From 9b7b240c8e4757bf0119db70da30722aa97fd6ae Mon Sep 17 00:00:00 2001
From: mlugg <mlugg@mlugg.co.uk>
Date: Wed, 22 Jan 2025 01:51:55 +0000
Subject: [PATCH] std.builtin: make `returnError` not take the error trace

It's now unnecessary to explicitly pass this, because it receives an
implicit error trace parameter anyway, so can just use
`@errorReturnTrace()`. The previous commit updated Sema to expect this
new interface. This saves an AIR instruction at all `returnError` call
sites.
---
 lib/std/builtin.zig | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/std/builtin.zig b/lib/std/builtin.zig
index 763db8448c..73a47fa3af 100644
--- a/lib/std/builtin.zig
+++ b/lib/std/builtin.zig
@@ -1150,9 +1150,10 @@ pub const panicInactiveUnionField = Panic.inactiveUnionField;
 /// To be deleted after zig1.wasm is updated.
 pub const panic_messages = Panic.messages;
 
-pub noinline fn returnError(st: *StackTrace) void {
+pub noinline fn returnError() void {
     @branchHint(.unlikely);
     @setRuntimeSafety(false);
+    const st = @errorReturnTrace().?;
     if (st.index < st.instruction_addresses.len)
         st.instruction_addresses[st.index] = @returnAddress();
     st.index += 1;