stage2: panic from packedStructToInt

[scheibo]

Zig Version

0.10.0-dev.3590+a12abc6d6

Steps to Reproduce

const std = @import("std");

pub const Foo = packed struct {
    type: Foo.Type = .A,
    _: u2 = 0,
    data: u4 = 0,

    pub const Type = enum(u2) {
        A,
        B,
        C,
    };

    comptime {
        std.debug.assert(@sizeOf(Foo) == 1);
    }
};

test "Foo" {
    const foo: Foo = .{ .type = .B, .data = 4 };
    try std.testing.expectEqual(0b0100_0001, @bitCast(u8, foo));
}

zig test -fno-stage1 main.zig

Expected Behavior

$ zig test -fno-stage1 main.zig 
All 1 tests passed.

I expect this code to either pass like on stage 1 or to provide an error message indicating what should be changed.

Actual Behavior

With -fno-stage1 the self hosted compiler panics:

$ zig test -fno-stage1 main.zig 
thread 11257471 panic: reached unreachable code
/Users/kjs/Code/src/github.com/scheibo/zig/src/value.zig:1313:25: 0x10654b3ef in value.Value.packedStructToInt (zig1)
                else => unreachable,
                        ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/value.zig:1274:55: 0x1065480ea in value.Value.writeToMemory (zig1)
                    const host_int = packedStructToInt(val, ty, target, &buf);
                                                      ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Sema.zig:24894:22: 0x1065a5289 in Sema.bitCastVal (zig1)
    val.writeToMemory(old_ty, sema.mod, buffer);
                     ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Sema.zig:24828:47: 0x1064d887e in Sema.bitCast (zig1)
        const result_val = try sema.bitCastVal(block, inst_src, val, old_ty, dest_ty, 0);
                                              ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Sema.zig:8526:24: 0x1062776ce in Sema.zirBitcast (zig1)
    return sema.bitCast(block, dest_ty, operand, operand_src);
                       ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Sema.zig:713:65: 0x1060f7df4 in Sema.analyzeBodyInner (zig1)
            .bitcast                      => try sema.zirBitcast(block, inst),
                                                                ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Sema.zig:621:45: 0x1060f31fd in Sema.analyzeBodyBreak (zig1)
    const break_inst = sema.analyzeBodyInner(block, body) catch |err| switch (err) {
                                            ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Sema.zig:586:50: 0x1064d8ae1 in Sema.resolveBody (zig1)
    const break_data = (try sema.analyzeBodyBreak(block, body)) orelse
                                                 ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Sema.zig:5563:56: 0x10627ace8 in Sema.zirCall (zig1)
        resolved_args[arg_index] = try sema.resolveBody(block, args_body[arg_start..arg_end], inst);
                                                       ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Sema.zig:719:62: 0x1060f82cb in Sema.analyzeBodyInner (zig1)
            .call                         => try sema.zirCall(block, inst),
                                                             ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Sema.zig:604:30: 0x1060ec5cb in Sema.analyzeBody (zig1)
    _ = sema.analyzeBodyInner(block, body) catch |err| switch (err) {
                             ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Module.zig:5501:21: 0x105f1e16e in Module.analyzeFnBody (zig1)
    sema.analyzeBody(&inner_block, fn_info.body) catch |err| switch (err) {
                    ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Module.zig:4212:40: 0x105efeb04 in Module.ensureFuncBodyAnalyzed (zig1)
            var air = mod.analyzeFnBody(func, sema_arena) catch |err| switch (err) {
                                       ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Compilation.zig:2966:42: 0x105c546bb in Compilation.processOneJob (zig1)
            module.ensureFuncBodyAnalyzed(func) catch |err| switch (err) {
                                         ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Compilation.zig:2898:30: 0x105c43f6e in Compilation.performAllTheWork (zig1)
            try processOneJob(comp, work_item);
                             ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/Compilation.zig:2238:31: 0x105c3c766 in Compilation.update (zig1)
    try comp.performAllTheWork(main_progress_node);
                              ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/main.zig:3327:20: 0x105bd4790 in main.updateModule (zig1)
    try comp.update();
                   ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/main.zig:3016:17: 0x105b2a8e7 in main.buildOutputType (zig1)
    updateModule(gpa, comp, hook) catch |err| switch (err) {
                ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/main.zig:236:31: 0x105ad65cd in main.mainArgs (zig1)
        return buildOutputType(gpa, arena, args, .zig_test);
                              ^
/Users/kjs/Code/src/github.com/scheibo/zig/src/stage1.zig:48:24: 0x105ad5d5a in main (zig1)
        stage2.mainArgs(gpa, arena, args) catch unreachable;
                       ^
???:?:?: 0x117cba52d in ??? (???)
???:?:?: 0x0 in ??? (???)
Abort trap: 6

[ThreeFx]

The same problem occurs in intToPackedStruct in the other conversion direction.

[scheibo]

I have verified that this bug no longer reproduces in stage 2 as of 0.10.0-dev.4640+20925b2f5 (I think maybe thanks to #13221?) Thanks!