Use target:as<> instead of static_cast for target casting

12 files changed, 67 insertions, 60 deletions

diff --git a/build2/algorithm.ixx b/build2/algorithm.ixx
index 0c171fd..b8c33d4 100644
--- a/build2/algorithm.ixx
+++ b/build2/algorithm.ixx
@@ -56,8 +56,8 @@ namespace build2
           const string* ext,
           const scope* scope)
   {
-    return static_cast<T&> (
-      search (T::static_type, dir, out, name, ext, scope));
+    return search (
+      T::static_type, dir, out, name, ext, scope).template as<T> ();
   }
 
   pair<const rule*, match_result>
diff --git a/build2/bin/rule.cxx b/build2/bin/rule.cxx
index a73ad3d..9adb692 100644
--- a/build2/bin/rule.cxx
+++ b/build2/bin/rule.cxx
@@ -48,7 +48,7 @@ namespace build2
     match_result lib_rule::
     match (slock& ml, action act, target& xt, const string&) const
     {
-      lib& t (static_cast<lib&> (xt));
+      lib& t (xt.as<lib> ());
 
       // @@ We have to re-query it on each match_only()!
 
@@ -104,7 +104,7 @@ namespace build2
     recipe lib_rule::
     apply (slock& ml, action act, target& xt) const
     {
-      lib& t (static_cast<lib&> (xt));
+      lib& t (xt.as<lib> ());
 
       const match_data& md (t.data<match_data> ());
       const string& type (md.type);
@@ -126,7 +126,7 @@ namespace build2
     target_state lib_rule::
     perform (action act, const target& xt)
     {
-      const lib& t (static_cast<const lib&> (xt));
+      const lib& t (xt.as<lib> ());
 
       const match_data& md (t.data<match_data> ());
       const string& type (md.type);
diff --git a/build2/cc/common.cxx b/build2/cc/common.cxx
index 654ff53..7b8499c 100644
--- a/build2/cc/common.cxx
+++ b/build2/cc/common.cxx
@@ -439,7 +439,7 @@ namespace build2
       if (const lib* l = xt->is_a<lib> ())
         xt = &link_member (*l, lo); // Pick liba{} or libs{}.
 
-      return static_cast<const file&> (*xt);
+      return xt->as<file> ();
     }
 
     // Note that pk's scope should not be NULL (even if dir is absolute). If
@@ -563,7 +563,7 @@ namespace build2
                                 trace));
 
         assert (!exist || !p.second);
-        r = static_cast<T*> (&p.first);
+        r = &p.first.template as<T> ();
       };
 
       auto search =[&a, &s,
diff --git a/build2/cc/compile.cxx b/build2/cc/compile.cxx
index 98d1218..5090f11 100644
--- a/build2/cc/compile.cxx
+++ b/build2/cc/compile.cxx
@@ -115,7 +115,7 @@ namespace build2
           continue;
 
         process_libraries (bs, lo, sys_lib_dirs,
-                           static_cast<const file&> (*pt), a,
+                           pt->as<file> (), a,
                            nullptr, nullptr, optf);
       }
     }
@@ -155,7 +155,7 @@ namespace build2
           continue;
 
         process_libraries (bs, lo, sys_lib_dirs,
-                           static_cast<const file&> (*pt), a,
+                           pt->as<file> (), a,
                            nullptr, nullptr, optf);
       }
     }
@@ -198,7 +198,7 @@ namespace build2
           continue;
 
         process_libraries (bs, lo, sys_lib_dirs,
-                           static_cast<const file&> (*pt), a,
+                           pt->as<file> (), a,
                            nullptr, nullptr, optf);
       }
     }
@@ -208,7 +208,7 @@ namespace build2
     {
       tracer trace (x, "compile::apply");
 
-      file& t (static_cast<file&> (xt));
+      file& t (xt.as<file> ());
       const match_data& md (t.data<match_data> ());
 
       const scope& bs (t.base_scope ());
@@ -1405,7 +1405,7 @@ namespace build2
     target_state compile::
     perform_update (action a, const target& xt) const
     {
-      const file& t (static_cast<const file&> (xt));
+      const file& t (xt.as<file> ());
 
       // Update prerequisites and determine if any relevant ones render us
       // out-of-date. Note that currently we treat all the prerequisites
@@ -1632,7 +1632,7 @@ namespace build2
     target_state compile::
     perform_clean (action a, const target& xt) const
     {
-      const file& t (static_cast<const file&> (xt));
+      const file& t (xt.as<file> ());
 
       if (cid == "msvc")
         return clean_extra (a, t, {".d", ".idb", ".pdb"});
diff --git a/build2/cc/link.cxx b/build2/cc/link.cxx
index 6c17037..2bdf8c1 100644
--- a/build2/cc/link.cxx
+++ b/build2/cc/link.cxx
@@ -297,7 +297,7 @@ namespace build2
         lk = b;
         append_ext (lk);
 
-        libi& li (static_cast<libi&> (*ls.member));
+        libi& li (ls.member->as<libi> ());
         lk = li.derive_path (move (lk), tsys == "mingw32" ? "a" : "lib");
       }
       else if (!v.empty ())
@@ -322,7 +322,7 @@ namespace build2
 
       tracer trace (x, "link::apply");
 
-      file& t (static_cast<file&> (xt));
+      file& t (xt.as<file> ());
 
       const scope& bs (t.base_scope ());
       const scope& rs (*bs.root_scope ());
@@ -341,7 +341,7 @@ namespace build2
         else
           t.member = &search (tt, t.dir, t.out, t.name, nullptr, nullptr);
 
-        file& r (static_cast<file&> (*t.member));
+        file& r (t.member->as<file> ());
         r.recipe (a, group_recipe);
         return r;
       };
@@ -541,7 +541,7 @@ namespace build2
         //
         if (group)
         {
-          obj& o (static_cast<obj&> (ot));
+          obj& o (ot.as<obj> ());
 
           switch (lt)
           {
@@ -680,7 +680,7 @@ namespace build2
           // (see search_library() for details).
           //
           if (win && f->member != nullptr && f->is_a<libs> ())
-            f = static_cast<const file*> (f->member.get ());
+            f = &f->member->as<file> ();
 
           args.push_back (relative (f->path ()).string ());
         }
@@ -727,7 +727,7 @@ namespace build2
           // (see search_library() for details).
           //
           if (win && f->member != nullptr && f->is_a<libs> ())
-            f = static_cast<const file*> (f->member.get ());
+            f = &f->member->as<file> ();
 
           cs.append (f->path ().string ());
         }
@@ -893,11 +893,11 @@ namespace build2
     {
       tracer trace (x, "link::perform_update");
 
+      const file& t (xt.as<file> ());
+
       auto oop (a.outer_operation ());
       bool for_install (oop == install_id || oop == uninstall_id);
 
-      const file& t (static_cast<const file&> (xt));
-
       const scope& bs (t.base_scope ());
       const scope& rs (*bs.root_scope ());
 
@@ -1369,7 +1369,7 @@ 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<const file&> (*t.member));
+              auto& imp (t.member->as<file> ());
               out2 = "/IMPLIB:" + relative (imp.path ()).string ();
               args.push_back (out2.c_str ());
             }
@@ -1379,9 +1379,9 @@ namespace build2
             //
             if (find_option ("/DEBUG", args, true))
             {
+
               auto& pdb (
-                static_cast<const file&> (
-                  lt == otype::e ? *t.member : *t.member->member));
+                (lt == otype::e ? t.member : t.member->member)->as<file> ());
               out1 = "/PDB:" + relative (pdb.path ()).string ();
               args.push_back (out1.c_str ());
             }
@@ -1415,7 +1415,7 @@ namespace build2
                 // On Windows libs{} is the DLL and its first ad hoc group
                 // member is the import library.
                 //
-                auto& imp (static_cast<const file&> (*t.member));
+                auto& imp (t.member->as<file> ());
                 out = "-Wl,--out-implib=" + relative (imp.path ()).string ();
                 args.push_back (out.c_str ());
               }
@@ -1629,7 +1629,7 @@ namespace build2
     target_state link::
     perform_clean (action a, const target& xt) const
     {
-      const file& t (static_cast<const file&> (xt));
+      const file& t (xt.as<file> ());
 
       switch (link_type (t))
       {
diff --git a/build2/cc/msvc.cxx b/build2/cc/msvc.cxx
index 86a7d38..94064ca 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<const file&> (*t.member).path ().leaf ());
+          path imp (t.member->as<file> ().path ().leaf ());
 
           if (l.find (imp.string ()) != string::npos &&
               l.find (imp.base ().string () + ".exp") != string::npos)
@@ -276,7 +276,7 @@ namespace build2
                                 true, // Implied.
                                 trace));
         assert (!exist || !p.second);
-        T& t (static_cast<T&> (p.first));
+        T& t (p.first.template as<T> ());
 
         if (t.path ().empty ())
           t.path (move (f));
@@ -340,7 +340,7 @@ namespace build2
                                   true, // Implied.
                                   trace));
           assert (!exist || !p.second);
-          r = static_cast<libs*> (&p.first);
+          r = &p.first.as<libs> ();
 
           if (r->member == nullptr)
           {
diff --git a/build2/cc/windows-rpath.cxx b/build2/cc/windows-rpath.cxx
index 94b1145..46a3d3a 100644
--- a/build2/cc/windows-rpath.cxx
+++ b/build2/cc/windows-rpath.cxx
@@ -137,8 +137,7 @@ namespace build2
             //
             const string* pdb (
               l->member != nullptr && l->member->member != nullptr
-              ? &static_cast<const file&> (
-                  *l->member->member).path ().string ()
+              ? &l->member->member->as<file> ().path ().string ()
               : nullptr);
 
             r.insert (windows_dll {f, pdb, string ()});
diff --git a/build2/cli/rule b/build2/cli/rule
index 1fbbde4..03fd471 100644
--- a/build2/cli/rule
+++ b/build2/cli/rule
@@ -14,6 +14,8 @@ namespace build2
 {
   namespace cli
   {
+    // @@ Redo as two separate rules?
+    //
     class compile: public rule
     {
     public:
diff --git a/build2/cli/rule.cxx b/build2/cli/rule.cxx
index 5dcec99..7928c5c 100644
--- a/build2/cli/rule.cxx
+++ b/build2/cli/rule.cxx
@@ -199,7 +199,7 @@ namespace build2
       }
       else
       {
-        cli_cxx& g (static_cast<cli_cxx&> (*xt.group));
+        cli_cxx& g (xt.group->as<cli_cxx> ());
         build2::match (ml, a, g);
         return group_recipe; // Execute the group's recipe.
       }
@@ -230,7 +230,7 @@ namespace build2
     target_state compile::
     perform_update (action a, const target& xt)
     {
-      const cli_cxx& t (static_cast<const cli_cxx&> (xt));
+      const cli_cxx& t (xt.as<cli_cxx> ());
 
       // Update prerequisites and determine if any relevant ones render us
       // out-of-date. Note that currently we treat all the prerequisites
@@ -322,7 +322,7 @@ namespace build2
     target_state compile::
     perform_clean (action a, const target& xt)
     {
-      const cli_cxx& t (static_cast<const cli_cxx&> (xt));
+      const cli_cxx& t (xt.as<cli_cxx> ());
 
       // The reverse order of update: first delete the files, then clean
       // prerequisites. Also update timestamp in case there are operations
diff --git a/build2/install/rule.cxx b/build2/install/rule.cxx
index 3be7eef..3a5bd3d 100644
--- a/build2/install/rule.cxx
+++ b/build2/install/rule.cxx
@@ -614,7 +614,7 @@ namespace build2
     target_state file_rule::
     perform_install (action a, const target& xt) const
     {
-      const file& t (static_cast<const file&> (xt));
+      const file& t (xt.as<file> ());
       assert (!t.path ().empty ()); // Should have been assigned by update.
 
       auto install_target = [this] (const file& t, const path& p, bool verbose)
@@ -663,7 +663,7 @@ namespace build2
       for (const target* m (t.member); m != nullptr; m = m->member)
       {
         if (const path* p = lookup_install<path> (*m, "install"))
-          install_target (static_cast<const file&> (*m), *p, false);
+          install_target (m->as<file> (), *p, false);
       }
 
       // Finally install the target itself (since we got here we know the
@@ -872,7 +872,7 @@ namespace build2
     target_state file_rule::
     perform_uninstall (action a, const target& xt) const
     {
-      const file& t (static_cast<const file&> (xt));
+      const file& t (xt.as<file> ());
       assert (!t.path ().empty ()); // Should have been assigned by update.
 
       auto uninstall_target = [this] (
@@ -930,9 +930,8 @@ namespace build2
       for (const target* m (t.member); m != nullptr; m = m->member)
       {
         if (const path* p = lookup_install<path> (*m, "install"))
-          r |= uninstall_target (static_cast<const file&> (*m),
-                                 *p,
-                                 r != target_state::changed);
+          r |= uninstall_target (
+            m->as<file> (), *p, r != target_state::changed);
       }
 
       // Finally handle installable prerequisites.
diff --git a/build2/target b/build2/target
index 2eb6a2c..48c80e7 100644
--- a/build2/target
+++ b/build2/target
@@ -112,8 +112,6 @@ namespace build2
     optional<string>* ext_; // Reference to value in target_key.
 
   public:
-    using action_type = build2::action;
-
     // For targets that are in the src tree of a project we also keep the
     // corresponding out directory. As a result we may end up with multiple
     // targets for the same file if we are building multiple configurations of
@@ -240,6 +238,8 @@ namespace build2
     }
 
   public:
+    using action_type = build2::action;
+
     // Reset the target before matching it to a rule. The default
     // implementation clears the auxilary data and prerequisite_targets.
     //
@@ -540,9 +540,12 @@ namespace build2
   private:
     recipe_type recipe_;
 
-    // Target type info.
+    // Target type info and casting.
     //
   public:
+    bool
+    is_a (const target_type& tt) const {return type ().is_a (tt);}
+
     template <typename T>
     T*
     is_a () {return dynamic_cast<T*> (this);}
@@ -551,8 +554,15 @@ namespace build2
     const T*
     is_a () const {return dynamic_cast<const T*> (this);}
 
-    bool
-    is_a (const target_type& tt) const {return type ().is_a (tt);}
+    // Unchecked cast.
+    //
+    template <typename T>
+    T&
+    as () {return static_cast<T&> (*this);}
+
+    template <typename T>
+    const T&
+    as () const {return static_cast<const T&> (*this);}
 
     // Dynamic derivation to support define.
     //
@@ -1074,14 +1084,13 @@ namespace build2
             optional<string> ext,
             tracer& t)
     {
-      return static_cast<T&> (
-        insert (tt,
-                move (dir),
-                move (out),
-                move (name),
-                move (ext),
-                true,
-                t).first);
+      return insert (tt,
+                     move (dir),
+                     move (out),
+                     move (name),
+                     move (ext),
+                     true,
+                     t).first.template as<T> ();
     }
 
     template <typename T>
@@ -1092,8 +1101,7 @@ namespace build2
             const optional<string>& ext,
             tracer& t)
     {
-      return static_cast<T&> (
-        insert (T::static_type, dir, out, name, ext, true, t).first);
+      return insert<T> (T::static_type, dir, out, name, ext, t);
     }
 
     template <typename T>
@@ -1103,8 +1111,7 @@ namespace build2
             const string& name,
             tracer& t)
     {
-      return static_cast<T&> (
-        insert (T::static_type, dir, out, name, nullopt, true, t).first);
+      return insert<T> (dir, out, name, nullopt, t);
     }
 
     // Note: not MT-safe so can only be used during serial execution.
@@ -1149,7 +1156,7 @@ namespace build2
     mtime (bool load = true) const
     {
       const mtime_target& t (state_ == target_state::group
-                             ? static_cast<const mtime_target&> (*group)
+                             ? group->as<mtime_target> ()
                              : *this);
 
       if (load && t.mtime_ == timestamp_unknown)
diff --git a/build2/test/rule.cxx b/build2/test/rule.cxx
index 38c24f9..35302e1 100644
--- a/build2/test/rule.cxx
+++ b/build2/test/rule.cxx
@@ -640,7 +640,7 @@ namespace build2
       auto& pts (tt.prerequisite_targets);
       if (pts.size () != 0 && pts[0] != nullptr)
       {
-        const file& it (static_cast<const file&> (*pts[0]));
+        const file& it (pts[0]->as<file> ());
         assert (!it.path ().empty ()); // Should have been assigned by update.
         args.push_back (it.path ().string ().c_str ());
       }
@@ -660,7 +660,7 @@ namespace build2
       process_path dpp;
       if (pts.size () != 0 && pts[1] != nullptr)
       {
-        const file& ot (static_cast<const file&> (*pts[1]));
+        const file& ot (pts[1]->as<file> ());
         assert (!ot.path ().empty ()); // Should have been assigned by update.
 
         dpp = run_search (dp, true);