Memory Leak?
**Disclaimer**: I don't know what I am doing. I am trying to learn Zig and I noticed this and I was wondering if you could help explain what is going on.
**EDIT**: I can stop the leak by freeing the allocation inside of the loop. Is this the correct thing to do?
Zig: `zig-linux-x86_64-0.14.0-dev`
trying `chameleon`, `/magurotuna/zig-deque`, `std.io.getStdOut`
```zig
// setup:
var gpa = std.heap.GeneralPurposeAllocator(.{}){};
defer _ = gpa.deinit();
const allocator = gpa.allocator();
var deque = try Deque(usize).init(allocator);
defer deque.deinit();
try deque.pushBack(1);
try deque.pushBack(2);
try deque.pushFront(42);
const writer = std.io.getStdOut().writer();
var c = Chameleon.initRuntime(.{ .allocator = allocator });
var it = deque.iterator();
```
then when trying to print values using the iterator
```zig
// NO MEMORY LEAK
while (it.next()) |val| {
try writer.print("{d} \n", .{val.*});
}
```
^-- No memory leak
```zig
// MEMORY LEAK
while (it.next()) |val| {
try writer.print("{s} \n", .{try c.green().bold().fmt("{d}", .{val.*})});
}
```
^-- memory leak
```zig
// FIXED? MEMORY LEAK
while (it.next()) |val| {
const fmt_text = try c.green().bold().fmt("{d}", .{val.*});
try writer.print("{s} \n", .{});
defer allocator.free(fmt_text);
}
```
^-- FIXED? memory leak. Is this correct?
and this is the leak message:
```
error(gpa): memory address 0x7f1f4ab20000 leaked:
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/mem.zig:3317:36: 0x1043d50 in concatMaybeSentinel__anon_3572 (deque_test)
const buf = try allocator.alloc(T, total_len);
^
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/mem.zig:3291:31: 0x103d588 in concat__anon_2508 (deque_test)
return concatMaybeSentinel(allocator, T, slices, null);
^
/.cache/zig/p/12208314a762057bf5ed82b26b02cbfcf426066b9920bfdd1ddcb68d1d0c55c45ce3/src/api/Runtime.zig:25:30: 0x103d1a2 in fmt__anon_2476 (deque_test)
return std.mem.concat(self.allocator, u8, &.{ self.open.items, formatted, self.close.items });
^
../src/main.zig:34:62: 0x103dc48 in main (deque_test)
try writer.print("{s} \n", .{try c.green().bold().fmt("{d}", .{val.*})});
^
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/start.zig:656:37: 0x103ceda in posixCallMainAndExit (deque_test)
const result = root.main() catch |err| {
^
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/start.zig:271:5: 0x103ca8d in _start (deque_test)
asm volatile (switch (native_arch) {
^
error(gpa): memory address 0x7f1f4ab20020 leaked:
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/mem.zig:3317:36: 0x1043d50 in concatMaybeSentinel__anon_3572 (deque_test)
const buf = try allocator.alloc(T, total_len);
^
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/mem.zig:3291:31: 0x103d588 in concat__anon_2508 (deque_test)
return concatMaybeSentinel(allocator, T, slices, null);
^
/.cache/zig/p/12208314a762057bf5ed82b26b02cbfcf426066b9920bfdd1ddcb68d1d0c55c45ce3/src/api/Runtime.zig:25:30: 0x103d1a2 in fmt__anon_2476 (deque_test)
return std.mem.concat(self.allocator, u8, &.{ self.open.items, formatted, self.close.items });
^
../src/main.zig:34:62: 0x103dc48 in main (deque_test)
try writer.print("{s} \n", .{try c.green().bold().fmt("{d}", .{val.*})});
^
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/start.zig:656:37: 0x103ceda in posixCallMainAndExit (deque_test)
const result = root.main() catch |err| {
^
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/start.zig:271:5: 0x103ca8d in _start (deque_test)
asm volatile (switch (native_arch) {
^
error(gpa): memory address 0x7f1f4ab20040 leaked:
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/mem.zig:3317:36: 0x1043d50 in concatMaybeSentinel__anon_3572 (deque_test)
const buf = try allocator.alloc(T, total_len);
^
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/mem.zig:3291:31: 0x103d588 in concat__anon_2508 (deque_test)
return concatMaybeSentinel(allocator, T, slices, null);
^
/.cache/zig/p/12208314a762057bf5ed82b26b02cbfcf426066b9920bfdd1ddcb68d1d0c55c45ce3/src/api/Runtime.zig:25:30: 0x103d1a2 in fmt__anon_2476 (deque_test)
return std.mem.concat(self.allocator, u8, &.{ self.open.items, formatted, self.close.items });
^
../src/main.zig:34:62: 0x103dc48 in main (deque_test)
try writer.print("{s} \n", .{try c.green().bold().fmt("{d}", .{val.*})});
^
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/start.zig:656:37: 0x103ceda in posixCallMainAndExit (deque_test)
const result = root.main() catch |err| {
^
/zig/zig-linux-x86_64-0.14.0-dev.3286+05d8b565a/lib/std/start.zig:271:5: 0x103ca8d in _start (deque_test)
asm volatile (switch (native_arch) {
^
```
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