From f2a24b48e1221a8954ddf16e9070e1470ee13e8d Mon Sep 17 00:00:00 2001
From: kcbanner <kcbanner@gmail.com>
Date: Sat, 23 Sep 2023 13:03:03 -0400
Subject: sema: rework the comptime representation of comptime unions

When the tag is not known, it's set to `.none`. In this case, the value is either an
array of bytes (for extern unions) or an integer (for packed unions).
---
 src/InternPool.zig | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

(limited to 'src/InternPool.zig')

diff --git a/src/InternPool.zig b/src/InternPool.zig
index 79d4127787..7c8702a716 100644
--- a/src/InternPool.zig
+++ b/src/InternPool.zig
@@ -1105,7 +1105,10 @@ pub const Key = union(enum) {
     pub const Union = extern struct {
         /// This is the union type; not the field type.
         ty: Index,
-        /// Indicates the active field.
+        /// Indicates the active field. This could be `none`, which indicates the tag is not known. `none` is only a valid value for extern and packed unions.
+        /// In those cases, the type of `val` is:
+        ///   extern: a u8 array of the same byte length as the union
+        ///   packed: an unsigned integer with the same bit size as the union
         tag: Index,
         /// The value of the active field.
         val: Index,
@@ -5130,7 +5133,6 @@ pub fn get(ip: *InternPool, gpa: Allocator, key: Key) Allocator.Error!Index {
 
         .un => |un| {
             assert(un.ty != .none);
-            assert(un.tag != .none);
             assert(un.val != .none);
             ip.items.appendAssumeCapacity(.{
                 .tag = .union_value,
-- 
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