From 4c798bb0bd0043459f5b979ab3dfaee9a6f5ac97 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alex=20R=C3=B8nne=20Petersen?= <alex@alexrp.com>
Date: Fri, 26 Sep 2025 16:01:43 +0200
Subject: [PATCH] std.builtin: define VaList as `struct { __ap: *anyopaque }`
 for Arm per AAPCS

---
 lib/std/builtin.zig | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/lib/std/builtin.zig b/lib/std/builtin.zig
index e942f9877f..ca7d9e251a 100644
--- a/lib/std/builtin.zig
+++ b/lib/std/builtin.zig
@@ -844,6 +844,12 @@ pub const VaListAarch64 = extern struct {
     __vr_offs: c_int,
 };
 
+/// This data structure is used by the Zig language code generation and
+/// therefore must be kept in sync with the compiler implementation.
+pub const VaListArm = extern struct {
+    __ap: *anyopaque,
+};
+
 /// This data structure is used by the Zig language code generation and
 /// therefore must be kept in sync with the compiler implementation.
 pub const VaListHexagon = extern struct {
@@ -899,10 +905,7 @@ pub const VaList = switch (builtin.cpu.arch) {
             .stage2_llvm => @compileError("disabled due to miscompilations"),
         },
     },
-    .arm, .armeb, .thumb, .thumbeb => switch (builtin.os.tag) {
-        .ios, .macos, .tvos, .watchos, .visionos => *u8,
-        else => *anyopaque,
-    },
+    .arm, .armeb, .thumb, .thumbeb => VaListArm,
     .amdgcn => *u8,
     .avr => *anyopaque,
     .bpfel, .bpfeb => *anyopaque,