From d593b19735eec451b091fd46e4cb066e3478d6c9 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Tue, 29 Nov 2022 14:02:20 +0200
Subject: Move buildfiles to root_extra, use vector instead of unordered_set

---
 libbuild2/file.cxx   |  4 ++--
 libbuild2/file.hxx   |  5 +++--
 libbuild2/parser.cxx |  4 +++-
 libbuild2/scope.hxx  | 28 +++++++++++++++++++---------
 4 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/libbuild2/file.cxx b/libbuild2/file.cxx
index 3ded45e..b93a20a 100644
--- a/libbuild2/file.cxx
+++ b/libbuild2/file.cxx
@@ -307,7 +307,7 @@ namespace build2
   {
     tracer trace ("source_once");
 
-    if (!once.buildfiles.insert (bf).second)
+    if (!once.root_extra->insert_buildfile (bf))
     {
       l5 ([&]{trace << "skipping already sourced " << bf;});
       return false;
@@ -954,7 +954,7 @@ namespace build2
     // process hard to reason about. But we may try to bootstrap the same
     // root scope multiple time.
     //
-    else if (rs.buildfiles.insert (bf).second)
+    else if (rs.root_extra->insert_buildfile (bf))
     {
       // Extract the project name and amalgamation variable value so that
       // we can make them available while loading bootstrap.build.
diff --git a/libbuild2/file.hxx b/libbuild2/file.hxx
index f5eb3f9..5847498 100644
--- a/libbuild2/file.hxx
+++ b/libbuild2/file.hxx
@@ -116,10 +116,11 @@ namespace build2
   bool
   source_once (scope& root, scope& base, const path&);
 
-  // As above but checks against the specified scope rather than base.
+  // As above but checks against the specified root scope rather than this
+  // root scope.
   //
   LIBBUILD2_SYMEXPORT bool
-  source_once (scope& root, scope& base, const path&, scope& once);
+  source_once (scope& root, scope& base, const path&, scope& once_root);
 
   // Create project's root scope. Only set the src_root variable if the passed
   // src_root value is not empty.
diff --git a/libbuild2/parser.cxx b/libbuild2/parser.cxx
index b4df45b..29fe23f 100644
--- a/libbuild2/parser.cxx
+++ b/libbuild2/parser.cxx
@@ -3050,7 +3050,9 @@ namespace build2
 
       l6 ([&]{trace (l) << "absolute path " << p;});
 
-      if (!root_->buildfiles.insert (p).second) // Note: may be "new" root.
+      // Note: may be "new" root.
+      //
+      if (!root_->root_extra->insert_buildfile (p))
       {
         l5 ([&]{trace (l) << "skipping already included " << p;});
         continue;
diff --git a/libbuild2/scope.hxx b/libbuild2/scope.hxx
index 7989d59..3d31ff1 100644
--- a/libbuild2/scope.hxx
+++ b/libbuild2/scope.hxx
@@ -4,8 +4,6 @@
 #ifndef LIBBUILD2_SCOPE_HXX
 #define LIBBUILD2_SCOPE_HXX
 
-#include <unordered_set>
-
 #include <libbuild2/types.hxx>
 #include <libbuild2/forward.hxx>
 #include <libbuild2/utility.hxx>
@@ -302,13 +300,6 @@ namespace build2
     //
     variable_type_map target_vars;
 
-    // Set of buildfiles already loaded for this scope. The included
-    // buildfiles are checked against the project's root scope while
-    // imported -- against the global scope (global_scope).
-    //
-  public:
-    std::unordered_set<path> buildfiles;
-
     // Target types.
     //
     // Note that target types are project-wide (even if the module that
@@ -523,6 +514,25 @@ namespace build2
       //
       module_map modules;
 
+      // Buildfiles already loaded for this project.
+      //
+      // We don't expect too many of them per project so let's use vector
+      // with linear search.
+      //
+      paths buildfiles;
+
+      bool
+      insert_buildfile (const path& f)
+      {
+        bool r (find (buildfiles.begin (),
+                      buildfiles.end (),
+                      f) == buildfiles.end ());
+        if (r)
+          buildfiles.push_back (f);
+
+        return r;
+      }
+
       // Variable override cache.
       //
       mutable variable_override_cache override_cache;
-- 
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