Move in build system module to separate library

32 files changed, 324 insertions, 146 deletions

diff --git a/bootstrap-mingw.bat b/bootstrap-mingw.bat
index 73b76f3..5061753 100644
--- a/bootstrap-mingw.bat
+++ b/bootstrap-mingw.bat
@@ -66,7 +66,6 @@ set "src=%src% build2\c"
 set "src=%src% build2\cc"
 set "src=%src% build2\cxx"
 set "src=%src% build2\version"
-set "src=%src% build2\in"
 
 set "src=%src% libbuild2"
 set "src=%src% libbuild2\config"
@@ -74,6 +73,7 @@ set "src=%src% libbuild2\dist"
 set "src=%src% libbuild2\test"
 set "src=%src% libbuild2\test\script"
 set "src=%src% libbuild2\install"
+set "src=%src% libbuild2\in"
 
 set "src=%src% %libbutl%\libbutl"
 
diff --git a/bootstrap-msvc.bat b/bootstrap-msvc.bat
index a011162..e4e2a66 100644
--- a/bootstrap-msvc.bat
+++ b/bootstrap-msvc.bat
@@ -97,7 +97,6 @@ set "src=%src% build2\c"
 set "src=%src% build2\cc"
 set "src=%src% build2\cxx"
 set "src=%src% build2\version"
-set "src=%src% build2\in"
 
 set "src=%src% libbuild2"
 set "src=%src% libbuild2\config"
@@ -105,6 +104,7 @@ set "src=%src% libbuild2\dist"
 set "src=%src% libbuild2\test"
 set "src=%src% libbuild2\test\script"
 set "src=%src% libbuild2\install"
+set "src=%src% libbuild2\in"
 
 set "src=%src% %libbutl%\libbutl"
 
diff --git a/bootstrap.gmake b/bootstrap.gmake
index 04716be..793f3d0 100644
--- a/bootstrap.gmake
+++ b/bootstrap.gmake
@@ -134,15 +134,15 @@ bin           \
 c             \
 cc            \
 cxx           \
-version       \
-in
+version
 
 libbuild2_sub := \
 config           \
 dist             \
 test/script      \
 test             \
-install
+install          \
+in
 
 build2_src    := $(wildcard $(src_root)/build2/*.cxx)
 build2_src    += $(foreach d,$(build2_sub),$(wildcard $(src_root)/build2/$d/*.cxx))
diff --git a/bootstrap.sh b/bootstrap.sh
index 51e5e9d..7e754b0 100755
--- a/bootstrap.sh
+++ b/bootstrap.sh
@@ -123,7 +123,6 @@ src="$src build2/cc/*.cxx"
 src="$src build2/cxx/*.cxx"
 src="$src build2/cli/*.cxx"
 src="$src build2/version/*.cxx"
-src="$src build2/in/*.cxx"
 src="$src build2/bash/*.cxx"
 
 src="$src libbuild2/*.cxx"
@@ -132,6 +131,7 @@ src="$src libbuild2/dist/*.cxx"
 src="$src libbuild2/test/*.cxx"
 src="$src libbuild2/test/script/*.cxx"
 src="$src libbuild2/install/*.cxx"
+src="$src libbuild2/in/*.cxx"
 
 src="$src $libbutl/libbutl/*.cxx"
 
diff --git a/build/export.build b/build/export.build
index 4847950..345baf0 100644
--- a/build/export.build
+++ b/build/export.build
@@ -11,12 +11,20 @@ if ($import.target == exe{b})
 
   export $out_root/build2/exe{b}
 }
-elif ($import.target == lib{build2})
+else
 {
   $out_root/
   {
     include libbuild2/
   }
 
-  export $out_root/libbuild2/lib{build2}
+  d = [dir_path] $out_root/libbuild2/
+  if ($import.target != lib{build2})
+  {
+    # Assume one of the modules.
+    #
+    d += $regex.replace($name($import.target), '^build2-(.+)', '\1')
+  }
+
+  export $d/$import.target
 }
diff --git a/build2/b.cxx b/build2/b.cxx
index a76a8e4..907784b 100644
--- a/build2/b.cxx
+++ b/build2/b.cxx
@@ -42,20 +42,18 @@
 
 #include <libbuild2/parser.hxx>
 
+#include <build2/b-options.hxx>
+
+// Build system modules.
+//
 #include <libbuild2/dist/init.hxx>
 #include <libbuild2/test/init.hxx>
 #include <libbuild2/config/init.hxx>
 #include <libbuild2/install/init.hxx>
 
-#include <build2/b-options.hxx>
-
-using namespace butl;
-using namespace std;
-
+#include <libbuild2/in/init.hxx>
 #include <build2/version/init.hxx>
 
-#include <build2/in/init.hxx>
-
 #include <build2/bin/init.hxx>
 #include <build2/c/init.hxx>
 #include <build2/cc/init.hxx>
@@ -66,6 +64,9 @@ using namespace std;
 #  include <build2/bash/init.hxx>
 #endif
 
+using namespace butl;
+using namespace std;
+
 namespace build2
 {
   static options ops;
@@ -437,46 +438,51 @@ main (int argc, char* argv[])
       using mf = module_functions;
       auto& bm (builtin_modules);
 
-      bm["config"]  = config::build2_config_load ();
-      bm["dist"]    = dist::build2_dist_load ();
-      bm["test"]    = test::build2_test_load ();
-      bm["install"] = install::build2_install_load ();
-
-      bm["version"] = mf {&version::boot, &version::init};
-
-      bm["in.base"]  = mf {nullptr, &in::base_init};
-      bm["in"]       = mf {nullptr, &in::init};
-
-      bm["bin.vars"] = mf {nullptr, &bin::vars_init};
-      bm["bin.config"] = mf {nullptr, &bin::config_init};
-      bm["bin"] = mf {nullptr, &bin::init};
-      bm["bin.ar.config"] = mf {nullptr, &bin::ar_config_init};
-      bm["bin.ar"] = mf {nullptr, &bin::ar_init};
-      bm["bin.ld.config"] = mf {nullptr, &bin::ld_config_init};
-      bm["bin.ld"] = mf {nullptr, &bin::ld_init};
-      bm["bin.rc.config"] = mf {nullptr, &bin::rc_config_init};
-      bm["bin.rc"] = mf {nullptr, &bin::rc_init};
-
-      bm["cc.core.vars"] = mf {nullptr, &cc::core_vars_init};
-      bm["cc.core.guess"] = mf {nullptr, &cc::core_guess_init};
-      bm["cc.core.config"] = mf {nullptr, &cc::core_config_init};
-      bm["cc.core"] = mf {nullptr, &cc::core_init};
-      bm["cc.config"] = mf {nullptr, &cc::config_init};
-      bm["cc"] = mf {nullptr, &cc::init};
-
-      bm["c.guess"] = mf {nullptr, &c::guess_init};
-      bm["c.config"] = mf {nullptr, &c::config_init};
-      bm["c"] = mf {nullptr, &c::init};
-
-      bm["cxx.guess"] = mf {nullptr, &cxx::guess_init};
-      bm["cxx.config"] = mf {nullptr, &cxx::config_init};
-      bm["cxx"] = mf {nullptr, &cxx::init};
+      auto reg = [] (module_load_function* lf)
+      {
+        for (const module_functions* i (lf ()); i->name != nullptr; ++i)
+          builtin_modules[i->name] = *i;
+      };
+
+      reg (&config::build2_config_load);
+      reg (&dist::build2_dist_load);
+      reg (&test::build2_test_load);
+      reg (&install::build2_install_load);
+
+      bm["version"] = mf {"version", &version::boot, &version::init};
+
+      reg (&in::build2_in_load);
+
+      bm["bin.vars"] = mf {"bin.vars", nullptr, &bin::vars_init};
+      bm["bin.config"] = mf {"bin.config", nullptr, &bin::config_init};
+      bm["bin"] = mf {"bin", nullptr, &bin::init};
+      bm["bin.ar.config"] = mf {"bin.ar.config", nullptr, &bin::ar_config_init};
+      bm["bin.ar"] = mf {"bin.ar", nullptr, &bin::ar_init};
+      bm["bin.ld.config"] = mf {"bin.ld.config", nullptr, &bin::ld_config_init};
+      bm["bin.ld"] = mf {"bin.ld", nullptr, &bin::ld_init};
+      bm["bin.rc.config"] = mf {"bin.rc.config", nullptr, &bin::rc_config_init};
+      bm["bin.rc"] = mf {"bin.rc", nullptr, &bin::rc_init};
+
+      bm["cc.core.vars"] = mf {"cc.core.vars", nullptr, &cc::core_vars_init};
+      bm["cc.core.guess"] = mf {"cc.core.guess", nullptr, &cc::core_guess_init};
+      bm["cc.core.config"] = mf {"cc.core.config", nullptr, &cc::core_config_init};
+      bm["cc.core"] = mf {"cc.core", nullptr, &cc::core_init};
+      bm["cc.config"] = mf {"cc.config", nullptr, &cc::config_init};
+      bm["cc"] = mf {"cc", nullptr, &cc::init};
+
+      bm["c.guess"] = mf {"c.guess", nullptr, &c::guess_init};
+      bm["c.config"] = mf {"c.config", nullptr, &c::config_init};
+      bm["c"] = mf {"c", nullptr, &c::init};
+
+      bm["cxx.guess"] = mf {"cxx.guess", nullptr, &cxx::guess_init};
+      bm["cxx.config"] = mf {"cxx.config", nullptr, &cxx::config_init};
+      bm["cxx"] = mf {"cxx", nullptr, &cxx::init};
 
 #ifndef BUILD2_BOOTSTRAP
-      bm["cli.config"] = mf {nullptr, &cli::config_init};
-      bm["cli"] = mf {nullptr, &cli::init};
+      bm["cli.config"] = mf {"cli.config", nullptr, &cli::config_init};
+      bm["cli"] = mf {"cli", nullptr, &cli::init};
 
-      bm["bash"] = mf {nullptr, &bash::init};
+      bm["bash"] = mf {"bash", nullptr, &bash::init};
 #endif
     }
 
diff --git a/build2/bash/rule.cxx b/build2/bash/rule.cxx
index 72e3219..a612d23 100644
--- a/build2/bash/rule.cxx
+++ b/build2/bash/rule.cxx
@@ -11,7 +11,7 @@
 #include <libbuild2/algorithm.hxx>
 #include <libbuild2/diagnostics.hxx>
 
-#include <build2/in/target.hxx>
+#include <libbuild2/in/target.hxx>
 
 #include <build2/bash/target.hxx>
 #include <build2/bash/utility.hxx>
diff --git a/build2/bash/rule.hxx b/build2/bash/rule.hxx
index a6ec235..c160bb7 100644
--- a/build2/bash/rule.hxx
+++ b/build2/bash/rule.hxx
@@ -10,7 +10,7 @@
 
 #include <libbuild2/install/rule.hxx>
 
-#include <build2/in/rule.hxx>
+#include <libbuild2/in/rule.hxx>
 
 namespace build2
 {
diff --git a/build2/buildfile b/build2/buildfile
index eb22266..a940793 100644
--- a/build2/buildfile
+++ b/build2/buildfile
@@ -6,12 +6,19 @@ import libs  = libbutl%lib{butl}
 import libs += libpkgconf%lib{pkgconf}
 
 include ../libbuild2/
+libs += ../libbuild2/lib{build2}
+
+for m: in
+{
+  include ../libbuild2/in/
+  libs += ../libbuild2/$m/lib{build2-$m}
+}
 
 ./: exe{b}: {hxx ixx txx cxx}{+b} libue{b}
 
 libue{b}: {hxx ixx txx cxx}{** -b -b-options -**.test...} \
           {hxx ixx cxx}{b-options}                        \
-          ../libbuild2/lib{build2} $libs
+          $libs
 
 # Unit tests.
 #
diff --git a/build2/in/init.hxx b/build2/in/init.hxx
deleted file mode 100644
index 3cf8ebf..0000000
--- a/build2/in/init.hxx
+++ /dev/null
@@ -1,37 +0,0 @@
-// file      : build2/in/init.hxx -*- C++ -*-
-// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
-// license   : MIT; see accompanying LICENSE file
-
-#ifndef BUILD2_IN_INIT_HXX
-#define BUILD2_IN_INIT_HXX
-
-#include <libbuild2/types.hxx>
-#include <libbuild2/utility.hxx>
-
-#include <libbuild2/module.hxx>
-
-namespace build2
-{
-  namespace in
-  {
-    bool
-    base_init (scope&,
-               scope&,
-               const location&,
-               unique_ptr<module_base>&,
-               bool,
-               bool,
-               const variable_map&);
-
-    bool
-    init (scope&,
-          scope&,
-          const location&,
-          unique_ptr<module_base>&,
-          bool,
-          bool,
-          const variable_map&);
-  }
-}
-
-#endif // BUILD2_IN_INIT_HXX
diff --git a/build2/version/rule.cxx b/build2/version/rule.cxx
index 912efe3..f110e3e 100644
--- a/build2/version/rule.cxx
+++ b/build2/version/rule.cxx
@@ -8,7 +8,7 @@
 #include <libbuild2/target.hxx>
 #include <libbuild2/diagnostics.hxx>
 
-#include <build2/in/target.hxx>
+#include <libbuild2/in/target.hxx>
 
 #include <build2/version/module.hxx>
 #include <build2/version/utility.hxx>
diff --git a/build2/version/rule.hxx b/build2/version/rule.hxx
index 6d841df..7bfb783 100644
--- a/build2/version/rule.hxx
+++ b/build2/version/rule.hxx
@@ -10,7 +10,7 @@
 
 #include <libbuild2/install/rule.hxx>
 
-#include <build2/in/rule.hxx>
+#include <libbuild2/in/rule.hxx>
 
 namespace build2
 {
diff --git a/libbuild2/buildfile b/libbuild2/buildfile
index f23f023..edabfc3 100644
--- a/libbuild2/buildfile
+++ b/libbuild2/buildfile
@@ -2,17 +2,21 @@
 # copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
 # license   : MIT; see accompanying LICENSE file
 
+./: lib{build2} in/
+
 import int_libs = libbutl%lib{butl}
 
-# The config, test, install, and dist are "core modules" that come bundled
-# with libbuild2. Note that the core can still function without them or with
-# their alternative implementations.
+lib{build2}: libul{build2}: {hxx ixx txx cxx}{* -config -version -*.test...} \
+                            {hxx}{config version}
+
+# These are "core modules" that come bundled with libbuild2 (see also unit
+# tests loop below). Note that the build system core can still function
+# without them or with their alternative implementations.
 #
-./: lib{build2}: libul{build2}: {hxx ixx txx cxx}{** -config      \
-                                                     -version     \
-                                                     -**.test...} \
-                                {hxx}{config version}             \
-                                $int_libs
+for m: config dist install test
+  libul{build2}: $m/{hxx ixx txx cxx}{** -**.test...}
+
+libul{build2}: $int_libs
 
 # Include the generated config and version headers into the distribution (so
 # that we don't pick up installed ones) and don't remove them when cleaning in
@@ -35,7 +39,11 @@ exe{*.test}:
   install = false
 }
 
-for t: cxx{**.test...}
+for t:         cxx{ *.test...} \
+        config/cxx{**.test...} \
+          dist/cxx{**.test...} \
+       install/cxx{**.test...} \
+          test/cxx{**.test...}
 {
   d = $directory($t)
   n = $name($t)...
diff --git a/libbuild2/config/init.cxx b/libbuild2/config/init.cxx
index 73275c6..b790569 100644
--- a/libbuild2/config/init.cxx
+++ b/libbuild2/config/init.cxx
@@ -145,15 +145,21 @@ namespace build2
       return true;
     }
 
-    module_functions
+    static const module_functions mod_functions[] =
+    {
+      {"config", &boot,   &init},
+      {nullptr,  nullptr, nullptr}
+    };
+
+    const module_functions*
     build2_config_load ()
     {
       // Initialize the config entry points in the build system core.
       //
-      config_save_variable = &config::save_variable;
-      config_preprocess_create = &config::preprocess_create;
+      config_save_variable = &save_variable;
+      config_preprocess_create = &preprocess_create;
 
-      return module_functions {&boot, &init};
+      return mod_functions;
     }
   }
 }
diff --git a/libbuild2/config/init.hxx b/libbuild2/config/init.hxx
index ff5e923..f900801 100644
--- a/libbuild2/config/init.hxx
+++ b/libbuild2/config/init.hxx
@@ -28,7 +28,7 @@ namespace build2
           bool,
           const variable_map&);
 
-    extern "C" LIBBUILD2_SYMEXPORT module_functions
+    extern "C" LIBBUILD2_SYMEXPORT const module_functions*
     build2_config_load ();
   }
 }
diff --git a/libbuild2/dist/init.cxx b/libbuild2/dist/init.cxx
index 959b2dd..4729938 100644
--- a/libbuild2/dist/init.cxx
+++ b/libbuild2/dist/init.cxx
@@ -183,10 +183,16 @@ namespace build2
       return true;
     }
 
-    module_functions
+    static const module_functions mod_functions[] =
+    {
+      {"dist",  &boot,   &init},
+      {nullptr, nullptr, nullptr}
+    };
+
+    const module_functions*
     build2_dist_load ()
     {
-      return module_functions {&boot, &init};
+      return mod_functions;
     }
   }
 }
diff --git a/libbuild2/dist/init.hxx b/libbuild2/dist/init.hxx
index 41c82a7..cfcb3af 100644
--- a/libbuild2/dist/init.hxx
+++ b/libbuild2/dist/init.hxx
@@ -28,7 +28,7 @@ namespace build2
           bool,
           const variable_map&);
 
-    extern "C" LIBBUILD2_SYMEXPORT module_functions
+    extern "C" LIBBUILD2_SYMEXPORT const module_functions*
     build2_dist_load ();
   }
 }
diff --git a/libbuild2/in/buildfile b/libbuild2/in/buildfile
new file mode 100644
index 0000000..ae07e27
--- /dev/null
+++ b/libbuild2/in/buildfile
@@ -0,0 +1,62 @@
+# file      : libbuild2/in/buildfile
+# copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+# license   : MIT; see accompanying LICENSE file
+
+import int_libs = libbutl%lib{butl}
+
+include ../
+int_libs += ../lib{build2}
+
+./: lib{build2-in}: libul{build2-in}: {hxx ixx txx cxx}{** -**.test...} \
+  $int_libs
+
+# Unit tests.
+#
+exe{*.test}:
+{
+  test = true
+  install = false
+}
+
+for t: cxx{**.test...}
+{
+  d = $directory($t)
+  n = $name($t)...
+
+  ./: $d/exe{$n}: $t $d/{hxx ixx txx}{+$n} $d/testscript{+$n}
+  $d/exe{$n}: libul{build2-in}: bin.whole = false
+}
+
+# Build options.
+#
+obja{*}: cxx.poptions += -DLIBBUILD2_IN_STATIC_BUILD
+objs{*}: cxx.poptions += -DLIBBUILD2_IN_SHARED_BUILD
+
+# Export options.
+#
+lib{build2-in}:
+{
+  cxx.export.poptions = "-I$out_root" "-I$src_root"
+  cxx.export.libs = $int_libs
+}
+
+liba{build2-in}: cxx.export.poptions += -DLIBBUILD2_IN_STATIC
+libs{build2-in}: cxx.export.poptions += -DLIBBUILD2_IN_SHARED
+
+# For pre-releases use the complete version to make sure they cannot be used
+# in place of another pre-release or the final version. See the version module
+# for details on the version.* variable values.
+#
+if $version.pre_release
+  lib{build2-in}: bin.lib.version = @"-$version.project_id"
+else
+  lib{build2-in}: bin.lib.version = @"-$version.major.$version.minor"
+
+# Install into the libbuild2/in/ subdirectory of, say, /usr/include/
+# recreating subdirectories.
+#
+{hxx ixx txx}{*}:
+{
+  install         = include/libbuild2/in/
+  install.subdirs = true
+}
diff --git a/libbuild2/in/export.hxx b/libbuild2/in/export.hxx
new file mode 100644
index 0000000..47909e7
--- /dev/null
+++ b/libbuild2/in/export.hxx
@@ -0,0 +1,34 @@
+#pragma once
+
+// Normally we don't export class templates (but do complete specializations),
+// inline functions, and classes with only inline member functions. Exporting
+// classes that inherit from non-exported/imported bases (e.g., std::string)
+// will end up badly. The only known workarounds are to not inherit or to not
+// export. Also, MinGW GCC doesn't like seeing non-exported functions being
+// used before their inline definition. The workaround is to reorder code. In
+// the end it's all trial and error.
+
+#if defined(LIBBUILD2_IN_STATIC)         // Using static.
+#  define LIBBUILD2_IN_SYMEXPORT
+#elif defined(LIBBUILD2_IN_STATIC_BUILD) // Building static.
+#  define LIBBUILD2_IN_SYMEXPORT
+#elif defined(LIBBUILD2_IN_SHARED)       // Using shared.
+#  ifdef _WIN32
+#    define LIBBUILD2_IN_SYMEXPORT __declspec(dllimport)
+#  else
+#    define LIBBUILD2_IN_SYMEXPORT
+#  endif
+#elif defined(LIBBUILD2_IN_SHARED_BUILD) // Building shared.
+#  ifdef _WIN32
+#    define LIBBUILD2_IN_SYMEXPORT __declspec(dllexport)
+#  else
+#    define LIBBUILD2_IN_SYMEXPORT
+#  endif
+#else
+// If none of the above macros are defined, then we assume we are being used
+// by some third-party build system that cannot/doesn't signal the library
+// type. Note that this fallback works for both static and shared but in case
+// of shared will be sub-optimal compared to having dllimport.
+//
+#  define LIBBUILD2_IN_SYMEXPORT         // Using static or shared.
+#endif
diff --git a/build2/in/init.cxx b/libbuild2/in/init.cxx
index f01fe20..6ef996b 100644
--- a/build2/in/init.cxx
+++ b/libbuild2/in/init.cxx
@@ -1,16 +1,16 @@
-// file      : build2/in/init.cxx -*- C++ -*-
+// file      : libbuild2/in/init.cxx -*- C++ -*-
 // copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
 // license   : MIT; see accompanying LICENSE file
 
-#include <build2/in/init.hxx>
+#include <libbuild2/in/init.hxx>
 
 #include <libbuild2/scope.hxx>
 #include <libbuild2/context.hxx>
 #include <libbuild2/variable.hxx>
 #include <libbuild2/diagnostics.hxx>
 
-#include <build2/in/rule.hxx>
-#include <build2/in/target.hxx>
+#include <libbuild2/in/rule.hxx>
+#include <libbuild2/in/target.hxx>
 
 using namespace std;
 
@@ -106,5 +106,21 @@ namespace build2
 
       return true;
     }
+
+    static const module_functions mod_functions[] =
+    {
+      // NOTE: don't forget to also update the documentation in init.hxx if
+      //       changing anything here.
+
+      {"in.base", nullptr, base_init},
+      {"in",      nullptr, init},
+      {nullptr,   nullptr, nullptr}
+    };
+
+    const module_functions*
+    build2_in_load ()
+    {
+      return mod_functions;
+    }
   }
 }
diff --git a/libbuild2/in/init.hxx b/libbuild2/in/init.hxx
new file mode 100644
index 0000000..b82c77e
--- /dev/null
+++ b/libbuild2/in/init.hxx
@@ -0,0 +1,30 @@
+// file      : libbuild2/in/init.hxx -*- C++ -*-
+// copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef LIBBUILD2_IN_INIT_HXX
+#define LIBBUILD2_IN_INIT_HXX
+
+#include <libbuild2/types.hxx>
+#include <libbuild2/utility.hxx>
+
+#include <libbuild2/module.hxx>
+
+#include <libbuild2/in/export.hxx>
+
+namespace build2
+{
+  namespace in
+  {
+    // Module `in` does not require bootstrapping.
+    //
+    // Submodules:
+    //
+    // `in.base`  -- only variables and target types.
+    //
+    extern "C" LIBBUILD2_IN_SYMEXPORT const module_functions*
+    build2_in_load ();
+  }
+}
+
+#endif // LIBBUILD2_IN_INIT_HXX
diff --git a/build2/in/rule.cxx b/libbuild2/in/rule.cxx
index 8a3244d..bdc9b24 100644
--- a/build2/in/rule.cxx
+++ b/libbuild2/in/rule.cxx
@@ -1,8 +1,8 @@
-// file      : build2/in/rule.cxx -*- C++ -*-
+// file      : libbuild2/in/rule.cxx -*- C++ -*-
 // copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
 // license   : MIT; see accompanying LICENSE file
 
-#include <build2/in/rule.hxx>
+#include <libbuild2/in/rule.hxx>
 
 #include <cstdlib> // strtoull()
 
@@ -14,7 +14,7 @@
 #include <libbuild2/filesystem.hxx>
 #include <libbuild2/diagnostics.hxx>
 
-#include <build2/in/target.hxx>
+#include <libbuild2/in/target.hxx>
 
 using namespace std;
 using namespace butl;
diff --git a/build2/in/rule.hxx b/libbuild2/in/rule.hxx
index 71dc032..0daf6c0 100644
--- a/build2/in/rule.hxx
+++ b/libbuild2/in/rule.hxx
@@ -1,15 +1,17 @@
-// file      : build2/in/rule.hxx -*- C++ -*-
+// file      : libbuild2/in/rule.hxx -*- C++ -*-
 // copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
 // license   : MIT; see accompanying LICENSE file
 
-#ifndef BUILD2_IN_RULE_HXX
-#define BUILD2_IN_RULE_HXX
+#ifndef LIBBUILD2_IN_RULE_HXX
+#define LIBBUILD2_IN_RULE_HXX
 
 #include <libbuild2/types.hxx>
 #include <libbuild2/utility.hxx>
 
 #include <libbuild2/rule.hxx>
 
+#include <libbuild2/in/export.hxx>
+
 namespace build2
 {
   namespace in
@@ -22,7 +24,7 @@ namespace build2
     // Note also that currently this rule ignores the dry-run mode (see
     // perform_update() for the rationale).
     //
-    class rule: public build2::rule
+    class LIBBUILD2_IN_SYMEXPORT rule: public build2::rule
     {
     public:
       // The rule id is used to form the rule name/version entry in depdb. The
@@ -85,4 +87,4 @@ namespace build2
   }
 }
 
-#endif // BUILD2_IN_RULE_HXX
+#endif // LIBBUILD2_IN_RULE_HXX
diff --git a/build2/in/target.cxx b/libbuild2/in/target.cxx
index 8dc520b..490ab10 100644
--- a/build2/in/target.cxx
+++ b/libbuild2/in/target.cxx
@@ -1,8 +1,8 @@
-// file      : build2/in/target.cxx -*- C++ -*-
+// file      : libbuild2/in/target.cxx -*- C++ -*-
 // copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
 // license   : MIT; see accompanying LICENSE file
 
-#include <build2/in/target.hxx>
+#include <libbuild2/in/target.hxx>
 
 using namespace std;
 
diff --git a/build2/in/target.hxx b/libbuild2/in/target.hxx
index 47b0eed..5e3438d 100644
--- a/build2/in/target.hxx
+++ b/libbuild2/in/target.hxx
@@ -1,15 +1,17 @@
-// file      : build2/in/target.hxx -*- C++ -*-
+// file      : libbuild2/in/target.hxx -*- C++ -*-
 // copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
 // license   : MIT; see accompanying LICENSE file
 
-#ifndef BUILD2_IN_TARGET_HXX
-#define BUILD2_IN_TARGET_HXX
+#ifndef LIBBUILD2_IN_TARGET_HXX
+#define LIBBUILD2_IN_TARGET_HXX
 
 #include <libbuild2/types.hxx>
 #include <libbuild2/utility.hxx>
 
 #include <libbuild2/target.hxx>
 
+#include <libbuild2/in/export.hxx>
+
 namespace build2
 {
   namespace in
@@ -31,7 +33,7 @@ namespace build2
     // the target-dependent search comes in: we take into account the target
     // we are a prerequisite of.
     //
-    class in: public file
+    class LIBBUILD2_IN_SYMEXPORT in: public file
     {
     public:
       using file::file;
@@ -43,4 +45,4 @@ namespace build2
   }
 }
 
-#endif // BUILD2_IN_TARGET_HXX
+#endif // LIBBUILD2_IN_TARGET_HXX
diff --git a/libbuild2/install/init.cxx b/libbuild2/install/init.cxx
index fb3d9ea..060007b 100644
--- a/libbuild2/install/init.cxx
+++ b/libbuild2/install/init.cxx
@@ -300,10 +300,16 @@ namespace build2
       return true;
     }
 
-    module_functions
+    static const module_functions mod_functions[] =
+    {
+      {"install", &boot,   &init},
+      {nullptr,   nullptr, nullptr}
+    };
+
+    const module_functions*
     build2_install_load ()
     {
-      return module_functions {&boot, &init};
+      return mod_functions;
     }
   }
 }
diff --git a/libbuild2/install/init.hxx b/libbuild2/install/init.hxx
index fa0a1e1..b2daea0 100644
--- a/libbuild2/install/init.hxx
+++ b/libbuild2/install/init.hxx
@@ -28,7 +28,7 @@ namespace build2
           bool,
           const variable_map&);
 
-    extern "C" LIBBUILD2_SYMEXPORT module_functions
+    extern "C" LIBBUILD2_SYMEXPORT const module_functions*
     build2_install_load ();
   }
 }
diff --git a/libbuild2/module.hxx b/libbuild2/module.hxx
index 7d94837..c32fc9a 100644
--- a/libbuild2/module.hxx
+++ b/libbuild2/module.hxx
@@ -50,24 +50,31 @@ namespace build2
           bool optional,              // Loaded with using? (optional module).
           const variable_map& hints); // Configuration hints (see below).
 
+  // If the boot function is not NULL, then such a module is said to require
+  // bootstrapping and must be loaded in bootstrap.build.
+  //
   struct module_functions
   {
-    module_boot_function* boot;
-    module_init_function* init;
+    const char*           name = nullptr; // Module/submodule name.
+    module_boot_function* boot = nullptr;
+    module_init_function* init = nullptr;
   };
 
-  // The build2_<modname>_load() function will be written in C++ and will be
+  // The build2_<name>_load() function will be written in C++ and will be
   // called from C++ but we need to suppress name mangling to be able to use
-  // dlsym() or equivalent.
+  // dlsym() or equivalent, thus extern "C".
   //
-  // Note that the load() function is guaranteed to be called during serial
-  // execution (either from main() or during the load phase).
+  // The <name> part in the function name is the main module name without
+  // submodule components (for example, `c` in `c.config`) and the load
+  // function is expected to return boot/init functions for all its submodules
+  // (if any) as well as for the module itself as an array of module_functions
+  // terminated with an all-NULL entry.
   //
-  // @@ I wonder if returning a "C++ struct" (it contains pointer to functions
-  //    with signatures containing C++ type) is kosher.
+  // Note that the load function is guaranteed to be called during serial
+  // execution (either from main() or during the load phase).
   //
   extern "C"
-  using module_load_function = module_functions ();
+  using module_load_function = const module_functions* ();
 
   // Loaded modules state.
   //
@@ -119,6 +126,9 @@ namespace build2
 
   // Builtin modules.
   //
+  // @@ Maybe this should be renamed to loaded modules?
+  // @@ We can also change it to std::map<const char*, const module_functions*>
+  //
   using available_module_map = std::map<string, module_functions>;
   LIBBUILD2_SYMEXPORT extern available_module_map builtin_modules;
 }
diff --git a/libbuild2/test/init.cxx b/libbuild2/test/init.cxx
index 3d13acc..a5afea0 100644
--- a/libbuild2/test/init.cxx
+++ b/libbuild2/test/init.cxx
@@ -220,12 +220,18 @@ namespace build2
       return true;
     }
 
-    module_functions
+    static const module_functions mod_functions[] =
+    {
+      {"test",  &boot,   &init},
+      {nullptr, nullptr, nullptr}
+    };
+
+    const module_functions*
     build2_test_load ()
     {
       script::regex::init ();
 
-      return module_functions {&boot, &init};
+      return mod_functions;
     }
   }
 }
diff --git a/libbuild2/test/init.hxx b/libbuild2/test/init.hxx
index a76b720..57f6bfa 100644
--- a/libbuild2/test/init.hxx
+++ b/libbuild2/test/init.hxx
@@ -28,7 +28,7 @@ namespace build2
           bool,
           const variable_map&);
 
-    extern "C" LIBBUILD2_SYMEXPORT module_functions
+    extern "C" LIBBUILD2_SYMEXPORT const module_functions*
     build2_test_load ();
   }
 }
diff --git a/tests/libbuild2/buildfile b/tests/libbuild2/buildfile
index 4d3a42f..51b2f5b 100644
--- a/tests/libbuild2/buildfile
+++ b/tests/libbuild2/buildfile
@@ -2,7 +2,8 @@
 # copyright : Copyright (c) 2014-2019 Code Synthesis Ltd
 # license   : MIT; see accompanying LICENSE file
 
-import libs = build2%lib{build2}
+import libs  = build2%lib{build2}
+import libs += build2%lib{build2-in}
 
 exe{driver}: {hxx cxx}{*} $libs testscript
 
diff --git a/tests/libbuild2/driver.cxx b/tests/libbuild2/driver.cxx
index 3df2fbe..d9c086a 100644
--- a/tests/libbuild2/driver.cxx
+++ b/tests/libbuild2/driver.cxx
@@ -8,6 +8,8 @@
 #include <libbuild2/context.hxx>   // sched, reset()
 #include <libbuild2/scheduler.hxx>
 
+#include <libbuild2/in/init.hxx>
+
 using namespace build2;
 
 int
@@ -17,6 +19,9 @@ main (int, char* argv[])
   //
   init_diag (1);
   init (argv[0]);
+
+  in::build2_in_load ();
+
   sched.startup (1);  // Serial execution.
   reset (strings ()); // No command line variables.