From e3f077ba7584f65561e21ca195215abd341b9147 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Mon, 7 Feb 2022 07:59:48 +0200
Subject: Add support for meta-operation wildcard in scope::insert_rule()

---
 build2/cli/init.cxx  | 16 +++++-----------
 libbuild2/parser.cxx |  6 ++++++
 libbuild2/scope.hxx  | 26 +++++++++++++++++++++++++-
 3 files changed, 36 insertions(+), 12 deletions(-)

diff --git a/build2/cli/init.cxx b/build2/cli/init.cxx
index 2a07196..a00fd7f 100644
--- a/build2/cli/init.cxx
+++ b/build2/cli/init.cxx
@@ -246,6 +246,9 @@ namespace build2
 
       // Register our rules.
       //
+      // Other rules (e.g., cc::compile) may need to have the group members
+      // resolved/linked up. Looks like a general pattern: groups should
+      // resolve on *(update).
       {
         auto reg = [&rs, &m] (meta_operation_id mid, operation_id oid)
         {
@@ -255,17 +258,8 @@ namespace build2
           rs.insert_rule<cxx::ixx> (mid, oid, "cli.compile", m);
         };
 
-        reg (perform_id, update_id);
-        reg (perform_id, clean_id);
-
-        // Other rules (e.g., cc::compile) may need to have the group members
-        // resolved/linked up. Looks like a general pattern: groups should
-        // resolve on *(update).
-        //
-        // @@ meta-op wildcard?
-        //
-        reg (configure_id, update_id);
-        reg (dist_id, update_id);
+        reg (0 /* wildcard */, update_id);
+        reg (perform_id,       clean_id);
       }
 
       return true;
diff --git a/libbuild2/parser.cxx b/libbuild2/parser.cxx
index 9f69117..f42666b 100644
--- a/libbuild2/parser.cxx
+++ b/libbuild2/parser.cxx
@@ -1171,6 +1171,12 @@ namespace build2
                 skip:
                   ;
                 }
+
+                // @@ TODO: if this rule does dynamic member discovery of a
+                //    see-through target group, then we may also need to
+                //    register update for other meta-operations (see, for
+                //    example, wildcard update registration in the cli
+                //    module).
               }
             }
           }
diff --git a/libbuild2/scope.hxx b/libbuild2/scope.hxx
index f82db72..e3ebdef 100644
--- a/libbuild2/scope.hxx
+++ b/libbuild2/scope.hxx
@@ -423,13 +423,37 @@ namespace build2
       rules.insert<T> (a, move (hint), r);
     }
 
+    // 0 meta-operation id is treated as an (emulated) wildcard.
+    //
+    // Emulated means that we just iterate over all the meta-operations known
+    // to this project (and they should all be known at this point) and
+    // register the rule for each of them.
+    //
     template <typename T>
     void
     insert_rule (meta_operation_id mid, operation_id oid,
                  string hint,
                  const rule& r)
     {
-      rules.insert<T> (mid, oid, move (hint), r);
+      if (mid != 0)
+        rules.insert<T> (mid, oid, move (hint), r);
+      else
+      {
+        auto& ms (root_scope ()->root_extra->meta_operations);
+
+        for (size_t i (1), n (ms.size ()); i != n; ++i)
+        {
+          // Skip a few well-known meta-operations that cannot possibly
+          // trigger a rule match.
+          //
+          if (ms[i] != nullptr &&
+              i != noop_id     &&
+              i != info_id     &&
+              i != create_id   &&
+              i != disfigure_id)
+            rules.insert<T> (i, oid, hint, r);
+        }
+      }
     }
 
     // Operation callbacks.
-- 
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