From 60a5ce1bed306f7ad64cf5208c7224f4f14be34e Mon Sep 17 00:00:00 2001
From: 0z5a <dezhen.lu@student.uni-tuebingen.de>
Date: Fri, 13 Nov 2026 08:59:50 +0100
Subject: [PATCH] Check the in-use allocator count after the loop in
 debug_in_use

debug_in_use(count) checked "count != 0" inside the loop over the
allocator pool, right after the first allocator.  Any call with
count > 0 therefore failed with "two few allocators in use" unless the
first allocator in the pool was the only one in use: debug_in_use(2)
always failed, and with count > 0 an empty pool was not reported at all.

Move the check after the loop so the count is compared once every
allocator has been visited.  The in-tree callers only pass 0, which
behaves as before.

func/teardown now calls debug_in_use with one and two scoped
allocators held.
---
 src/snmalloc/global/globalalloc.h  |  8 ++++----
 src/test/func/teardown/teardown.cc | 16 ++++++++++++++++
 2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/src/snmalloc/global/globalalloc.h b/src/snmalloc/global/globalalloc.h
index 7607e582a..ca9aaf509 100644
--- a/src/snmalloc/global/globalalloc.h
+++ b/src/snmalloc/global/globalalloc.h
@@ -120,11 +120,11 @@ namespace snmalloc
         count--;
       }
       alloc = AllocPool<Config_>::iterate(alloc);
+    }
 
-      if (count != 0)
-      {
-        error("Error: two few allocators in use.");
-      }
+    if (count != 0)
+    {
+      error("Error: two few allocators in use.");
     }
   }
 
diff --git a/src/test/func/teardown/teardown.cc b/src/test/func/teardown/teardown.cc
index 02129374d..3ad56925d 100644
--- a/src/test/func/teardown/teardown.cc
+++ b/src/test/func/teardown/teardown.cc
@@ -112,6 +112,20 @@ void f(size_t size)
   fflush(stdout);
 }
 
+void check_debug_in_use()
+{
+  {
+    auto a = snmalloc::get_scoped_allocator();
+    snmalloc::debug_in_use(1);
+    {
+      auto b = snmalloc::get_scoped_allocator();
+      snmalloc::debug_in_use(2);
+    }
+    snmalloc::debug_in_use(1);
+  }
+  snmalloc::debug_in_use(0);
+}
+
 int main(int, char**)
 {
   setup();
@@ -142,4 +156,6 @@ int main(int, char**)
     f(shifted(7) - 1);
     printf("\n");
   }
+
+  check_debug_in_use();
 }