1 files changed, 61 insertions, 9 deletions

diff --git a/libbuild2/cc/link-rule.cxx b/libbuild2/cc/link-rule.cxx
index 08a60b9..417cba5 100644
--- a/libbuild2/cc/link-rule.cxx
+++ b/libbuild2/cc/link-rule.cxx
@@ -2585,6 +2585,24 @@ namespace build2
         // We don't rpath system libraries. Why, you may ask? There are many
         // good reasons and I have them written on a napkin somewhere...
         //
+        // Well, the main reason is that we naturally assume the dynamic
+        // linker searches there by default and so there is no need for rpath.
+        // Plus, rpath would prevent "overriding" distribution-system
+        // (/usr/lib) libraries with user-system (/usr/local/lib).
+        //
+        // Note, however, that some operating systems don't search in
+        // /usr/local/lib by default (for example, Fedora, RHEL, Mac OS since
+        // version 13). In a sense, on these platforms /usr/local is
+        // "half-system" in that the system compiler by default searches in
+        // /usr/local/include and/or /usr/local/lib (see config_module::init()
+        // for background) but the dynamic linker does not. While we could
+        // hack this test for such platforms and add rpath for /usr/local/lib,
+        // this is still feels wrong (the user can always "fix" such an
+        // operating system by instructing the dynamic linker to search in
+        // /usr/local/lib, as many, including ourselves, do). So for now we
+        // are not going to do anything. In the end, the user can always add
+        // an rpath for /usr/local/lib manually.
+        //
         // We also assume system libraries can only depend on other system
         // libraries and so can prune the traversal.
         //
@@ -2596,18 +2614,26 @@ namespace build2
           size_t p (path::traits_type::rfind_separator (f));
           assert (p != string::npos);
 
+          // For good measure, also suppress duplicates at the options level.
+          // This will take care of different libraries built in the same
+          // directory, system-installed, etc.
+
           if (d.rpath)
           {
             string o ("-Wl,-rpath,");
             o.append (f, 0, (p != 0 ? p : 1)); // Don't include trailing slash.
-            d.args.push_back (move (o));
+
+            if (find (d.args.begin (), d.args.end (), o) == d.args.end ())
+              d.args.push_back (move (o));
           }
 
           if (d.rpath_link)
           {
             string o ("-Wl,-rpath-link,");
             o.append (f, 0, (p != 0 ? p : 1));
-            d.args.push_back (move (o));
+
+            if (find (d.args.begin (), d.args.end (), o) == d.args.end ())
+              d.args.push_back (move (o));
           }
         };
 
@@ -2660,7 +2686,9 @@ namespace build2
             if ((c
                  ? f.compare (p, string::npos, e)
                  : icasecmp (f.c_str () + p, e)) == 0)
+            {
               append (f);
+            }
           }
         }
 
@@ -2671,13 +2699,22 @@ namespace build2
       {
         // Top-level shared library dependency.
         //
+        // As above, suppress duplicates.
+        //
+        if (find (d.ls.begin (), d.ls.end (), &l) != d.ls.end ())
+          return;
+
         if (!l.path ().empty ()) // Not binless.
         {
           // It is either matched or imported so should be a cc library.
           //
           if (!cast_false<bool> (l.vars[c_system]))
           {
-            args.push_back ("-Wl,-rpath," + l.path ().directory ().string ());
+            string o ("-Wl,-rpath," + l.path ().directory ().string ());
+
+            if (find (args.begin (), args.end (), o) == args.end ())
+              args.push_back (move (o));
+
             ls.push_back (&l);
           }
         }
@@ -3332,6 +3369,9 @@ namespace build2
                 origin = p.directory ();
             }
 
+            // Note: suppress duplicates at the options level, similar to
+            // rpath_libraries().
+
             bool origin_used (false);
             for (const dir_path& p: cast<dir_paths> (l))
             {
@@ -3368,7 +3408,8 @@ namespace build2
               else
                 o += p.string ();
 
-              sargs.push_back (move (o));
+              if (find (sargs.begin (), sargs.end (), o) == sargs.end ())
+                sargs.push_back (move (o));
             }
 
             // According to the Internet, `-Wl,-z,origin` is not needed except
@@ -3386,7 +3427,12 @@ namespace build2
               fail << ctgt << " does not support rpath-link";
 
             for (const dir_path& p: cast<dir_paths> (l))
-              sargs.push_back ("-Wl,-rpath-link," + p.string ());
+            {
+              string o ("-Wl,-rpath-link," + p.string ());
+
+              if (find (sargs.begin (), sargs.end (), o) == sargs.end ())
+                sargs.push_back (move (o));
+            }
           }
         }
 
@@ -3433,13 +3479,19 @@ namespace build2
 
           append_args (sargs1);
         }
-        else
+        else if (b != x)
         {
-          append_option_values (
-            args,
+          // Use the more canonical combined form (-L/usr/local/lib) even
+          // though it's less efficient (the split one is just too much of an
+          // eye-sore in the logs).
+          //
+          append_combined_option_values (
+            sargs1,
             "-L",
             b, x,
-            [] (const dir_path& d) {return d.string ().c_str ();});
+            [] (const dir_path& d) -> const string& {return d.string ();});
+
+          append_args (sargs1);
         }
       }