Redesign src/out scoping

We no longer enter paths from the src tree into scope map. Instead, targets
from the src tree now include their out tree directory (in essence their
"configuration"). This is then used to find a target's scope. See the
comment in class target for details.

The result of this change is that we can now again build multiple
configurations (out trees) for same project at once.

1 files changed, 12 insertions, 17 deletions

diff --git a/build2/context.cxx b/build2/context.cxx
index a36b2b6..a27d4ff 100644
--- a/build2/context.cxx
+++ b/build2/context.cxx
@@ -77,9 +77,9 @@ namespace build2
     // <build2/path-map> for details.
     //
     {
-      auto i (scopes.insert (dir_path ("/"), nullptr, true, false));
-      global_scope = i->second;
-      global_scope->out_path_ = global_scope->src_path_ = &i->first;
+      auto i (scopes.insert (dir_path ("/"), false));
+      global_scope = &i->second;
+      global_scope->out_path_ = &i->first;
     }
 
     scope& gs (*global_scope);
@@ -182,10 +182,7 @@ namespace build2
 
       if (c == '!' || !dir.empty ())
       {
-        scope& s (c == '!'
-                  ? gs
-                  : *scopes.insert (dir, nullptr, true, false)->second);
-
+        scope& s (c == '!' ? gs : scopes.insert (dir, false)->second);
         auto p (s.vars.assign (*o));
 
         if (!p.second)
@@ -412,31 +409,29 @@ namespace build2
   dir_path
   src_out (const dir_path& out, scope& s)
   {
-    scope& rs (*s.root_scope ());
-    return src_out (out, rs.out_path (), rs.src_path ());
+    return src_out (out, s.out_path (), s.src_path ());
   }
 
   dir_path
   out_src (const dir_path& src, scope& s)
   {
-    scope& rs (*s.root_scope ());
-    return out_src (src, rs.out_path (), rs.src_path ());
+    return out_src (src, s.out_path (), s.src_path ());
   }
 
   dir_path
   src_out (const dir_path& o,
-           const dir_path& out_root, const dir_path& src_root)
+           const dir_path& out_base, const dir_path& src_base)
   {
-    assert (o.sub (out_root));
-    return src_root / o.leaf (out_root);
+    assert (o.sub (out_base));
+    return src_base / o.leaf (out_base);
   }
 
   dir_path
   out_src (const dir_path& s,
-           const dir_path& out_root, const dir_path& src_root)
+           const dir_path& out_base, const dir_path& src_base)
   {
-    assert (s.sub (src_root));
-    return out_root / s.leaf (src_root);
+    assert (s.sub (src_base));
+    return out_base / s.leaf (src_base);
   }
 
   // relative()