Redesign obj to exe/lib mapping

Specifically:

* objso{} and libso{} target types have been renamed to objs{} and libs{}

* obje{} has been added (so now we have obje{}, obja{}, and objs{})

* obje{} is now used for building exe{}

* object file extensions have been changed to use "hierarchical extensions"
  that reflect the extension of the corresponding exe/lib target (instead of
  the -so suffix we used), specifically:

  obje{}: foo.o, (UNIX), foo.exe.o (MinGW), foo.exe.obj (Windows)
  obja{}: foo.a.o (UNIX, MinGW), foo.lib.obj (Windows)
  objs{}: foo.so.o (UNIX), foo.dylib.o (Darwin), foo.dll.o (MinGW),
          foo.dll.obj (Windows)

15 files changed, 463 insertions, 284 deletions

diff --git a/build2/bin/module.cxx b/build2/bin/module.cxx
index 306d8de..334384a 100644
--- a/build2/bin/module.cxx
+++ b/build2/bin/module.cxx
@@ -31,7 +31,7 @@ namespace build2
     //
     static const strings exe_lib {"shared", "static"};
     static const strings liba_lib {"static"};
-    static const strings libso_lib {"shared"};
+    static const strings libs_lib {"shared"};
 
     // Apply the specified stem to the config.bin.pattern. If there is no
     // pattern, then return the stem itself. Assume the pattern is valid,
@@ -73,22 +73,22 @@ namespace build2
 
         // Note: some overridable, some not.
         //
-        v.insert<string>    ("config.bin.target",    true);
-        v.insert<string>    ("config.bin.pattern",   true);
+        v.insert<string>    ("config.bin.target",   true);
+        v.insert<string>    ("config.bin.pattern",  true);
 
-        v.insert<path>      ("config.bin.ar",        true);
-        v.insert<path>      ("config.bin.ranlib",    true);
+        v.insert<path>      ("config.bin.ar",       true);
+        v.insert<path>      ("config.bin.ranlib",   true);
 
-        v.insert<string>    ("config.bin.lib",       true);
-        v.insert<strings>   ("config.bin.exe.lib",   true);
-        v.insert<strings>   ("config.bin.liba.lib",  true);
-        v.insert<strings>   ("config.bin.libso.lib", true);
-        v.insert<dir_paths> ("config.bin.rpath",     true);
+        v.insert<string>    ("config.bin.lib",      true);
+        v.insert<strings>   ("config.bin.exe.lib",  true);
+        v.insert<strings>   ("config.bin.liba.lib", true);
+        v.insert<strings>   ("config.bin.libs.lib", true);
+        v.insert<dir_paths> ("config.bin.rpath",    true);
 
         v.insert<string>    ("bin.lib");
         v.insert<strings>   ("bin.exe.lib");
         v.insert<strings>   ("bin.liba.lib");
-        v.insert<strings>   ("bin.libso.lib");
+        v.insert<strings>   ("bin.libs.lib");
         v.insert<dir_paths> ("bin.rpath");
 
         v.insert<string>    ("bin.libprefix",        true);
@@ -133,12 +133,12 @@ namespace build2
           v = required (r, "config.bin.liba.lib", liba_lib).first;
       }
 
-      // config.bin.libso.lib
+      // config.bin.libs.lib
       //
       {
-        value& v (b.assign ("bin.libso.lib"));
+        value& v (b.assign ("bin.libs.lib"));
         if (!v)
-          v = required (r, "config.bin.libso.lib", libso_lib).first;
+          v = required (r, "config.bin.libs.lib", libs_lib).first;
       }
 
       // config.bin.rpath
@@ -353,13 +353,14 @@ namespace build2
       {
         auto& t (b.target_types);
 
-        t.insert<obja>  ();
-        t.insert<objso> ();
-        t.insert<obj>   ();
-        t.insert<exe>   ();
-        t.insert<liba>  ();
-        t.insert<libso> ();
-        t.insert<lib>   ();
+        t.insert<obje> ();
+        t.insert<obja> ();
+        t.insert<objs> ();
+        t.insert<obj>  ();
+        t.insert<exe>  ();
+        t.insert<liba> ();
+        t.insert<libs> ();
+        t.insert<lib>  ();
       }
 
       // Register rules.
@@ -407,15 +408,15 @@ namespace build2
       // And a library that wants to override any such overrides (e.g.,
       // because it does have main()) can do:
       //
-      // libso{foo}: install.mode=755
+      // libs{foo}: install.mode=755
       //
       // Everyone is happy then? Not Windows users. When targeting Windows
-      // libso{} is an import library and shouldn't be exec.
+      // libs{} is an import library and shouldn't be exec.
       //
-      install_path<libso> (b, dir_path ("lib")); // Install into install.lib.
+      install_path<libs> (b, dir_path ("lib")); // Install into install.lib.
 
       if (tclass == "windows")
-        install_mode<libso> (b, "644");
+        install_mode<libs> (b, "644");
 
       install_path<liba> (b, dir_path ("lib"));  // Install into install.lib.
       install_mode<liba> (b, "644");
diff --git a/build2/bin/rule.cxx b/build2/bin/rule.cxx
index 072e931..7710a53 100644
--- a/build2/bin/rule.cxx
+++ b/build2/bin/rule.cxx
@@ -23,7 +23,7 @@ namespace build2
     match (action a, target& t, const string&) const
     {
       fail << diag_doing (a, t) << " target group" <<
-        info << "explicitly select either obja{} or objso{} member";
+        info << "explicitly select obje{}, obja{}, or objs{} member";
 
       return nullptr;
     }
@@ -33,25 +33,25 @@ namespace build2
 
     // lib
     //
-    // The whole logic is pretty much as if we had our two group
-    // members as our prerequisites.
+    // The whole logic is pretty much as if we had our two group members as
+    // our prerequisites.
     //
     match_result lib_rule::
-    match (action a, target& xt, const string&) const
+    match (action act, target& xt, const string&) const
     {
       lib& t (static_cast<lib&> (xt));
 
       // @@ We have to re-query it on each match_only()!
 
       // Get the library type to build. If not set for a target, this
-      // should be configured at the project scope by init_lib().
+      // should be configured at the project scope by init().
       //
       const string& type (cast<string> (t["bin.lib"]));
 
-      bool ar (type == "static" || type == "both");
-      bool so (type == "shared" || type == "both");
+      bool a (type == "static" || type == "both");
+      bool s (type == "shared" || type == "both");
 
-      if (!ar && !so)
+      if (!a && !s)
         fail << "unknown library type: " << type <<
           info << "'static', 'shared', or 'both' expected";
 
@@ -63,20 +63,20 @@ namespace build2
       // meta-information about the library, such as the options to use
       // when linking it, etc.
       //
-      if (ar)
+      if (a)
       {
         if (t.a == nullptr)
           t.a = &search<liba> (t.dir, t.out, t.name, nullptr, nullptr);
 
-        match_only (a, *t.a);
+        match_only (act, *t.a);
       }
 
-      if (so)
+      if (s)
       {
-        if (t.so == nullptr)
-          t.so = &search<libso> (t.dir, t.out, t.name, nullptr, nullptr);
+        if (t.s == nullptr)
+          t.s = &search<libs> (t.dir, t.out, t.name, nullptr, nullptr);
 
-        match_only (a, *t.so);
+        match_only (act, *t.s);
       }
 
       match_result mr (t, &type);
@@ -84,35 +84,35 @@ namespace build2
       // If there is an outer operation, indicate that we match
       // unconditionally so that we don't override ourselves.
       //
-      if (a.outer_operation () != 0)
-        mr.recipe_action = action (a.meta_operation (), a.operation ());
+      if (act.outer_operation () != 0)
+        mr.recipe_action = action (act.meta_operation (), act.operation ());
 
       return mr;
     }
 
     recipe lib_rule::
-    apply (action a, target& xt, const match_result& mr) const
+    apply (action act, target& xt, const match_result& mr) const
     {
       lib& t (static_cast<lib&> (xt));
 
       const string& type (*static_cast<const string*> (mr.cpvalue));
 
-      bool ar (type == "static" || type == "both");
-      bool so (type == "shared" || type == "both");
+      bool a (type == "static" || type == "both");
+      bool s (type == "shared" || type == "both");
 
       // Now we do full match.
       //
-      if (ar)
-        build2::match (a, *t.a);
+      if (a)
+        build2::match (act, *t.a);
 
-      if (so)
-        build2::match (a, *t.so);
+      if (s)
+        build2::match (act, *t.s);
 
       return &perform;
     }
 
     target_state lib_rule::
-    perform (action a, target& xt)
+    perform (action act, target& xt)
     {
       lib& t (static_cast<lib&> (xt));
 
@@ -122,11 +122,12 @@ namespace build2
       //
       //
       const string& type (cast<string> (t["bin.lib"]));
-      bool ar (type == "static" || type == "both");
-      bool so (type == "shared" || type == "both");
 
-      target* m1 (ar ? t.a : nullptr);
-      target* m2 (so ? t.so : nullptr);
+      bool a (type == "static" || type == "both");
+      bool s (type == "shared" || type == "both");
+
+      target* m1 (a ? t.a : nullptr);
+      target* m2 (s ? t.s : nullptr);
 
       if (current_mode == execution_mode::last)
         swap (m1, m2);
@@ -134,10 +135,10 @@ namespace build2
       target_state r (target_state::unchanged);
 
       if (m1 != nullptr)
-        r |= execute (a, *m1);
+        r |= execute (act, *m1);
 
       if (m2 != nullptr)
-        r |= execute (a, *m2);
+        r |= execute (act, *m2);
 
       return r;
     }
diff --git a/build2/bin/target b/build2/bin/target
index f386592..8c32e84 100644
--- a/build2/bin/target
+++ b/build2/bin/target
@@ -16,6 +16,16 @@ namespace build2
   {
     // The obj{} target group.
     //
+    class obje: public file
+    {
+    public:
+      using file::file;
+
+    public:
+      static const target_type static_type;
+      virtual const target_type& dynamic_type () const {return static_type;}
+    };
+
     class obja: public file
     {
     public:
@@ -26,7 +36,7 @@ namespace build2
       virtual const target_type& dynamic_type () const {return static_type;}
     };
 
-    class objso: public file
+    class objs: public file
     {
     public:
       using file::file;
@@ -41,8 +51,9 @@ namespace build2
     public:
       using target::target;
 
+      obje* e {nullptr};
       obja* a {nullptr};
-      objso* so {nullptr};
+      objs* s {nullptr};
 
     public:
       static const target_type static_type;
@@ -71,7 +82,7 @@ namespace build2
       virtual const target_type& dynamic_type () const {return static_type;}
     };
 
-    class libso: public file
+    class libs: public file
     {
     public:
       using file::file;
@@ -87,7 +98,7 @@ namespace build2
       using target::target;
 
       liba* a {nullptr};
-      libso* so {nullptr};
+      libs* s {nullptr};
 
       virtual void
       reset (action_type);
diff --git a/build2/bin/target.cxx b/build2/bin/target.cxx
index f141d97..3f16467 100644
--- a/build2/bin/target.cxx
+++ b/build2/bin/target.cxx
@@ -13,14 +13,41 @@ namespace build2
     extern const char ext_var[] = "extension"; // VC 19 rejects constexpr.
 
     static target*
+    obje_factory (const target_type&,
+                  dir_path dir,
+                  dir_path out,
+                  string n,
+                  const string* ext)
+    {
+      obj* o (targets.find<obj> (dir, out, n));
+      obje* e (new obje (move (dir), move (out), move (n), ext));
+
+      if ((e->group = o))
+        o->e = e;
+
+      return e;
+    }
+
+    const target_type obje::static_type
+    {
+      "obje",
+      &file::static_type,
+      &obje_factory,
+      &target_extension_var<ext_var, nullptr>,
+      nullptr,
+      &search_target, // Note: not _file(); don't look for an existing file.
+      false
+    };
+
+    static target*
     obja_factory (const target_type&,
                   dir_path dir,
                   dir_path out,
                   string n,
-                  const string* e)
+                  const string* ext)
     {
       obj* o (targets.find<obj> (dir, out, n));
-      obja* a (new obja (move (dir), move (out), move (n), e));
+      obja* a (new obja (move (dir), move (out), move (n), ext));
 
       if ((a->group = o))
         o->a = a;
@@ -40,26 +67,26 @@ namespace build2
     };
 
     static target*
-    objso_factory (const target_type&,
+    objs_factory (const target_type&,
                    dir_path dir,
                    dir_path out,
                    string n,
-                   const string* e)
+                   const string* ext)
     {
       obj* o (targets.find<obj> (dir, out, n));
-      objso* so (new objso (move (dir), move (out), move (n), e));
+      objs* s (new objs (move (dir), move (out), move (n), ext));
 
-      if ((so->group = o))
-        o->so = so;
+      if ((s->group = o))
+        o->s = s;
 
-      return so;
+      return s;
     }
 
-    const target_type objso::static_type
+    const target_type objs::static_type
     {
-      "objso",
+      "objs",
       &file::static_type,
-      &objso_factory,
+      &objs_factory,
       &target_extension_var<ext_var, nullptr>,
       nullptr,
       &search_target, // Note: not _file(); don't look for an existing file.
@@ -71,17 +98,22 @@ namespace build2
                  dir_path dir,
                  dir_path out,
                  string n,
-                 const string* e)
+                 const string* ext)
     {
+      obje* e (targets.find<obje> (dir, out, n));
       obja* a (targets.find<obja> (dir, out, n));
-      objso* so (targets.find<objso> (dir, out, n));
-      obj* o (new obj (move (dir), move (out), move (n), e));
+      objs* s (targets.find<objs> (dir, out, n));
+
+      obj* o (new obj (move (dir), move (out), move (n), ext));
+
+      if ((o->e = e))
+        e->group = o;
 
       if ((o->a = a))
         a->group = o;
 
-      if ((o->so = so))
-        so->group = o;
+      if ((o->s = s))
+        s->group = o;
 
       return o;
     }
@@ -124,12 +156,12 @@ namespace build2
                   dir_path d,
                   dir_path o,
                   string n,
-                  const string* e)
+                  const string* ext)
     {
       // Only link-up to the group if the types match exactly.
       //
       lib* l (t == liba::static_type ? targets.find<lib> (d, o, n) : nullptr);
-      liba* a (new liba (move (d), move (o), move (n), e));
+      liba* a (new liba (move (d), move (o), move (n), ext));
 
       if ((a->group = l))
         l->a = a;
@@ -161,28 +193,28 @@ namespace build2
     };
 
     static target*
-    libso_factory (const target_type& t,
-                   dir_path d,
-                   dir_path o,
-                   string n,
-                   const string* e)
+    libs_factory (const target_type& t,
+                  dir_path d,
+                  dir_path o,
+                  string n,
+                  const string* ext)
     {
       // Only link-up to the group if the types match exactly.
       //
-      lib* l (t == libso::static_type ? targets.find<lib> (d, o, n) : nullptr);
-      libso* so (new libso (move (d), move (o), move (n), e));
+      lib* l (t == libs::static_type ? targets.find<lib> (d, o, n) : nullptr);
+      libs* s (new libs (move (d), move (o), move (n), ext));
 
-      if ((so->group = l))
-        l->so = so;
+      if ((s->group = l))
+        l->s = s;
 
-      return so;
+      return s;
     }
 
-    const target_type libso::static_type
+    const target_type libs::static_type
     {
-      "libso",
+      "libs",
       &file::static_type,
-      &libso_factory,
+      &libs_factory,
       &target_extension_var<ext_var, nullptr>,
       nullptr,
       &search_file,
@@ -203,17 +235,18 @@ namespace build2
                  dir_path d,
                  dir_path o,
                  string n,
-                 const string* e)
+                 const string* ext)
     {
       liba* a (targets.find<liba> (d, o, n));
-      libso* so (targets.find<libso> (d, o, n));
-      lib* l (new lib (move (d), move (o), move (n), e));
+      libs* s (targets.find<libs> (d, o, n));
+
+      lib* l (new lib (move (d), move (o), move (n), ext));
 
       if ((l->a = a))
         a->group = l;
 
-      if ((l->so = so))
-        so->group = l;
+      if ((l->s = s))
+        s->group = l;
 
       return l;
     }
diff --git a/build2/buildfile b/build2/buildfile
index 5474fbd..cbd09e8 100644
--- a/build2/buildfile
+++ b/build2/buildfile
@@ -44,6 +44,7 @@ exe{b}:                                       \
  config/{hxx         cxx}{ module           } \
  config/{hxx         cxx}{ operation        } \
  config/{hxx     txx cxx}{ utility          } \
+    cxx/{hxx         cxx}{ common           } \
     cxx/{hxx         cxx}{ compile          } \
     cxx/{hxx         cxx}{ guess            } \
     cxx/{hxx         cxx}{ install          } \
diff --git a/build2/cxx/common b/build2/cxx/common
new file mode 100644
index 0000000..77f1149
--- /dev/null
+++ b/build2/cxx/common
@@ -0,0 +1,60 @@
+// file      : build2/cxx/common -*- C++ -*-
+// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef BUILD2_CXX_COMMON
+#define BUILD2_CXX_COMMON
+
+#include <build2/types>
+#include <build2/utility>
+
+#include <build2/bin/target>
+
+namespace build2
+{
+  namespace cxx
+  {
+    // Compile/link output type (executable, static, or shared).
+    //
+    enum class otype {e, a, s};
+
+    inline otype
+    compile_type (target& t)
+    {
+      return
+        t.is_a<bin::obje> () ? otype::e :
+        t.is_a<bin::obja> () ? otype::a :
+        otype::s;
+    }
+
+    inline otype
+    link_type (target& t)
+    {
+      return
+        t.is_a<bin::exe> ()  ? otype::e :
+        t.is_a<bin::liba> () ? otype::a :
+        otype::s;
+    }
+
+    // Library link order.
+    //
+    enum class lorder {a, s, a_s, s_a};
+
+    // The reason we pass scope and not the target is because this function is
+    // called not only for exe/lib but also for obj as part of the library
+    // meta-information protocol implementation. Normally the bin.*.lib values
+    // will be project-wide. With this scheme they can be customized on the
+    // per-directory basis but not per-target which means all exe/lib in the
+    // same directory have to have the same link order.
+    //
+    lorder
+    link_order (scope& base, otype);
+
+    // Given the link order return the library member (liba or libs) to link.
+    //
+    target&
+    link_member (bin::lib&, lorder);
+  }
+}
+
+#endif // BUILD2_CXX_COMMON
diff --git a/build2/cxx/common.cxx b/build2/cxx/common.cxx
new file mode 100644
index 0000000..0b66eb5
--- /dev/null
+++ b/build2/cxx/common.cxx
@@ -0,0 +1,70 @@
+// file      : build2/cxx/common.cxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#include <build2/cxx/common>
+
+#include <build2/variable>
+#include <build2/algorithm>
+
+using namespace std;
+
+namespace build2
+{
+  namespace cxx
+  {
+    using namespace bin;
+
+    lorder
+    link_order (scope& bs, otype ot)
+    {
+      const char* var;
+
+      switch (ot)
+      {
+      case otype::e: var = "bin.exe.lib";  break;
+      case otype::a: var = "bin.liba.lib"; break;
+      case otype::s: var = "bin.libs.lib"; break;
+      }
+
+      const auto& v (cast<strings> (bs[var]));
+      return v[0] == "shared"
+        ? v.size () > 1 && v[1] == "static" ? lorder::s_a : lorder::s
+        : v.size () > 1 && v[1] == "shared" ? lorder::a_s : lorder::a;
+    }
+
+    target&
+    link_member (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
+              fail << (ls ? "shared" : "static") << " variant of " << l
+                   << " is not available";
+          }
+        }
+      }
+
+      target* r (ls ? static_cast<target*> (l.s) : l.a);
+
+      if (r == nullptr)
+        r = &search (ls ? libs::static_type : liba::static_type,
+                     prerequisite_key {nullptr, l.key (), nullptr});
+
+      return *r;
+    }
+  }
+}
diff --git a/build2/cxx/compile.cxx b/build2/cxx/compile.cxx
index 504df7f..645e818 100644
--- a/build2/cxx/compile.cxx
+++ b/build2/cxx/compile.cxx
@@ -21,6 +21,7 @@
 #include <build2/cxx/target>
 
 #include <build2/cxx/link>
+#include <build2/cxx/common>
 #include <build2/cxx/utility>
 
 
@@ -69,15 +70,57 @@ namespace build2
       path_target& t (static_cast<path_target&> (xt));
 
       scope& rs (t.root_scope ());
+
       const string& cid (cast<string> (rs["cxx.id"]));
+      const string& tsys (cast<string> (rs["cxx.target.system"]));
       const string& tclass (cast<string> (rs["cxx.target.class"]));
 
+      otype ct (compile_type (t));
+
       // Derive file name from target name.
       //
       if (t.path ().empty ())
       {
-        const char* ext (cid == "msvc" ? "obj" : "o");
-        t.derive_path (ext, nullptr, (t.is_a<objso> () ? "-so" : nullptr));
+        const char* e (nullptr);
+
+        if (tsys == "win32-msvc")
+        {
+          switch (ct)
+          {
+          case otype::e: e = "exe.obj"; break;
+          case otype::a: e = "lib.obj"; break;
+          case otype::s: e = "dll.obj"; break;
+          }
+        }
+        else if (tsys == "mingw32")
+        {
+          switch (ct)
+          {
+          case otype::e: e = "exe.o"; break;
+          case otype::a: e = "a.o";   break;
+          case otype::s: e = "dll.o"; break;
+          }
+        }
+        else if (tsys == "darwin")
+        {
+          switch (ct)
+          {
+          case otype::e: e = "o";       break;
+          case otype::a: e = "a.o";     break;
+          case otype::s: e = "dylib.o"; break;
+          }
+        }
+        else
+        {
+          switch (ct)
+          {
+          case otype::e: e = "o"; break;
+          case otype::a: e = "a.o"; break;
+          case otype::s: e = "so.o"; break;
+          }
+        }
+
+        t.derive_path (e);
       }
 
       // Inject dependency on the output directory.
@@ -102,7 +145,7 @@ namespace build2
         // meta-information protocol". See also append_lib_options()
         // above.
         //
-        if (p.is_a<lib> () || p.is_a<liba> () || p.is_a<libso> ())
+        if (p.is_a<lib> () || p.is_a<liba> () || p.is_a<libs> ())
         {
           if (a.operation () == update_id)
           {
@@ -184,7 +227,7 @@ namespace build2
         {
           target& pt (*p.target); // Already searched and matched.
 
-          if (pt.is_a<lib> () || pt.is_a<liba> () || pt.is_a<libso> ())
+          if (pt.is_a<lib> () || pt.is_a<liba> () || pt.is_a<libs> ())
             hash_lib_options (cs, pt, "cxx.export.poptions");
         }
 
@@ -192,7 +235,7 @@ namespace build2
         hash_options (cs, t, "cxx.coptions");
         hash_std (cs, rs, cid, t);
 
-        if (t.is_a<objso> ())
+        if (ct == otype::s)
         {
           // On Darwin, Win32 -fPIC is the default.
           //
@@ -369,7 +412,7 @@ namespace build2
         if (t == nullptr)
           continue;
 
-        if (t->is_a<lib> () || t->is_a<liba> () || t->is_a<libso> ())
+        if (t->is_a<lib> () || t->is_a<liba> () || t->is_a<libs> ())
           append_lib_prefixes (m, *t);
       }
 
@@ -389,7 +432,7 @@ namespace build2
       {
         target& pt (*p.target); // Already searched and matched.
 
-        if (pt.is_a<lib> () || pt.is_a<liba> () || pt.is_a<libso> ())
+        if (pt.is_a<lib> () || pt.is_a<liba> () || pt.is_a<libs> ())
           append_lib_prefixes (m, pt);
       }
 
@@ -617,7 +660,7 @@ namespace build2
         {
           target& pt (*p.target); // Already searched and matched.
 
-          if (pt.is_a<lib> () || pt.is_a<liba> () || pt.is_a<libso> ())
+          if (pt.is_a<lib> () || pt.is_a<liba> () || pt.is_a<libs> ())
             append_lib_options (args, pt, "cxx.export.poptions");
         }
 
@@ -628,7 +671,7 @@ namespace build2
         append_options (args, t, "cxx.coptions");
         append_std (args, rs, cid, t, cxx_std);
 
-        if (t.is_a<objso> ())
+        if (t.is_a<objs> ())
         {
           // On Darwin, Win32 -fPIC is the default.
           //
@@ -1181,19 +1224,22 @@ namespace build2
       if (s == nullptr)
         return target_state::unchanged;
 
-      // Translate paths to relative (to working directory) ones. This
-      // results in easier to read diagnostics.
-      //
-      path relo (relative (t.path ()));
-      path rels (relative (s->path ()));
-
       scope& rs (t.root_scope ());
+
       const path& cxx (cast<path> (rs["config.cxx"]));
       const string& cid (cast<string> (rs["cxx.id"]));
       const string& tclass (cast<string> (rs["cxx.target.class"]));
 
+      otype ct (compile_type (t));
+
       cstrings args {cxx.string ().c_str ()};
 
+      // Translate paths to relative (to working directory) ones. This
+      // results in easier to read diagnostics.
+      //
+      path relo (relative (t.path ()));
+      path rels (relative (s->path ()));
+
       // Add cxx.export.poptions from prerequisite libraries. Note that
       // here we don't need to see group members (see apply()).
       //
@@ -1201,7 +1247,7 @@ namespace build2
       {
         target& pt (*p.target); // Already searched and matched.
 
-        if (pt.is_a<lib> () || pt.is_a<liba> () || pt.is_a<libso> ())
+        if (pt.is_a<lib> () || pt.is_a<liba> () || pt.is_a<libs> ())
           append_lib_options (args, pt, "cxx.export.poptions");
       }
 
@@ -1268,7 +1314,7 @@ namespace build2
       }
       else
       {
-        if (t.is_a<objso> ())
+        if (ct == otype::s)
         {
           // On Darwin, Win32 -fPIC is the default.
           //
diff --git a/build2/cxx/install.cxx b/build2/cxx/install.cxx
index f6f502a..e07d115 100644
--- a/build2/cxx/install.cxx
+++ b/build2/cxx/install.cxx
@@ -6,8 +6,9 @@
 
 #include <build2/bin/target>
 
-#include <build2/cxx/target>
 #include <build2/cxx/link>
+#include <build2/cxx/common>
+#include <build2/cxx/target>
 
 using namespace std;
 
@@ -31,17 +32,20 @@ namespace build2
       // If this is a shared library prerequisite, install it as long as it
       // is in the same amalgamation as we are.
       //
-      if ((t.is_a<exe> () || t.is_a<libso> ()) &&
-          (p.is_a<lib> () || p.is_a<libso> ()))
+      // @@ Shouldn't we also install a static library prerequisite of a
+      //    static library?
+      //
+      if ((t.is_a<exe> () || t.is_a<libs> ()) &&
+          (p.is_a<lib> () || p.is_a<libs> ()))
       {
         target* pt (&p.search ());
 
         // If this is the lib{} group, pick a member which we would link.
         //
         if (lib* l = pt->is_a<lib> ())
-          pt = &link::link_member (*l, link::link_order (t));
+          pt = &link_member (*l, link_order (t.base_scope (), link_type (t)));
 
-        if (pt->is_a<libso> ()) // Can be liba{}.
+        if (pt->is_a<libs> ()) // Can be liba{}.
           return pt->in (t.weak_scope ()) ? pt : nullptr;
       }
 
diff --git a/build2/cxx/link b/build2/cxx/link
index ca45e17..4f00ea0 100644
--- a/build2/cxx/link
+++ b/build2/cxx/link
@@ -33,26 +33,6 @@ namespace build2
 
       static link instance;
 
-    public:
-      enum class type {e, a, so};
-      enum class order {a, so, a_so, so_a};
-
-      static type
-      link_type (target& t)
-      {
-        return t.is_a<bin::exe> ()
-          ? type::e
-          : (t.is_a<bin::liba> () ? type::a : type::so);
-      }
-
-      static order
-      link_order (target&);
-
-      // Determine the library member (liba or libso) to link.
-      //
-      static target&
-      link_member (bin::lib&, order);
-
     private:
       friend class compile;
 
diff --git a/build2/cxx/link.cxx b/build2/cxx/link.cxx
index 181c2b8..002cd42 100644
--- a/build2/cxx/link.cxx
+++ b/build2/cxx/link.cxx
@@ -19,6 +19,7 @@
 #include <build2/bin/target>
 #include <build2/cxx/target>
 
+#include <build2/cxx/common>
 #include <build2/cxx/utility>
 
 using namespace std;
@@ -30,58 +31,6 @@ namespace build2
   {
     using namespace bin;
 
-    link::order link::
-    link_order (target& t)
-    {
-      const char* var;
-
-      switch (link_type (t))
-      {
-      case type::e:  var = "bin.exe.lib";   break;
-      case type::a:  var = "bin.liba.lib";  break;
-      case type::so: var = "bin.libso.lib"; break;
-      }
-
-      const auto& v (cast<strings> (t[var]));
-      return v[0] == "shared"
-        ? v.size () > 1 && v[1] == "static" ? order::so_a : order::so
-        : v.size () > 1 && v[1] == "shared" ? order::a_so : order::a;
-    }
-
-    target& link::
-    link_member (bin::lib& l, order lo)
-    {
-      bool lso (true);
-      const string& at (cast<string> (l["bin.lib"])); // Available types.
-
-      switch (lo)
-      {
-      case order::a:
-      case order::a_so:
-        lso = false; // Fall through.
-      case order::so:
-      case order::so_a:
-        {
-          if (lso ? at == "static" : at == "shared")
-          {
-            if (lo == order::a_so || lo == order::so_a)
-              lso = !lso;
-            else
-              fail << (lso ? "shared" : "static") << " build of " << l
-                   << " is not available";
-          }
-        }
-      }
-
-      target* r (lso ? static_cast<target*> (l.so) : l.a);
-
-      if (r == nullptr)
-        r = &search (lso ? libso::static_type : liba::static_type,
-                     prerequisite_key {nullptr, l.key (), nullptr});
-
-      return *r;
-    }
-
     // Extract system library search paths from GCC or compatible (Clang,
     // Intel C++) using the -print-search-dirs option.
     //
@@ -261,7 +210,7 @@ namespace build2
       const string& tsys (cast<string> (rs["cxx.target.system"]));
 
       bool l (p.is_a<lib> ());
-      const string* ext (l ? nullptr : p.ext); // Only for liba/libso.
+      const string* ext (l ? nullptr : p.ext); // Only for liba/libs.
 
       // Then figure out what we need to search for.
       //
@@ -302,12 +251,12 @@ namespace build2
         }
       }
 
-      // libso
+      // libs
       //
       path sn;
       const string* se (nullptr);
 
-      if (l || p.is_a<libso> ())
+      if (l || p.is_a<libs> ())
       {
         const char* e ("");
 
@@ -358,7 +307,7 @@ namespace build2
         spc = extract_library_paths (p.scope);
 
       liba* a (nullptr);
-      libso* s (nullptr);
+      libs* s (nullptr);
 
       path f; // Reuse the buffer.
       const dir_path* pd;
@@ -390,7 +339,7 @@ namespace build2
           }
         }
 
-        // libso
+        // libs
         //
         if (!sn.empty ())
         {
@@ -403,7 +352,7 @@ namespace build2
             // Above we searched for the import library (.dll.a) but if it's
             // not found, then we also search for the .dll (unless the
             // extension was specified explicitly) since we can link to it
-            // directly. Note also that the resulting libso{} would end up
+            // directly. Note also that the resulting libs{} would end up
             // being the .dll.
             //
             if (mt == timestamp_nonexistent && ext == nullptr)
@@ -416,7 +365,7 @@ namespace build2
 
           if (mt != timestamp_nonexistent)
           {
-            s = &targets.insert<libso> (d, dir_path (), p.name, se, trace);
+            s = &targets.insert<libs> (d, dir_path (), p.name, se, trace);
 
             if (s->path ().empty ())
               s->path (move (f));
@@ -444,7 +393,7 @@ namespace build2
         // It should automatically link-up to the members we have found.
         //
         assert (l.a == a);
-        assert (l.so == s);
+        assert (l.s == s);
 
         // Set the bin.lib variable to indicate what's available.
         //
@@ -474,11 +423,11 @@ namespace build2
       //
       // - if there is no .o, are we going to check if the one derived
       //   from target exist or can be built? A: No.
-      //   What if there is a library. Probably ok if .a, not if .so.
+      //   What if there is a library. Probably ok if static, not if shared,
       //   (i.e., a utility library).
       //
 
-      type lt (link_type (t));
+      otype lt (link_type (t));
 
       // Scan prerequisites and see if we can work with what we've got.
       //
@@ -495,22 +444,34 @@ namespace build2
         {
           seen_c = seen_c || true;
         }
+        else if (p.is_a<obj> ())
+        {
+          seen_obj = seen_obj || true;
+        }
+        else if (p.is_a<obje> ())
+        {
+          if (lt != otype::e)
+            fail << "obje{} as prerequisite of " << t;
+
+          seen_obj = seen_obj || true;
+        }
         else if (p.is_a<obja> ())
         {
-          if (lt == type::so)
-            fail << "shared library " << t << " prerequisite " << p
-                 << " is static object";
+          if (lt != otype::a)
+            fail << "obja{} as prerequisite of " << t;
 
           seen_obj = seen_obj || true;
         }
-        else if (p.is_a<objso> () ||
-                 p.is_a<obj> ())
+        else if (p.is_a<objs> ())
         {
+          if (lt != otype::s)
+            fail << "objs{} as prerequisite of " << t;
+
           seen_obj = seen_obj || true;
         }
-        else if (p.is_a<liba> ()  ||
-                 p.is_a<libso> () ||
-                 p.is_a<lib> ())
+        else if (p.is_a<lib> ()  ||
+                 p.is_a<liba> () ||
+                 p.is_a<libs> ())
         {
           seen_lib = seen_lib || true;
         }
@@ -530,7 +491,7 @@ namespace build2
       // "library meta-information protocol". Don't do this if we are
       // called from the install rule just to check if we would match.
       //
-      if (seen_lib && lt != type::e &&
+      if (seen_lib && lt != otype::e &&
           a.operation () != install_id && a.outer_operation () != install_id)
       {
         if (t.group != nullptr)
@@ -540,7 +501,7 @@ namespace build2
 
         for (prerequisite_member p: group_prerequisite_members (a, t))
         {
-          if (p.is_a<lib> () || p.is_a<liba> () || p.is_a<libso> ())
+          if (p.is_a<lib> () || p.is_a<liba> () || p.is_a<libs> ())
           {
             target* pt (nullptr);
 
@@ -583,9 +544,8 @@ namespace build2
       const string& tsys (cast<string> (rs["cxx.target.system"]));
       const string& tclass (cast<string> (rs["cxx.target.class"]));
 
-      type lt (link_type (t));
-      order lo (link_order (t));
-      bool so (lt == type::so);
+      otype lt (link_type (t));
+      lorder lo (link_order (bs, lt));
 
       // Derive file name from target name.
       //
@@ -596,7 +556,7 @@ namespace build2
 
         switch (lt)
         {
-        case type::e:
+        case otype::e:
           {
             if (tclass == "windows")
               e = "exe";
@@ -605,7 +565,7 @@ namespace build2
 
             break;
           }
-        case type::a:
+        case otype::a:
           {
             // To be anally precise, let's use the ar id to decide how to name
             // the library in case, for example, someone wants to archive
@@ -626,7 +586,7 @@ namespace build2
 
             break;
           }
-        case type::so:
+        case otype::s:
           {
             //@@ VC: DLL name.
 
@@ -637,9 +597,9 @@ namespace build2
             }
             else if (tclass == "windows")
             {
-              // On Windows libso{} is an ad hoc group. The libso{} itself is
+              // On Windows libs{} is an ad hoc group. The libs{} itself is
               // the import library and we add dll{} as a member (see below).
-              // While at first it may seem strange that libso{} is the import
+              // While at first it may seem strange that libs{} is the import
               // library and not the DLL, if you meditate on it, you will see
               // it makes a lot of sense: our main task here is building and
               // for that we need the import library, not the DLL.
@@ -697,7 +657,7 @@ namespace build2
       {
         // DLL
         //
-        if (so)
+        if (lt == otype::s)
         {
           file& dll (add_adhoc (t, "dll"));
 
@@ -707,7 +667,7 @@ namespace build2
 
         // PDB
         //
-        if (lt != type::a &&
+        if (lt != otype::a &&
             cid == "msvc" &&
             find_option ("/DEBUG", t, "cxx.loptions", true))
         {
@@ -734,6 +694,10 @@ namespace build2
       // When cleaning, ignore prerequisites that are not in the same
       // or a subdirectory of our project root.
       //
+      const target_type& ott (lt == otype::e ? obje::static_type :
+                              lt == otype::a ? obja::static_type :
+                              objs::static_type);
+
       for (prerequisite_member p: group_prerequisite_members (a, t))
       {
         target* pt (nullptr);
@@ -758,11 +722,15 @@ namespace build2
           //
           if (obj* o = pt->is_a<obj> ())
           {
-            pt = so ? static_cast<target*> (o->so) : o->a;
+            switch (lt)
+            {
+            case otype::e: pt = o->e; break;
+            case otype::a: pt = o->a; break;
+            case otype::s: pt = o->s; break;
+            }
 
             if (pt == nullptr)
-              pt = &search (so ? objso::static_type : obja::static_type,
-                            p.key ());
+              pt = &search (ott, p.key ());
           }
           else if (lib* l = pt->is_a<lib> ())
           {
@@ -785,10 +753,7 @@ namespace build2
         bool group (!p.prerequisite.belongs (t)); // Group's prerequisite.
 
         const prerequisite_key& cp (p.key ()); // c(xx){} prerequisite key.
-        const target_type& otype (
-          group
-          ? obj::static_type
-          : (so ? objso::static_type : obja::static_type));
+        const target_type& tt (group ? obj::static_type : ott);
 
         // Come up with the obj*{} target. The c(xx){} prerequisite directory
         // can be relative (to the scope) or absolute. If it is relative, then
@@ -807,7 +772,7 @@ namespace build2
           {
             if (!cpd.sub (rs.src_path ()))
               fail << "out of project prerequisite " << cp <<
-                info << "specify corresponding " << otype.name << "{} "
+                info << "specify corresponding " << tt.name << "{} "
                    << "target explicitly";
 
             d = rs.out_path () / cpd.leaf (rs.src_path ());
@@ -817,7 +782,7 @@ namespace build2
         // obj*{} is always in the out tree.
         //
         target& ot (
-          search (otype, d, dir_path (), *cp.tk.name, nullptr, cp.scope));
+          search (tt, d, dir_path (), *cp.tk.name, nullptr, cp.scope));
 
         // If we are cleaning, check that this target is in the same or
         // a subdirectory of our project root.
@@ -838,11 +803,16 @@ namespace build2
         if (group)
         {
           obj& o (static_cast<obj&> (ot));
-          pt = so ? static_cast<target*> (o.so) : o.a;
+
+          switch (lt)
+          {
+          case otype::e: pt = o.e; break;
+          case otype::a: pt = o.a; break;
+          case otype::s: pt = o.s; break;
+          }
 
           if (pt == nullptr)
-            pt = &search (so ? objso::static_type : obja::static_type,
-                          o.dir, o.out, o.name, o.ext, nullptr);
+            pt = &search (ott, o.dir, o.out, o.name, o.ext, nullptr);
         }
         else
           pt = &ot;
@@ -869,9 +839,9 @@ namespace build2
               (p.is_a<cxx> () && (p1.is_a<hxx> () ||
                                   p1.is_a<ixx> () ||
                                   p1.is_a<txx> ())) ||
-              p1.is_a<lib> ()  ||
+              p1.is_a<lib>  () ||
               p1.is_a<liba> () ||
-              p1.is_a<libso> ())
+              p1.is_a<libs> ())
           {
             continue;
           }
@@ -893,7 +863,7 @@ namespace build2
                    << "be incompatible with existing target " << *pt <<
                 info << "existing prerequisite " << p1 << " does not match "
                    << cp <<
-                info << "specify corresponding " << otype.name << "{} target "
+                info << "specify corresponding " << tt.name << "{} target "
                    << "explicitly";
 
             found = true;
@@ -918,7 +888,7 @@ namespace build2
           //
           for (prerequisite& p: group_prerequisites (t))
           {
-            if (p.is_a<lib> () || p.is_a<liba> () || p.is_a<libso> ())
+            if (p.is_a<lib> () || p.is_a<liba> () || p.is_a<libs> ())
               ot.prerequisites.emplace_back (p);
           }
 
@@ -948,7 +918,7 @@ namespace build2
           args.push_back (relative (pa->path ()).string ()); // string()&&
           append_libraries (args, *pa);
         }
-        else if (libso* ps = pt->is_a<libso> ())
+        else if (libs* ps = pt->is_a<libs> ())
           args.push_back (relative (ps->path ()).string ()); // string()&&
       }
     }
@@ -963,17 +933,17 @@ namespace build2
           cs.append (pa->path ().string ());
           hash_libraries (cs, *pa);
         }
-        else if (libso* ps = pt->is_a<libso> ())
+        else if (libs* ps = pt->is_a<libs> ())
           cs.append (ps->path ().string ());
       }
     }
 
     static void
-    append_rpath_link (strings& args, libso& t)
+    append_rpath_link (strings& args, libs& t)
     {
       for (target* pt: t.prerequisite_targets)
       {
-        if (libso* ls = pt->is_a<libso> ())
+        if (libs* ls = pt->is_a<libs> ())
         {
           args.push_back ("-Wl,-rpath-link," +
                           ls->path ().directory ().string ());
@@ -1002,8 +972,7 @@ namespace build2
 
       file& t (static_cast<file&> (xt));
 
-      type lt (link_type (t));
-      bool so (lt == type::so);
+      otype lt (link_type (t));
 
       // Update prerequisites.
       //
@@ -1020,7 +989,7 @@ namespace build2
       path manifest; // Manifest itself (msvc) or compiled object file.
       timestamp rpath_timestamp (timestamp_nonexistent); // DLLs timestamp.
 
-      if (lt == type::e && tclass == "windows")
+      if (lt == otype::e && tclass == "windows")
       {
         // First determine if we need to add our rpath emulating assembly. The
         // assembly itself is generated later, after updating the target. Omit
@@ -1130,7 +1099,7 @@ namespace build2
 
       // Then the linker checksum (ar/ranlib or C++ compiler).
       //
-      if (lt == type::a)
+      if (lt == otype::a)
       {
         ranlib = rs["config.bin.ranlib"];
 
@@ -1195,7 +1164,7 @@ namespace build2
         args.push_back (m);
       }
 
-      if (lt == type::a)
+      if (lt == otype::a)
       {
         if (cid == "msvc") ;
         else
@@ -1238,7 +1207,7 @@ namespace build2
         {
           // Set soname.
           //
-          if (so)
+          if (lt == otype::s)
           {
             const string& leaf (t.path ().leaf ().string ());
 
@@ -1277,7 +1246,7 @@ namespace build2
           //
           for (target* pt: t.prerequisite_targets)
           {
-            if (libso* ls = pt->is_a<libso> ())
+            if (libs* ls = pt->is_a<libs> ())
             {
               if (a.outer_operation () != install_id)
               {
@@ -1330,11 +1299,12 @@ namespace build2
           path_target* ppt;
           liba* a (nullptr);
 
-          if ((ppt = pt->is_a<obja> ())  ||
-              (ppt = pt->is_a<objso> ()) ||
-              (lt != type::a &&
+          if ((ppt = pt->is_a<obje> ()) ||
+              (ppt = pt->is_a<obja> ()) ||
+              (ppt = pt->is_a<objs> ()) ||
+              (lt != otype::a &&
                ((ppt = a = pt->is_a<liba> ()) ||
-                (ppt = pt->is_a<libso> ()))))
+                (ppt =     pt->is_a<libs> ()))))
           {
             cs.append (ppt->path ().string ());
 
@@ -1353,7 +1323,7 @@ namespace build2
 
         // Treat them as inputs, not options.
         //
-        if (lt != type::a)
+        if (lt != otype::a)
           hash_options (cs, t, "cxx.libs");
 
         if (dd.expect (cs.string ()) != nullptr)
@@ -1387,7 +1357,7 @@ namespace build2
 
       switch (lt)
       {
-      case type::e:
+      case otype::e:
         {
           if (cid == "msvc")
           {
@@ -1449,7 +1419,7 @@ namespace build2
 
           break;
         }
-      case type::a:
+      case otype::a:
         {
           args[0] = cast<path> (rs["config.bin.ar"]).string ().c_str ();
 
@@ -1470,7 +1440,7 @@ namespace build2
 
           break;
         }
-      case type::so:
+      case otype::s:
         {
           if (cid == "msvc")
           {
@@ -1489,7 +1459,7 @@ namespace build2
 
             if (tsys == "mingw32")
             {
-              // On Windows libso{} is the import stub and its first ad hoc
+              // On Windows libs{} is the import stub and its first ad hoc
               // group member is dll{}.
               //
               out = "-Wl,--out-implib=" + relt.string ();
@@ -1514,13 +1484,13 @@ namespace build2
       {
         path_target* ppt;
         liba* a (nullptr);
-        libso* so (nullptr);
 
-        if ((ppt = pt->is_a<obja> ())  ||
-            (ppt = pt->is_a<objso> ()) ||
-            (lt != type::a &&
+        if ((ppt = pt->is_a<obje> ()) ||
+            (ppt = pt->is_a<obja> ()) ||
+            (ppt = pt->is_a<objs> ()) ||
+            (lt != otype::a &&
              ((ppt = a = pt->is_a<liba> ()) ||
-              (ppt = so = pt->is_a<libso> ()))))
+              (ppt     = pt->is_a<libs> ()))))
         {
           sargs.push_back (relative (ppt->path ()).string ()); // string()&&
 
@@ -1543,7 +1513,7 @@ namespace build2
       for (size_t i (0); i != sargs.size (); ++i)
         args.push_back (sargs[i].c_str ());
 
-      if (lt != type::a)
+      if (lt != otype::a)
         append_options (args, t, "cxx.libs");
 
       args.push_back (nullptr);
@@ -1615,7 +1585,7 @@ namespace build2
       // For Windows generate rpath-emulating assembly (unless updaing for
       // install).
       //
-      if (lt == type::e && tclass == "windows")
+      if (lt == otype::e && tclass == "windows")
       {
         if (a.outer_operation () != install_id)
           windows_rpath_assembly (t, rpath_timestamp, scratch);
@@ -1644,12 +1614,12 @@ namespace build2
 
       switch (link_type (t))
       {
-      case type::a:
+      case otype::a:
         {
           e = {"+.d"};
           break;
         }
-      case type::e:
+      case otype::e:
         {
           if (tclass == "windows")
           {
@@ -1671,7 +1641,7 @@ namespace build2
 
           break;
         }
-      case type::so:
+      case otype::s:
         {
           e = {"+.d"};
           break;
diff --git a/build2/cxx/module.cxx b/build2/cxx/module.cxx
index 6a5469c..69e76a3 100644
--- a/build2/cxx/module.cxx
+++ b/build2/cxx/module.cxx
@@ -316,38 +316,40 @@ namespace build2
 
         auto& r (b.rules);
 
-        r.insert<obja> (perform_update_id, "cxx.compile", compile::instance);
+        r.insert<obje> (perform_update_id, "cxx.compile", compile::instance);
+        r.insert<obje> (perform_clean_id, "cxx.compile", compile::instance);
 
         r.insert<obja> (perform_update_id, "cxx.compile", compile::instance);
         r.insert<obja> (perform_clean_id, "cxx.compile", compile::instance);
 
-        r.insert<objso> (perform_update_id, "cxx.compile", compile::instance);
-        r.insert<objso> (perform_clean_id, "cxx.compile", compile::instance);
+        r.insert<objs> (perform_update_id, "cxx.compile", compile::instance);
+        r.insert<objs> (perform_clean_id, "cxx.compile", compile::instance);
 
-        r.insert<exe> (perform_update_id, "cxx.link", link::instance);
-        r.insert<exe> (perform_clean_id, "cxx.link", link::instance);
+        r.insert<exe>  (perform_update_id, "cxx.link", link::instance);
+        r.insert<exe>  (perform_clean_id, "cxx.link", link::instance);
 
         r.insert<liba> (perform_update_id, "cxx.link", link::instance);
         r.insert<liba> (perform_clean_id, "cxx.link", link::instance);
 
-        r.insert<libso> (perform_update_id, "cxx.link", link::instance);
-        r.insert<libso> (perform_clean_id, "cxx.link", link::instance);
+        r.insert<libs> (perform_update_id, "cxx.link", link::instance);
+        r.insert<libs> (perform_clean_id, "cxx.link", link::instance);
 
-        // Register for configure so that we detect unresolved imports
-        // during configuration rather that later, e.g., during update.
+        // Register for configure so that we detect unresolved imports during
+        // configuration rather that later, e.g., during update.
         //
+        r.insert<obje> (configure_update_id, "cxx.compile", compile::instance);
         r.insert<obja> (configure_update_id, "cxx.compile", compile::instance);
-        r.insert<objso> (configure_update_id, "cxx.compile", compile::instance);
+        r.insert<objs> (configure_update_id, "cxx.compile", compile::instance);
 
-        r.insert<exe> (configure_update_id, "cxx.link", link::instance);
+        r.insert<exe>  (configure_update_id, "cxx.link", link::instance);
         r.insert<liba> (configure_update_id, "cxx.link", link::instance);
-        r.insert<libso> (configure_update_id, "cxx.link", link::instance);
+        r.insert<libs> (configure_update_id, "cxx.link", link::instance);
 
         //@@ Should we check if install module was loaded (see bin)?
         //
-        r.insert<exe> (perform_install_id, "cxx.install", install::instance);
+        r.insert<exe>  (perform_install_id, "cxx.install", install::instance);
         r.insert<liba> (perform_install_id, "cxx.install", install::instance);
-        r.insert<libso> (perform_install_id, "cxx.install", install::instance);
+        r.insert<libs> (perform_install_id, "cxx.install", install::instance);
       }
 
       // Configure "installability" of our target types.
diff --git a/build2/cxx/utility.cxx b/build2/cxx/utility.cxx
index ed57fd2..cf9c4d0 100644
--- a/build2/cxx/utility.cxx
+++ b/build2/cxx/utility.cxx
@@ -79,7 +79,7 @@ namespace build2
 
       for (target* t: l.prerequisite_targets)
       {
-        if (t->is_a<lib> () || t->is_a<liba> () || t->is_a<libso> ())
+        if (t->is_a<lib> () || t->is_a<liba> () || t->is_a<libs> ())
           append_lib_options (args, *t, var);
       }
 
@@ -93,7 +93,7 @@ namespace build2
 
       for (target* t: l.prerequisite_targets)
       {
-        if (t->is_a<lib> () || t->is_a<liba> () || t->is_a<libso> ())
+        if (t->is_a<lib> () || t->is_a<liba> () || t->is_a<libs> ())
           hash_lib_options (csum, *t, var);
       }
 
diff --git a/build2/cxx/windows-rpath.cxx b/build2/cxx/windows-rpath.cxx
index 8f19f79..0bd4bc5 100644
--- a/build2/cxx/windows-rpath.cxx
+++ b/build2/cxx/windows-rpath.cxx
@@ -49,7 +49,7 @@ namespace build2
 
       for (target* pt: t.prerequisite_targets)
       {
-        if (libso* ls = pt->is_a<libso> ())
+        if (libs* ls = pt->is_a<libs> ())
         {
           // This can be an installed library in which case we will have just
           // the import stub but may also have just the DLL. For now we don't
@@ -84,7 +84,7 @@ namespace build2
     {
       for (target* pt: t.prerequisite_targets)
       {
-        if (libso* ls = pt->is_a<libso> ())
+        if (libs* ls = pt->is_a<libs> ())
         {
           if (ls->member == nullptr)
             continue;
diff --git a/build2/target b/build2/target
index 955c2f9..28753df 100644
--- a/build2/target
+++ b/build2/target
@@ -192,7 +192,7 @@ namespace build2
     // is an explicit mechanism for discovering the group's members.
     //
     // However, sometimes, we may want to create a group on the fly out of a
-    // normal target type. For example, we have the libso{} target type. But
+    // normal target type. For example, we have the libs{} target type. But
     // on Windows a shared library consist of (at least) two files: the import
     // library and the DLL itself. So we somehow need to be able to capture
     // that. One approach would be to imply the presence of the second file.