Commit 24fb6d1f301ee44bbfe865a6130c038094c32b60 | zig

author	David Rubin <david@vortan.dev> 2024-02-06 11:04:09-08:00
committer	GitHub <noreply@github.com> 2024-02-06 21:04:09+02:00
log	24fb6d1f301ee44bbfe865a6130c038094c32b60
tree	f1b5548dc278da43a173d4eeb54346d817f5d187
parent	52066bf8e4855e610754603cbcc64dbfd16796fe
signature	Signed by PGP key B5690EEEBB952194

Make `@intFromEnum` an error for empty enums

2 files changed, 26 insertions(+), 1 deletions(-)

src
- Sema.zig
test
- cases
  - compile_errors
    int_from_enum_undefined.zig

src/Sema.zig+14-1

 @@ -8629,6 +8629,7 @@ fn zirIntFromEnum(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError
                     .{src},
                 );
             };
             break :blk try sema.unionToTag(block, tag_ty, operand, operand_src);
         },
         else => {
 @@ -8638,14 +8639,25 @@ fn zirIntFromEnum(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError
         },
     };
     const enum_tag_ty = sema.typeOf(enum_tag);
     const int_tag_ty = enum_tag_ty.intTagType(mod);
+    // TODO: use correct solution
+    // https://github.com/ziglang/zig/issues/15909
+    if (enum_tag_ty.enumFieldCount(mod) == 0 and !enum_tag_ty.isNonexhaustiveEnum(mod)) {
+        return sema.fail(block, operand_src, "cannot use @intFromEnum on empty enum '{}'", .{
+            enum_tag_ty.fmt(mod),
+        });
+    }
     if (try sema.typeHasOnePossibleValue(enum_tag_ty)) |opv| {
         return Air.internedToRef((try mod.getCoerced(opv, int_tag_ty)).toIntern());
     }
     if (try sema.resolveValue(enum_tag)) |enum_tag_val| {
+        if (enum_tag_val.isUndef(mod)) {
+            return mod.undefRef(int_tag_ty);
+        }
         const val = try enum_tag_val.intFromEnum(enum_tag_ty, mod);
         return Air.internedToRef(val.toIntern());
     }
 @@ -20944,6 +20956,7 @@ fn zirTagName(sema: *Sema, block: *Block, inst: Zir.Inst.Index) CompileError!Air
     if (enum_ty.enumFieldCount(mod) == 0) {
         // TODO I don't think this is the correct way to handle this but
         // it prevents a crash.
+        // https://github.com/ziglang/zig/issues/15909
         return sema.fail(block, operand_src, "cannot get @tagName of empty enum '{}'", .{
             enum_ty.fmt(mod),
         });

test/cases/compile_errors/int_from_enum_undefined.zig created+12

...	@@ -0,0 +1,12 @@
1	export fn a() void {
2	const E = enum {};
3	var e: E = undefined;
4	_ = &e;
5	_ = @intFromEnum(e);
6	}
7
8	// error
9	// backend=stage2
10	// target=native
11	//
12	// :5:22: error: cannot use @intFromEnum on empty enum 'tmp.a.E'