From 537b26034925bf7452db2ff4cd6b29de92d77471 Mon Sep 17 00:00:00 2001
From: Tetralux <tetralux@teknik.io>
Date: Mon, 16 Sep 2019 01:35:01 +0000
Subject: [PATCH 1/2] Add FixedBufferAllocator.reset

---
 std/heap.zig | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/std/heap.zig b/std/heap.zig
index d14f34dd6e..046103c445 100644
--- a/std/heap.zig
+++ b/std/heap.zig
@@ -480,6 +480,10 @@ pub const FixedBufferAllocator = struct {
     fn shrink(allocator: *Allocator, old_mem: []u8, old_align: u29, new_size: usize, new_align: u29) []u8 {
         return old_mem[0..new_size];
     }
+
+    pub inline fn reset(self: *FixedBufferAllocator) void {
+        self.end_index = 0;
+    }
 };
 
 // FIXME: Exposed LLVM intrinsics is a bug
@@ -775,6 +779,26 @@ test "FixedBufferAllocator" {
     try testAllocatorAlignedShrink(&fixed_buffer_allocator.allocator);
 }
 
+test "FixedBufferAllocator.reset" {
+    var buf: [8]u8 align(@alignOf(usize)) = undefined;
+    var fba = FixedBufferAllocator.init(buf[0..]);
+
+    const X = 0xeeeeeeeeeeeeeeee;
+    const Y = 0xffffffffffffffff;
+
+    var x = try fba.allocator.create(u64);
+    x.* = X;
+    testing.expectError(error.OutOfMemory, fba.allocator.create(u64));
+
+    fba.reset();
+    var y = try fba.allocator.create(u64);
+    y.* = Y;
+
+    // we expect Y to have overwritten X.
+    testing.expect(x.* == y.*);
+    testing.expect(y.* == Y);
+}
+
 test "FixedBufferAllocator Reuse memory on realloc" {
     var small_fixed_buffer: [10]u8 = undefined;
     // check if we re-use the memory

From 86b6790b6a7fc7fb6b85d5e970259af60ddd0290 Mon Sep 17 00:00:00 2001
From: Tetralux <tetralux@teknik.io>
Date: Sat, 21 Sep 2019 15:42:26 +0000
Subject: [PATCH 2/2] Remove 'inline', as per @andrewrk

---
 std/heap.zig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/std/heap.zig b/std/heap.zig
index 046103c445..a07f750567 100644
--- a/std/heap.zig
+++ b/std/heap.zig
@@ -481,7 +481,7 @@ pub const FixedBufferAllocator = struct {
         return old_mem[0..new_size];
     }
 
-    pub inline fn reset(self: *FixedBufferAllocator) void {
+    pub fn reset(self: *FixedBufferAllocator) void {
         self.end_index = 0;
     }
 };