self-hosted: fix error messages not cleaning up correctly

1 files changed, 10 insertions, 2 deletions

diff --git a/std/mem.zig b/std/mem.zig
index 2a5b0366a9..43961a6d14 100644
--- a/std/mem.zig
+++ b/std/mem.zig
@@ -35,6 +35,7 @@ pub const Allocator = struct {
     freeFn: fn (self: *Allocator, old_mem: []u8) void,
 
     /// Call `destroy` with the result
+    /// TODO this is deprecated. use createOne instead
     pub fn create(self: *Allocator, init: var) Error!*@typeOf(init) {
         const T = @typeOf(init);
         if (@sizeOf(T) == 0) return &(T{});
@@ -44,6 +45,14 @@ pub const Allocator = struct {
         return ptr;
     }
 
+    /// Call `destroy` with the result.
+    /// Returns undefined memory.
+    pub fn createOne(self: *Allocator, comptime T: type) Error!*T {
+        if (@sizeOf(T) == 0) return &(T{});
+        const slice = try self.alloc(T, 1);
+        return &slice[0];
+    }
+
     /// `ptr` should be the return value of `create`
     pub fn destroy(self: *Allocator, ptr: var) void {
         const non_const_ptr = @intToPtr([*]u8, @ptrToInt(ptr));
@@ -149,13 +158,12 @@ pub fn copyBackwards(comptime T: type, dest: []T, source: []const T) void {
     @setRuntimeSafety(false);
     assert(dest.len >= source.len);
     var i = source.len;
-    while(i > 0){
+    while (i > 0) {
         i -= 1;
         dest[i] = source[i];
     }
 }
 
-
 pub fn set(comptime T: type, dest: []T, value: T) void {
     for (dest) |*d|
         d.* = value;