a/src/crypt.h b/src/crypt.h
index 062625e..e87de0a 100644
--- a/src/crypt.h
+++ b/src/crypt.h
@@ -25,8 +25,8 @@ struct encryptor
 
   encryptor() {}
 private:
-  encryptor(const encryptor&);
-  encryptor& operator=(const encryptor&);
+  encryptor(const encryptor&) DELETE_METHOD;
+  encryptor& operator=(const encryptor&) DELETE_METHOD;
 };
 
 struct decryptor
@@ -55,8 +55,8 @@ struct decryptor
 
   decryptor() {}
 private:
-  decryptor(const decryptor&);
-  decryptor& operator=(const decryptor&);
+  decryptor(const decryptor&) DELETE_METHOD;
+  decryptor& operator=(const decryptor&) DELETE_METHOD;
 };
 
 /** Generate keying material from an initial key of some kind, a salt
@@ -95,8 +95,8 @@ struct key_generator
   virtual ~key_generator();
   key_generator() {}
 private:
-  key_generator(const decryptor&);
-  key_generator& operator=(const decryptor&);
+  key_generator(const key_generator&) DELETE_METHOD;
+  key_generator& operator=(const key_generator&) DELETE_METHOD;
 };
 
 #endif



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