Add support for applying backward compatibility workarounds to packages.manifest file generated by rep-create

7 files changed, 132 insertions, 12 deletions

diff --git a/bpkg/fetch-pkg.cxx b/bpkg/fetch-pkg.cxx
index 6d9e921..64abb43 100644
--- a/bpkg/fetch-pkg.cxx
+++ b/bpkg/fetch-pkg.cxx
@@ -168,8 +168,14 @@ namespace bpkg
   pkg_repository_manifests
   pkg_fetch_repositories (const dir_path& d, bool iu)
   {
-    return fetch_manifest<pkg_repository_manifests> (
-      nullptr, d / repositories_file, iu).first;
+    pkg_repository_manifests r (
+      fetch_manifest<pkg_repository_manifests> (
+        nullptr, d / repositories_file, iu).first);
+
+    if (r.empty ())
+      r.emplace_back (repository_manifest ()); // Add the base repository.
+
+    return r;
   }
 
   pair<pkg_repository_manifests, string/*checksum*/>
@@ -184,9 +190,15 @@ namespace bpkg
     path& f (*u.path);
     f /= repositories_file;
 
-    return rl.remote ()
+    pair<pkg_repository_manifests, string> r (
+      rl.remote ()
       ? fetch_manifest<pkg_repository_manifests> (o, u, iu)
-      : fetch_manifest<pkg_repository_manifests> (&o, f, iu);
+      : fetch_manifest<pkg_repository_manifests> (&o, f, iu));
+
+    if (r.first.empty ())
+      r.first.emplace_back (repository_manifest ()); // Add the base repository.
+
+    return r;
   }
 
   pkg_package_manifests
diff --git a/bpkg/rep-create.cli b/bpkg/rep-create.cli
index be4cc42..9d062ec 100644
--- a/bpkg/rep-create.cli
+++ b/bpkg/rep-create.cli
@@ -36,6 +36,17 @@ namespace bpkg
       "Ignore unknown manifest entries."
     }
 
+    butl::standard_version --min-bpkg-version
+    {
+      "<ver>",
+      "Apply backward compatibility workarounds to the generated
+       \cb{packages.manifest} file so that it can be consumed by \cb{bpkg}
+       versions greater or equal to the specified version. If unspecified,
+       then the \cb{min-bpkg-version} value from the \cb{repositories.manifest}
+       file is used, if present. If the manifest value is not specified
+       either, then no backward compatibility workarounds are applied."
+    }
+
     string --key
     {
       "<name>",
diff --git a/bpkg/rep-create.cxx b/bpkg/rep-create.cxx
index d820836..8de8c22 100644
--- a/bpkg/rep-create.cxx
+++ b/bpkg/rep-create.cxx
@@ -162,6 +162,15 @@ namespace bpkg
                                })
                   << " prerequisite repository(s)";});
 
+    optional<standard_version> rmv (
+      rms.header && rms.header->min_bpkg_version
+      ? rms.header->min_bpkg_version
+      : nullopt);
+
+    optional<standard_version> opv (o.min_bpkg_version_specified ()
+                                    ? o.min_bpkg_version ()
+                                    : optional<standard_version> ());
+
     // While we could have serialized as we go along, the order of
     // packages will be pretty much random and not reproducible. By
     // collecting all the manifests in a map we get a sorted list.
@@ -182,6 +191,16 @@ namespace bpkg
       manifests.emplace_back (move (m));
     }
 
+    // Issue a warning if --min-bpkg-version option and the repositories
+    // manifest's min-bpkg-version value are both specified and don't match.
+    // Let's issue it after the added repositories are printed to stdout, so
+    // that it doesn't go unnoticed.
+    //
+    if (opv && rmv && *opv != *rmv)
+      warn << "--min-bpkg-version option value " << *opv << " differs from "
+           << "minimum bpkg version " << *rmv << " specified in "
+           << d / repositories_file;
+
     // Serialize packages manifest, optionally generate the signature manifest.
     //
     path p (d / packages_file);
@@ -197,7 +216,7 @@ namespace bpkg
         ofdstream ofs (p, fdopen_mode::binary);
 
         manifest_serializer s (ofs, p.string ());
-        manifests.serialize (s);
+        manifests.serialize (s, opv ? opv : rmv);
         ofs.close ();
       }
 
diff --git a/bpkg/rep-fetch.cxx b/bpkg/rep-fetch.cxx
index 73c9058..cefa799 100644
--- a/bpkg/rep-fetch.cxx
+++ b/bpkg/rep-fetch.cxx
@@ -161,7 +161,8 @@ namespace bpkg
     M r;
     if (exists (f))
       r = parse_manifest<M> (f, iu, rl, fragment);
-    else
+
+    if (r.empty ())
       r.emplace_back (repository_manifest ()); // Add the base repository.
 
     return r;
diff --git a/bpkg/types-parsers.cxx b/bpkg/types-parsers.cxx
index d5ddb28..97ebafe 100644
--- a/bpkg/types-parsers.cxx
+++ b/bpkg/types-parsers.cxx
@@ -92,6 +92,35 @@ namespace bpkg
       }
     }
 
+    void parser<butl::standard_version>::
+    parse (butl::standard_version& x, bool& xs, scanner& s)
+    {
+      using butl::standard_version;
+
+      xs = true;
+
+      const char* o (s.next ());
+
+      if (!s.more ())
+        throw missing_value (o);
+
+      const char* v (s.next ());
+
+      try
+      {
+        // Note that we allow all kinds of versions, so that the caller can
+        // restrict them as they wish after the parsing.
+        //
+        x = standard_version (v,
+                              standard_version::allow_earliest |
+                              standard_version::allow_stub);
+      }
+      catch (const invalid_argument& e)
+      {
+        throw invalid_value (o, v, e.what ());
+      }
+    }
+
     void parser<auth>::
     parse (auth& x, bool& xs, scanner& s)
     {
diff --git a/bpkg/types-parsers.hxx b/bpkg/types-parsers.hxx
index d687156..007d754 100644
--- a/bpkg/types-parsers.hxx
+++ b/bpkg/types-parsers.hxx
@@ -7,6 +7,8 @@
 #ifndef BPKG_TYPES_PARSERS_HXX
 #define BPKG_TYPES_PARSERS_HXX
 
+#include <libbutl/standard-version.hxx>
+
 #include <libbpkg/manifest.hxx>
 
 #include <bpkg/types.hxx>
@@ -59,6 +61,19 @@ namespace bpkg
     };
 
     template <>
+    struct parser<butl::standard_version>
+    {
+      static void
+      parse (butl::standard_version&, bool&, scanner&);
+
+      static void
+      merge (butl::standard_version& b, const butl::standard_version& a)
+      {
+        b = a;
+      }
+    };
+
+    template <>
     struct parser<auth>
     {
       static void
diff --git a/doc/manual.cli b/doc/manual.cli
index cbca17d..86fe17f 100644
--- a/doc/manual.cli
+++ b/doc/manual.cli
@@ -1772,12 +1772,12 @@ The repository fragment id this repository belongs to.
 terminology and semantics.
 
 The repository list manifest (the \c{repositories.manifest} file found in the
-repository root directory) describes the repository. It is a sequence of
-repository manifests consisting of the base repository manifest (that is, the
-manifest for the repository that is being described) as well as manifests for
-its prerequisite and complement repositories. The individual repository
-manifests can appear in any order and the base repository manifest can be
-omitted.
+repository root directory) describes the repository. It starts with an
+optional header manifest optionally followed by a sequence of repository
+manifests consisting of the base repository manifest (that is, the manifest
+for the repository that is being described) as well as manifests for its
+prerequisite and complement repositories. The individual repository manifests
+can appear in any order and the base repository manifest can be omitted.
 
 The \c{fragment} values can only be present in a merged
 \c{repositories.manifest} file for a multi-fragment repository.
@@ -1789,6 +1789,8 @@ repository could look like this:
 # math/testing
 #
 : 1
+min-bpkg-version: 0.14.0
+:
 email: math-pkg@example.org
 summary: Math package repository
 :
@@ -1814,6 +1816,37 @@ Then the completement's location would be:
 https://pkg.example.org/1/math/stable
 \
 
+The header manifest synopsis is presented next followed by the detailed
+description of each value in subsequent sections.
+
+\
+[min-bpkg-version]: <ver>
+[compression]: <compressions>
+\
+
+\h2#manifest-repository-list-header-min-bpkg-version|\c{min-bpkg-version}|
+
+\
+[min-bpkg-version]: <ver>
+\
+
+The earliest version of \cb{bpkg} that is compatible with this repository.
+Note that if specified, it must be the first value in the header.
+
+
+\h2#manifest-repository-list-header-compression|\c{compression}|
+
+\
+[compression]: <compressions>
+
+<compressions> = <compression> [ <compression>]*
+\
+
+Available compressed variants of the \c{packages.manifest} file. The format is
+a space-separated list of the compression methods. The \c{none} method means
+no compression. Absent \c{compression} value is equivalent to specifying it
+with the \c{none} value.
+
 
 \h#manifest-signature-pkg|Signature Manifest for \cb{pkg} Repositories|