Add support for arguments in default options files helpers

5 files changed, 354 insertions, 148 deletions

diff --git a/libbutl/default-options.ixx b/libbutl/default-options.ixx
index 7e4c378..4a551ac 100644
--- a/libbutl/default-options.ixx
+++ b/libbutl/default-options.ixx
@@ -12,4 +12,15 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
       cmd_ops,
       [] (const default_options_entry<O>&, const O&) {});
   }
+
+  template <typename O, typename AS>
+  inline AS
+  merge_default_arguments (const default_options<O>& def_ops,
+                           const AS& cmd_args)
+  {
+    return merge_default_arguments (
+      def_ops,
+      cmd_args,
+      [] (const default_options_entry<O>&, const AS&) {});
+  }
 }
diff --git a/libbutl/default-options.mxx b/libbutl/default-options.mxx
index e9f92d3..aeb246d 100644
--- a/libbutl/default-options.mxx
+++ b/libbutl/default-options.mxx
@@ -6,6 +6,7 @@
 #endif
 
 #ifndef __cpp_lib_modules_ts
+#include <string>
 #include <vector>
 
 #include <utility>      // move(), forward(), make_pair()
@@ -50,17 +51,21 @@ LIBBUTL_MODEXPORT namespace butl
   template <typename O>
   struct default_options_entry
   {
-    path file;
-    O    options;
-    bool remote;
+    path                         file;
+    O                            options;
+    small_vector<std::string, 1> arguments;
+    bool                         remote;
   };
 
   template <typename O>
   using default_options = small_vector<default_options_entry<O>, 4>;
 
-  // Search for and load (using scanner S and parsing in the U::fail mode for
-  // both options and arguments) the specified list of options files in the
-  // specified directories returning a vector of option class instances (O).
+  // Search for and load the specified list of options files in the specified
+  // directories returning a vector of option class instances (O). If args is
+  // false, only options are allowed and are parsed using scanner S in the
+  // U::fail mode. If args is true, then both options and arguments are
+  // allowed in any order with options parsed in the U::stop mode.
+  //
   // Pass each default options file path to the specified function prior to
   // load (can be used for tracing, etc). The function signature is:
   //
@@ -106,33 +111,44 @@ LIBBUTL_MODEXPORT namespace butl
                         const optional<dir_path>& home_dir,
                         const optional<dir_path>& extra_dir,
                         const default_options_files&,
-                        F&&);
+                        F&&,
+                        bool args = false);
 
-  // Merge the default options and the command line options.
+  // Merge the default options/arguments and the command line
+  // options/arguments.
   //
-  // Note that this is the default implementation and in some cases you may
+  // Note that these are the default implementations and in some cases you may
   // want to provide an options class-specific version that verifies/sanitizes
-  // the default options (e.g., you may not want to allow certain options to
-  // be specified in the default options files) or warns/prompts about
-  // potentially dangerous options if they came from the remote options files.
+  // the default options/arguments (e.g., you may not want to allow certain
+  // options to be specified in the default options files) or warns/prompts
+  // about potentially dangerous options if they came from the remote options
+  // files.
   //
   template <typename O>
   O
   merge_default_options (const default_options<O>&, const O& cmd_ops);
 
-  // As above but pass each default option to the specified function prior to
-  // merging. The function signature is:
+  template <typename O, typename AS>
+  AS
+  merge_default_arguments (const default_options<O>&, const AS& cmd_args);
+
+  // As above but pass each default option/argument entry to the specified
+  // function prior to merging. The function signature is:
   //
   // void (const default_options_entry<O>&, const O& cmd_ops)
   //
-  // This version can be used to verify the default options. For example, you
-  // may want to disallow certain options from being specified in the default
-  // options files.
+  // This version can be used to verify the default options/arguments. For
+  // example, you may want to disallow certain options/arguments from being
+  // specified in the default options files.
   //
   template <typename O, typename F>
   O
   merge_default_options (const default_options<O>&, const O&, F&&);
 
+  template <typename O, typename AS, typename F>
+  AS
+  merge_default_arguments (const default_options<O>&, const AS&, F&&);
+
   // Find a common start (parent) directory stopping at home or root
   // (excluding).
   //
diff --git a/libbutl/default-options.txx b/libbutl/default-options.txx
index 730d588..5245bd6 100644
--- a/libbutl/default-options.txx
+++ b/libbutl/default-options.txx
@@ -31,6 +31,7 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
   template <typename O, typename S, typename U, typename F>
   bool
   load_default_options_files (const dir_path& d,
+                              bool args,
                               bool remote,
                               const small_vector<path, 2>& fs,
                               F&& fn,
@@ -42,7 +43,7 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
 
     bool r (true);
 
-    auto load = [&fs, &fn, &def_ops, &r] (const dir_path& d, bool remote)
+    auto load = [args, &fs, &fn, &def_ops, &r] (const dir_path& d, bool rem)
     {
       using namespace std;
 
@@ -54,7 +55,7 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
         {
           if (file_exists (p)) // Follows symlinks.
           {
-            fn (p, remote, false /* overwrite */);
+            fn (p, rem, false /* overwrite */);
 
             S s (p.string ());
 
@@ -65,14 +66,26 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
             //    this in CLI.
             //
             O o;
-            o.parse (s, U::fail, U::fail);
+            small_vector<std::string, 1> as;
+
+            if (args)
+            {
+              while (s.more ())
+              {
+                if (!o.parse (s, U::fail, U::stop))
+                  as.push_back (s.next ());
+              }
+            }
+            else
+              o.parse (s, U::fail, U::fail);
 
             if (o.no_default_options ())
               r = false;
 
             def_ops.push_back (default_options_entry<O> {move (p),
                                                          move (o),
-                                                         remote});
+                                                         move (as),
+                                                         rem});
           }
         }
         catch (std::system_error& e)
@@ -102,7 +115,8 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
                         const optional<dir_path>& home_dir,
                         const optional<dir_path>& extra_dir,
                         const default_options_files& ofs,
-                        F&& fn)
+                        F&& fn,
+                        bool args)
   {
     if (sys_dir)
       assert (sys_dir->absolute () && sys_dir->normalized ());
@@ -192,6 +206,7 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
           if (load_extra && extra_dir->sub (d))
           {
             load = load_default_options_files<O, S, U> (*extra_dir,
+                                                        args,
                                                         false /* remote */,
                                                         ofs.files,
                                                         std::forward<F> (fn),
@@ -204,6 +219,7 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
 
           if (load && options_dir_exists (od))
             load = load_default_options_files<O, S, U> (od,
+                                                        args,
                                                         remote,
                                                         ofs.files,
                                                         std::forward<F> (fn),
@@ -219,6 +235,7 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
 
     if (load && load_extra)
       load = load_default_options_files<O, S, U> (*extra_dir,
+                                                  args,
                                                   false /* remote */,
                                                   ofs.files,
                                                   std::forward<F> (fn),
@@ -230,6 +247,7 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
 
       if (options_dir_exists (d))
         load = load_default_options_files<O, S, U> (d,
+                                                    args,
                                                     false /* remote */,
                                                     ofs.files,
                                                     std::forward<F> (fn),
@@ -238,6 +256,7 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
 
     if (load && sys_dir && options_dir_exists (*sys_dir))
       load_default_options_files<O, S, U> (*sys_dir,
+                                           args,
                                            false /* remote */,
                                            ofs.files,
                                            std::forward<F> (fn),
@@ -269,4 +288,26 @@ LIBBUTL_MODEXPORT namespace butl //@@ MOD Clang needs this for some reason.
     r.merge (cmd_ops);
     return r;
   }
+
+  template <typename O, typename  AS, typename F>
+  AS
+  merge_default_arguments (const default_options<O>& def_ops,
+                           const AS& cmd_args,
+                           F&& fn)
+  {
+    AS r;
+    for (const default_options_entry<O>& e: def_ops)
+    {
+      fn (e, cmd_args);
+      r.insert (r.end (), e.arguments.begin (), e.arguments.end ());
+    }
+
+    // Optimize for the common case.
+    //
+    if (r.empty ())
+      return cmd_args;
+
+    r.insert (r.end (), cmd_args.begin (), cmd_args.end ());
+    return r;
+  }
 }
diff --git a/tests/default-options/driver.cxx b/tests/default-options/driver.cxx
index c6ac671..574e002 100644
--- a/tests/default-options/driver.cxx
+++ b/tests/default-options/driver.cxx
@@ -7,6 +7,7 @@
 #include <string>
 #include <vector>
 #include <iostream>
+#include <stdexcept> // invalid_argument
 #endif
 
 // Other includes.
@@ -57,6 +58,9 @@ using namespace butl;
 // -x
 //    Extra directory.
 //
+// -a
+//    Default arguments are allowed in the options files.
+//
 // -e
 //    Print the default options entries (rather than the merged options) to
 //    STDOUT one per line in the following format:
@@ -76,19 +80,59 @@ main (int argc, const char* argv[])
   public:
     scanner (const string& f): ifs_ (f, fdopen_mode::in, ifdstream::badbit) {}
 
-    optional<string>
+    bool
+    more ()
+    {
+      if (peeked_)
+        return true;
+
+      if (!eof_)
+        eof_ = ifs_.peek () == ifdstream::traits_type::eof ();
+
+      return !eof_;
+    }
+
+    string
+    peek ()
+    {
+      assert (more ());
+
+      if (peeked_)
+        return *peeked_;
+
+      string s;
+      getline (ifs_, s);
+
+      peeked_ = move (s);
+      return *peeked_;
+    }
+
+    string
     next ()
     {
+      assert (more ());
+
       string s;
-      return !eof (getline (ifs_, s)) ? optional<string> (move (s)) : nullopt;
+      if (peeked_)
+      {
+        s = move (*peeked_);
+        peeked_ = nullopt;
+      }
+      else
+        getline (ifs_, s);
+
+      return s;
     }
 
   private:
     ifdstream ifs_;
+    bool eof_ = false;
+    optional<string> peeked_;
   };
 
   enum class unknow_mode
   {
+    stop,
     fail
   };
 
@@ -96,15 +140,28 @@ main (int argc, const char* argv[])
   {
   public:
     bool
-    parse (scanner& s, unknow_mode, unknow_mode)
+    parse (scanner& s, unknow_mode, unknow_mode m)
     {
       bool r (false);
-      while (optional<string> o = s.next ())
+      while (s.more ())
       {
-        if (*o == "--no-default-options")
+        string a (s.peek ());
+
+        if (a.compare (0, 2, "--") != 0)
+        {
+          switch (m)
+          {
+          case unknow_mode::stop: return r;
+          case unknow_mode::fail: throw invalid_argument (a);
+          }
+        }
+
+        s.next ();
+
+        if (a == "--no-default-options")
           no_default_options_ = true;
 
-        push_back (move (*o));
+        push_back (move (a));
         r = true;
       }
       return r;
@@ -132,50 +189,58 @@ main (int argc, const char* argv[])
   optional<dir_path> sys_dir;
   optional<dir_path> home_dir;
   optional<dir_path> extra_dir;
+  bool args (false);
   vector<dir_path> dirs;
   options cmd_ops;
+  vector<string> cmd_args;
   bool print_entries (false);
   bool trace (false);
 
   for (int i (1); i != argc; ++i)
   {
-    string op (argv[i]);
+    string a (argv[i]);
 
-    if (op == "-f")
+    if (a == "-f")
     {
       assert (++i != argc);
       fs.files.push_back (path (argv[i]));
     }
-    else if (op == "-d")
+    else if (a == "-d")
     {
       assert (++i != argc);
       dirs.emplace_back (argv[i]);
     }
-    else if (op == "-s")
+    else if (a == "-s")
     {
       assert (++i != argc);
       sys_dir = dir_path (argv[i]);
     }
-    else if (op == "-h")
+    else if (a == "-h")
     {
       assert (++i != argc);
       home_dir = dir_path (argv[i]);
     }
-    else if (op == "-x")
+    else if (a == "-x")
     {
       assert (++i != argc);
       extra_dir = dir_path (argv[i]);
     }
-    else if (op == "-e")
+    else if (a == "-a")
+    {
+      args = true;
+    }
+    else if (a == "-e")
     {
       print_entries = true;
     }
-    else if (op == "-t")
+    else if (a == "-t")
     {
       trace = true;
     }
+    else if (a.compare (0, 2, "--") == 0)
+      cmd_ops.push_back (move (a));
     else
-      cmd_ops.push_back (argv[i]);
+      cmd_args.push_back (move (a));
   }
 
   // Deduce a common start directory.
@@ -184,8 +249,11 @@ main (int argc, const char* argv[])
 
   // Load and print the default options.
   //
-  default_options<options> def_ops (
-    load_default_options<options, scanner, unknow_mode> (
+  default_options<options> def_ops;
+
+  try
+  {
+    def_ops = load_default_options<options, scanner, unknow_mode> (
       sys_dir,
       home_dir,
       extra_dir,
@@ -195,7 +263,14 @@ main (int argc, const char* argv[])
         if (trace)
           cerr << (overwrite ? "overwriting " : "loading ")
                << (remote ? "remote " : "local ") << f << endl;
-      }));
+      },
+      args);
+  }
+  catch (const invalid_argument& e)
+  {
+    cerr << "error: unexpected argument '" << e.what () << "'" << endl;
+    return 1;
+  }
 
   if (print_entries)
   {
@@ -211,18 +286,40 @@ main (int argc, const char* argv[])
         cout << o;
       }
 
+      if (args)
+      {
+        cout << "|";
+
+        for (const string& a: e.arguments)
+        {
+          if (&a != &e.arguments[0])
+            cout << ' ';
+
+          cout << a;
+        }
+
+      }
+
       cout << (e.remote ? ",true" : ",false") << endl;
     }
   }
 
   // Merge the options and print the result.
   //
-  options ops (merge_default_options (def_ops, cmd_ops));
-
   if (!print_entries)
   {
+    options ops (merge_default_options (def_ops, cmd_ops));
+
     for (const string& o: ops)
       cout << o << endl;
+
+    if (args)
+    {
+      vector<string> as (merge_default_arguments (def_ops, cmd_args));
+
+      for (const string& a: as)
+        cout << a << endl;
+    }
   }
 
   return 0;
diff --git a/tests/default-options/testscript b/tests/default-options/testscript
index fa65e62..b168ca9 100644
--- a/tests/default-options/testscript
+++ b/tests/default-options/testscript
@@ -4,9 +4,9 @@
 # Note that when cross-testing the driver may not be able to run the command
 # due to the meaningless program path.
 #
-+if ($test.target != $build.host)
-  exit
-end
+#+if ($test.target != $build.host)
+#  exit
+#end
 
 : basic
 :
@@ -14,46 +14,46 @@ end
   sys_dir = $canonicalize([dir_path] $~/build2)
   +mkdir -p $sys_dir/local
 
-  +echo 'sys-foo' >=$sys_dir/foo
-  +echo 'sys-bar' >=$sys_dir/bar
-  +echo 'sys-local-foo' >=$sys_dir/local/foo
-  +echo 'sys-local-bar' >=$sys_dir/local/bar
+  +echo '--sys-foo' >=$sys_dir/foo
+  +echo '--sys-bar' >=$sys_dir/bar
+  +echo '--sys-local-foo' >=$sys_dir/local/foo
+  +echo '--sys-local-bar' >=$sys_dir/local/bar
 
   home_dir = $canonicalize([dir_path] $~/home)
   +mkdir -p $home_dir/.build2/local/
 
-  +echo 'home-foo'       >=$home_dir/.build2/foo
-  +echo 'home-bar'       >=$home_dir/.build2/bar
-  +echo 'home-local-foo' >=$home_dir/.build2/local/foo
-  +echo 'home-local-bar' >=$home_dir/.build2/local/bar
+  +echo '--home-foo'       >=$home_dir/.build2/foo
+  +echo '--home-bar'       >=$home_dir/.build2/bar
+  +echo '--home-local-foo' >=$home_dir/.build2/local/foo
+  +echo '--home-local-bar' >=$home_dir/.build2/local/bar
 
   work_dir = $home_dir/work
   +mkdir -p $work_dir/.build2/local/
 
   d = $work_dir/.build2
 
-  +echo 'work-foo'       >=$d/foo
-  +echo 'work-bar'       >=$d/bar
-  +echo 'work-local-foo' >=$d/local/foo
-  +echo 'work-local-bar' >=$d/local/bar
+  +echo '--work-foo'       >=$d/foo
+  +echo '--work-bar'       >=$d/bar
+  +echo '--work-local-foo' >=$d/local/foo
+  +echo '--work-local-bar' >=$d/local/bar
 
   d = $work_dir/project/.build2
   +mkdir -p $d/local/
 
   +touch $work_dir/project/.git
 
-  +echo 'project-foo'       >=$d/foo
-  +echo 'project-bar'       >=$d/bar
-  +echo 'project-local-foo' >=$d/local/foo
-  +echo 'project-local-bar' >=$d/local/bar
+  +echo '--project-foo'       >=$d/foo
+  +echo '--project-bar'       >=$d/bar
+  +echo '--project-local-foo' >=$d/local/foo
+  +echo '--project-local-bar' >=$d/local/bar
 
   d = $work_dir/project/package/.build2
   +mkdir -p $d/local/
 
-  +echo 'package-foo'       >=$d/foo
-  +echo 'package-bar'       >=$d/bar
-  +echo 'package-local-foo' >=$d/local/foo
-  +echo 'package-local-bar' >=$d/local/bar
+  +echo '--package-foo'       >=$d/foo
+  +echo '--package-bar'       >=$d/bar
+  +echo '--package-local-foo' >=$d/local/foo
+  +echo '--package-local-bar' >=$d/local/bar
 
   +echo '--no-default-options' >=$d/local/baz
 
@@ -62,26 +62,26 @@ end
   : entries
   :
   $* -e -t -f foo -f bar -d $start_dir -s $sys_dir -h $home_dir >>/~%EOO%d 2>>/~%EOE%d
-    %\.+/build2/foo,sys-foo,false%
-    %\.+/build2/bar,sys-bar,false%
-    %\.+/build2/local/foo,sys-local-foo,false%
-    %\.+/build2/local/bar,sys-local-bar,false%
-    %\.+/home/.build2/foo,home-foo,false%
-    %\.+/home/.build2/bar,home-bar,false%
-    %\.+/home/.build2/local/foo,home-local-foo,false%
-    %\.+/home/.build2/local/bar,home-local-bar,false%
-    %\.+/home/work/.build2/foo,work-foo,false%
-    %\.+/home/work/.build2/bar,work-bar,false%
-    %\.+/home/work/.build2/local/foo,work-local-foo,false%
-    %\.+/home/work/.build2/local/bar,work-local-bar,false%
-    %\.+/home/work/project/.build2/foo,project-foo,true%
-    %\.+/home/work/project/.build2/bar,project-bar,true%
-    %\.+/home/work/project/.build2/local/foo,project-local-foo,true%
-    %\.+/home/work/project/.build2/local/bar,project-local-bar,true%
-    %\.+/home/work/project/package/.build2/foo,package-foo,true%
-    %\.+/home/work/project/package/.build2/bar,package-bar,true%
-    %\.+/home/work/project/package/.build2/local/foo,package-local-foo,true%
-    %\.+/home/work/project/package/.build2/local/bar,package-local-bar,true%
+    %\.+/build2/foo,--sys-foo,false%
+    %\.+/build2/bar,--sys-bar,false%
+    %\.+/build2/local/foo,--sys-local-foo,false%
+    %\.+/build2/local/bar,--sys-local-bar,false%
+    %\.+/home/.build2/foo,--home-foo,false%
+    %\.+/home/.build2/bar,--home-bar,false%
+    %\.+/home/.build2/local/foo,--home-local-foo,false%
+    %\.+/home/.build2/local/bar,--home-local-bar,false%
+    %\.+/home/work/.build2/foo,--work-foo,false%
+    %\.+/home/work/.build2/bar,--work-bar,false%
+    %\.+/home/work/.build2/local/foo,--work-local-foo,false%
+    %\.+/home/work/.build2/local/bar,--work-local-bar,false%
+    %\.+/home/work/project/.build2/foo,--project-foo,true%
+    %\.+/home/work/project/.build2/bar,--project-bar,true%
+    %\.+/home/work/project/.build2/local/foo,--project-local-foo,true%
+    %\.+/home/work/project/.build2/local/bar,--project-local-bar,true%
+    %\.+/home/work/project/package/.build2/foo,--package-foo,true%
+    %\.+/home/work/project/package/.build2/bar,--package-bar,true%
+    %\.+/home/work/project/package/.build2/local/foo,--package-local-foo,true%
+    %\.+/home/work/project/package/.build2/local/bar,--package-local-bar,true%
     EOO
     %loading local \.+/home/work/project/package/.build2/local/bar%
     %loading local \.+/home/work/project/package/.build2/local/foo%
@@ -111,37 +111,37 @@ end
 
   : merged
   :
-  $* -f foo -f bar -d $start_dir -s $sys_dir -h $home_dir cmd-foo cmd-bar >>EOO
-    sys-foo
-    sys-bar
-    sys-local-foo
-    sys-local-bar
-    home-foo
-    home-bar
-    home-local-foo
-    home-local-bar
-    work-foo
-    work-bar
-    work-local-foo
-    work-local-bar
-    project-foo
-    project-bar
-    project-local-foo
-    project-local-bar
-    package-foo
-    package-bar
-    package-local-foo
-    package-local-bar
-    cmd-foo
-    cmd-bar
+  $* -f foo -f bar -d $start_dir -s $sys_dir -h $home_dir --cmd-foo --cmd-bar >>EOO
+    --sys-foo
+    --sys-bar
+    --sys-local-foo
+    --sys-local-bar
+    --home-foo
+    --home-bar
+    --home-local-foo
+    --home-local-bar
+    --work-foo
+    --work-bar
+    --work-local-foo
+    --work-local-bar
+    --project-foo
+    --project-bar
+    --project-local-foo
+    --project-local-bar
+    --package-foo
+    --package-bar
+    --package-local-foo
+    --package-local-bar
+    --cmd-foo
+    --cmd-bar
     EOO
 
   : no-default-options
   :
   $* -e -t -f foo -f baz -f bar -d $start_dir -s $sys_dir -h $home_dir >>/~%EOO%d 2>>/~%EOE%d
-    %\.+/home/work/project/package/.build2/local/foo,package-local-foo,true%
+    %\.+/home/work/project/package/.build2/local/foo,--package-local-foo,true%
     %\.+/home/work/project/package/.build2/local/baz,--no-default-options,true%
-    %\.+/home/work/project/package/.build2/local/bar,package-local-bar,true%
+    %\.+/home/work/project/package/.build2/local/bar,--package-local-bar,true%
     EOO
     %loading local \.+/home/work/project/package/.build2/local/bar%
     %loading local \.+/home/work/project/package/.build2/local/baz%
@@ -152,6 +152,47 @@ end
     EOE
 }
 
+: args
+:
+{
+  home_dir = $canonicalize([dir_path] $~/home)
+  +mkdir -p $home_dir/.build2
+  +echo '--home' >=$home_dir/.build2/ops
+  +echo 'home'   >+$home_dir/.build2/ops
+
+  start_dir = $canonicalize([dir_path] $home_dir/start)
+  +mkdir -p $start_dir/.build2
+  +echo '--start1' >=$start_dir/.build2/ops
+  +echo 'start2'   >+$start_dir/.build2/ops
+  +echo '--start3' >+$start_dir/.build2/ops
+  +echo 'start4'   >+$start_dir/.build2/ops
+
+  : allowed
+  :
+  $* -a -e -f ops -d $start_dir -h $home_dir >>/~%EOO%d
+    %\.+/home/.build2/ops,--home\|home,false%
+    %\.+/home/start/.build2/ops,--start1 --start3\|start2 start4,false%
+    EOO
+
+  : disallowed
+  :
+  $* -e -f ops -d $start_dir -h $home_dir 2>>EOE != 0
+    error: unexpected argument 'start2'
+    EOE
+
+  : merged
+  :
+  $* -a -f ops -d $start_dir -h $home_dir cmd >>EOO
+    --home
+    --start1
+    --start3
+    home
+    start2
+    start4
+    cmd
+    EOO
+}
+
 : common-start
 :
 {
@@ -166,10 +207,10 @@ end
 
   +mkdir -p $work_dir/.build2 $cfg1/.build2 $cfg2/.build2 $cfg3/.build2
 
-  +echo 'work' >=$work_dir/.build2/ops
-  +echo 'cfg1' >=$cfg1/.build2/ops
-  +echo 'cfg2' >=$cfg2/.build2/ops
-  +echo 'cfg3' >=$cfg3/.build2/ops
+  +echo '--work' >=$work_dir/.build2/ops
+  +echo '--cfg1' >=$cfg1/.build2/ops
+  +echo '--cfg2' >=$cfg2/.build2/ops
+  +echo '--cfg3' >=$cfg3/.build2/ops
 
   : exists
   :
@@ -177,29 +218,29 @@ end
     : single
     :
     $* -f ops -d $cfg3 -h $home_dir >>EOO
-      work
-      cfg2
-      cfg3
+      --work
+      --cfg2
+      --cfg3
       EOO
 
     : same
     :
     $* -f ops -d $cfg1 -d $cfg1 -h $home_dir >>EOO
-      work
-      cfg1
+      --work
+      --cfg1
       EOO
 
     : adjacent
     :
     $* -f ops -d $cfg1 -d $cfg2 -h $home_dir >>EOO
-      work
+      --work
       EOO
 
     : nested
     :
     $* -f ops -d $cfg2 -d $cfg3 -h $home_dir >>EOO
-      work
-      cfg2
+      --work
+      --cfg2
       EOO
   }
 
@@ -209,7 +250,7 @@ end
     : home-reached
     :
     $* -f ops -d $cfg1 -d $cfg2 -h $work_dir >>EOO
-      work
+      --work
       EOO
 
     : root-reached
@@ -229,20 +270,20 @@ end
   {
     home_dir = $canonicalize([dir_path] $~/home);
     mkdir -p $home_dir/.build2;
-    echo 'home' >=$home_dir/.build2/ops;
+    echo '--home' >=$home_dir/.build2/ops;
 
     extra_dir = $canonicalize([dir_path] $home_dir/extra);
     mkdir -p $extra_dir;
-    echo 'extra' >=$extra_dir/ops;
+    echo '--extra' >=$extra_dir/ops;
 
     start_dir = $canonicalize([dir_path] $home_dir/start);
     mkdir -p $start_dir/.build2;
-    echo 'start' >=$start_dir/.build2/ops;
+    echo '--start' >=$start_dir/.build2/ops;
 
     $* -e -f ops -d $start_dir -h $home_dir -x $extra_dir >>/~%EOO%d
-      %\.+/home/.build2/ops,home,false%
-      %\.+/home/extra/ops,extra,false%
-      %\.+/home/start/.build2/ops,start,false%
+      %\.+/home/.build2/ops,--home,false%
+      %\.+/home/extra/ops,--extra,false%
+      %\.+/home/start/.build2/ops,--start,false%
       EOO
   }
 
@@ -251,56 +292,56 @@ end
   {
     home_dir = $canonicalize([dir_path] $~/home);
     mkdir -p $home_dir/.build2;
-    echo 'home' >=$home_dir/.build2/ops;
+    echo '--home' >=$home_dir/.build2/ops;
 
     d = $home_dir/project/.build2;
     mkdir -p $d;
-    echo 'project' >=$d/ops;
+    echo '--project' >=$d/ops;
 
     touch $home_dir/project/.git;
 
     d = $home_dir/project/package/.build2;
     mkdir -p $d;
-    echo 'package' >=$d/ops;
+    echo '--package' >=$d/ops;
 
     extra_dir = $canonicalize([dir_path] $home_dir/project/package/extra1);
     mkdir -p $extra_dir;
-    echo 'extra1' >=$extra_dir/ops;
+    echo '--extra1' >=$extra_dir/ops;
 
     start_dir = $canonicalize([dir_path] $home_dir/project/package);
 
     $* -e -f ops -d $start_dir -h $home_dir -x $extra_dir >>/~%EOO%d;
-      %\.+/home/.build2/ops,home,false%
-      %\.+/home/project/.build2/ops,project,true%
-      %\.+/home/project/package/.build2/ops,package,true%
-      %\.+/home/project/package/extra1/ops,extra1,false%
+      %\.+/home/.build2/ops,--home,false%
+      %\.+/home/project/.build2/ops,--project,true%
+      %\.+/home/project/package/.build2/ops,--package,true%
+      %\.+/home/project/package/extra1/ops,--extra1,false%
       EOO
 
     extra_dir = $canonicalize([dir_path] $home_dir/project/package/.build2);
 
     $* -e -f ops -d $start_dir -h $home_dir -x $extra_dir/ >>/~%EOO%d;
-      %\.+/home/.build2/ops,home,false%
-      %\.+/home/project/.build2/ops,project,true%
-      %\.+/home/project/package/.build2/ops,package,false%
+      %\.+/home/.build2/ops,--home,false%
+      %\.+/home/project/.build2/ops,--project,true%
+      %\.+/home/project/package/.build2/ops,--package,false%
       EOO
 
     extra_dir = $canonicalize([dir_path] $home_dir/project/extra2);
     mkdir -p $extra_dir;
-    echo 'extra2' >=$extra_dir/ops;
+    echo '--extra2' >=$extra_dir/ops;
 
     $* -e -f ops -d $start_dir -h $home_dir -x $extra_dir >>/~%EOO%d;
-      %\.+/home/.build2/ops,home,false%
-      %\.+/home/project/.build2/ops,project,true%
-      %\.+/home/project/extra2/ops,extra2,false%
-      %\.+/home/project/package/.build2/ops,package,true%
+      %\.+/home/.build2/ops,--home,false%
+      %\.+/home/project/.build2/ops,--project,true%
+      %\.+/home/project/extra2/ops,--extra2,false%
+      %\.+/home/project/package/.build2/ops,--package,true%
       EOO
 
     extra_dir = $canonicalize([dir_path] $home_dir/project/.build2);
 
     $* -e -f ops -d $start_dir -h $home_dir -x $extra_dir/ >>/~%EOO%d
-      %\.+/home/.build2/ops,home,false%
-      %\.+/home/project/.build2/ops,project,false%
-      %\.+/home/project/package/.build2/ops,package,true%
+      %\.+/home/.build2/ops,--home,false%
+      %\.+/home/project/.build2/ops,--project,false%
+      %\.+/home/project/package/.build2/ops,--package,true%
       EOO
   }
 }