changed cygwin linkage behaviour, if dynamic libraries are used (see change notes)

git-svn-id: https://svn.dealii.org/trunk@11137 0785d39b-7218-0410-832d-ea1e28bc413d

diff --git a/deal.II/aclocal.m4 b/deal.II/aclocal.m4
index a2738443dfe53f8ec390a020d1d9befb64730433..f432ad077d02cab38252120dbbc2b5d800b54131 100644 (file)
--- a/deal.II/aclocal.m4
+++ b/deal.II/aclocal.m4
@@ -378,8 +378,15 @@ AC_DEFUN(DEAL_II_SET_CXX_FLAGS, dnl
        ;;
 
       *cygwin* )
+        dnl On Cygwin, when using shared libraries, there might occur 
+        dnl difficulties when linking libraries for several dimensions,
+        dnl as some symbols are defined in all of them. This leads to a
+        dnl linker error. We force the linker to ignore multiple symbols,
+        dnl but of course this might lead to strange program behaviour if
+        dnl you accidentally defined one symbol multiple times...
+        dnl (added 2005/07/13, Ralf B. Schulz)
         CXXFLAGSPIC=
-        LDFLAGSPIC=
+        LDFLAGSPIC=-Xlinker --allow-multiple-definition
         ;;
 
       *)
@@ -1980,7 +1987,7 @@ AC_DEFUN(DEAL_II_CHECK_ABORT, dnl
   AC_TRY_COMPILE(
     [
 #include <cstdlib>
-extern "C" void abort () {}
+extern "C" void abort () { for(;;) ; }
     ],
     [
     ],

diff --git a/deal.II/doc/news/changes.html b/deal.II/doc/news/changes.html
index 8b372db8ef42a6d09979b290d0b0d9166fb173dd..de8f9a1246a7d9712e87d4a00c3eae40f0bc6d2e 100644 (file)
--- a/deal.II/doc/news/changes.html
+++ b/deal.II/doc/news/changes.html
@@ -142,6 +142,17 @@ inconvenience this causes.
 <h3>General</h3>
 
 <ol>
+  <li> <p>
+       Changed: Cygwin has problems linking against deal.II DLLs if you
+       link against more than one dimension dependent library. The linker
+       might issue error messages about multiple defined symbols. This is now
+       detected, and the linker is forced to ignore these errors. However, if
+       you accidentally defined symbols twice you might have a hard time
+       debugging now... In this case remove the <code>-Xlinker 
+       --allow-multiple-definition</code> flag from Make.global_options.
+       <br>
+       (Ralf B. Schulz, 2005/07/13)
+       </p>
   <li> <p>
        Changed: Under Cygwin, linking against LAPACK and UMFPACK did
        not work. This is now fixed in the Makefiles. Changes only