From f49dff64c64baf8be48cc987b4ed61712afabc3d Mon Sep 17 00:00:00 2001
From: Veikka Tuominen <git@vexu.eu>
Date: Wed, 24 Aug 2022 20:50:43 +0300
Subject: [PATCH] Sema: check one possible value earlier in
 `zirValidateArrayInit`

Closes #12566
---
 src/Sema.zig            | 26 +++++++++++++-------------
 test/behavior/tuple.zig | 11 +++++++++++
 2 files changed, 24 insertions(+), 13 deletions(-)

diff --git a/src/Sema.zig b/src/Sema.zig
index 4e1b885486..22aa26f737 100644
--- a/src/Sema.zig
+++ b/src/Sema.zig
@@ -4071,6 +4071,19 @@ fn zirValidateArrayInit(
 
         // Determine whether the value stored to this pointer is comptime-known.
 
+        if (array_ty.isTuple()) {
+            if (array_ty.structFieldValueComptime(i)) |opv| {
+                element_vals[i] = opv;
+                continue;
+            }
+        } else {
+            // Array has one possible value, so value is always comptime-known
+            if (opt_opv) |opv| {
+                element_vals[i] = opv;
+                continue;
+            }
+        }
+
         const elem_ptr_air_ref = sema.inst_map.get(elem_ptr).?;
         const elem_ptr_air_inst = Air.refToIndex(elem_ptr_air_ref).?;
         // Find the block index of the elem_ptr so that we can look at the next
@@ -4087,19 +4100,6 @@ fn zirValidateArrayInit(
         }
         first_block_index = @minimum(first_block_index, block_index);
 
-        if (array_ty.isTuple()) {
-            if (array_ty.structFieldValueComptime(i)) |opv| {
-                element_vals[i] = opv;
-                continue;
-            }
-        } else {
-            // Array has one possible value, so value is always comptime-known
-            if (opt_opv) |opv| {
-                element_vals[i] = opv;
-                continue;
-            }
-        }
-
         // If the next instructon is a store with a comptime operand, this element
         // is comptime.
         const next_air_inst = block.instructions.items[block_index + 1];
diff --git a/test/behavior/tuple.zig b/test/behavior/tuple.zig
index 14297bd61c..971e52a0b5 100644
--- a/test/behavior/tuple.zig
+++ b/test/behavior/tuple.zig
@@ -290,3 +290,14 @@ test "coerce tuple to tuple" {
     };
     try S.foo(.{123});
 }
+
+test "tuple type with void field" {
+    if (builtin.zig_backend == .stage2_c) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_aarch64) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_arm) return error.SkipZigTest; // TODO
+    if (builtin.zig_backend == .stage2_x86_64) return error.SkipZigTest; // TODO
+
+    const T = std.meta.Tuple(&[_]type{void});
+    const x = T{{}};
+    try expect(@TypeOf(x[0]) == void);
+}