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, 24 insertions, 17 deletions

diff --git a/build2/dist/operation.cxx b/build2/dist/operation.cxx
index 9ae5773..aea957a 100644
--- a/build2/dist/operation.cxx
+++ b/build2/dist/operation.cxx
@@ -139,21 +139,30 @@ namespace build2
       // ignored on the next step if the user explicitly marked them
       // nodist.
       //
-      auto add_adhoc = [&src_root, &trace] (const dir_path& d, const char* f)
+      auto add_adhoc = [&trace] (scope& rs, const char* f)
+      {
+        path p (rs.src_path () / path (f));
+        if (file_exists (p))
         {
-          path p (d / path (f));
-          if (file_exists (p))
-          {
-            const char* e (p.extension ());
-            targets.insert<buildfile> (
-              p.directory (),
-              p.leaf ().base ().string (),
-              &extension_pool.find (e == nullptr ? "" : e), // Specified.
-              trace);
-          }
-        };
+          dir_path d (p.directory ());
 
-      add_adhoc (src_root, "build/export.build");
+          // Figure out if we need out.
+          //
+          dir_path out (rs.src_path () != rs.out_path ()
+                        ? out_src (d, rs)
+                        : dir_path ());
+
+          const char* e (p.extension ());
+          targets.insert<buildfile> (
+            move (d),
+            move (out),
+            p.leaf ().base ().string (),
+            &extension_pool.find (e == nullptr ? "" : e), // Specified.
+            trace);
+        }
+      };
+
+      add_adhoc (*rs, "build/export.build");
 
       // The same for subprojects that have been loaded.
       //
@@ -168,12 +177,10 @@ namespace build2
           if (nrs.out_path () != out_nroot) // This subproject not loaded.
             continue;
 
-          const dir_path& src_nroot (nrs.src_path ());
-
-          if (!src_nroot.sub (src_root)) // Not a strong amalgamation.
+          if (!nrs.src_path ().sub (src_root)) // Not a strong amalgamation.
             continue;
 
-          add_adhoc (src_nroot, "build/export.build");
+          add_adhoc (nrs, "build/export.build");
         }
       }