Revert "libutil: drop Pool resources on exceptional free"

This reverts commit de2884b82b376d10de5c400d8e73bc7d98f195d2.

Change-Id: I1fa301149d7c2ed3d266a40c15b2d010e12e44e6

src/libutil/pool.hh

@@ -1,7 +1,6 @@
 #pragma once
 ///@file
 
-#include <exception>
 #include <functional>
 #include <limits>
 #include <list>
@@ -119,7 +118,7 @@ public:
             if (!r) return;
             {
                 auto state_(pool.state.lock());
-                if (!bad && !std::uncaught_exceptions())
+                if (!bad)
                     state_->idle.push_back(ref<R>(r));
                 assert(state_->inUse);
                 state_->inUse--;
@@ -135,12 +134,6 @@ public:
 
     Handle get()
     {
-        // we do not want to handle the complexity that comes with allocating
-        // resources during stack unwinding. it would be possible to do this,
-        // but doing so requires more per-handle bookkeeping to properly free
-        // resources allocated during unwinding. that effort is not worth it.
-        assert(std::uncaught_exceptions() == 0);
-
         {
             auto state_(state.lock());
 

tests/unit/libutil/pool.cc

@@ -109,19 +109,4 @@ namespace nix {
             ASSERT_NE(h->num, counter);
         }
     }
-
-    TEST(Pool, throwingOperationDropsResource)
-    {
-        auto createResource = []() { return make_ref<TestResource>(); };
-
-        Pool<TestResource> pool = Pool<TestResource>((size_t)1, createResource);
-
-        ASSERT_THROW({
-            auto _r = pool.get();
-            ASSERT_EQ(pool.count(), 1);
-            throw 1;
-        }, int);
-
-        ASSERT_EQ(pool.count(), 0);
-    }
 }