From 9c196efa2afe0e337ac0b16bd1138e89393f6106 Mon Sep 17 00:00:00 2001
From: Benjamin Feng <benjamin.feng@glassdoor.com>
Date: Thu, 30 Jan 2020 01:12:21 -0600
Subject: [PATCH] Add explicit error message for too many frees

---
 lib/std/testing/leak_count_allocator.zig | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/std/testing/leak_count_allocator.zig b/lib/std/testing/leak_count_allocator.zig
index 1d65b8c560..65244e529b 100644
--- a/lib/std/testing/leak_count_allocator.zig
+++ b/lib/std/testing/leak_count_allocator.zig
@@ -33,6 +33,9 @@ pub const LeakCountAllocator = struct {
     fn shrink(allocator: *std.mem.Allocator, old_mem: []u8, old_align: u29, new_size: usize, new_align: u29) []u8 {
         const self = @fieldParentPtr(LeakCountAllocator, "allocator", allocator);
         if (new_size == 0) {
+            if (self.count == 0) {
+                std.debug.panic("error - too many calls to free, most likely double free", .{});
+            }
             self.count -= 1;
         }
         return self.internal_allocator.shrinkFn(self.internal_allocator, old_mem, old_align, new_size, new_align);