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

8 files changed, 89 insertions, 97 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 {};
     }
 
diff --git a/tests/pkg-build.test b/tests/pkg-build.test
index 4df4499..4b0c57b 100644
--- a/tests/pkg-build.test
+++ b/tests/pkg-build.test
@@ -30,7 +30,7 @@
 # |   |-- libfoo-1.0.0.tar.gz
 # |   `-- repositories.manifest
 # |
-# |-- t3                        -> t2 (prerequisite)
+# |-- t3                        -> t2 (prerequisite repository)
 # |   |-- libbaz-1.0.0.tar.gz   -> libbar
 # |   |-- libfox-1.0.0.tar.gz
 # |   `-- repositories.manifest
@@ -39,16 +39,16 @@
 # |   |-- libfoo-1.1.0.tar.gz
 # |   `-- repositories.manifest
 # |
-# |-- t4b                       -> t4a (prerequisite)
+# |-- t4b                       -> t4a (prerequisite repository)
 # |   |-- libbar-1.1.0.tar.gz   -> libfoo == 1.1.0
 # |   `-- repositories.manifest
 # |
-# |-- t4c                       -> t4b (prerequisite)
+# |-- t4c                       -> t4b (prerequisite repository)
 # |   |-- libbaz-1.1.0.tar.gz   -> libfoo, libbar
 # |   |-- libfoo-1.0.0.tar.gz
 # |   `-- repositories.manifest
 # |
-# |-- t4d                       -> t4c (complement)
+# |-- t4d                       -> t4c (complement repository)
 # |   |-- libbiz-1.0.0.tar.gz   -> libfox, libfoo, libbaz
 # |   |-- libfox-1.0.0.tar.gz
 # |   `-- repositories.manifest
@@ -65,7 +65,7 @@
 # |   `-- *
 # |
 # `-- git
-#     |-- libbar.git            -> style-basic.git (prerequisite)
+#     |-- libbar.git            -> style-basic.git (prerequisite repository)
 #     |-- libbaz.git
 #     `-- style-basic.git
 
@@ -92,7 +92,7 @@ end
 
 pkg_configure += -d cfg "config.cxx=$config.cxx" 2>!
 pkg_disfigure += -d cfg
-pkg_drop      += -d cfg --drop-prerequisite 2>!
+pkg_drop      += -d cfg 2>!
 pkg_fetch     += -d cfg 2>!
 pkg_purge     += -d cfg
 pkg_status    += -d cfg
@@ -237,11 +237,11 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
 {
   test.arguments += --print-only
 
-  : unknown-prerequisite
+  : unknown-dependency
   :
   $clone_root_cfg;
   $* $src/libbar-1.0.0.tar.gz 2>>EOE != 0
-    error: unknown prerequisite libfoo of package libbar
+    error: unknown dependency libfoo of package libbar
     info: while satisfying libbar/1.0.0
     EOE
 
@@ -250,7 +250,7 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
   {
     +$clone_root_cfg && $rep_add $rep/t2 && $rep_fetch
 
-    : build-prerequisite
+    : build-dependency
     :
     {
       $clone_cfg;
@@ -282,7 +282,7 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
         EOE
     }
 
-    : upgrade-prerequisite
+    : upgrade-dependency
     :
     {
       $clone_cfg;
@@ -306,7 +306,7 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
       $pkg_purge libfoo 2>'purged libfoo/0.0.1'
     }
 
-    : downgrade-prerequisite
+    : downgrade-dependency
     :
     {
       $clone_cfg && $pkg_unpack -e $src/libfoo-1.1.0;
@@ -732,7 +732,7 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
 {
   test.arguments += --yes
 
-  : wth-prerequisites
+  : with-dependencies
   :
   {
     $clone_root_cfg && $rep_add $rep/t4c && $rep_fetch;
@@ -983,7 +983,7 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
     }
   }
 
-  : drop-prerequisites
+  : drop-dependencies
   :
   {
     $clone_root_cfg && $rep_add $rep/t2 && $rep_fetch;
@@ -1060,9 +1060,9 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
     $pkg_purge     libfoo 2>'purged libfoo/1.0.0'
   }
 
-  : local-prerequisite
+  : local-dependency
   :
-  : Test that the local package can be built against the local prerequisite
+  : Test that the local package can be built against the local dependency
   : package.
   :
   {
@@ -1107,7 +1107,7 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
   }
 }
 
-: prerequisite
+: dependency
 :
 {
   +$clone_cfg
@@ -1115,7 +1115,7 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
 
   : drop
   :
-  : Test --drop-prerequisite option.
+  : Test dropping of unused dependencies (default behavior).
   :
   {
     $clone_cfg;
@@ -1133,7 +1133,7 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
       updated libbar/1.0.0
       EOE
 
-    $* --drop-prerequisite libbar/1.2.0 <'y' 2>>~%EOE%;
+    $* libbar/1.2.0 <'y' 2>>~%EOE%;
         upgrade libbar/1.2.0
       continue? [Y/n] disfigured libbar/1.0.0
       %.*
@@ -1154,7 +1154,7 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
 
   : keep
   :
-  : Test --keep-prerequisite option.
+  : Test keeping of unused dependencies (--keep-unused option).
   :
   {
     $clone_cfg;
@@ -1172,7 +1172,7 @@ rep_fetch     += -d cfg --auth all --trust-yes 2>!
       updated libbar/1.0.0
       EOE
 
-    $* --keep-prerequisite libbar/1.2.0 <'y' 2>>~%EOE%;
+    $* --keep-unused libbar/1.2.0 <'y' 2>>~%EOE%;
         upgrade libbar/1.2.0
       continue? [Y/n] disfigured libbar/1.0.0
       %.*
@@ -1849,7 +1849,7 @@ else
 
   : prerequisite-repo
   :
-  : Prerequisite package of the dependent being built is in the prerequisite
+  : Dependency package of the dependent being built is in the prerequisite
   : repository.
   :
   {
diff --git a/tests/pkg-drop.test b/tests/pkg-drop.test
index f7666b5..e10bbe2 100644
--- a/tests/pkg-drop.test
+++ b/tests/pkg-drop.test
@@ -10,10 +10,10 @@
 # |-- t4a
 # |   |-- libfoo-1.1.0.tar.gz
 # |   `-- repositories.manifest
-# |-- t4b                     -> t4a (prerequisite)
+# |-- t4b                     -> t4a (prerequisite repository)
 # |   |-- libbar-1.1.0.tar.gz -> libfoo == 1.1.0
 # |   `-- repositories.manifest
-# |-- t4c                     -> t4b (prerequisite)
+# |-- t4c                     -> t4b (prerequisite repository)
 # |   |-- libbaz-1.1.0.tar.gz -> libfoo, libbar
 # |   |-- libfoo-1.0.0.tar.gz
 # |   `-- repositories.manifest
@@ -60,7 +60,7 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
   %error: package libfoo/1.0.0 does not exist in configuration cfg[/\\]%
   EOE
 
-: prerequisites-or-dependents
+: dependencies-or-dependents
 :
 {
   +$clone_cfg && $rep_add $rep/t4c && $rep_fetch
@@ -81,7 +81,7 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
   :
   {
     # Prepare the nested tests to use configuration from the enclosing
-    # 'prerequisites-or-dependents' group scope.
+    # 'dependencies-or-dependents' group scope.
     #
     clone_cfg = cp -r $~/../cfg ./
 
@@ -156,11 +156,11 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
     }
   }
 
-  : prerequisites
+  : dependencies
   :
   {
     # Prepare the nested tests to use configuration from the enclosing
-    # 'prerequisites-or-dependents' group scope.
+    # 'dependencies-or-dependents' group scope.
     #
     clone_cfg = cp -r $~/../cfg ./
 
@@ -198,7 +198,7 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
 
     : dependencies
     :
-    : Note that we do not move this test to the prerequisites-and-dependents
+    : Note that we do not move this test to the dependencies-and-dependents
     : group as the configuration repository set would be different.
     :
     $clone_cfg;
@@ -225,7 +225,7 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
    -$pkg_status libfoo/1.1.0 >'libfoo available [1.1.0]'
 }
 
-: prerequisites-and-dependents
+: dependencies-and-dependents
 :
 {
   +$clone_cfg && $rep_add $rep/t4d && $rep_fetch
@@ -234,7 +234,7 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
   clone_cfg = cp -r ../../cfg ./
   test.arguments += --print-only
 
-  : drop-prerequisites-no-dependents
+  : drop-dependencies-no-dependents
   :
   {
     test.arguments += --yes
@@ -262,7 +262,7 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
       EOO
   }
 
-  : drop-prerequisites
+  : drop-dependencies
   :
   {
     test.arguments += --yes --drop-dependent
@@ -312,7 +312,7 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
       EOO
   }
 
-  : keep-prerequisites
+  : keep-dependencies
   {
     test.arguments += --no --drop-dependent
 
@@ -377,8 +377,7 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
 
 : keep-drop-options
 :
-: Test --drop-dependent, --keep-dependent, --drop-prerequisite,
-: --keep-prerequisite  option.
+: Test --drop-dependent, --keep-dependent, --keep-unused, option.
 :
 {
   +$clone_cfg && $rep_add $rep/t4b && $rep_fetch
@@ -401,12 +400,12 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
       EOE
   }
 
-  : drop-prerequisite
+  : drop-dependency
   :
   {
     $clone_cfg && $pkg_build libbar;
 
-    $* --drop-prerequisite libbar 2>>EOE
+    $* libbar 2>>EOE
       disfigured libbar
       disfigured libfoo
       purged libbar
@@ -414,12 +413,12 @@ $* libfoo/1.0.0 2>>~%EOE% != 0
       EOE
   }
 
-  : keep-prerequisite
+  : keep-dependency
   :
   {
     $clone_cfg && $pkg_build libbar;
 
-    $* --keep-prerequisite libbar 2>>EOE;
+    $* --keep-unused libbar 2>>EOE;
       disfigured libbar
       purged libbar
       EOE
diff --git a/tests/pkg-system.test b/tests/pkg-system.test
index b0878e2..ced16f0 100644
--- a/tests/pkg-system.test
+++ b/tests/pkg-system.test
@@ -563,7 +563,7 @@ rep_fetch  += -d cfg --auth all --trust-yes 2>!
     $clone_cfg;
 
     $pkg_build foo 2>>EOE != 0;
-      error: prerequisite libbar >= 2 of package foo is not available in source
+      error: dependency libbar >= 2 of package foo is not available in source
         info: specify ?sys:libbar if it is available from the system
       info: while satisfying foo/2
       EOE
@@ -616,7 +616,7 @@ rep_fetch  += -d cfg --auth all --trust-yes 2>!
     # Fail to build foo.
     #
     $pkg_build foo 2>>EOE != 0;
-      error: prerequisite libbar >= 2 of package foo is not available in source
+      error: dependency libbar >= 2 of package foo is not available in source
         info: sys:libbar/1 does not satisfy the constrains
       info: while satisfying foo/2
       EOE
@@ -651,7 +651,7 @@ rep_fetch  += -d cfg --auth all --trust-yes 2>!
     # Fail to build foo and sys:libbar/1.
     #
     $pkg_build foo 'sys:libbar/1' 2>>EOE != 0;
-      error: prerequisite libbar >= 2 of package foo is not available in source
+      error: dependency libbar >= 2 of package foo is not available in source
         info: sys:libbar/1 does not satisfy the constrains
       info: while satisfying foo/2
       EOE
@@ -692,7 +692,7 @@ rep_fetch  += -d cfg --auth all --trust-yes 2>!
     # Fail to build sys:libbar/1.1 and foo.
     #
     $pkg_build 'sys:libbar/1.1' foo 2>>EOE != 0;
-      error: prerequisite libbar >= 2 of package foo is not available in source
+      error: dependency libbar >= 2 of package foo is not available in source
         info: sys:libbar/1.1 does not satisfy the constrains
       info: while satisfying foo/2
       EOE
@@ -751,7 +751,7 @@ rep_fetch  += -d cfg --auth all --trust-yes 2>!
     # Fail to build foo.
     #
     $pkg_build foo 2>>EOE != 0;
-      error: prerequisite libbar >= 2 of package foo is not available in source
+      error: dependency libbar >= 2 of package foo is not available in source
         info: sys:libbar/1 does not satisfy the constrains
       info: while satisfying foo/2
       EOE
@@ -799,7 +799,7 @@ rep_fetch  += -d cfg --auth all --trust-yes 2>!
     $clone_cfg;
 
     $pkg_build foo 2>>EOE != 0;
-      error: prerequisite libbar >= 2 of package foo is not available in source
+      error: dependency libbar >= 2 of package foo is not available in source
         info: specify ?sys:libbar if it is available from the system
       info: while satisfying foo/2
       EOE
@@ -813,7 +813,7 @@ rep_fetch  += -d cfg --auth all --trust-yes 2>!
       EOE
 
     $pkg_build foo '?sys:libbar/1' 2>>EOE != 0;
-      error: prerequisite libbar >= 2 of package foo is not available in source
+      error: dependency libbar >= 2 of package foo is not available in source
         info: sys:libbar/1 does not satisfy the constrains
       info: while satisfying foo/2
       EOE