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).

1 files changed, 2 insertions, 29 deletions

diff --git a/src/Module.zig b/src/Module.zig
index 09e136cde8..349a7d4ba5 100644
--- a/src/Module.zig
+++ b/src/Module.zig
@@ -5823,7 +5823,7 @@ pub fn markReferencedDeclsAlive(mod: *Module, val: Value) Allocator.Error!void {
         .aggregate => |aggregate| for (aggregate.storage.values()) |elem|
             try mod.markReferencedDeclsAlive(elem.toValue()),
         .un => |un| {
-            try mod.markReferencedDeclsAlive(un.tag.toValue());
+            if (un.tag != .none) try mod.markReferencedDeclsAlive(un.tag.toValue());
             try mod.markReferencedDeclsAlive(un.val.toValue());
         },
         else => {},
@@ -6607,7 +6607,7 @@ pub fn unionFieldNormalAlignment(mod: *Module, u: InternPool.UnionType, field_in
 
 pub fn unionTagFieldIndex(mod: *Module, u: InternPool.UnionType, enum_tag: Value) ?u32 {
     const ip = &mod.intern_pool;
-    if (enum_tag.toIntern() == .undef) return null;
+    if (enum_tag.toIntern() == .none) return null;
     assert(ip.typeOf(enum_tag.toIntern()) == u.enum_tag_ty);
     const enum_type = ip.indexToKey(u.enum_tag_ty).enum_type;
     return enum_type.tagValueIndex(ip, enum_tag.toIntern());
@@ -6673,30 +6673,3 @@ pub fn structPackedFieldBitOffset(
     }
     unreachable; // index out of bounds
 }
-
-pub fn unionLargestField(mod: *Module, u: InternPool.UnionType) struct {
-    ty: Type,
-    index: u32,
-    size: u64,
-} {
-    const fields = u.field_types.get(&mod.intern_pool);
-    assert(fields.len != 0);
-    var largest_field_ty: Type = undefined;
-    var largest_field_size: u64 = 0;
-    var largest_field_index: u32 = 0;
-    for (fields, 0..) |union_field, i| {
-        const field_ty = union_field.toType();
-        const size: u32 = @intCast(field_ty.abiSize(mod));
-        if (size > largest_field_size) {
-            largest_field_ty = field_ty;
-            largest_field_size = size;
-            largest_field_index = @intCast(i);
-        }
-    }
-
-    return .{
-        .ty = largest_field_ty,
-        .index = largest_field_index,
-        .size = largest_field_size,
-    };
-}