Use combined -L option form for extra system search paths

The split one was just too much of an eye-sore in the logs.

3 files changed, 47 insertions, 16 deletions

diff --git a/libbuild2/cc/link-rule.cxx b/libbuild2/cc/link-rule.cxx
index 6b0c337..417cba5 100644
--- a/libbuild2/cc/link-rule.cxx
+++ b/libbuild2/cc/link-rule.cxx
@@ -3479,13 +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);
         }
       }
 
diff --git a/libbuild2/utility.hxx b/libbuild2/utility.hxx
index b534f41..151b409 100644
--- a/libbuild2/utility.hxx
+++ b/libbuild2/utility.hxx
@@ -877,17 +877,29 @@ namespace build2
   //
   template <typename I, typename F>
   void
-  append_option_values (cstrings&,
-                        const char* opt,
-                        I begin, I end,
-                        F&& get = [] (const string& s) {return s.c_str ();});
+  append_option_values (
+    cstrings&,
+    const char* opt,
+    I begin, I end,
+    F&& get = [] (const string& s) {return s.c_str ();});
 
   template <typename I, typename F>
   void
-  append_option_values (sha256&,
-                        const char* opt,
-                        I begin, I end,
-                        F&& get = [] (const string& s) {return s;});
+  append_option_values (
+    sha256&,
+    const char* opt,
+    I begin, I end,
+    F&& get = [] (const string& s) -> const string& {return s;});
+
+  // As above but in a combined form (e.g., -L/usr/local/lib).
+  //
+  template <typename I, typename F>
+  void
+  append_combined_option_values (
+    strings&,
+    const char* opt,
+    I begin, I end,
+    F&& get = [] (const string& s) -> const string& {return s;});
 
   // As above but append a single option (used for append/hash uniformity).
   //
diff --git a/libbuild2/utility.txx b/libbuild2/utility.txx
index d2fc29c..cdf510f 100644
--- a/libbuild2/utility.txx
+++ b/libbuild2/utility.txx
@@ -5,16 +5,16 @@ namespace build2
 {
   template <typename I, typename F>
   void
-  append_option_values (cstrings& args, const char* o, I b, I e, F&& get)
+  append_option_values (cstrings& ss, const char* o, I b, I e, F&& get)
   {
     if (b != e)
     {
-      args.reserve (args.size () + (e - b));
+      ss.reserve (ss.size () + (e - b));
 
       for (; b != e; ++b)
       {
-        args.push_back (o);
-        args.push_back (get (*b));
+        ss.push_back (o);
+        ss.push_back (get (*b));
       }
     }
   }
@@ -30,6 +30,19 @@ namespace build2
     }
   }
 
+  template <typename I, typename F>
+  void
+  append_combined_option_values (strings& ss, const char* o, I b, I e, F&& get)
+  {
+    if (b != e)
+    {
+      ss.reserve (ss.size () + (e - b));
+
+      for (; b != e; ++b)
+        ss.push_back (string (o) += get (*b));
+    }
+  }
+
   template <typename K>
   basic_path<char, K>
   relative (const basic_path<char, K>& p)