From 3925bdc7708abd4387a5ffb0db60bc57098f2669 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 16 Jan 2024 08:07:04 +0200
Subject: Add add_adhoc_member_identity(), use to fix ad hoc pattern rule logic

---
 libbuild2/adhoc-rule-regex-pattern.cxx | 12 +++++-----
 libbuild2/algorithm.cxx                | 43 ++++++++++++++++++++++++++++++++++
 libbuild2/algorithm.hxx                | 26 ++++++++++++++++++--
 3 files changed, 73 insertions(+), 8 deletions(-)

diff --git a/libbuild2/adhoc-rule-regex-pattern.cxx b/libbuild2/adhoc-rule-regex-pattern.cxx
index cd8c241..9101000 100644
--- a/libbuild2/adhoc-rule-regex-pattern.cxx
+++ b/libbuild2/adhoc-rule-regex-pattern.cxx
@@ -366,7 +366,9 @@ namespace build2
 
       // @@ TODO: save location in constructor?
       //
-      optional<string> ext (target::split_name (n, location ()));
+      location loc;
+
+      optional<string> ext (target::split_name (n, loc));
 
       if (g != nullptr)
       {
@@ -425,16 +427,14 @@ namespace build2
       }
       else
       {
-        // @@ TODO: currently this uses type as the ad hoc member identity.
-        //          Use inject_adhoc_group_member() variant?
-        //
-        add_adhoc_member (
+        add_adhoc_member_identity (
           t,
           e.type,
           move (d),
           dir_path (), // Always in out.
           move (n),
-          move (ext));
+          move (ext),
+          loc);
       }
     }
   }
diff --git a/libbuild2/algorithm.cxx b/libbuild2/algorithm.cxx
index df8e650..2abf391 100644
--- a/libbuild2/algorithm.cxx
+++ b/libbuild2/algorithm.cxx
@@ -400,6 +400,49 @@ namespace build2
     return *m;
   };
 
+  pair<target&, bool>
+  add_adhoc_member_identity (target& t,
+                             const target_type& tt,
+                             dir_path dir,
+                             dir_path out,
+                             string n,
+                             optional<string> ext,
+                             const location& loc)
+  {
+    // NOTE: see similar code in parser::enter_adhoc_members().
+
+    tracer trace ("add_adhoc_member_identity");
+
+    pair<target&, ulock> r (
+      t.ctx.targets.insert_locked (tt,
+                                   move (dir),
+                                   move (out),
+                                   move (n),
+                                   move (ext),
+                                   target_decl::implied,
+                                   trace,
+                                   true /* skip_find */));
+    target& m (r.first);
+
+    // Add as an ad hoc member at the end of the chain skipping duplicates.
+    //
+    const_ptr<target>* mp (&t.adhoc_member);
+    for (; *mp != nullptr; mp = &(*mp)->adhoc_member)
+    {
+      if (*mp == &m)
+        return {m, false};
+    }
+
+    if (!r.second)
+      fail (loc) << "target " << m << " already exists and cannot be made "
+                 << "ad hoc member of group " << t;
+
+    m.group = &t;
+    *mp = &m;
+
+    return {m, true};
+  }
+
   static bool
   trace_target (const target& t, const vector<name>& ns)
   {
diff --git a/libbuild2/algorithm.hxx b/libbuild2/algorithm.hxx
index 2c57b74..dd5d367 100644
--- a/libbuild2/algorithm.hxx
+++ b/libbuild2/algorithm.hxx
@@ -274,11 +274,15 @@ namespace build2
   //
   // Note that here and in find_adhoc_member() below (as well as in
   // perform_clean_extra()) we use target type (as opposed to, say, type and
-  // name) as the member's identity. This fits our current needs where every
+  // name) as the member's identity. This fits common needs where every
   // (rule-managed) ad hoc member has a unique target type and we have no need
   // for multiple members of the same type. This also allows us to support
   // things like changing the ad hoc member name by declaring it in a
-  // buildfile.
+  // buildfile. However, if this semantics is not appropriate, use the
+  // add_adhoc_member_identity() version below.
+  //
+  // Note that the current implementation asserts if the member target already
+  // exists but is not already a member.
   //
   LIBBUILD2_SYMEXPORT target&
   add_adhoc_member (target&,
@@ -309,6 +313,24 @@ namespace build2
     return add_adhoc_member<T> (g, T::static_type, e);
   }
 
+  // Add an ad hoc member using the member identity (as opposed to only its
+  // type as in add_adhoc_member() above) to suppress diplicates. See also
+  // dyndep::inject_adhoc_group_member().
+  //
+  // Return the member target as well as an indication of whether it was added
+  // or was already a member. Fail if the member target already exists but is
+  // not a member since it's not possible to make it a member in an MT-safe
+  // manner.
+  //
+  LIBBUILD2_SYMEXPORT pair<target&, bool>
+  add_adhoc_member_identity (target&,
+                             const target_type&,
+                             dir_path dir,
+                             dir_path out,
+                             string name,
+                             optional<string> ext,
+                             const location& = location ());
+
   // Find an ad hoc member of the specified target type returning NULL if not
   // found.
   //
-- 
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