Replace --{drop,keep}-prerequisites with --keep-unused

5 files changed, 45 insertions, 52 deletions

diff --git a/bpkg/package.hxx b/bpkg/package.hxx
index c14f7fc..38aa3ee 100644
--- a/bpkg/package.hxx
+++ b/bpkg/package.hxx
@@ -312,6 +312,14 @@ namespace bpkg
 
   // dependencies
   //
+  // Note on the terminology: we use the term "dependency" or "dependency
+  // package" to refer to a general concept of package dependency. This would
+  // include dependency alternatives, optional/conditional dependencies, etc.
+  //
+  // In contrast, below we use (mostly internally) the term "prerequisite
+  // package" to refer to the "effective" dependency that has been resolved to
+  // the actual package object.
+  //
   #pragma db value(dependency_constraint) definition
   #pragma db value(dependency) definition
   #pragma db member(dependency::constraint) column("")
diff --git a/bpkg/pkg-build.cli b/bpkg/pkg-build.cli
index b7a75dc..8312450 100644
--- a/bpkg/pkg-build.cli
+++ b/bpkg/pkg-build.cli
@@ -32,9 +32,11 @@ namespace bpkg
      \h|DESCRIPTION|
 
      The \cb{pkg-build} command builds one or more packages including all
-     their prerequisites. Besides building new packages, this command is also
+     their dependencies. Besides building new packages, this command is also
      used to upgrade or downgrade packages that are already present in the
-     configuration.
+     configuration. And unless the \c{\b{--keep-unused}|\b{-K}} option is
+     specified, \cb{pkg-build} will also drop dependency packages that would
+     otherwise no longer be used.
 
      The first form (one or more packages are specified) builds new or
      upgrades (by default or if \cb{--upgrade} is specified) or patches (if
@@ -200,28 +202,22 @@ namespace bpkg
        \cb{install} or \cb{test}."
     }
 
-    bool --drop-prerequisite|-D
+    bool --keep-unused|-K
     {
-      "Drop without confirmation prerequsite packages that were automatically
-       built and will no longer be necessary."
-    }
-
-    bool --keep-prerequisite|-K
-    {
-      "Don't offer to drop prerequsite packages that were automatically built
-       and will no longer be necessary."
+      "Don't drop dependency packages that were automatically built but will no
+       longer be used."
     }
 
     bool --update-dependent|-U
     {
       "Update without confirmation dependent packages that are reconfigured
-       due to their prerequisites being upgraded or downgraded."
+       due to their dependencies being upgraded or downgraded."
     }
 
     bool --leave-dependent|-L
     {
       "Don't offer to update dependent packages that are reconfigured due to
-       their prerequisites being upgraded or downgraded."
+       their dependencies being upgraded or downgraded."
     }
 
     bool --configure-only|-c
diff --git a/bpkg/pkg-build.cxx b/bpkg/pkg-build.cxx
index 4ba838c..b24ac70 100644
--- a/bpkg/pkg-build.cxx
+++ b/bpkg/pkg-build.cxx
@@ -702,7 +702,7 @@ namespace bpkg
           if (dap == nullptr)
           {
             diag_record dr (fail);
-            dr << "unknown prerequisite " << d << " of package " << name;
+            dr << "unknown dependency " << d << " of package " << name;
 
             if (!ar->location.empty ())
               dr << info << "repository " << ar->location << " appears to "
@@ -724,14 +724,14 @@ namespace bpkg
           if (dap->stub ())
           {
             if (dap->system_version () == nullptr)
-              fail << "prerequisite " << d << " of package " << name << " is "
+              fail << "dependency " << d << " of package " << name << " is "
                    << "not available in source" <<
                 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 "
+              fail << "dependency " << d << " of package " << name << " is "
                    << "not available in source" <<
                 info << "sys:" << dn << "/" << *dap->system_version ()
                    << " does not satisfy the constrains";
@@ -1483,11 +1483,6 @@ namespace bpkg
         fail << n << " requires explicit --upgrade|-u or --patch|-p";
     }
 
-    if (o.drop_prerequisite () && o.keep_prerequisite ())
-      fail << "both --drop-prerequisite|-D and --keep-prerequisite|-K "
-           << "specified" <<
-        info << "run 'bpkg help pkg-build' for more information";
-
     if (o.update_dependent () && o.leave_dependent ())
       fail << "both --update-dependent|-U and --leave-dependent|-L "
            << "specified" <<
@@ -2379,6 +2374,11 @@ namespace bpkg
           {
             if (optional<version> v = evaluate_dependency (db, sp))
             {
+              // Skip unused if we were instructed to keep them.
+              //
+              if (o.keep_unused () && v->empty ())
+                continue;
+
               dep_pkgs.push_back (dep_pkg {sp->name, *v});
               refine = true;
             }
diff --git a/bpkg/pkg-drop.cli b/bpkg/pkg-drop.cli
index 7f9dc19..cbf2279 100644
--- a/bpkg/pkg-drop.cli
+++ b/bpkg/pkg-drop.cli
@@ -21,10 +21,11 @@ namespace bpkg
 
      The \cb{pkg-drop} command drops one or more packages from the
      configuration. If the packages being dropped still have dependent
-     packages, then those will have to be drop as well and you will be prompted
-     to confirm. Similarly, if the packages being dropped have prerequisite
-     packages that would otherwise no longer be needed, you will be offered to
-     drop those as well.
+     packages, then those will have to be drop as well and you will be
+     prompted to confirm. And if the packages being dropped have dependency
+     packages that would otherwise no longer be used, then they will be
+     dropped as well unless the \c{\b{--keep-unused}|\b{-K}} option is
+     specified.
 
      The \cb{pkg-drop} command also supports several options (described below)
      that allow you to control the amount of work that will be done."
@@ -47,27 +48,21 @@ namespace bpkg
        with \cb{--print-only|-p}."
     }
 
-    bool --drop-dependent
+    bool --keep-unused|-K
     {
-      "Don't warn about or ask for confirmation if dropping dependent
-       packages."
+      "Don't drop dependency packages that were automatically built but will no
+       longer be used."
     }
 
-    bool --keep-dependent|-K
+    bool --drop-dependent|-D
     {
-      "Issue an error if attempting to drop dependent packages."
-    }
-
-    bool --drop-prerequisite|-D
-    {
-      "Drop without confirmation prerequsite packages that were automatically
-       built and will no longer be necessary."
+      "Don't warn about or ask for confirmation if dropping dependent
+       packages."
     }
 
-    bool --keep-prerequisite
+    bool --keep-dependent
     {
-      "Don't offer to drop prerequsite packages that were automatically built
-       and will no longer be necessary."
+      "Issue an error if attempting to drop dependent packages."
     }
 
     bool --print-only|-p
diff --git a/bpkg/pkg-drop.cxx b/bpkg/pkg-drop.cxx
index 0127fb6..2ba4b72 100644
--- a/bpkg/pkg-drop.cxx
+++ b/bpkg/pkg-drop.cxx
@@ -417,11 +417,6 @@ namespace bpkg
            << "specified" <<
         info << "run 'bpkg help pkg-drop' for more information";
 
-    if (o.drop_prerequisite () && o.keep_prerequisite ())
-      fail << "both --drop-prerequisite|-D and --keep-prerequisite "
-           << "specified" <<
-        info << "run 'bpkg help pkg-drop' for more information";
-
     if (!args.more ())
       fail << "package name argument expected" <<
         info << "run 'bpkg help pkg-drop' for more information";
@@ -537,15 +532,14 @@ namespace bpkg
       // some that we can drop, ask the user for confirmation.
       //
       if (pkgs.filter_prerequisites (db) &&
-          !o.keep_prerequisite () &&
-          !(drop_prq = o.drop_prerequisite ()) &&
+          !o.keep_unused ()              &&
           !(drop_prq = o.yes ()) && !o.no ())
       {
         {
           diag_record dr (text);
 
-          dr << "following prerequisite packages were automatically "
-             << "built and will no longer be necessary:";
+          dr << "following dependencies were automatically built but will "
+             << "no longer be used:";
 
           for (const drop_package& dp: pkgs)
           {
@@ -555,7 +549,7 @@ namespace bpkg
           }
         }
 
-        drop_prq = yn_prompt ("drop prerequisite packages? [Y/n]", 'y');
+        drop_prq = yn_prompt ("drop unused packages? [Y/n]", 'y');
 
         if (drop_prq)
           print_plan = true;
@@ -623,14 +617,14 @@ namespace bpkg
       {
         diag_record dr (text);
 
-        dr << "following prerequisite packages were automatically "
-           << "built and will no longer be necessary:";
+        dr << "following dependencies were automatically built but will "
+           << "no longer be used:";
 
         for (const drop_package& dp: pkgs)
           dr << text << dp.package->name;
       }
 
-      if (!yn_prompt ("drop prerequisite packages? [Y/n]", 'y'))
+      if (!yn_prompt ("drop unused packages? [Y/n]", 'y'))
         return {};
     }