From: Andrew Nelless <andrew@nelless.net>
Date: Thu, 10 Mar 2016 19:59:50 +0000 (+0000)
Subject: Fix Boost component library detection.
X-Git-Tag: dnsdist-1.0.0-beta1~113^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e512f4f99403601638a08f738a55d9854caa8680;p=thirdparty%2Fpdns.git

Fix Boost component library detection.

On some platforms the Boost context headers are being shipped on
architectures where the library can't be built. Here we patch
boost.m4 to set HAVE_BOOST_<component> definitions based on
whether the library actually exists.

This should also fix builds against Boost 1.58.0, which shipped
a broken context/all.hpp header when compiling in modes before
C++14 (see: https://svn.boost.org/trac/boost/ticket/11223 )
---

diff --git a/m4/boost.m4 b/m4/boost.m4
index a4a75fc385..9df0429614 100644
--- a/m4/boost.m4
+++ b/m4/boost.m4
@@ -328,14 +328,14 @@ CPPFLAGS="$CPPFLAGS $BOOST_CPPFLAGS"
 AC_CACHE_CHECK([for the Boost $1 library], [Boost_lib],
                [_BOOST_FIND_LIBS($@)])
 case $Boost_lib in #(
-  (no) _AC_MSG_LOG_CONFTEST
-    AC_MSG_ERROR([cannot find the flags to link with Boost $1])
+  (yes) _AC_MSG_LOG_CONFTEST
+    AC_DEFINE(AS_TR_CPP([HAVE_BOOST_$1]), [1], [Defined if the Boost $1 library is available])dnl
+    AC_SUBST(AS_TR_CPP([BOOST_$1_LDFLAGS]), [$Boost_lib_LDFLAGS])dnl
+    AC_SUBST(AS_TR_CPP([BOOST_$1_LDPATH]), [$Boost_lib_LDPATH])dnl
+    AC_SUBST([BOOST_LDPATH], [$Boost_lib_LDPATH])dnl
+    AC_SUBST(AS_TR_CPP([BOOST_$1_LIBS]), [$Boost_lib_LIBS])dnl
     ;;
 esac
-AC_SUBST(AS_TR_CPP([BOOST_$1_LDFLAGS]), [$Boost_lib_LDFLAGS])dnl
-AC_SUBST(AS_TR_CPP([BOOST_$1_LDPATH]), [$Boost_lib_LDPATH])dnl
-AC_SUBST([BOOST_LDPATH], [$Boost_lib_LDPATH])dnl
-AC_SUBST(AS_TR_CPP([BOOST_$1_LIBS]), [$Boost_lib_LIBS])dnl
 CPPFLAGS=$boost_save_CPPFLAGS
 AS_VAR_POPDEF([Boost_lib])dnl
 AS_VAR_POPDEF([Boost_lib_LDFLAGS])dnl
diff --git a/pdns/mtasker_context.cc b/pdns/mtasker_context.cc
index 549d7c6b0e..e1e2553033 100644
--- a/pdns/mtasker_context.cc
+++ b/pdns/mtasker_context.cc
@@ -1,10 +1,7 @@
-#include <boost/version.hpp>
+#include "config.h"
 
-/* Boost Context was introduced in 1.51 (Aug 2012), but it's probably not worth
- * supporting it because there was an immediate API break in 1.52 (Nov 2012)
- */
-#if BOOST_VERSION <= 105100
-#include "mtasker_ucontext.cc"
-#else
+#if defined(HAVE_BOOST_CONTEXT)
 #include "mtasker_fcontext.cc"
+#else
+#include "mtasker_ucontext.cc"
 #endif
diff --git a/pdns/recursordist/configure.ac b/pdns/recursordist/configure.ac
index a4b02d58d0..c606064cb7 100644
--- a/pdns/recursordist/configure.ac
+++ b/pdns/recursordist/configure.ac
@@ -33,21 +33,34 @@ AC_PROG_LIBTOOL
 
 PDNS_CHECK_OS
 
+# Boost Context was introduced in 1.51 (Aug 2012), but there was an immediate
+# API break in 1.52 (Nov 2012), so we only support that, and later.
+
 AC_DEFUN([PDNS_SELECT_CONTEXT_IMPL], [
-    AC_MSG_CHECKING([for Boost version >= 1.52])
-    AC_PREPROC_IFELSE([AC_LANG_SOURCE([[
-#include <boost/version.hpp>
-#if BOOST_VERSION <= 105100
-#error
-#endif
-    ]])], [
-        AC_MSG_RESULT([yes])
-        AC_MSG_NOTICE([MTasker will use the Boost Context library for context switching])
-        BOOST_CONTEXT
-    ], [
-        AC_MSG_RESULT([no])
-        AC_MSG_NOTICE([MTasker will use System V contexts for context switching])
-    ])
+  AC_MSG_CHECKING([whether Boost is new enough to use the context library...])
+  if test $boost_major_version -ge 152; then
+    AC_MSG_RESULT([yes])
+    if test $boost_major_version -ge 157; then
+      BOOST_THREAD([$1])
+      m4_pattern_allow([^BOOST_THREAD_(LIBS|LDFLAGS)$])dnl
+      LIBS="$LIBS $BOOST_THREAD_LIBS"
+      LDFLAGS="$LDFLAGS $BOOST_THREAD_LDFLAGS"
+    fi
+    AC_MSG_NOTICE([checking whether the Boost context library actually links...])
+    BOOST_FIND_LIB([context], [], [boost/context/fcontext.hpp], [[]])
+    case $boost_cv_lib_context in
+      (yes)
+        AC_MSG_NOTICE([MTasker will use the Boost context library for context switching])
+        ;;
+      *)
+        AC_MSG_NOTICE([Boost context library is missing])
+        AC_MSG_NOTICE([MTasker will use System V ucontexts for context switching])
+        ;;
+    esac
+  else
+    AC_MSG_RESULT([no])
+    AC_MSG_NOTICE([MTasker will use System V ucontexts for context switching])
+  fi
 ])
 
 BOOST_REQUIRE([1.35])