From 41c1f41245db26acb1bb8c624bae47140bcc56aa Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Thu, 10 Oct 2024 12:39:42 +0200
Subject: Don't match group-based targets with fallback rule during configure
 (GH #364)

Membership of such targets can only be accurately determined by the ad hoc
recipe.
---
 libbuild2/build/script/builtin.cli |  7 ++++---
 libbuild2/config/init.cxx          |  3 ++-
 libbuild2/rule.cxx                 |  4 ++--
 libbuild2/rule.hxx                 | 13 +++++++++++--
 4 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/libbuild2/build/script/builtin.cli b/libbuild2/build/script/builtin.cli
index 5aea034..9639477 100644
--- a/libbuild2/build/script/builtin.cli
+++ b/libbuild2/build/script/builtin.cli
@@ -103,9 +103,10 @@ namespace build2
         // Dynamic target extraction options.
         //
         // This functionality is enabled with the --dyn-target option. Only
-        // the make format is supported, where the listed targets are added as
-        // ad hoc group members (unless already specified as static members).
-        // This functionality is not available in the byproduct mode.
+        // the `make` and `lines` formats are supported (see above), where the
+        // listed targets are added as ad hoc group members (unless already
+        // specified as static members). This functionality is not available
+        // in the byproduct mode.
         //
         string --target-what;         // Target kind, e.g., "source".
 
diff --git a/libbuild2/config/init.cxx b/libbuild2/config/init.cxx
index b8ba31d..776299c 100644
--- a/libbuild2/config/init.cxx
+++ b/libbuild2/config/init.cxx
@@ -27,6 +27,7 @@ namespace build2
   namespace config
   {
     static const file_rule file_rule_ (true /* check_type */);
+    static const noop_rule noop_rule_ (true /* exclude_group */);
 
     void
     functions (function_map&); // functions.cxx
@@ -733,7 +734,7 @@ namespace build2
 
       // This allows a custom configure rule while doing nothing by default.
       //
-      rs.insert_rule<target> (configure_id, 0, "config.noop", noop_rule::instance);
+      rs.insert_rule<target> (configure_id, 0, "config.noop", noop_rule_);
 
       // We need this rule for out-of-any-project dependencies (for example,
       // libraries imported from /usr/lib). We are registering it on the
diff --git a/libbuild2/rule.cxx b/libbuild2/rule.cxx
index dc1c96c..b504dc7 100644
--- a/libbuild2/rule.cxx
+++ b/libbuild2/rule.cxx
@@ -430,9 +430,9 @@ namespace build2
   // noop_rule
   //
   bool noop_rule::
-  match (action, target&) const
+  match (action, target& t) const
   {
-    return true;
+    return !exclude_group_ || !t.is_a<group> ();
   }
 
   recipe noop_rule::
diff --git a/libbuild2/rule.hxx b/libbuild2/rule.hxx
index eceb6ad..71782c0 100644
--- a/libbuild2/rule.hxx
+++ b/libbuild2/rule.hxx
@@ -209,8 +209,17 @@ namespace build2
     virtual recipe
     apply (action, target&) const override;
 
-    noop_rule () {}
-    static const noop_rule instance;
+    // If exclude_group is true then exclude the group-based targets (since
+    // their membership can only be accurately determined by the ad hoc
+    // recipe).
+    //
+    explicit
+    noop_rule (bool exclude_group = false): exclude_group_ (exclude_group) {}
+
+    static const noop_rule instance; // Note: does not exclude group.
+
+  private:
+    bool exclude_group_;
   };
 
   // Ad hoc rule.
-- 
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