Add support for build-time dependencies

7 files changed, 179 insertions, 13 deletions

diff --git a/bpkg/package.xml b/bpkg/package.xml
index 0602880..78a49d4 100644
--- a/bpkg/package.xml
+++ b/bpkg/package.xml
@@ -106,6 +106,7 @@
       <column name="version_revision" type="INTEGER" null="true"/>
       <column name="index" type="INTEGER" null="true"/>
       <column name="conditional" type="INTEGER" null="true"/>
+      <column name="buildtime" type="INTEGER" null="true"/>
       <column name="comment" type="TEXT" null="true"/>
       <foreign-key name="object_id_fk" on-delete="CASCADE">
         <column name="name"/>
diff --git a/bpkg/pkg-build.cxx b/bpkg/pkg-build.cxx
index a022130..d9847f2 100644
--- a/bpkg/pkg-build.cxx
+++ b/bpkg/pkg-build.cxx
@@ -499,6 +499,31 @@ namespace bpkg
           fail << "multiple dependency alternatives not yet supported";
 
         const dependency& d (da.front ());
+        const string& dn (d.name);
+
+        if (da.buildtime)
+        {
+          // Handle special names.
+          //
+          if (dn == "build2")
+          {
+            if (d.constraint)
+              satisfy_build2 (options, name, d);
+
+            continue;
+          }
+          else if (dn == "bpkg")
+          {
+            if (d.constraint)
+              satisfy_bpkg (options, name, d);
+
+            continue;
+          }
+          // else
+          //
+          // @@ TODO: in the future we would need to at least make sure the
+          // build and target machines are the same. See also pkg-configure.
+        }
 
         // The first step is to always find the available package even
         // if, in the end, it won't be the one we select. If we cannot
@@ -521,7 +546,7 @@ namespace bpkg
         // either way, resolving it to 1.0.0 is the conservative choice and
         // the user can always override it by explicitly building libhello.
         //
-        auto rp (find_available (db, d.name, ar, d.constraint));
+        auto rp (find_available (db, dn, ar, d.constraint));
         shared_ptr<available_package>& dap (rp.first);
 
         if (dap == nullptr)
@@ -550,14 +575,14 @@ namespace bpkg
           if (dap->system_version () == nullptr)
             fail << "prerequisite " << d << " of package " << name << " is "
                  << "not available in source" <<
-              info << "specify ?sys:" << d.name << " if it is available "
-                 << "from the system";
+              info << "specify ?sys:" << dn << " if it is available from the "
+                 << "system";
 
           if (!satisfies (*dap->system_version (), d.constraint))
           {
             fail << "prerequisite " << d << " of package " << name << " is "
                  << "not available in source" <<
-              info << "sys:" << d.name << "/" << *dap->system_version ()
+              info << "sys:" << dn << "/" << *dap->system_version ()
                  << " does not satisfy the constrains";
           }
 
@@ -579,11 +604,11 @@ namespace bpkg
         // worse, downgrade).
         //
         bool force (false);
-        shared_ptr<selected_package> dsp (db.find<selected_package> (d.name));
+        shared_ptr<selected_package> dsp (db.find<selected_package> (dn));
         if (dsp != nullptr)
         {
           if (dsp->state == package_state::broken)
-            fail << "unable to build broken package " << d.name <<
+            fail << "unable to build broken package " << dn <<
               info << "use 'pkg-purge --force' to remove";
 
           if (satisfies (dsp->version, d.constraint))
@@ -777,6 +802,12 @@ namespace bpkg
           {
             assert (!da.conditional && da.size () == 1); // @@ TODO
             const dependency& d (da.front ());
+            const string& dn (d.name);
+
+            // Skip special names.
+            //
+            if (da.buildtime && (dn == "build2" || dn == "bpkg"))
+              continue;
 
             update (order (d.name, false));
           }
diff --git a/bpkg/pkg-configure.cxx b/bpkg/pkg-configure.cxx
index 81b1fe3..2bb834f 100644
--- a/bpkg/pkg-configure.cxx
+++ b/bpkg/pkg-configure.cxx
@@ -61,6 +61,32 @@ namespace bpkg
         {
           const string& n (d.name);
 
+          if (da.buildtime)
+          {
+            // Handle special names.
+            //
+            if (n == "build2")
+            {
+              if (d.constraint)
+                satisfy_build2 (o, m.name, d);
+
+              satisfied = true;
+              break;
+            }
+            else if (n == "bpkg")
+            {
+              if (d.constraint)
+                satisfy_bpkg (o, m.name, d);
+
+              satisfied = true;
+              break;
+            }
+            // else
+            //
+            // @@ TODO: in the future we would need to at least make sure the
+            // build and target machines are the same. See also pkg-build.
+          }
+
           if (shared_ptr<selected_package> dp = db.find<selected_package> (n))
           {
             if (dp->state != package_state::configured)
diff --git a/bpkg/satisfaction b/bpkg/satisfaction
index a140b5f..ae78a98 100644
--- a/bpkg/satisfaction
+++ b/bpkg/satisfaction
@@ -9,6 +9,7 @@
 #include <bpkg/utility>
 
 #include <bpkg/package>
+#include <bpkg/common-options>
 
 namespace bpkg
 {
@@ -36,6 +37,14 @@ namespace bpkg
   {
     return l ? (!r || satisfies (*l, *r)) : !r;
   }
+
+  // Special build-time dependencies.
+  //
+  void
+  satisfy_build2 (const common_options&, const string& pkg, const dependency&);
+
+  void
+  satisfy_bpkg (const common_options&, const string& pkg, const dependency&);
 }
 
 #endif // BPKG_SATISFACTION
diff --git a/bpkg/satisfaction.cxx b/bpkg/satisfaction.cxx
index bddf7e7..2e2b269 100644
--- a/bpkg/satisfaction.cxx
+++ b/bpkg/satisfaction.cxx
@@ -4,8 +4,13 @@
 
 #include <bpkg/satisfaction>
 
+#include <butl/process>
+#include <butl/fdstream>
+
+#include <bpkg/utility>
 #include <bpkg/package-odb>
 #include <bpkg/diagnostics>
+#include <bpkg/bpkg-version>
 
 using namespace std;
 using namespace butl;
@@ -93,4 +98,90 @@ namespace bpkg
 
     return s;
   }
+
+  static version build2_version;
+
+  void
+  satisfy_build2 (const common_options& co,
+                  const string& pkg,
+                  const dependency& d)
+  {
+    assert (d.name == "build2");
+
+    // Extract, parse, and cache build2 version string.
+    //
+    if (build2_version.empty ())
+    {
+      const char* args[] = {name_b (co), "--version", nullptr};
+
+      try
+      {
+        process_path pp (process::path_search (args[0], exec_dir));
+
+        if (verb >= 3)
+          print_process (args);
+
+        process pr (pp, args, 0, -1); // Redirect STDOUT to pipe.
+
+        string l;
+        try
+        {
+          ifdstream is (pr.in_ofd, fdstream_mode::skip);
+          getline (is, l);
+          is.close ();
+
+          if (pr.wait () && l.compare (0, 7, "build2 ") == 0)
+          {
+            try
+            {
+              build2_version = version (string (l, 7));
+            }
+            catch (const invalid_argument&) {} // Fall through.
+          }
+
+          // Fall through.
+        }
+        catch (const ifdstream::failure&)
+        {
+          pr.wait ();
+          // Fall through.
+        }
+
+        if (build2_version.empty ())
+          fail << "unable to determine build2 version of " << args[0];
+      }
+      catch (const process_error& e)
+      {
+        error << "unable to execute " << args[0] << ": " << e.what ();
+
+        if (e.child ())
+          exit (1);
+
+        throw failed ();
+      }
+    }
+
+    if (!satisfies (build2_version, d.constraint))
+      fail << "unable to satisfy constraint (" << d << ") for package "
+           << pkg <<
+        info << "available build2 version is " << build2_version;
+  }
+
+  static version bpkg_version;
+
+  void
+  satisfy_bpkg (const common_options&, const string& pkg, const dependency& d)
+  {
+    assert (d.name == "bpkg");
+
+    // Parse and cache bpkg version string.
+    //
+    if (bpkg_version.empty ())
+      bpkg_version = version (BPKG_VERSION_STR);
+
+    if (!satisfies (bpkg_version, d.constraint))
+      fail << "unable to satisfy constraint (" << d << ") for package "
+           << pkg <<
+        info << "available bpkg version is " << bpkg_version;
+  }
 }
diff --git a/bpkg/utility b/bpkg/utility
index a4bc6d3..b7dbf36 100644
--- a/bpkg/utility
+++ b/bpkg/utility
@@ -76,8 +76,8 @@ namespace bpkg
 
   // Process.
   //
-  // The process command line is printed for verbosity >= 2 (essential
-  // command lines).
+  // By default the process command line is printed for verbosity >= 2
+  // (essential command lines).
   //
   // If fallback is specified, then this directory is searched for the
   // executable as a last resort.
@@ -102,6 +102,9 @@ namespace bpkg
   //
   class common_options;
 
+  const char*
+  name_b (const common_options&);
+
   void
   run_b (const common_options&,
          const dir_path& configuration,
diff --git a/bpkg/utility.cxx b/bpkg/utility.cxx
index 002d316..5d37972 100644
--- a/bpkg/utility.cxx
+++ b/bpkg/utility.cxx
@@ -7,6 +7,7 @@
 #include <iostream>     // cout, cin
 
 #include <butl/process>
+#include <butl/fdstream>
 
 #include <bpkg/diagnostics>
 #include <bpkg/common-options>
@@ -195,6 +196,14 @@ namespace bpkg
     }
   }
 
+  const char*
+  name_b (const common_options& co)
+  {
+    return co.build_specified ()
+      ? co.build ().string ().c_str ()
+      : "b" BPKG_EXE_SUFFIX;
+  }
+
   void
   run_b (const common_options& co,
          const dir_path& c,
@@ -203,11 +212,7 @@ namespace bpkg
          const strings& pvars,
          const strings& cvars)
   {
-    const char* b (co.build_specified ()
-                   ? co.build ().string ().c_str ()
-                   : "b" BPKG_EXE_SUFFIX);
-
-    cstrings args {b};
+    cstrings args {name_b (co)};
 
     // Map verbosity level. If we are running quiet or at level 1,
     // then run build2 quiet. Otherwise, run it at the same level