From 75d454b6a63d701c557d88773525d07e67083ae3 Mon Sep 17 00:00:00 2001
From: Zack Puhl <github@xmit.xyz>
Date: Sun, 25 Jan 2026 10:12:44 -0500
Subject: [PATCH] Add mem_allocator `realloc_array` Macros (#2760)

* Add mem_allocator `realloc_array` Macros

* test, ensure `realloc_array` to 0 size returns `null`

* update release notes

---------

Co-authored-by: Christoffer Lerno <christoffer@aegik.com>
---
 lib/std/core/mem_allocator.c3          | 25 +++++++++++++++++++++++++
 releasenotes.md                        |  1 +
 test/unit/stdlib/core/mem_allocator.c3 |  7 +++++++
 3 files changed, 33 insertions(+)

diff --git a/lib/std/core/mem_allocator.c3 b/lib/std/core/mem_allocator.c3
index eb56626f3..a1afcd57d 100644
--- a/lib/std/core/mem_allocator.c3
+++ b/lib/std/core/mem_allocator.c3
@@ -304,6 +304,31 @@ macro alloc_array_try(Allocator allocator, $Type, usz elements) @nodiscard
 	return (($Type*)malloc_try(allocator, $Type.sizeof * elements))[:elements];
 }
 
+<*
+ @require $Type.alignof <= mem::DEFAULT_MEM_ALIGNMENT : "Types with alignment exceeding the default must use 'alloc_array_aligned' instead"
+*>
+macro realloc_array(Allocator allocator, void* ptr, $Type, usz elements) @nodiscard
+{
+	return realloc_array_try(allocator, ptr, $Type, elements)!!;
+}
+
+<*
+ Allocate using an aligned allocation. This is necessary for types with a default memory alignment
+ exceeding DEFAULT_MEM_ALIGNMENT. IMPORTANT! It must be freed using free_aligned.
+*>
+macro realloc_array_aligned(Allocator allocator, void* ptr, $Type, usz elements) @nodiscard
+{
+	return (($Type*)realloc_aligned(allocator, ptr, $Type.sizeof * elements, $Type.alignof))[:elements]!!;
+}
+
+<*
+ @require $Type.alignof <= mem::DEFAULT_MEM_ALIGNMENT : "Types with alignment exceeding the default must use 'alloc_array_aligned' instead"
+*>
+macro realloc_array_try(Allocator allocator, void* ptr, $Type, usz elements) @nodiscard
+{
+	return (($Type*)realloc_try(allocator, ptr, $Type.sizeof * elements))[:elements];
+}
+
 <*
  Clone a value.
 
diff --git a/releasenotes.md b/releasenotes.md
index c3067ff59..959b6187b 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -159,6 +159,7 @@
 - Add `mem::store` and `mem::load` which may combine both aligned and volatile operations.
 - Deprecated `EMPTY_MACRO_SLOT` and its related uses, in favor of `optional_param = ...` named macro arguments. #2805
 - Add tracking of peak memory usage in the tracking allocator.
+- Added `realloc_array`, `realloc_array_aligned`, and `realloc_array_try` to `allocator::`. #2760
 
 ## 0.7.8 Change list
 
diff --git a/test/unit/stdlib/core/mem_allocator.c3 b/test/unit/stdlib/core/mem_allocator.c3
index ee1f65fa4..fe23457ce 100644
--- a/test/unit/stdlib/core/mem_allocator.c3
+++ b/test/unit/stdlib/core/mem_allocator.c3
@@ -23,3 +23,10 @@ fn void test_new_aligned_compiles() @test
 	Bar* bar = allocator::new_aligned(mem, Bar, {.x = 1, .y = 2, .foos = {}})!!;
 	allocator::free_aligned(mem, bar);
 }
+
+fn void test_realloc_array_to_zero() @test
+{
+	usz* x = mem::talloc_array(usz, 24);
+	x = allocator::realloc_array(tmem, x, usz, 0);
+	test::@check(x == null, "Zero-sized reallocation's pointer is not null: %p", x);
+}