install: Do not remove compiler-defined RPATH entries

Some compilers may add their own RPATH entries when invoking the linker.
For example, a GCC installation may contain the following definition in
the specs file:

  *link_libgcc:
  %D -rpath <<some specific rpath in which libstdc++.so can be found>>

In this case binaries may contain RPATH entries that CMake did not add.
When we update the RPATH on installation we must preserve these entries
even if CMake thinks the INSTALL_RPATH value should be empty.

Fix this by always using file(RPATH_CHANGE) and teach it to behave as
file(RPATH_REMOVE) if the actual RPATH in the file is empty after
replacing the build-tree RPATH with the install-tree RPATH.  This will
preserve any compiler-added RPATH value instead of removing it.

1 files changed, 4 insertions, 12 deletions

diff --git a/Source/cmInstallTargetGenerator.cxx b/Source/cmInstallTargetGenerator.cxx
index 1158a27..5e88fa2 100644
--- a/Source/cmInstallTargetGenerator.cxx
+++ b/Source/cmInstallTargetGenerator.cxx
@@ -791,18 +791,10 @@ cmInstallTargetGenerator
       }
 
     // Write a rule to run chrpath to set the install-tree RPATH
-    if(newRpath.empty())
-      {
-      os << indent << "file(RPATH_REMOVE\n"
-         << indent << "     FILE \"" << toDestDirPath << "\")\n";
-      }
-    else
-      {
-      os << indent << "file(RPATH_CHANGE\n"
-         << indent << "     FILE \"" << toDestDirPath << "\"\n"
-         << indent << "     OLD_RPATH \"" << oldRpath << "\"\n"
-         << indent << "     NEW_RPATH \"" << newRpath << "\")\n";
-      }
+    os << indent << "file(RPATH_CHANGE\n"
+       << indent << "     FILE \"" << toDestDirPath << "\"\n"
+       << indent << "     OLD_RPATH \"" << oldRpath << "\"\n"
+       << indent << "     NEW_RPATH \"" << newRpath << "\")\n";
     }
 }