From a3cdcd275c5bcb63bf459b1fa031513ae8662ffa Mon Sep 17 00:00:00 2001
From: Karen Arutyunov <karen@codesynthesis.com>
Date: Thu, 1 Sep 2016 15:29:00 +0300
Subject: Make ?sys: to change preference to system

---
 bpkg/package       | 25 +++++++++++++++++++++++++
 bpkg/pkg-build.cxx | 25 +++++++++++++++++++++++--
 tests/test.sh      | 22 ++++++++++++++--------
 3 files changed, 62 insertions(+), 10 deletions(-)

diff --git a/bpkg/package b/bpkg/package
index f70a198..6f1d955 100644
--- a/bpkg/package
+++ b/bpkg/package
@@ -384,6 +384,31 @@ namespace bpkg
       return system_version_ ? &*system_version_ : nullptr;
     }
 
+    // As above but also return an indication if the version information is
+    // authoritative.
+    //
+    pair<const version_type*, bool>
+    system_version_authoritative () const
+    {
+      const system_package* sp (system_repository.find (id.name));
+
+      if (!system_version_)
+      {
+        if (sp != nullptr)
+        {
+          // Only cache if it is authoritative.
+          //
+          if (sp->authoritative)
+            system_version_ = sp->version;
+          else
+            return make_pair (&sp->version, false);
+        }
+      }
+
+      return make_pair (system_version_ ?  &*system_version_ : nullptr,
+                        sp != nullptr ? sp->authoritative : false);
+    }
+
     // Database mapping.
     //
     #pragma db member(id) id column("")
diff --git a/bpkg/pkg-build.cxx b/bpkg/pkg-build.cxx
index d88e312..a022130 100644
--- a/bpkg/pkg-build.cxx
+++ b/bpkg/pkg-build.cxx
@@ -536,8 +536,15 @@ namespace bpkg
 
         // If all that's available is a stub then we need to make sure the
         // package is present in the system repository and it's version
-        // satisfies the constraint.
+        // satisfies the constraint. If a source package is available but there
+        // is an optional system package specified on the command line and it's
+        // version satisfies the constraint then the system package should be
+        // preferred. To recognize such a case we just need to check if the
+        // authoritative system version is set and it satisfies the constraint.
+        // If the corresponding system package is non-optional it will be
+        // preferred anyway.
         //
+        bool system (false);
         if (dap->stub ())
         {
           if (dap->system_version () == nullptr)
@@ -553,6 +560,17 @@ namespace bpkg
               info << "sys:" << d.name << "/" << *dap->system_version ()
                  << " does not satisfy the constrains";
           }
+
+          system = true;
+        }
+        else
+        {
+          auto p (dap->system_version_authoritative ());
+
+          if (p.first != nullptr &&
+              p.second && // Authoritative.
+              satisfies (*p.first, d.constraint))
+            system = true;
         }
 
         // Next see if this package is already selected. If we already
@@ -569,7 +587,10 @@ namespace bpkg
               info << "use 'pkg-purge --force' to remove";
 
           if (satisfies (dsp->version, d.constraint))
+          {
             rp = make_available (options, cd, db, dsp);
+            system = dsp->system ();
+          }
           else
             // Remember that we may be forcing up/downgrade; we will deal
             // with it below.
@@ -584,7 +605,7 @@ namespace bpkg
           nullopt,      // Hold package.
           nullopt,      // Hold version.
           {},           // Constraints.
-          dap->stub (), // System.
+          system,       // System.
           {name},       // Required by.
           false};       // Reconfigure.
 
diff --git a/tests/test.sh b/tests/test.sh
index f6cd89a..85fde8e 100755
--- a/tests/test.sh
+++ b/tests/test.sh
@@ -1823,13 +1823,12 @@ stat libbaz 'configured 2; available sys:?'
 test pkg-drop -y foo libbar
 
 build foo ?sys:libbar<<EOF
-build libbaz/2 (required by libbar)
-build libbar/2 (required by foo)
+configure sys:libbar/* (required by foo)
 build foo/2
 EOF
 stat foo 'configured 2 hold_package; available sys:?'
-stat libbar 'configured 2; available sys:?'
-stat libbaz 'configured 2; available sys:?'
+stat libbar 'configured,system *; available 2 1 sys:?'
+stat libbaz 'available 2 sys:?'
 
 # Drop all, configure libbar/1, then fail to build foo and foo ?sys:libbar/2,
 # but succeed to build foo sys:libbar/2.
@@ -1841,18 +1840,25 @@ build libbaz/2 (required by libbar)
 build libbar/1
 EOF
 stat libbar 'configured 1 hold_package hold_version; available 2 sys:?'
+stat libbaz 'configured 2; available sys:?'
 
 fail build foo
 
-# libbar/2 is picked up (not optional sys:libbar/2) as a foo dependent and so
-# fail to upgrade held version 1.
-#
-fail build foo ?sys:libbar/2
+build foo ?sys:libbar/2<<EOF
+reconfigure sys:libbar/2 (required by foo)
+build foo/2
+EOF
+stat foo 'configured 2 hold_package; available sys:?'
+stat libbar 'configured,system 2 hold_package hold_version; available sys:?'
+stat libbaz 'available 2 sys:?'
 
 build foo sys:libbar/2 <<EOF
 reconfigure sys:libbar/2
 build foo/2
 EOF
+stat foo 'configured 2 hold_package; available sys:?'
+stat libbar 'configured,system 2 hold_package hold_version; available sys:?'
+stat libbaz 'available 2 sys:?'
 
 # Fetch system/t2 repository: foo/2 (->libbar>=2), libbar/0+1
 #
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