@errorCast into an inferred error set causes compiler crash #21222

NicoElbers · 2024-08-27T21:54:34Z

Zig Version

0.14.0-dev.1307+849c31a6c

Steps to Reproduce and Observed Behavior

bug.zig:

fn func() !void {
    return;
}

pub fn main() !void {
    const res = func();

    const err = @as(@TypeOf(res), @errorCast(error.Err));
    _ = try err;
}

run zig build-exe bug.zig

observe:

❯ zig build-exe bug.zig
[4]    99609 segmentation fault (core dumped)  zig build-exe bug.zig

full dump of a debug compiler here: https://pastebin.com/9bncrwdm

Expected Behavior

A compiling program, as what would happen if func returned anyerror!void

The text was updated successfully, but these errors were encountered:

NicoElbers · 2024-08-27T22:00:35Z

for additional information, a program where error.Err should be in the inferred error set also crashes:

fn func() !void {
    return error.Err;
}

pub fn main() !void {
    const res = func();

    const err = @as(@TypeOf(res), @errorCast(error.Err));
    _ = try err;
}

nektro · 2024-08-27T22:01:31Z

debug compiler stack trace

thread 104550 panic: reached unreachable code
Analyzing bug.zig
      %9 = ret_type() node_offset:5:1 to :5:7
      %10 = dbg_stmt(2, 5)
      %11 = decl_val("func") token_offset:6:17 to :6:21
      %12 = dbg_stmt(2, 21)
      %13 = call(.auto, %11, []) node_offset:6:17 to :6:23
      %14 = dbg_var_val(%13, "res")
      %15 = save_err_ret_index(%13)
      %16 = dbg_stmt(4, 5)
      %17 = block_comptime({
        %18 = typeof_builtin({
          %19 = break_inline(%18, %13)
        }) node_offset:8:21 to :8:33
        %20 = break(%17, %18)
      }) node_offset:8:21 to :8:33
      %21 = dbg_stmt(4, 35)
      %22 = error_value("Err") token_offset:8:52 to :8:55
    > %23 = extended(error_cast(%17, %22)) node_offset:8:35 to :8:56
      %24 = as_node(%17, %23) node_offset:8:35 to :8:56
      %25 = dbg_var_val(%24, "err")
      %26 = save_err_ret_index(%24)
      %27 = dbg_stmt(5, 9)
      %28 = try(%24, {
        %29 = err_union_code(%24) node_offset:9:9 to :9:16
        %30 = dbg_stmt(5, 9)
        %31 = ret_node(%29) node_offset:9:9 to :9:16
      }) node_offset:9:9 to :9:16
      %32 = ensure_result_non_error(%28) node_offset:9:9 to :9:16
      %33 = restore_err_ret_index_unconditional(.none) node_offset:5:1 to :5:7
      %34 = ret_implicit(@void_value) token_offset:10:1 to :10:1
    For full context, use the command
      zig ast-check -t bug.zig

  in /home/nico/personal-projects/zig/compiler/stage3/lib/zig/std/start.zig
    > %1937 = is_non_err(%1936) 
  in /home/nico/personal-projects/zig/compiler/stage3/lib/zig/std/start.zig
    > %1939 = block({%1934..%1938}) 
  in /home/nico/personal-projects/zig/compiler/stage3/lib/zig/std/start.zig
    > %1901 = switch_block(%1897,
        else => {%1919..%2022},
        @void_type => {%1902..%1910},
        @noreturn_type, @u8_type => {%1911..%1918}) 
  in /home/nico/personal-projects/zig/compiler/stage3/lib/zig/std/start.zig
    > %1698 = call(.auto, %1696, []) 
  in /home/nico/personal-projects/zig/compiler/stage3/lib/zig/std/start.zig
    > %1533 = call(.auto, %1531, [
        {%1534},
        {%1535},
        {%1536},
      ]) 
  in /home/nico/personal-projects/zig/compiler/stage3/lib/zig/std/start.zig
    > %1530 = field_call(nodiscard .auto, %1528, "exit", [
        {%1531..%1537},
      ]) 

/home/nico/personal-projects/zig/compiler/src/Type.zig:3003:22: 0xb5e66c5 in errorSetNames (zig)
            .none => unreachable, // unresolved inferred error set
                     ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:22993:53: 0xb1a95e1 in zirErrorCast (zig)
        const dest_err_names = dest_ty.errorSetNames(mod);
                                                    ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:1272:65: 0xacfab8b in analyzeBodyInner (zig)
                    .error_cast         => try sema.zirErrorCast(         block, extended),
                                                                ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:915:26: 0xb5fbde1 in analyzeFnBody (zig)
    sema.analyzeBodyInner(block, body) catch |err| switch (err) {
                         ^
/home/nico/personal-projects/zig/compiler/src/Zcu/PerThread.zig:2176:23: 0xb0b752d in analyzeFnBody (zig)
    sema.analyzeFnBody(&inner_block, fn_info.body) catch |err| switch (err) {
                      ^
/home/nico/personal-projects/zig/compiler/src/Zcu/PerThread.zig:792:35: 0xacae04d in ensureFuncBodyAnalyzedInner (zig)
    var air = try pt.analyzeFnBody(func_index);
                                  ^
/home/nico/personal-projects/zig/compiler/src/Zcu/PerThread.zig:698:81: 0xa86a713 in ensureFuncBodyAnalyzed (zig)
    const ies_outdated, const analysis_fail = if (pt.ensureFuncBodyAnalyzedInner(func_index, func_outdated)) |result|
                                                                                ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:35950:38: 0xad2114d in resolveInferredErrorSet (zig)
        try pt.ensureFuncBodyAnalyzed(func_index);
                                     ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:32616:69: 0xb1d6421 in analyzeIsNonErrComptimeOnly (zig)
                const resolved_ty = try sema.resolveInferredErrorSet(block, src, set_ty);
                                                                    ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:32645:56: 0xb67e8c9 in analyzeIsNonErr (zig)
    const result = try sema.analyzeIsNonErrComptimeOnly(block, src, operand);
                                                       ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:19294:32: 0xb12cc22 in zirIsNonErr (zig)
    return sema.analyzeIsNonErr(block, src, operand);
                               ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:1087:66: 0xacf4729 in analyzeBodyInner (zig)
            .is_non_err                   => try sema.zirIsNonErr(block, inst),
                                                                 ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:6016:34: 0xb6a8db8 in resolveBlockBody (zig)
        if (sema.analyzeBodyInner(child_block, body)) |_| {
                                 ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:5993:33: 0xb1d9378 in zirBlock (zig)
    return sema.resolveBlockBody(parent_block, src, &child_block, body, inst, &label.merges);
                                ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:1593:49: 0xad011f7 in analyzeBodyInner (zig)
                    break :blk try sema.zirBlock(block, inst, tags[@intFromEnum(inst)] == .block_comptime);
                                                ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:6016:34: 0xb6a8db8 in resolveBlockBody (zig)
        if (sema.analyzeBodyInner(child_block, body)) |_| {
                                 ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:10972:45: 0xb69f5fd in resolveProngComptime (zig)
                return sema.resolveBlockBody(spa.parent_block, src, child_block, prong_body, spa.switch_block_inst, merges);
                                            ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:13244:36: 0xb69f1e5 in resolveSwitchComptime (zig)
    return spa.resolveProngComptime(
                                   ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:12364:37: 0xb13d8f8 in zirSwitchBlock (zig)
        return resolveSwitchComptime(
                                    ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:1110:69: 0xacf5555 in analyzeBodyInner (zig)
            .switch_block                 => try sema.zirSwitchBlock(block, inst, false),
                                                                    ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:915:26: 0xb5fbde1 in analyzeFnBody (zig)
    sema.analyzeBodyInner(block, body) catch |err| switch (err) {
                         ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:7812:31: 0xb1f2df4 in analyzeCall (zig)
            sema.analyzeFnBody(&child_block, fn_info.body) catch |err| switch (err) {
                              ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:6986:43: 0xb11d298 in zirCall__anon_408486 (zig)
    const call_inst = try sema.analyzeCall(block, func, func_ty, callee_src, call_src, modifier, ensure_result_used, args_info, call_dbg_node, .call);
                                          ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:1045:62: 0xacf2ce9 in analyzeBodyInner (zig)
            .call                         => try sema.zirCall(block, inst, .direct),
                                                             ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:915:26: 0xb5fbde1 in analyzeFnBody (zig)
    sema.analyzeBodyInner(block, body) catch |err| switch (err) {
                         ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:7812:31: 0xb1f2df4 in analyzeCall (zig)
            sema.analyzeFnBody(&child_block, fn_info.body) catch |err| switch (err) {
                              ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:6986:43: 0xb11d298 in zirCall__anon_408486 (zig)
    const call_inst = try sema.analyzeCall(block, func, func_ty, callee_src, call_src, modifier, ensure_result_used, args_info, call_dbg_node, .call);
                                          ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:1045:62: 0xacf2ce9 in analyzeBodyInner (zig)
            .call                         => try sema.zirCall(block, inst, .direct),
                                                             ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:933:30: 0xa89a2d7 in analyzeInlineBody (zig)
    if (sema.analyzeBodyInner(block, body)) |_| {
                             ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:959:39: 0xa57ea3e in resolveInlineBody (zig)
    return (try sema.analyzeInlineBody(block, body, break_target)) orelse .unreachable_value;
                                      ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:7278:65: 0xb74acb5 in analyzeArg (zig)
                const uncoerced_arg = try sema.resolveInlineBody(block, arg_body, zir_call.call_inst);
                                                                ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:7865:49: 0xb1f430b in analyzeCall (zig)
            arg_out.* = try args_info.analyzeArg(sema, block, arg_idx, param_ty, func_ty_info, func);
                                                ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:6986:43: 0xb11e5d3 in zirCall__anon_408488 (zig)
    const call_inst = try sema.analyzeCall(block, func, func_ty, callee_src, call_src, modifier, ensure_result_used, args_info, call_dbg_node, .call);
                                          ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:1046:62: 0xacf2d86 in analyzeBodyInner (zig)
            .field_call                   => try sema.zirCall(block, inst, .field),
                                                             ^
/home/nico/personal-projects/zig/compiler/src/Sema.zig:915:26: 0xb5fbde1 in analyzeFnBody (zig)
    sema.analyzeBodyInner(block, body) catch |err| switch (err) {
                         ^
/home/nico/personal-projects/zig/compiler/src/Zcu/PerThread.zig:2176:23: 0xb0b752d in analyzeFnBody (zig)
    sema.analyzeFnBody(&inner_block, fn_info.body) catch |err| switch (err) {
                      ^
/home/nico/personal-projects/zig/compiler/src/Zcu/PerThread.zig:792:35: 0xacae04d in ensureFuncBodyAnalyzedInner (zig)
    var air = try pt.analyzeFnBody(func_index);
                                  ^
/home/nico/personal-projects/zig/compiler/src/Zcu/PerThread.zig:698:81: 0xa86a713 in ensureFuncBodyAnalyzed (zig)
    const ies_outdated, const analysis_fail = if (pt.ensureFuncBodyAnalyzedInner(func_index, func_outdated)) |result|
                                                                                ^
/home/nico/personal-projects/zig/compiler/src/Compilation.zig:3693:38: 0xa554237 in processOneJob (zig)
            pt.ensureFuncBodyAnalyzed(func) catch |err| switch (err) {
                                     ^
/home/nico/personal-projects/zig/compiler/src/Compilation.zig:3638:30: 0xa2d5d51 in performAllTheWorkInner (zig)
            try processOneJob(@intFromEnum(Zcu.PerThread.Id.main), comp, job, main_progress_node);
                             ^
/home/nico/personal-projects/zig/compiler/src/Compilation.zig:3508:36: 0xa16d460 in performAllTheWork (zig)
    try comp.performAllTheWorkInner(main_progress_node);
                                   ^
/home/nico/personal-projects/zig/compiler/src/Compilation.zig:2269:31: 0xa168c09 in update (zig)
    try comp.performAllTheWork(main_progress_node);
                              ^
/home/nico/personal-projects/zig/compiler/src/main.zig:4453:20: 0xa16eb7d in updateModule (zig)
    try comp.update(prog_node);
                   ^
/home/nico/personal-projects/zig/compiler/src/main.zig:3500:21: 0xa1d7f0a in buildOutputType (zig)
        updateModule(comp, color, root_prog_node) catch |err| switch (err) {
                    ^
/home/nico/personal-projects/zig/compiler/src/main.zig:258:31: 0xa020046 in mainArgs (zig)
        return buildOutputType(gpa, arena, args, .{ .build = .Exe });
                              ^
/home/nico/personal-projects/zig/compiler/src/main.zig:199:20: 0xa01d015 in main (zig)
    return mainArgs(gpa, arena, args);
                   ^
/nix/store/046rjdgb75qdq31pqjx0hqy9gdg8m8gv-zig-0.14.0-dev.1261+c26206112/lib/std/start.zig:614:37: 0xa01cb3e in main (zig)
            const result = root.main() catch |err| {
                                    ^
???:?:?: 0x7f825837714d in ??? (libc.so.6)
Unwind information for `libc.so.6:0x7f825837714d` was not available, trace may be incomplete

[2]    104550 IOT instruction (core dumped)  ../../compiler/stage3/bin/zig build-exe bug.zig

rohlem · 2024-08-28T09:34:33Z

Maybe known, but you can work around the current bug by stripping the error set's identity (undocumented - #20862):

fn func() !void {
    return;
}
fn StripErrorSetIdentity(T: type) type {
    return switch (@typeInfo(T)) {
        else => |tag| @compileError("invalid input type: " ++ @typeName(T) ++ " | " ++ @tagName(tag)),
        .ErrorSet => T || error{},
        .ErrorUnion => |u| StripErrorSetIdentity(u.error_set)!u.payload,
    };
}
pub fn main() !void {
    const res = func();
    const Res = StripErrorSetIdentity(@TypeOf(res));

    const err = @as(Res, @errorCast(error.Err));
    _ = try err;
}

Due to a compiler bug involving inferred error sets (ziglang/zig#21222) I have to use this workaround

NicoElbers added the bug Observed behavior contradicts documented or intended behavior label Aug 27, 2024

Vexu added the frontend Tokenization, parsing, AstGen, Sema, and Liveness. label Sep 1, 2024

Vexu added this to the 0.15.0 milestone Sep 1, 2024

Rexicon226 mentioned this issue Sep 5, 2024

unreachable hit using try @errorCast on error set in function with IES #21317

Closed

NicoElbers added a commit to NicoElbers/ztest that referenced this issue Sep 7, 2024

dummyIPC give explicit error type

db8a0dc

Due to a compiler bug involving inferred error sets (ziglang/zig#21222) I have to use this workaround

Rexicon226 linked a pull request Sep 8, 2024 that will close this issue

sema: make @errorCast into an IES resolve it #21349

Open

NicoElbers added a commit to NicoElbers/ztest that referenced this issue Sep 11, 2024

dummyIPC give explicit error type

47f7a84

Due to a compiler bug involving inferred error sets (ziglang/zig#21222) I have to use this workaround

NicoElbers added a commit to NicoElbers/ztest that referenced this issue Sep 30, 2024

dummyIPC give explicit error type

12acf9c

Due to a compiler bug involving inferred error sets (ziglang/zig#21222) I have to use this workaround

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@errorCast into an inferred error set causes compiler crash #21222

@errorCast into an inferred error set causes compiler crash #21222

NicoElbers commented Aug 27, 2024

NicoElbers commented Aug 27, 2024

nektro commented Aug 27, 2024

rohlem commented Aug 28, 2024 •

edited

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@errorCast into an inferred error set causes compiler crash #21222

@errorCast into an inferred error set causes compiler crash #21222

Comments

NicoElbers commented Aug 27, 2024

Zig Version

Steps to Reproduce and Observed Behavior

Expected Behavior

NicoElbers commented Aug 27, 2024

nektro commented Aug 27, 2024

rohlem commented Aug 28, 2024 • edited Loading

rohlem commented Aug 28, 2024 •

edited

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