Pass const target& to recipes

14 files changed, 244 insertions, 164 deletions

diff --git a/build2/cc/common b/build2/cc/common
index 06df4c3..860913e 100644
--- a/build2/cc/common
+++ b/build2/cc/common
@@ -184,18 +184,16 @@ namespace build2
       //
     public:
       void
-      process_libraries (const scope&,
-                         lorder,
-                         const dir_paths&,
-                         file&,
-                         bool,
-                         const function<bool (file&, bool)>&,
-                         const function<void (file*, const string&, bool)>&,
-                         const function<void (file&,
-                                              const string&,
-                                              bool,
-                                              bool)>&,
-                         bool = false) const;
+      process_libraries (
+        const scope&,
+        lorder,
+        const dir_paths&,
+        const file&,
+        bool,
+        const function<bool (const file&, bool)>&,
+        const function<void (const file*, const string&, bool)>&,
+        const function<void (const file&, const string&, bool, bool)>&,
+        bool = false) const;
 
       target*
       search_library (const dir_paths& sysd,
@@ -209,7 +207,7 @@ namespace build2
       }
 
     private:
-      file&
+      const file&
       resolve_library (const scope&,
                        name,
                        lorder,
diff --git a/build2/cc/common.cxx b/build2/cc/common.cxx
index e7b26a1..62a4ab2 100644
--- a/build2/cc/common.cxx
+++ b/build2/cc/common.cxx
@@ -49,14 +49,14 @@ namespace build2
       const scope& top_bs,
       lorder top_lo,
       const dir_paths& top_sysd,
-      file& l,
+      const file& l,
       bool la,
-      const function<bool (file&,
+      const function<bool (const file&,
                            bool la)>& proc_impl, // Implementation?
-      const function<void (file*,                // Can be NULL.
+      const function<void (const file*,          // Can be NULL.
                            const string& path,   // Library path.
                            bool sys)>& proc_lib, // True if system library.
-      const function<void (file&,
+      const function<void (const file&,
                            const string& type,   // cc.type
                            bool com,             // cc. or x.
                            bool exp)>& proc_opt, // *.export.
@@ -213,10 +213,10 @@ namespace build2
       //
       if (impl && !c_e_libs.defined () && !x_e_libs.defined ())
       {
-        for (target* p: l.prerequisite_targets)
+        for (const target* p: l.prerequisite_targets)
         {
           bool a;
-          file* f;
+          const file* f;
 
           if ((a = (f = p->is_a<liba> ()) != nullptr)
               ||   (f = p->is_a<libs> ()) != nullptr)
@@ -287,7 +287,7 @@ namespace build2
             if (sysd == nullptr) find_sysd ();
             if (!lo) find_lo ();
 
-            file& t (resolve_library (bs, n, *lo, *sysd, usrd));
+            const file& t (resolve_library (bs, n, *lo, *sysd, usrd));
 
             if (proc_lib)
             {
@@ -385,7 +385,7 @@ namespace build2
     // will select exactly the same target as the library's matched rule and
     // that's the only way to guarantee it will be up-to-date.
     //
-    file& common::
+    const file& common::
     resolve_library (const scope& s,
                      name n,
                      lorder lo,
@@ -395,7 +395,7 @@ namespace build2
       if (n.type != "lib" && n.type != "liba" && n.type != "libs")
         fail << "target name " << n << " is not a library";
 
-      target* xt (nullptr);
+      const target* xt (nullptr);
 
       if (n.dir.absolute () && !n.qualified ())
       {
@@ -422,12 +422,12 @@ namespace build2
         //
         dir_path out;
         prerequisite_key pk {n.proj, {tt, &n.dir, &out, &n.value, ext}, &s};
-        xt = search_library (sysd, usrd, pk);
+        xt = search_library (sysd, usrd, pk); //@@ TM const
 
         if (xt == nullptr)
         {
           if (n.qualified ())
-            xt = &import (pk);
+            xt = &import (pk); //@@ TM const
           else
             fail << "unable to find library " << pk;
         }
@@ -435,10 +435,10 @@ namespace build2
 
       // If this is lib{}, pick appropriate member.
       //
-      if (lib* l = xt->is_a<lib> ())
+      if (const lib* l = xt->is_a<lib> ())
         xt = &link_member (*l, lo); // Pick liba{} or libs{}.
 
-      return static_cast<file&> (*xt);
+      return static_cast<const file&> (*xt);
     }
 
     // Note that pk's scope should not be NULL (even if dir is absolute). If
diff --git a/build2/cc/compile b/build2/cc/compile
index b6fc7d6..63ce286 100644
--- a/build2/cc/compile
+++ b/build2/cc/compile
@@ -33,17 +33,23 @@ namespace build2
       apply (slock&, action, target&) const override;
 
       target_state
-      perform_update (action, target&) const;
+      perform_update (action, const target&) const;
 
       target_state
-      perform_clean (action, target&) const;
+      perform_clean (action, const target&) const;
 
     private:
       void
-      append_lib_options (const scope&, cstrings&, target&, lorder) const;
+      append_lib_options (const scope&,
+                          cstrings&,
+                          const target&,
+                          lorder) const;
 
       void
-      hash_lib_options (const scope&, sha256&, target&, lorder) const;
+      hash_lib_options (const scope&,
+                        sha256&,
+                        const target&,
+                        lorder) const;
 
       // Mapping of include prefixes (e.g., foo in <foo/bar>) for auto-
       // generated headers to directories where they will be generated.
@@ -58,7 +64,7 @@ namespace build2
       using prefix_map = butl::dir_path_map<dir_path>;
 
       void
-      append_prefixes (prefix_map&, target&, const variable&) const;
+      append_prefixes (prefix_map&, const target&, const variable&) const;
 
       void
       append_lib_prefixes (const scope&, prefix_map&, target&, lorder) const;
diff --git a/build2/cc/compile.cxx b/build2/cc/compile.cxx
index 66ea9bd..98d1218 100644
--- a/build2/cc/compile.cxx
+++ b/build2/cc/compile.cxx
@@ -78,10 +78,11 @@ namespace build2
     void compile::
     append_lib_options (const scope& bs,
                         cstrings& args,
-                        target& t,
+                        const target& t,
                         lorder lo) const
     {
-      auto opt = [&args, this] (file& l, const string& t, bool com, bool exp)
+      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.
@@ -98,31 +99,35 @@ namespace build2
 
       // In case we don't have the "small function object" optimization.
       //
-      const function<void (file&, const string&, bool, bool)> optf (opt);
+      const function<void (const file&, const string&, bool, bool)> optf (opt);
 
       // Note that here we don't need to see group members (see apply()).
       //
-      for (prerequisite& p: group_prerequisites (t))
+      for (const prerequisite& p: const_group_prerequisites (t))
       {
-        target* pt (p.target); // Already searched and matched.
+        const target* pt (p.target); // Already searched and matched.
 
         bool a;
 
-        if (lib* l = pt->is_a<lib> ())
+        if (const lib* l = pt->is_a<lib> ())
           a = (pt = &link_member (*l, lo))->is_a<liba> ();
         else if (!(a = pt->is_a<liba> ()) && !pt->is_a<libs> ())
           continue;
 
         process_libraries (bs, lo, sys_lib_dirs,
-                           static_cast<file&> (*pt), a,
+                           static_cast<const file&> (*pt), a,
                            nullptr, nullptr, optf);
       }
     }
 
     void compile::
-    hash_lib_options (const scope& bs, sha256& cs, target& t, lorder lo) const
+    hash_lib_options (const scope& bs,
+                      sha256& cs,
+                      const target& t,
+                      lorder lo) const
     {
-      auto opt = [&cs, this] (file& l, const string& t, bool com, bool exp)
+      auto opt = [&cs, this] (
+        const file& l, const string& t, bool com, bool exp)
       {
         assert (exp);
 
@@ -136,21 +141,21 @@ namespace build2
 
       // In case we don't have the "small function object" optimization.
       //
-      const function<void (file&, const string&, bool, bool)> optf (opt);
+      const function<void (const file&, const string&, bool, bool)> optf (opt);
 
-      for (prerequisite& p: group_prerequisites (t))
+      for (const prerequisite& p: const_group_prerequisites (t))
       {
-        target* pt (p.target); // Already searched and matched.
+        const target* pt (p.target); // Already searched and matched.
 
         bool a;
 
-        if (lib* l = pt->is_a<lib> ())
+        if (const lib* l = pt->is_a<lib> ())
           a = (pt = &link_member (*l, lo))->is_a<liba> ();
         else if (!(a = pt->is_a<liba> ()) && !pt->is_a<libs> ())
           continue;
 
         process_libraries (bs, lo, sys_lib_dirs,
-                           static_cast<file&> (*pt), a,
+                           static_cast<const file&> (*pt), a,
                            nullptr, nullptr, optf);
       }
     }
@@ -164,7 +169,8 @@ namespace build2
                          target& t,
                          lorder lo) const
     {
-      auto opt = [&m, this] (file& l, const string& t, bool com, bool exp)
+      auto opt = [&m, this] (
+        const file& l, const string& t, bool com, bool exp)
       {
         assert (exp);
 
@@ -178,7 +184,7 @@ namespace build2
 
       // In case we don't have the "small function object" optimization.
       //
-      const function<void (file&, const string&, bool, bool)> optf (opt);
+      const function<void (const file&, const string&, bool, bool)> optf (opt);
 
       for (prerequisite& p: group_prerequisites (t))
       {
@@ -192,7 +198,7 @@ namespace build2
           continue;
 
         process_libraries (bs, lo, sys_lib_dirs,
-                           static_cast<file&> (*pt), a,
+                           static_cast<const file&> (*pt), a,
                            nullptr, nullptr, optf);
       }
     }
@@ -399,12 +405,15 @@ namespace build2
 
       switch (a)
       {
-      case perform_update_id:
-        return [this] (action a, target& t) {return perform_update (a, t);};
-      case perform_clean_id:
-        return [this] (action a, target& t) {return perform_clean (a, t);};
-      default:
-        return noop_recipe; // Configure update.
+      case perform_update_id: return [this] (action a, const target& t)
+        {
+          return perform_update (a, t);
+        };
+      case perform_clean_id: return [this] (action a, const target& t)
+        {
+          return perform_clean (a, t);
+        };
+      default: return noop_recipe; // Configure update.
       }
     }
 
@@ -440,7 +449,7 @@ namespace build2
     }
 
     void compile::
-    append_prefixes (prefix_map& m, target& t, const variable& var) const
+    append_prefixes (prefix_map& m, const target& t, const variable& var) const
     {
       tracer trace (x, "append_prefixes");
 
@@ -1394,15 +1403,15 @@ namespace build2
     msvc_filter_cl (ifdstream&, const path& src);
 
     target_state compile::
-    perform_update (action a, target& xt) const
+    perform_update (action a, const target& xt) const
     {
-      file& t (static_cast<file&> (xt));
+      const file& t (static_cast<const file&> (xt));
 
       // Update prerequisites and determine if any relevant ones render us
       // out-of-date. Note that currently we treat all the prerequisites
       // as potentially affecting the result (for simplicity/performance).
       //
-      file* s;
+      const file* s;
       {
         auto p (execute_prerequisites<file> (x_src, a, t, t.mtime ()));
 
@@ -1621,9 +1630,9 @@ namespace build2
     }
 
     target_state compile::
-    perform_clean (action a, target& xt) const
+    perform_clean (action a, const target& xt) const
     {
-      file& t (static_cast<file&> (xt));
+      const file& t (static_cast<const file&> (xt));
 
       if (cid == "msvc")
         return clean_extra (a, t, {".d", ".idb", ".pdb"});
diff --git a/build2/cc/install b/build2/cc/install
index ff7af4d..f676d72 100644
--- a/build2/cc/install
+++ b/build2/cc/install
@@ -30,11 +30,14 @@ namespace build2
       virtual match_result
       match (slock&, action, target&, const string&) const override;
 
+      virtual recipe
+      apply (slock&, action, target&) const override;
+
       virtual void
-      install_extra (file&, const install_dir&) const override;
+      install_extra (const file&, const install_dir&) const override;
 
       virtual bool
-      uninstall_extra (file&, const install_dir&) const override;
+      uninstall_extra (const file&, const install_dir&) const override;
 
     private:
       const link& link_;
diff --git a/build2/cc/install.cxx b/build2/cc/install.cxx
index 074654b..f022a92 100644
--- a/build2/cc/install.cxx
+++ b/build2/cc/install.cxx
@@ -66,17 +66,35 @@ namespace build2
       // ones building this target. So first run link's match().
       //
       match_result r (link_.match (ml, a, t, hint));
-      return r ? install::file_rule::match (ml, a, t, "") : r;
+      return r ? file_rule::match (ml, a, t, "") : r;
+    }
+
+    recipe install::
+    apply (slock& s, action a, target& t) const
+    {
+      recipe r (file_rule::apply (s, a, t));
+
+      // Derive shared library paths and cache them in the target's aux
+      // storage if we are (un)installing (used in *_extra() functions below).
+      //
+      if (a.operation () == install_id || a.operation () == uninstall_id)
+      {
+        file* f;
+        if ((f = t.is_a<libs> ()) != nullptr && tclass != "windows")
+          t.data (link_.derive_libs_paths (*f));
+      }
+
+      return r;
     }
 
     void install::
-    install_extra (file& t, const install_dir& id) const
+    install_extra (const file& t, const install_dir& id) const
     {
       if (t.is_a<libs> () && tclass != "windows")
       {
         // Here we may have a bunch of symlinks that we need to install.
         //
-        link::libs_paths lp (link_.derive_libs_paths (t));
+        auto& lp (t.data<link::libs_paths> ());
 
         auto ln = [&id, this] (const path& f, const path& l)
         {
@@ -87,7 +105,7 @@ namespace build2
         const path& so (lp.soname);
         const path& in (lp.interm);
 
-        const path* f (lp.real);
+        const path* f (&lp.real);
 
         if (!in.empty ()) {ln (*f, in); f = &in;}
         if (!so.empty ()) {ln (*f, so); f = &so;}
@@ -96,7 +114,7 @@ namespace build2
     }
 
     bool install::
-    uninstall_extra (file& t, const install_dir& id) const
+    uninstall_extra (const file& t, const install_dir& id) const
     {
       bool r (false);
 
@@ -104,7 +122,7 @@ namespace build2
       {
         // Here we may have a bunch of symlinks that we need to uninstall.
         //
-        link::libs_paths lp (link_.derive_libs_paths (t));
+        auto& lp (t.data<link::libs_paths> ());
 
         auto rm = [&id, this] (const path& l)
         {
diff --git a/build2/cc/link b/build2/cc/link
index d1b0e7a..c787015 100644
--- a/build2/cc/link
+++ b/build2/cc/link
@@ -31,10 +31,10 @@ namespace build2
       apply (slock&, action, target&) const override;
 
       target_state
-      perform_update (action, target&) const;
+      perform_update (action, const target&) const;
 
       target_state
-      perform_clean (action, target&) const;
+      perform_clean (action, const target&) const;
 
     private:
       friend class install;
@@ -50,19 +50,16 @@ namespace build2
         // The libs{} path is always the real path. On Windows the link path
         // is the import library.
         //
-        // @@ TODO: change real to reference, make other const once cache the
-        // object.
-        //
-              path  link;   // What we link: libfoo.so
-              path  soname; // SONAME:       libfoo-1.so, libfoo.so.1
-              path  interm; // Intermediate: libfoo.so.1.2
-        const path* real;   // Real:         libfoo.so.1.2.3
+        const path  link;   // What we link: libfoo.so
+        const path  soname; // SONAME:       libfoo-1.so, libfoo.so.1
+        const path  interm; // Intermediate: libfoo.so.1.2
+        const path& real;   // Real:         libfoo.so.1.2.3
 
         inline const path&
         effect_link () const {return link.empty () ? effect_soname () : link;}
 
         inline const path&
-        effect_soname () const {return soname.empty () ? *real : soname;}
+        effect_soname () const {return soname.empty () ? real : soname;}
       };
 
       libs_paths
@@ -71,13 +68,21 @@ namespace build2
       // Library handling.
       //
       void
-      append_libraries (strings&, file&, bool, const scope&, lorder) const;
+      append_libraries (strings&,
+                        const file&, bool,
+                        const scope&, lorder) const;
 
       void
-      hash_libraries (sha256&, file&, bool, const scope&, lorder) const;
+      hash_libraries (sha256&,
+                      const file&, bool,
+                      const scope&, lorder) const;
 
       void
-      rpath_libraries (strings&, target&, const scope&, lorder, bool) const;
+      rpath_libraries (strings&,
+                       const target&,
+                       const scope&,
+                       lorder,
+                       bool) const;
 
       // Windows rpath emulation (windows-rpath.cxx).
       //
@@ -93,13 +98,13 @@ namespace build2
       using windows_dlls = std::set<windows_dll>;
 
       timestamp
-      windows_rpath_timestamp (file&, const scope&, lorder) const;
+      windows_rpath_timestamp (const file&, const scope&, lorder) const;
 
       windows_dlls
-      windows_rpath_dlls (file&, const scope&, lorder) const;
+      windows_rpath_dlls (const file&, const scope&, lorder) const;
 
       void
-      windows_rpath_assembly (file&, const scope&, lorder,
+      windows_rpath_assembly (const file&, const scope&, lorder,
                               const string&,
                               timestamp,
                               bool) const;
@@ -107,7 +112,7 @@ namespace build2
       // Windows-specific (windows-manifest.cxx).
       //
       path
-      windows_manifest (file&, bool rpath_assembly) const;
+      windows_manifest (const file&, bool rpath_assembly) const;
 
     private:
       const string rule_id;
diff --git a/build2/cc/link.cxx b/build2/cc/link.cxx
index 83a7c0d..7c946aa 100644
--- a/build2/cc/link.cxx
+++ b/build2/cc/link.cxx
@@ -266,7 +266,6 @@ namespace build2
       // Now determine the paths.
       //
       path lk, so, in;
-      const path* re (nullptr);
 
       // We start with the basic path.
       //
@@ -310,7 +309,7 @@ namespace build2
       if (!v.empty ())
         b += v;
 
-      re = &ls.derive_path (move (b));
+      const path& re (ls.derive_path (move (b)));
 
       return libs_paths {move (lk), move (so), move (in), re};
     }
@@ -318,6 +317,9 @@ namespace build2
     recipe link::
     apply (slock& ml, action a, target& xt) const
     {
+      static_assert (sizeof (link::libs_paths) <= target::data_size,
+                     "insufficient space");
+
       tracer trace (x, "link::apply");
 
       file& t (static_cast<file&> (xt));
@@ -388,7 +390,7 @@ namespace build2
             if (tclass == "windows")
               add_adhoc (t, "libi");
 
-            derive_libs_paths (t);
+            t.data (derive_libs_paths (t)); // Cache in target.
             break;
           }
         }
@@ -645,18 +647,21 @@ namespace build2
 
       switch (a)
       {
-      case perform_update_id:
-        return [this] (action a, target& t) {return perform_update (a, t);};
-      case perform_clean_id:
-        return [this] (action a, target& t) {return perform_clean (a, t);};
-      default:
-        return noop_recipe; // Configure update.
+      case perform_update_id: return [this] (action a, const target& t)
+        {
+          return perform_update (a, t);
+        };
+      case perform_clean_id: return [this] (action a, const target& t)
+        {
+          return perform_clean (a, t);
+        };
+      default: return noop_recipe; // Configure update.
       }
     }
 
     void link::
     append_libraries (strings& args,
-                      file& l, bool la,
+                      const file& l, bool la,
                       const scope& bs, lorder lo) const
     {
       // Note: lack of the "small function object" optimization will really
@@ -664,9 +669,9 @@ namespace build2
       //
       bool win (tclass == "windows");
 
-      auto imp = [] (file&, bool la) {return la;};
+      auto imp = [] (const file&, bool la) {return la;};
 
-      auto lib = [&args, win] (file* f, const string& p, bool)
+      auto lib = [&args, win] (const file* f, const string& p, bool)
       {
         if (f != nullptr)
         {
@@ -675,7 +680,7 @@ namespace build2
           // (see search_library() for details).
           //
           if (win && f->member != nullptr && f->is_a<libs> ())
-            f = static_cast<file*> (f->member);
+            f = static_cast<const file*> (f->member.get ());
 
           args.push_back (relative (f->path ()).string ());
         }
@@ -683,11 +688,12 @@ namespace build2
           args.push_back (p);
       };
 
-      auto opt = [&args, this] (file& l, const string& t, bool com, bool exp)
+      auto opt = [&args, this] (
+        const file& l, const string& t, bool com, bool exp)
       {
         // If we need an interface value, then use the group (lib{}).
         //
-        if (target* g = exp && l.is_a<libs> () ? l.group : &l)
+        if (const target* g = exp && l.is_a<libs> () ? l.group : &l)
         {
           const variable& var (
             com
@@ -705,16 +711,14 @@ namespace build2
 
     void link::
     hash_libraries (sha256& cs,
-                    file& l,
-                    bool la,
-                    const scope& bs,
-                    lorder lo) const
+                    const file& l, bool la,
+                    const scope& bs, lorder lo) const
     {
       bool win (tclass == "windows");
 
-      auto imp = [] (file&, bool la) {return la;};
+      auto imp = [] (const file&, bool la) {return la;};
 
-      auto lib = [&cs, win] (file* f, const string& p, bool)
+      auto lib = [&cs, win] (const file* f, const string& p, bool)
       {
         if (f != nullptr)
         {
@@ -723,7 +727,7 @@ namespace build2
           // (see search_library() for details).
           //
           if (win && f->member != nullptr && f->is_a<libs> ())
-            f = static_cast<file*> (f->member);
+            f = static_cast<const file*> (f->member.get ());
 
           cs.append (f->path ().string ());
         }
@@ -731,9 +735,10 @@ namespace build2
           cs.append (p);
       };
 
-      auto opt = [&cs, this] (file& l, const string& t, bool com, bool exp)
+      auto opt = [&cs, this] (
+        const file& l, const string& t, bool com, bool exp)
       {
-        if (target* g = exp && l.is_a<libs> () ? l.group : &l)
+        if (const target* g = exp && l.is_a<libs> () ? l.group : &l)
         {
           const variable& var (
             com
@@ -751,7 +756,7 @@ namespace build2
 
     void link::
     rpath_libraries (strings& args,
-                     target& t,
+                     const target& t,
                      const scope& bs,
                      lorder lo,
                      bool for_install) const
@@ -765,7 +770,7 @@ namespace build2
           return;
       }
 
-      auto imp = [for_install] (file&, bool la)
+      auto imp = [for_install] (const file&, bool la)
       {
         // If we are not installing, then we only need to rpath interface
         // libraries (they will include rpath's for their implementations).
@@ -791,7 +796,7 @@ namespace build2
         bool for_install;
       } d {args, for_install};
 
-      auto lib = [&d, this] (file* l, const string& f, bool sys)
+      auto lib = [&d, this] (const file* l, const string& f, bool sys)
       {
         // We don't rpath system libraries. Why, you may ask? There are many
         // good reasons and I have them written on an napkin somewhere...
@@ -845,13 +850,13 @@ namespace build2
 
       // In case we don't have the "small function object" optimization.
       //
-      const function<bool (file&, bool)> impf (imp);
-      const function<void (file*, const string&, bool)> libf (lib);
+      const function<bool (const file&, bool)> impf (imp);
+      const function<void (const file*, const string&, bool)> libf (lib);
 
-      for (target* pt: t.prerequisite_targets)
+      for (const target* pt: t.prerequisite_targets)
       {
-        file* f;
-        liba* a;
+        const file* f;
+        const liba* a;
 
         if ((f = a = pt->is_a<liba> ()) ||
             (f =     pt->is_a<libs> ()))
@@ -884,14 +889,14 @@ namespace build2
     msvc_machine (const string& cpu); // msvc.cxx
 
     target_state link::
-    perform_update (action a, target& xt) const
+    perform_update (action a, const target& xt) const
     {
       tracer trace (x, "link::perform_update");
 
       auto oop (a.outer_operation ());
       bool for_install (oop == install_id || oop == uninstall_id);
 
-      file& t (static_cast<file&> (xt));
+      const file& t (static_cast<const file&> (xt));
 
       const scope& bs (t.base_scope ());
       const scope& rs (*bs.root_scope ());
@@ -1071,10 +1076,6 @@ namespace build2
       //
       cstrings args {nullptr}; // Reserve one for config.bin.ar/config.x.
 
-      libs_paths paths;
-      if (lt == otype::s)
-        paths = derive_libs_paths (t);
-
       // Storage.
       //
       string soname1, soname2;
@@ -1127,6 +1128,7 @@ namespace build2
           //
           if (lt == otype::s)
           {
+            const libs_paths& paths (t.data<libs_paths> ());
             const string& leaf (paths.effect_soname ().leaf ().string ());
 
             if (tclass == "macosx")
@@ -1195,11 +1197,11 @@ namespace build2
       {
         sha256 cs;
 
-        for (target* pt: t.prerequisite_targets)
+        for (const target* pt: t.prerequisite_targets)
         {
-          file* f;
-          liba* a (nullptr);
-          libs* s (nullptr);
+          const file* f;
+          const liba* a (nullptr);
+          const libs* s (nullptr);
 
           if ((f = pt->is_a<obje> ()) ||
               (f = pt->is_a<obja> ()) ||
@@ -1367,8 +1369,8 @@ namespace build2
               // derived from the import library by changing the extension.
               // Lucky for us -- there is no option to name it.
               //
-              auto imp (static_cast<file*> (t.member));
-              out2 = "/IMPLIB:" + relative (imp->path ()).string ();
+              auto& imp (static_cast<const file&> (*t.member));
+              out2 = "/IMPLIB:" + relative (imp.path ()).string ();
               args.push_back (out2.c_str ());
             }
 
@@ -1377,9 +1379,10 @@ namespace build2
             //
             if (find_option ("/DEBUG", args, true))
             {
-              auto pdb (static_cast<file*> (
-                          lt == otype::e ? t.member : t.member->member));
-              out1 = "/PDB:" + relative (pdb->path ()).string ();
+              auto& pdb (
+                static_cast<const file&> (
+                  lt == otype::e ? *t.member : *t.member->member));
+              out1 = "/PDB:" + relative (pdb.path ()).string ();
               args.push_back (out1.c_str ());
             }
 
@@ -1412,8 +1415,8 @@ namespace build2
                 // On Windows libs{} is the DLL and its first ad hoc group
                 // member is the import library.
                 //
-                auto imp (static_cast<file*> (t.member));
-                out = "-Wl,--out-implib=" + relative (imp->path ()).string ();
+                auto& imp (static_cast<const file&> (*t.member));
+                out = "-Wl,--out-implib=" + relative (imp.path ()).string ();
                 args.push_back (out.c_str ());
               }
             }
@@ -1428,11 +1431,11 @@ namespace build2
 
       args[0] = ld->recall_string ();
 
-      for (target* pt: t.prerequisite_targets)
+      for (const target* pt: t.prerequisite_targets)
       {
-        file* f;
-        liba* a (nullptr);
-        libs* s (nullptr);
+        const file* f;
+        const liba* a (nullptr);
+        const libs* s (nullptr);
 
         if ((f = pt->is_a<obje> ()) ||
             (f = pt->is_a<obja> ()) ||
@@ -1600,11 +1603,13 @@ namespace build2
           }
         };
 
+        const libs_paths& paths (t.data<libs_paths> ());
+
         const path& lk (paths.link);
         const path& so (paths.soname);
         const path& in (paths.interm);
 
-        const path* f (paths.real);
+        const path* f (&paths.real);
 
         if (!in.empty ()) {ln (f->leaf (), in); f = &in;}
         if (!so.empty ()) {ln (f->leaf (), so); f = &so;}
@@ -1622,11 +1627,9 @@ namespace build2
     }
 
     target_state link::
-    perform_clean (action a, target& xt) const
+    perform_clean (action a, const target& xt) const
     {
-      file& t (static_cast<file&> (xt));
-
-      libs_paths paths;
+      const file& t (static_cast<const file&> (xt));
 
       switch (link_type (t))
       {
@@ -1666,7 +1669,8 @@ namespace build2
             // Here we can have a bunch of symlinks that we need to remove. If
             // the paths are empty, then they will be ignored.
             //
-            paths = derive_libs_paths (t);
+            const libs_paths& paths (t.data<libs_paths> ());
+
             return clean_extra (a, t, {".d",
                                        paths.link.string ().c_str (),
                                        paths.soname.string ().c_str (),
diff --git a/build2/cc/msvc.cxx b/build2/cc/msvc.cxx
index 4ac82a0..fc2979c 100644
--- a/build2/cc/msvc.cxx
+++ b/build2/cc/msvc.cxx
@@ -69,7 +69,7 @@ namespace build2
         //
         if (lt == otype::s && l.compare (0, 3, "   ") == 0)
         {
-          path imp (static_cast<file*> (t.member)->path ().leaf ());
+          path imp (static_cast<const file&> (*t.member).path ().leaf ());
 
           if (l.find (imp.string ()) != string::npos &&
               l.find (imp.base ().string () + ".exp") != string::npos)
diff --git a/build2/cc/utility b/build2/cc/utility
index 050b645..bb7ed34 100644
--- a/build2/cc/utility
+++ b/build2/cc/utility
@@ -22,10 +22,10 @@ namespace build2
     // Compile/link output type.
     //
     otype
-    compile_type (target&);
+    compile_type (const target&);
 
     otype
-    link_type (target&);
+    link_type (const target&);
 
     // Library link order.
     //
@@ -41,8 +41,13 @@ namespace build2
 
     // Given the link order return the library member (liba or libs) to link.
     //
+    // Note that the const version assumes you have already called non-const.
+    //
     target&
     link_member (bin::lib&, lorder);
+
+    const target&
+    link_member (const bin::lib&, lorder);
   }
 }
 
diff --git a/build2/cc/utility.cxx b/build2/cc/utility.cxx
index 5c5d1fe..4ccdcaf 100644
--- a/build2/cc/utility.cxx
+++ b/build2/cc/utility.cxx
@@ -38,6 +38,37 @@ namespace build2
         : v.size () > 1 && v[1] == "shared" ? lorder::a_s : lorder::a;
     }
 
+    const target&
+    link_member (const bin::lib& l, lorder lo)
+    {
+      bool ls (true);
+      const string& at (cast<string> (l["bin.lib"])); // Available members.
+
+      switch (lo)
+      {
+      case lorder::a:
+      case lorder::a_s:
+        ls = false; // Fall through.
+      case lorder::s:
+      case lorder::s_a:
+        {
+          if (ls ? at == "static" : at == "shared")
+          {
+            if (lo == lorder::a_s || lo == lorder::s_a)
+              ls = !ls;
+            else
+              assert (false);
+          }
+        }
+      }
+
+      target* r (ls ? static_cast<target*> (l.s) : l.a);
+
+      assert (r != nullptr);
+
+      return *r;
+    }
+
     target&
     link_member (bin::lib& l, lorder lo)
     {
diff --git a/build2/cc/utility.ixx b/build2/cc/utility.ixx
index 8695a8e..bc9cd05 100644
--- a/build2/cc/utility.ixx
+++ b/build2/cc/utility.ixx
@@ -7,7 +7,7 @@ namespace build2
   namespace cc
   {
     inline otype
-    compile_type (target& t)
+    compile_type (const target& t)
     {
       return
         t.is_a<bin::obje> () ? otype::e :
@@ -16,7 +16,7 @@ namespace build2
     }
 
     inline otype
-    link_type (target& t)
+    link_type (const target& t)
     {
       return
         t.is_a<exe> ()       ? otype::e :
diff --git a/build2/cc/windows-manifest.cxx b/build2/cc/windows-manifest.cxx
index b0b0feb..0e38e7d 100644
--- a/build2/cc/windows-manifest.cxx
+++ b/build2/cc/windows-manifest.cxx
@@ -39,7 +39,7 @@ namespace build2
     // file corresponding to the exe{} target. Return the manifest file path.
     //
     path link::
-    windows_manifest (file& t, bool rpath_assembly) const
+    windows_manifest (const file& t, bool rpath_assembly) const
     {
       tracer trace (x, "windows_manifest");
 
diff --git a/build2/cc/windows-rpath.cxx b/build2/cc/windows-rpath.cxx
index 00911d4..94b1145 100644
--- a/build2/cc/windows-rpath.cxx
+++ b/build2/cc/windows-rpath.cxx
@@ -46,16 +46,16 @@ namespace build2
     // adding to the assembly or timestamp_nonexistent if there aren't any.
     //
     timestamp link::
-    windows_rpath_timestamp (file& t, const scope& bs, lorder lo) const
+    windows_rpath_timestamp (const file& t, const scope& bs, lorder lo) const
     {
       timestamp r (timestamp_nonexistent);
 
       // We need to collect all the DLLs, so go into implementation of both
       // shared and static (in case they depend on shared).
       //
-      auto imp = [] (file&, bool) {return true;};
+      auto imp = [] (const file&, bool) {return true;};
 
-      auto lib = [&r] (file* l, const string& f, bool sys)
+      auto lib = [&r] (const file* l, const string& f, bool sys)
       {
         // We don't rpath system libraries.
         //
@@ -97,10 +97,10 @@ namespace build2
           r = t;
       };
 
-      for (target* pt: t.prerequisite_targets)
+      for (const target* pt: t.prerequisite_targets)
       {
-        file* f;
-        liba* a;
+        const file* f;
+        const liba* a;
 
         if ((f = a = pt->is_a<liba> ()) ||
             (f =     pt->is_a<libs> ()))
@@ -116,15 +116,15 @@ namespace build2
     // duplicates).
     //
     auto link::
-    windows_rpath_dlls (file& t,
+    windows_rpath_dlls (const file& t,
                         const scope& bs,
                         lorder lo) const -> windows_dlls
     {
       windows_dlls r;
 
-      auto imp = [] (file&, bool) {return true;};
+      auto imp = [] (const file&, bool) {return true;};
 
-      auto lib = [&r] (file* l, const string& f, bool sys)
+      auto lib = [&r] (const file* l, const string& f, bool sys)
       {
         if (sys)
           return;
@@ -137,7 +137,8 @@ namespace build2
             //
             const string* pdb (
               l->member != nullptr && l->member->member != nullptr
-              ? &static_cast<file&> (*l->member->member).path ().string ()
+              ? &static_cast<const file&> (
+                  *l->member->member).path ().string ()
               : nullptr);
 
             r.insert (windows_dll {f, pdb, string ()});
@@ -178,10 +179,10 @@ namespace build2
         }
       };
 
-      for (target* pt: t.prerequisite_targets)
+      for (const target* pt: t.prerequisite_targets)
       {
-        file* f;
-        liba* a;
+        const file* f;
+        const liba* a;
 
         if ((f = a = pt->is_a<liba> ()) ||
             (f =     pt->is_a<libs> ()))
@@ -205,7 +206,7 @@ namespace build2
     // manifest file.
     //
     void link::
-    windows_rpath_assembly (file& t,
+    windows_rpath_assembly (const file& t,
                             const scope& bs,
                             lorder lo,
                             const string& tcpu,