From 2b922df93fcea9e3fad8e24b39c7fe579085d3ac Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Sat, 29 Jul 2017 10:29:59 +0200
Subject: Refine utility library semantics with "see through" theme

---
 build2/cc/compile.cxx | 26 ++++++++++++++++++++------
 build2/cc/link.cxx    | 10 ++++++----
 2 files changed, 26 insertions(+), 10 deletions(-)

(limited to 'build2/cc')

diff --git a/build2/cc/compile.cxx b/build2/cc/compile.cxx
index c0fc55b..62be69a 100644
--- a/build2/cc/compile.cxx
+++ b/build2/cc/compile.cxx
@@ -258,13 +258,18 @@ namespace build2
                         action act,
                         linfo li) const
     {
+      // See through utility libraries.
+      //
+      auto imp = [] (const file& l, bool la) {return la && l.is_a<libux> ();};
+
       auto opt = [&args, this] (
         const file& l, const string& t, bool com, bool exp)
       {
         // Note that in our model *.export.poptions are always "interface",
         // even if set on liba{}/libs{}, unlike loptions.
         //
-        assert (exp);
+        if (!exp) // Ignore libux.
+          return;
 
         const variable& var (
           com
@@ -276,6 +281,7 @@ namespace build2
 
       // In case we don't have the "small function object" optimization.
       //
+      const function<bool (const file&, bool)> impf (imp);
       const function<void (const file&, const string&, bool, bool)> optf (opt);
 
       for (prerequisite_member p: group_prerequisite_members (act, t))
@@ -295,7 +301,7 @@ namespace build2
 
           process_libraries (act, bs, li, sys_lib_dirs,
                              pt->as<file> (), a, 0, // Hack: lflags unused.
-                             nullptr, nullptr, optf);
+                             impf, nullptr, optf);
         }
       }
     }
@@ -307,10 +313,13 @@ namespace build2
                       action act,
                       linfo li) const
     {
+      auto imp = [] (const file& l, bool la) {return la && l.is_a<libux> ();};
+
       auto opt = [&cs, this] (
         const file& l, const string& t, bool com, bool exp)
       {
-        assert (exp);
+        if (!exp)
+          return;
 
         const variable& var (
           com
@@ -322,6 +331,7 @@ namespace build2
 
       // The same logic as in append_lib_options().
       //
+      const function<bool (const file&, bool)> impf (imp);
       const function<void (const file&, const string&, bool, bool)> optf (opt);
 
       for (prerequisite_member p: group_prerequisite_members (act, t))
@@ -339,7 +349,7 @@ namespace build2
 
           process_libraries (act, bs, li, sys_lib_dirs,
                              pt->as<file> (), a, 0, // Hack: lflags unused.
-                             nullptr, nullptr, optf);
+                             impf, nullptr, optf);
         }
       }
     }
@@ -354,10 +364,13 @@ namespace build2
                          action act,
                          linfo li) const
     {
+      auto imp = [] (const file& l, bool la) {return la && l.is_a<libux> ();};
+
       auto opt = [&m, this] (
         const file& l, const string& t, bool com, bool exp)
       {
-        assert (exp);
+        if (!exp)
+          return;
 
         const variable& var (
           com
@@ -369,6 +382,7 @@ namespace build2
 
       // The same logic as in append_lib_options().
       //
+      const function<bool (const file&, bool)> impf (imp);
       const function<void (const file&, const string&, bool, bool)> optf (opt);
 
       for (prerequisite_member p: group_prerequisite_members (act, t))
@@ -386,7 +400,7 @@ namespace build2
 
           process_libraries (act, bs, li, sys_lib_dirs,
                              pt->as<file> (), a, 0, // Hack: lflags unused.
-                             nullptr, nullptr, optf);
+                             impf, nullptr, optf);
         }
       }
     }
diff --git a/build2/cc/link.cxx b/build2/cc/link.cxx
index 1a5424b..25b6a28 100644
--- a/build2/cc/link.cxx
+++ b/build2/cc/link.cxx
@@ -1038,11 +1038,12 @@ namespace build2
           return;
       }
 
-      auto imp = [for_install] (const file&, bool la)
+      auto imp = [for_install] (const file& l, bool la)
       {
         // If we are not installing, then we only need to rpath interface
-        // libraries (they will include rpath's for their implementations).
-        // Otherwise, we have to do this recursively.
+        // libraries (they will include rpath's for their implementations)
+        // Otherwise, we have to do this recursively. In both cases we also
+        // want to see through utility libraries.
         //
         // The rpath-link part is tricky: ideally we would like to get only
         // implementations and only of shared libraries. We are not interested
@@ -1052,7 +1053,8 @@ namespace build2
         // we are going to rpath-link all of them which should be harmless
         // except for some noise on the command line.
         //
-        return for_install ? !la : false;
+        //
+        return (for_install ? !la : false) || l.is_a<libux> ();
       };
 
       // Package the data to keep within the 2-pointer small std::function
-- 
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