From 9bb8b63156f6dfb42f9ddab77f253ae0bda02d5a Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 21 Nov 2023 09:32:50 +0200
Subject: Add target::append_locked() variant

---
 libbuild2/target.cxx | 30 ++++++++++++++++++++++++++----
 libbuild2/target.hxx | 10 ++++++++--
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/libbuild2/target.cxx b/libbuild2/target.cxx
index b4c3968..bef7dce 100644
--- a/libbuild2/target.cxx
+++ b/libbuild2/target.cxx
@@ -143,7 +143,8 @@ namespace build2
   pair<lookup, size_t> target::
   lookup_original (const variable& var,
                    bool target_only,
-                   const scope* bs) const
+                   const scope* bs,
+                   bool locked) const
   {
     pair<lookup_type, size_t> r (lookup_type (), 0);
 
@@ -204,9 +205,14 @@ namespace build2
     {
       if (!target_only)
       {
-        target_key tk (key ());
-        target_key g1k (g1 != nullptr ? g1->key () : target_key {});
-        target_key g2k (g2 != nullptr ? g2->key () : target_key {});
+        auto key = [locked] (const target* t)
+        {
+          return locked ? t->key_locked () : t->key ();
+        };
+
+        target_key tk (key (this));
+        target_key g1k (g1 != nullptr ? key (g1) : target_key {});
+        target_key g2k (g2 != nullptr ? key (g2) : target_key {});
 
         if (bs == nullptr)
           bs = &base_scope ();
@@ -247,6 +253,22 @@ namespace build2
     return r;
   }
 
+  value& target::
+  append_locked (const variable& var)
+  {
+    auto l (lookup_original (var, false, nullptr, true /* locked */).first);
+
+    if (l.defined () && l.belongs (*this)) // Existing var in this target.
+      return vars.modify (l); // Ok since this is original.
+
+    value& r (assign (var)); // NULL.
+
+    if (l.defined ())
+      r = *l; // Copy value (and type) from the outer scope.
+
+    return r;
+  }
+
   pair<lookup, size_t> target::opstate::
   lookup_original (const variable& var, bool target_only) const
   {
diff --git a/libbuild2/target.hxx b/libbuild2/target.hxx
index 46c0949..5283ab8 100644
--- a/libbuild2/target.hxx
+++ b/libbuild2/target.hxx
@@ -782,12 +782,14 @@ namespace build2
 
     // If target_only is true, then only look in target and its target group
     // without continuing in scopes. As an optimization, the caller can also
-    // pass the base scope of the target, if already known.
+    // pass the base scope of the target, if already known. If locked is true,
+    // assume the targets mutex is locked.
     //
     pair<lookup_type, size_t>
     lookup_original (const variable&,
                      bool target_only = false,
-                     const scope* bs = nullptr) const;
+                     const scope* bs = nullptr,
+                     bool locked = false) const;
 
     // Return a value suitable for assignment. See scope for details.
     //
@@ -802,6 +804,10 @@ namespace build2
     value&
     append (const variable&);
 
+    // As above but assume the targets mutex is locked.
+    //
+    value&
+    append_locked (const variable&);
 
     // Rule hints.
     //
-- 
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