Come up with better version for uncommitted snapshots

Instead of leaving it as .z we now take the date of the previous commit and
increment it by a second. The main benefit of doing it this way is that once
committed, the new version does not "jump back" behind .z.

4 files changed, 59 insertions, 23 deletions

diff --git a/build2/version/init.cxx b/build2/version/init.cxx
index 7b8bd01..f793c98 100644
--- a/build2/version/init.cxx
+++ b/build2/version/init.cxx
@@ -163,9 +163,9 @@ namespace build2
       }
 
       // If this is the latest snapshot (i.e., the -a.1.z kind), then load the
-      // snapshot sn and id (e.g., commit date and id from git). If there is
-      // uncommitted stuff, then leave it as .z.
+      // snapshot number and id (e.g., commit date and id from git).
       //
+      bool committed (true);
       if (v.snapshot () && v.snapshot_sn == standard_version::latest_sn)
       {
         snapshot ss (extract_snapshot (rs));
@@ -174,7 +174,10 @@ namespace build2
         {
           v.snapshot_sn = ss.sn;
           v.snapshot_id = move (ss.id);
+          committed = ss.committed;
         }
+        else
+          committed = false;
       }
 
       // Set all the version.* variables.
@@ -215,16 +218,17 @@ namespace build2
       set ("version.pre_release_string", v.string_pre_release ());
       set ("version.pre_release_number", uint64_t (v.pre_release ()));
 
-      set ("version.snapshot",        v.snapshot ()); // bool
-      set ("version.snapshot_sn",     v.snapshot_sn); // uint64
-      set ("version.snapshot_id",     v.snapshot_id); // string
-      set ("version.snapshot_string", v.string_snapshot ());
+      set ("version.snapshot",           v.snapshot ()); // bool
+      set ("version.snapshot_sn",        v.snapshot_sn); // uint64
+      set ("version.snapshot_id",        v.snapshot_id); // string
+      set ("version.snapshot_string",    v.string_snapshot ());
+      set ("version.snapshot_committed", committed);     // bool
 
       set ("version.revision", uint64_t (v.revision));
 
       // Create the module.
       //
-      mod.reset (new module (move (v), move (ds)));
+      mod.reset (new module (move (v), committed, move (ds)));
 
       return true; // Init first (dist.package, etc).
     }
@@ -331,7 +335,7 @@ namespace build2
 
       // Complain if this is an uncommitted snapshot.
       //
-      if (v.snapshot_sn == standard_version::latest_sn)
+      if (v.snapshot () && !m.committed)
         fail << "distribution of uncommitted project " << rs.src_path ();
 
       // The plan is simple, re-serialize the manifest into a temporary file
diff --git a/build2/version/module.hxx b/build2/version/module.hxx
index 190d8d7..a5a667a 100644
--- a/build2/version/module.hxx
+++ b/build2/version/module.hxx
@@ -25,13 +25,19 @@ namespace build2
       static const string name;
 
       butl::standard_version version;
+      bool committed; // Whether this is a committed snapshot.
+
       dependency_constraints dependencies;
 
       const variable* in_symbol       = nullptr; // in.symbol
       const variable* in_substitution = nullptr; // in.substitution
 
-      module (butl::standard_version v, dependency_constraints d)
-          : version (move (v)), dependencies (move (d)) {}
+      module (butl::standard_version v,
+              bool c,
+              dependency_constraints d)
+          : version (move (v)),
+            committed (c),
+            dependencies (move (d)) {}
     };
   }
 }
diff --git a/build2/version/snapshot-git.cxx b/build2/version/snapshot-git.cxx
index b85b47e..751686e 100644
--- a/build2/version/snapshot-git.cxx
+++ b/build2/version/snapshot-git.cxx
@@ -31,9 +31,9 @@ namespace build2
       //
       {
         const char* args[] {"git", "-C", d, "status", "--porcelain", nullptr};
-
-        if (!run<string> (3, args, [](string& s) {return move (s);}).empty ())
-          return r;
+        r.committed = run<string> (3 /* verbosity */,
+                                   args,
+                                   [](string& s) {return move (s);}).empty ();
       }
 
       // Now extract the commit id and date. One might think that would be
@@ -45,7 +45,18 @@ namespace build2
       //
       // Where <len> is the size of <data> and <data> is the output of:
       //
-      // git cat-file commit ...
+      // git cat-file commit HEAD
+      //
+      // There is also one annoying special case: new repository without any
+      // commits. In this case the above command will fail (with diagnostics
+      // and non-zero exit code) because there is no HEAD. Of course, it can
+      // also fail for other reason (like broken repository) which would be
+      // hard to distinguish. Note, however, that we just ran git status and
+      // it would have most likely failed if this were the case. So here we
+      // (reluctantly) assume that the only reason git cat-file fails is if
+      // there is no HEAD (that we equal with the "new repository" condition
+      // which is, strictly speaking, might not be the case either). So we
+      // suppress any diagnostics, and handle non-zero exit code.
       //
       string data;
 
@@ -53,14 +64,16 @@ namespace build2
         "git", "-C", d, "cat-file", "commit", "HEAD", nullptr};
       process pr (run_start (3     /* verbosity */,
                              args,
-                             0     /* stdin */,
-                             -1    /* stdout */));
+                             0     /* stdin  */,
+                             -1    /* stdout */,
+                             false /* error  */));
 
+      string l;
       try
       {
         ifdstream is (move (pr.in_ofd), ifdstream::badbit);
 
-        for (string l; !eof (getline (is, l)); )
+        while (!eof (getline (is, l)))
         {
           data += l;
           data += '\n'; // We assume there is always a newline.
@@ -128,16 +141,28 @@ namespace build2
         // that.
       }
 
-      run_finish (args, pr);
+      if (!run_finish (args, pr, false /* error */, l))
+      {
+        // Presumably new repository without HEAD. Return uncommitted snapshot
+        // with UNIX epoch as timestamp.
+        //
+        r.sn = 19700101000000ULL;
+        r.committed = false;
+        return r;
+      }
 
       if (r.sn == 0)
         fail << "unable to extract git commit id/date for " << src_root;
 
-      sha1 cs;
-      cs.append ("commit " + to_string (data.size ())); // Includes '\0'.
-      cs.append (data.c_str (), data.size ());
-
-      r.id.assign (cs.string (), 12); // 12-characters abbreviated commit id.
+      if (r.committed)
+      {
+        sha1 cs;
+        cs.append ("commit " + to_string (data.size ())); // Includes '\0'.
+        cs.append (data.c_str (), data.size ());
+        r.id.assign (cs.string (), 12); // 12-characters abbreviated commit id.
+      }
+      else
+        r.sn++; // Add a second.
 
       return r;
     }
diff --git a/build2/version/snapshot.hxx b/build2/version/snapshot.hxx
index b7e6dd7..15f4b59 100644
--- a/build2/version/snapshot.hxx
+++ b/build2/version/snapshot.hxx
@@ -18,6 +18,7 @@ namespace build2
     {
       uint64_t sn = 0;
       string id;
+      bool committed = false;
 
       bool
       empty () const {return sn == 0;}