Add support for vars grouping for package commands

21 files changed, 153 insertions, 105 deletions

diff --git a/bpkg/auth.cxx b/bpkg/auth.cxx
index 787a705..7cdf39e 100644
--- a/bpkg/auth.cxx
+++ b/bpkg/auth.cxx
@@ -5,9 +5,8 @@
 #include <bpkg/auth.hxx>
 
 #include <ratio>
-#include <limits>    // numeric_limits
-#include <cstring>   // strlen(), strcmp()
-#include <iterator>  // ostreambuf_iterator
+#include <limits>   // numeric_limits
+#include <iterator> // ostreambuf_iterator
 
 #include <libbutl/sha256.mxx>
 #include <libbutl/base64.mxx>
diff --git a/bpkg/bpkg.cxx b/bpkg/bpkg.cxx
index 018ca7a..00f78cf 100644
--- a/bpkg/bpkg.cxx
+++ b/bpkg/bpkg.cxx
@@ -6,7 +6,6 @@
 #  include <signal.h> // signal()
 #endif
 
-#include <cstring>   // strcmp()
 #include <iostream>
 
 #include <bpkg/types.hxx>
@@ -321,20 +320,23 @@ try
     //
 #define PKG_COMMAND(CMD, SEP) COMMAND_IMPL(pkg_, "pkg-", CMD, SEP, true)
 
-    PKG_COMMAND (build,     true);  // Keeps the '--' separator in args.
+    // These commands need the '--' separator to be kept in args.
+    //
+    PKG_COMMAND (build,     true);
+    PKG_COMMAND (clean,     true);
+    PKG_COMMAND (configure, true);
+    PKG_COMMAND (install,   true);
+    PKG_COMMAND (test,      true);
+    PKG_COMMAND (uninstall, true);
+    PKG_COMMAND (update,    true);
+
     PKG_COMMAND (checkout,  false);
-    PKG_COMMAND (clean,     false);
-    PKG_COMMAND (configure, false);
     PKG_COMMAND (disfigure, false);
     PKG_COMMAND (drop,      false);
     PKG_COMMAND (fetch,     false);
-    PKG_COMMAND (install,   false);
     PKG_COMMAND (purge,     false);
     PKG_COMMAND (status,    false);
-    PKG_COMMAND (test,      false);
-    PKG_COMMAND (uninstall, false);
     PKG_COMMAND (unpack,    false);
-    PKG_COMMAND (update,    false);
     PKG_COMMAND (verify,    false);
 
     // rep-* commands
diff --git a/bpkg/diagnostics.cxx b/bpkg/diagnostics.cxx
index 400b352..1048e9b 100644
--- a/bpkg/diagnostics.cxx
+++ b/bpkg/diagnostics.cxx
@@ -4,7 +4,6 @@
 
 #include <bpkg/diagnostics.hxx>
 
-#include <cstring>  // strchr()
 #include <iostream>
 
 #include <odb/statement.hxx>
diff --git a/bpkg/fetch-git.cxx b/bpkg/fetch-git.cxx
index c2e1b36..ff5432e 100644
--- a/bpkg/fetch-git.cxx
+++ b/bpkg/fetch-git.cxx
@@ -286,6 +286,9 @@ namespace bpkg
   // command that we use to clone submodules. So to truncate local submodule
   // histories we will use the file URL notation for local repositories.
   //
+  // @@ An update: we don't use the 'submodule--helper clone' command anymore.
+  //    Should we switch to the local path notation for the file:// protocol?
+  //
   static string
   to_git_url (const repository_url& url)
   {
diff --git a/bpkg/pkg-build.cli b/bpkg/pkg-build.cli
index f5ece04..9aaf84e 100644
--- a/bpkg/pkg-build.cli
+++ b/bpkg/pkg-build.cli
@@ -22,7 +22,8 @@ namespace bpkg
 
      \c{\b{bpkg pkg-build}|\b{build} [<options>] [\b{--upgrade}|\b{-u} | \b{--patch}|\b{-p}]\n
         \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ [<cfg-var>... \b{--}] <pkg-spec>...\n
-        \b{bpkg pkg-build}|\b{build} [<options>] \ \b{--upgrade}|\b{-u} | \b{--patch}|\b{-p}}
+        \b{bpkg pkg-build}|\b{build} [<options>] \ \b{--upgrade}|\b{-u} | \b{--patch}|\b{-p}\n
+        \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ [<cfg-var>... \b{--}]}
 
      \c{<pkg-spec> = [<flags>](([<scheme>\b{:}]<pkg>[\b{/}<ver>])\b{,}...[\b{@}<rep-loc>] | \n
         \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ [\b{@}]<rep-loc> \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ | \n
@@ -104,7 +105,7 @@ namespace bpkg
      specified before packages (<pkg-spec>) and should be separated with
      \cb{--}. Such variables are effective only when configuring and only for
      packages that were explicitly specified on the command line (they can
-     also be specified to apply only to specific packages using the argument
+     also be specified to only apply to specific packages using the argument
      grouping mechanism discussed below). See \l{bpkg-pkg-configure(1)} for
      more information on configuration variables.
 
diff --git a/bpkg/pkg-build.cxx b/bpkg/pkg-build.cxx
index 27e509b..655f0de 100644
--- a/bpkg/pkg-build.cxx
+++ b/bpkg/pkg-build.cxx
@@ -7,7 +7,7 @@
 #include <map>
 #include <set>
 #include <list>
-#include <cstring>    // strlen(), strcmp(), strchr()
+#include <cstring>    // strlen()
 #include <iostream>   // cout
 #include <algorithm>  // find_if()
 
@@ -2297,14 +2297,14 @@ namespace bpkg
 
     vector<pkg_spec> specs;
     {
-      // Parse the global configuration variables until we reach the "--"
+      // Read the common configuration variables until we reach the "--"
       // separator, eos or an argument. Non-empty variables list should always
       // be terminated with the "--". Furthermore, argument list that contains
       // anything that looks like a variable (has the '=' character) should be
       // preceded with "--".
       //
-      strings config_vars;
-      bool vars_separated (false);
+      strings cvars;
+      bool sep (false); // Seen '--'.
 
       while (args.more ())
       {
@@ -2314,7 +2314,7 @@ namespace bpkg
         //
         if (strcmp (a, "--") == 0)
         {
-          vars_separated = true;
+          sep = true;
           args.next ();
           break;
         }
@@ -2333,10 +2333,10 @@ namespace bpkg
           fail << "unexpected options group for configuration variable '"
                << v << "'";
 
-        config_vars.push_back (move (v));
+        cvars.push_back (move (v));
       }
 
-      if (!config_vars.empty () && !vars_separated)
+      if (!cvars.empty () && !sep)
         fail << "configuration variables must be separated from packages "
              << "with '--'";
 
@@ -2351,7 +2351,7 @@ namespace bpkg
         // Make sure the argument can not be misinterpreted as a configuration
         // variable.
         //
-        if (a.find ('=') != string::npos && !vars_separated)
+        if (a.find ('=') != string::npos && !sep)
           fail << "unexpected configuration variable '" << a << "'" <<
             info << "use the '--' separator to treat it as a package";
 
@@ -2365,10 +2365,10 @@ namespace bpkg
           cli::scanner& ag (args.group ());
           po.parse (ag, cli::unknown_mode::fail, cli::unknown_mode::stop);
 
-          // Merge the global and package-specific configuration variables
-          // (globals go first).
+          // Merge the common and package-specific configuration variables
+          // (commons go first).
           //
-          ps.config_vars = config_vars;
+          ps.config_vars = cvars;
 
           while (ag.more ())
           {
@@ -4260,8 +4260,8 @@ namespace bpkg
       {
         if (*p.action == build_package::drop)
         {
-          // Note that the selected system package has already gone being
-          // disfigured (see above).
+          // Note that the selected system package is gone once disfigured
+          // (see above).
           //
           if (sp != nullptr)
           {
diff --git a/bpkg/pkg-clean.cli b/bpkg/pkg-clean.cli
index 9e40e89..8d57845 100644
--- a/bpkg/pkg-clean.cli
+++ b/bpkg/pkg-clean.cli
@@ -15,21 +15,22 @@ namespace bpkg
 
     "\h|SYNOPSIS|
 
-     \c{\b{bpkg pkg-clean}|\b{clean} [<options>] [<vars>] (<pkg> [<vars>])...\n
+     \c{\b{bpkg pkg-clean}|\b{clean} [<options>] [<vars>] <pkg>...\n
         \b{bpkg pkg-clean}|\b{clean} [<options>] [<vars>] \b{--all}|\b{-a}}
 
      \h|DESCRIPTION|
 
      The \cb{pkg-clean} command cleans the specified packages (the first form)
      or all the held packages (the second form, see \l{bpkg-pkg-status(1)}).
-     Underneath, this command doesn't do much more than run \cb{b clean}.
-
-     In the first form the specified packages must have been previously
+     Underneath, this command doesn't do much more than run \cb{b clean}. In
+     the first form the specified packages must have been previously
      configured with \l{bpkg-pkg-build(1)} or \l{bpkg-pkg-configure(1)}.
+
      Additional command line variables (<vars>, normally \cb{config.*}) can be
-     passed to the build system by either specifying them before the packages,
-     in which case they apply to the whole configuration, or after a specific
-     package, in which case they apply only to this package."
+     passed to the build system. Such variables apply to all the specified
+     packages but can also be specified to only apply to specific packages
+     using the argument grouping mechanism (see \l{bpkg-argument-grouping(1)}
+     for details)."
   }
 
   class pkg_clean_options: configuration_options
diff --git a/bpkg/pkg-clean.hxx b/bpkg/pkg-clean.hxx
index bfea24e..1a930e6 100644
--- a/bpkg/pkg-clean.hxx
+++ b/bpkg/pkg-clean.hxx
@@ -14,7 +14,7 @@
 namespace bpkg
 {
   inline int
-  pkg_clean (const pkg_clean_options& o, cli::scanner& args)
+  pkg_clean (const pkg_clean_options& o, cli::group_scanner& args)
   {
     return pkg_command ("clean",
                         o,
diff --git a/bpkg/pkg-command.cxx b/bpkg/pkg-command.cxx
index 6b82c29..c66c8da 100644
--- a/bpkg/pkg-command.cxx
+++ b/bpkg/pkg-command.cxx
@@ -129,32 +129,67 @@ namespace bpkg
                bool recursive,
                bool immediate,
                bool all,
-               cli::scanner& args)
+               cli::group_scanner& args)
   {
     tracer trace ("pkg_command");
 
     const dir_path& c (o.directory ());
     l4 ([&]{trace << "configuration: " << c;});
 
-    // First read the common variables.
+    // First sort arguments into the package names and variables.
     //
-    // @@ TODO: redo using argument groups.
-    //
-    auto read_vars = [&args](strings& v)
+    strings cvars;
+    bool sep (false); // Seen '--'.
+
+    struct pkg_arg
+    {
+      package_name name;
+      strings      vars;
+    };
+    vector<pkg_arg> pkg_args;
+
+    while (args.more ())
     {
-      for (; args.more (); args.next ())
+      string a (args.next ());
+
+      // If we see the "--" separator, then we are done parsing common
+      // variables.
+      //
+      if (!sep && a == "--")
       {
-        string a (args.peek ());
+        sep = true;
+        continue;
+      }
 
-        if (a.find ('=') == string::npos)
-          break;
+      if (!sep && a.find ('=') != string::npos)
+      {
+        // Make sure this is not a (misspelled) package name with an option
+        // group.
+        //
+        if (args.group ().more ())
+          fail << "unexpected options group for variable '" << a << "'";
 
-        v.push_back (move (a));
+        cvars.push_back (move (a));
       }
-    };
+      else
+      {
+        package_name n (parse_package_name (a, false /* allow_version */));
 
-    strings cvars;
-    read_vars (cvars);
+        // Read package-specific variables.
+        //
+        strings vars;
+        for (cli::scanner& ag (args.group ()); ag.more (); )
+        {
+          string a (ag.next ());
+          if (a.find ('=') == string::npos)
+            fail << "unexpected group argument '" << a << "'";
+
+          vars.push_back (move (a));
+        }
+
+        pkg_args.push_back (pkg_arg {move (n), move (vars)});
+      }
+    }
 
     // Check that options and arguments are consistent.
     //
@@ -168,10 +203,10 @@ namespace bpkg
         dr << fail << "both --immediate|-i and --recursive|-r specified";
       else if (all)
       {
-        if (args.more ())
+        if (!pkg_args.empty ())
           dr << fail << "both --all|-a and package argument specified";
       }
-      else if (!args.more ())
+      else if (pkg_args.empty ())
         dr << fail << "package name argument expected";
 
       if (!dr.empty ())
@@ -221,32 +256,24 @@ namespace bpkg
       }
       else
       {
-        while (args.more ())
+        for (auto& a: pkg_args)
         {
-          package_name n (parse_package_name (args.next (),
-                                              false /* allow_version */));
-
-          shared_ptr<selected_package> p (db.find<selected_package> (n));
+          shared_ptr<selected_package> p (db.find<selected_package> (a.name));
 
           if (p == nullptr)
-            fail << "package " << n << " does not exist in configuration "
-                 << c;
+            fail << "package " << a.name << " does not exist in "
+                 << "configuration " << c;
 
           if (p->state != package_state::configured)
-            fail << "package " << n << " is " << p->state <<
+            fail << "package " << a.name << " is " << p->state <<
               info << "expected it to be configured";
 
           if (p->substate == package_substate::system)
-            fail << "cannot " << cmd << " system package " << n;
+            fail << "cannot " << cmd << " system package " << a.name;
 
           l4 ([&]{trace << *p;});
 
-          // Read package-specific variables.
-          //
-          strings vars;
-          read_vars (vars);
-
-          add (p, move (vars));
+          add (p, move (a.vars));
         }
       }
 
diff --git a/bpkg/pkg-command.hxx b/bpkg/pkg-command.hxx
index 9b56142..8991263 100644
--- a/bpkg/pkg-command.hxx
+++ b/bpkg/pkg-command.hxx
@@ -28,7 +28,7 @@ namespace bpkg
                bool recursive,
                bool immediate,
                bool all,
-               cli::scanner& args);
+               cli::group_scanner& args);
 
   struct pkg_command_vars
   {
diff --git a/bpkg/pkg-configure.cli b/bpkg/pkg-configure.cli
index fd4453d..bc7c3de 100644
--- a/bpkg/pkg-configure.cli
+++ b/bpkg/pkg-configure.cli
@@ -25,8 +25,8 @@ namespace bpkg
 
      A source code package inherits the common \cb{build2} configuration
      values that were specified when creating the configuration
-     (\l{bpkg-cfg-create(1)}). Additional, package-specific configuration
-     variables can be specified before the package name.
+     (\l{bpkg-cfg-create(1)}). Additional package-specific configuration
+     variables can be passed to \cb{pkg-configure} (<cfg-var>).
 
      A system package is specified using the \c{\b{sys:}<pkg>[/<ver>]}
      syntax. If the package version (<ver>) is not specified, then it is
diff --git a/bpkg/pkg-configure.cxx b/bpkg/pkg-configure.cxx
index 6db60d4..d63b010 100644
--- a/bpkg/pkg-configure.cxx
+++ b/bpkg/pkg-configure.cxx
@@ -238,12 +238,21 @@ namespace bpkg
     //
     string n;
     strings vars;
+    bool sep (false); // Seen '--'.
 
     while (args.more ())
     {
       string a (args.next ());
 
-      if (a.find ('=') != string::npos)
+      // If we see the "--" separator, then we are done parsing variables.
+      //
+      if (!sep && a == "--")
+      {
+        sep = true;
+        continue;
+      }
+
+      if (!sep && a.find ('=') != string::npos)
         vars.push_back (move (a));
       else if (n.empty ())
         n = move (a);
diff --git a/bpkg/pkg-install.cli b/bpkg/pkg-install.cli
index a44522e..2b31763 100644
--- a/bpkg/pkg-install.cli
+++ b/bpkg/pkg-install.cli
@@ -15,7 +15,7 @@ namespace bpkg
 
     "\h|SYNOPSIS|
 
-     \c{\b{bpkg pkg-install}|\b{install} [<options>] [<vars>] (<pkg> [<vars>])...\n
+     \c{\b{bpkg pkg-install}|\b{install} [<options>] [<vars>] <pkg>...\n
         \b{bpkg pkg-install}|\b{install} [<options>] [<vars>] \b{--all}|\b{-a}}
 
      \h|DESCRIPTION|
@@ -25,20 +25,21 @@ namespace bpkg
      Additionally, immediate or all dependencies of these packages can be also
      installed by specifying the \c{\b{--immediate}|\b{-i}} or
      \c{\b{--recursive}|\b{-r}} options, respectively. Underneath, this
-     command doesn't do much more than run \cb{b install}.
+     command doesn't do much more than run \cb{b install}. In the first form
+     the specified packages must have been previously configured with
+     \l{bpkg-pkg-build(1)} or \l{bpkg-pkg-configure(1)}.
 
-     In the first form the specified packages must have been previously
-     configured with \l{bpkg-pkg-build(1)} or \l{bpkg-pkg-configure(1)}.
      Additional command line variables (<vars>, normally \cb{config.*}) can be
-     passed to the build system by either specifying them before the packages,
-     in which case they apply to the whole configuration, or after a specific
-     package, in which case they apply only to this package. In particular,
-     this mechanism can be used to specify the installation directory, for
-     example:
+     passed to the build system. Such variables apply to all the specified
+     packages but can also be specified to only apply to specific packages
+     using the argument grouping mechanism (see \l{bpkg-argument-grouping(1)}
+     for details). In particular, this mechanism can be used to specify the
+     installation directory, for example:
 
      \
      bpkg install config.install.root=/usr/local \
-       config.install.sudo=sudo libfoo libbar
+                  config.install.sudo=sudo       \
+                  libfoo libbar
      \
 
      Alternatively, the installation directory can be specified once when
diff --git a/bpkg/pkg-install.hxx b/bpkg/pkg-install.hxx
index f2969e8..99031ea 100644
--- a/bpkg/pkg-install.hxx
+++ b/bpkg/pkg-install.hxx
@@ -15,7 +15,7 @@
 namespace bpkg
 {
   inline int
-  pkg_install (const pkg_install_options& o, cli::scanner& args)
+  pkg_install (const pkg_install_options& o, cli::group_scanner& args)
   {
     return pkg_command ("install",
                         o,
diff --git a/bpkg/pkg-test.cli b/bpkg/pkg-test.cli
index 885996c..6593c4d 100644
--- a/bpkg/pkg-test.cli
+++ b/bpkg/pkg-test.cli
@@ -15,7 +15,7 @@ namespace bpkg
 
     "\h|SYNOPSIS|
 
-     \c{\b{bpkg pkg-test}|\b{test} [<options>] [<vars>] (<pkg> [<vars>])...\n
+     \c{\b{bpkg pkg-test}|\b{test} [<options>] [<vars>] <pkg>...\n
         \b{bpkg pkg-test}|\b{test} [<options>] [<vars>] \b{--all}|\b{-a}}
 
      \h|DESCRIPTION|
@@ -25,14 +25,15 @@ namespace bpkg
      Additionally, immediate or all dependencies of these packages can also be
      tested by specifying the \c{\b{--immediate}|\b{-i}} or
      \c{\b{--recursive}|\b{-r}} options, respectively. Underneath, this
-     command doesn't do much more than run \cb{b test}.
+     command doesn't do much more than run \cb{b test}. In the first form the
+     specified packages must have been previously configured with
+     \l{bpkg-pkg-build(1)} or \l{bpkg-pkg-configure(1)}.
 
-     In the first form the specified packages must have been previously
-     configured with \l{bpkg-pkg-build(1)} or \l{bpkg-pkg-configure(1)}.
      Additional command line variables (<vars>, normally \cb{config.*}) can be
-     passed to the build system by either specifying them before the packages,
-     in which case they apply to the whole configuration, or after a specific
-     package, in which case they apply only to this package."
+     passed to the build system. Such variables apply to all the specified
+     packages but can also be specified to only apply to specific packages
+     using the argument grouping mechanism (see \l{bpkg-argument-grouping(1)}
+     for details)."
   }
 
   class pkg_test_options: configuration_options
diff --git a/bpkg/pkg-test.hxx b/bpkg/pkg-test.hxx
index 1b8b670..a5ad022 100644
--- a/bpkg/pkg-test.hxx
+++ b/bpkg/pkg-test.hxx
@@ -14,7 +14,7 @@
 namespace bpkg
 {
   inline int
-  pkg_test (const pkg_test_options& o, cli::scanner& args)
+  pkg_test (const pkg_test_options& o, cli::group_scanner& args)
   {
     return pkg_command ("test",
                         o,
diff --git a/bpkg/pkg-uninstall.cli b/bpkg/pkg-uninstall.cli
index 1ac2546..0ceaf57 100644
--- a/bpkg/pkg-uninstall.cli
+++ b/bpkg/pkg-uninstall.cli
@@ -15,7 +15,7 @@ namespace bpkg
 
     "\h|SYNOPSIS|
 
-     \c{\b{bpkg pkg-uninstall}|\b{uninstall} [<options>] [<vars>] (<pkg> [<vars>])...\n
+     \c{\b{bpkg pkg-uninstall}|\b{uninstall} [<options>] [<vars>] <pkg>...\n
         \b{bpkg pkg-uninstall}|\b{uninstall} [<options>] [<vars>] \b{--all}|\b{-a}}
 
      \h|DESCRIPTION|
@@ -26,15 +26,15 @@ namespace bpkg
      these specified packages can be also uninstalled by specifying the
      \c{\b{--immediate}|\b{-i}} or \c{\b{--recursive}|\b{-r}} options,
      respectively. Underneath, this command doesn't do much more than run
-     \cb{b uninstall}.
+     \cb{b uninstall}. In the first form the specified packages must have been
+     previously configured with \l{bpkg-pkg-build(1)} or
+     \l{bpkg-pkg-configure(1)}.
 
-     In the first form the specified packages must have been previously
-     configured with \l{bpkg-pkg-build(1)} or \l{bpkg-pkg-configure(1)}.
      Additional command line variables (<vars>, normally \cb{config.*}) can be
-     passed to the build system by either specifying them before the packages,
-     in which case they apply to the whole configuration, or after a specific
-     package, in which case they apply only to this package. See
-     \l{bpkg-pkg-install(1)} for some examples."
+     passed to the build system. Such variables apply to all the specified
+     packages but can also be specified to only apply to specific packages
+     using the argument grouping mechanism (see \l{bpkg-argument-grouping(1)}
+     for details). See \l{bpkg-pkg-install(1)} for some examples."
   }
 
   class pkg_uninstall_options: configuration_options
diff --git a/bpkg/pkg-uninstall.hxx b/bpkg/pkg-uninstall.hxx
index 30bd52d..6079143 100644
--- a/bpkg/pkg-uninstall.hxx
+++ b/bpkg/pkg-uninstall.hxx
@@ -15,7 +15,7 @@
 namespace bpkg
 {
   inline int
-  pkg_uninstall (const pkg_uninstall_options& o, cli::scanner& args)
+  pkg_uninstall (const pkg_uninstall_options& o, cli::group_scanner& args)
   {
     return pkg_command ("uninstall", o,
                         "" /* cmd_variant */,
diff --git a/bpkg/pkg-update.cli b/bpkg/pkg-update.cli
index a77b473..86e0e45 100644
--- a/bpkg/pkg-update.cli
+++ b/bpkg/pkg-update.cli
@@ -15,7 +15,7 @@ namespace bpkg
 
     "\h|SYNOPSIS|
 
-     \c{\b{bpkg pkg-update}|\b{update} [<options>] [<vars>] (<pkg> [<vars>])...\n
+     \c{\b{bpkg pkg-update}|\b{update} [<options>] [<vars>] <pkg>...\n
         \b{bpkg pkg-update}|\b{update} [<options>] [<vars>] \b{--all}|\b{-a}}
 
      \h|DESCRIPTION|
@@ -24,14 +24,15 @@ namespace bpkg
      form) or all the held packages (the second form, see
      \l{bpkg-pkg-status(1)}). Underneath, this command doesn't do much more
      than run \cb{b update} (or one of its \c{update-for-*} variants; see
-     \cb{--for|-f}).
+     \cb{--for|-f}). In the first form the specified packages must have been
+     previously configured with \l{bpkg-pkg-build(1)} or
+     \l{bpkg-pkg-configure(1)}.
 
-     In the first form the specified packages must have been previously
-     configured with \l{bpkg-pkg-build(1)} or \l{bpkg-pkg-configure(1)}.
      Additional command line variables (<vars>, normally \cb{config.*}) can be
-     passed to the build system by either specifying them before the packages,
-     in which case they apply to the whole configuration, or after a specific
-     package, in which case they apply only to this package."
+     passed to the build system. Such variables apply to all the specified
+     packages but can also be specified to only apply to specific packages
+     using the argument grouping mechanism (see \l{bpkg-argument-grouping(1)}
+     for details)."
   }
 
   class pkg_update_options: configuration_options
diff --git a/bpkg/pkg-update.hxx b/bpkg/pkg-update.hxx
index 01c5e58..13d6ae9 100644
--- a/bpkg/pkg-update.hxx
+++ b/bpkg/pkg-update.hxx
@@ -15,7 +15,7 @@
 namespace bpkg
 {
   inline int
-  pkg_update (const pkg_update_options& o, cli::scanner& args)
+  pkg_update (const pkg_update_options& o, cli::group_scanner& args)
   {
     return pkg_command ("update",
                         o,
diff --git a/bpkg/utility.hxx b/bpkg/utility.hxx
index c0c361f..accfa99 100644
--- a/bpkg/utility.hxx
+++ b/bpkg/utility.hxx
@@ -7,6 +7,7 @@
 
 #include <memory>   // make_shared()
 #include <string>   // to_string()
+#include <cstring>  // strcmp(), strchr()
 #include <utility>  // move(), forward(), declval(), make_pair()
 #include <cassert>  // assert()
 #include <iterator> // make_move_iterator()
@@ -32,6 +33,9 @@ namespace bpkg
   using std::make_move_iterator;
   using std::to_string;
 
+  using std::strcmp;
+  using std::strchr;
+
   // <libbutl/utility.mxx>
   //
   using butl::casecmp;