From b014bc77c8c5b89a8c0b5d4a995726ec6b350939 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Felix=20=28xq=29=20Quei=C3=9Fner?= <git@mq32.de>
Date: Fri, 2 Oct 2020 09:37:01 +0200
Subject: [PATCH] Fixes std.meta.Tuple and std.meta.ArgsTuple for zero-sized
 types (like void).

---
 lib/std/meta.zig | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/lib/std/meta.zig b/lib/std/meta.zig
index f02055a7ab..508e0590d6 100644
--- a/lib/std/meta.zig
+++ b/lib/std/meta.zig
@@ -846,14 +846,15 @@ pub fn ArgsTuple(comptime Function: type) type {
 
     var argument_field_list: [function_info.args.len]std.builtin.TypeInfo.StructField = undefined;
     inline for (function_info.args) |arg, i| {
+        const T = arg.arg_type.?;
         @setEvalBranchQuota(10_000);
         var num_buf: [128]u8 = undefined;
         argument_field_list[i] = std.builtin.TypeInfo.StructField{
             .name = std.fmt.bufPrint(&num_buf, "{d}", .{i}) catch unreachable,
-            .field_type = arg.arg_type.?,
-            .default_value = @as(?(arg.arg_type.?), null),
+            .field_type = T,
+            .default_value = @as(?T, null),
             .is_comptime = false,
-            .alignment = @alignOf(arg.arg_type.?),
+            .alignment = if (@sizeOf(T) > 0) @alignOf(T) else 0,
         };
     }
 
@@ -884,7 +885,7 @@ pub fn Tuple(comptime types: []const type) type {
             .field_type = T,
             .default_value = @as(?T, null),
             .is_comptime = false,
-            .alignment = @alignOf(T),
+            .alignment = if (@sizeOf(T) > 0) @alignOf(T) else 0,
         };
     }
 
@@ -927,12 +928,12 @@ test "ArgsTuple" {
     TupleTester.assertTuple(.{}, ArgsTuple(fn () void));
     TupleTester.assertTuple(.{u32}, ArgsTuple(fn (a: u32) []const u8));
     TupleTester.assertTuple(.{ u32, f16 }, ArgsTuple(fn (a: u32, b: f16) noreturn));
-    TupleTester.assertTuple(.{ u32, f16, []const u8 }, ArgsTuple(fn (a: u32, b: f16, c: []const u8) noreturn));
+    TupleTester.assertTuple(.{ u32, f16, []const u8, void }, ArgsTuple(fn (a: u32, b: f16, c: []const u8, void) noreturn));
 }
 
 test "Tuple" {
     TupleTester.assertTuple(.{}, Tuple(&[_]type{}));
     TupleTester.assertTuple(.{u32}, Tuple(&[_]type{u32}));
     TupleTester.assertTuple(.{ u32, f16 }, Tuple(&[_]type{ u32, f16 }));
-    TupleTester.assertTuple(.{ u32, f16, []const u8 }, Tuple(&[_]type{ u32, f16, []const u8 }));
+    TupleTester.assertTuple(.{ u32, f16, []const u8, void }, Tuple(&[_]type{ u32, f16, []const u8, void }));
 }