Compiler crash hits data.live_set.count() == 0 assert in Liveness.zig

[eshom]

Zig Version

0.15.0-dev.1253+fc4b7c968

Steps to Reproduce and Observed Behavior

src/main.zig

const std = @import("std");

pub fn main() !void {
    const c = @cImport({
        @cInclude("pty.h");
    });

    var master_fd: c_int = 0;
    var pid: c.pid_t = 0;

    pid = c.forkpty(&master_fd, null, null, null);
    if (pid == -1) {
        std.debug.print("forkpty failed\n", .{});
        return;
    }

    if (pid == 0) {
        var args = [_:null]?[*:0]const u8{ "/bin/sh", "-il" };
        const err = std.posix.execvpeZ(args[0].?, &args, std.c.environ);
        std.log.err("exec failed: {}", .{err});
    } else {
        std.debug.print("Parent process: forkpty succeeded\n", .{});

        const master_file = std.fs.File{ .handle = master_fd };
        var buf: [1024:0]u8 = undefined;

        // compiler crash
        if (master_file.read(buf[0..])) |read_results| {
            std.debug.print("read result: {}\n", .{read_results});
        } else |err| {
            std.debug.print("Read error: {}\n", .{err});
        }

        // Below doesn't crash

        // const read_result = master_file.read(buf[0..]) catch |err| {
        //     std.debug.print("Read error: {}\n", .{err});
        //     std.process.exit(0);
        // };

        // const read_result = try master_file.read(buf[0..]);
        // std.debug.print("read result: {}\n", .{read_result});
    }
}

Output:

❯ ~/.local/share/zig/zig-dev-debug/bin/zig run -lc test10.zig
thread 37941 panic: reached unreachable code
/home/erez/src/zig/build/stage3/lib/zig/std/debug.zig:559:14: 0x624b349 in assert (std.zig)
    if (!ok) unreachable; // assertion failure
             ^
/home/erez/src/zig/src/Air/Liveness.zig:178:15: 0x7a0e924 in analyze (main.zig)
        assert(data.live_set.count() == 0);
              ^
/home/erez/src/zig/src/Zcu/PerThread.zig:4361:21: 0x72fd170 in runCodegenInner (main.zig)
        try .analyze(zcu, air.*, ip)
                    ^
/home/erez/src/zig/src/Zcu/PerThread.zig:4310:46: 0x6dd04f7 in runCodegen (main.zig)
    const success: bool = if (runCodegenInner(pt, func_index, air)) |mir| success: {
                                             ^
/home/erez/src/zig/src/Compilation.zig:5425:18: 0x72bd3a1 in workerZcuCodegen (main.zig)
    pt.runCodegen(func_index, &air, out);
                 ^
/home/erez/src/zig/build/stage3/lib/zig/std/Thread/Pool.zig:180:50: 0x72bd7dc in runFn (std.zig)
            @call(.auto, func, .{id.?} ++ closure.arguments);
                                                 ^
/home/erez/src/zig/build/stage3/lib/zig/std/Thread/Pool.zig:293:27: 0x720245d in worker (std.zig)
            runnable.runFn(runnable, id);
                          ^
/home/erez/src/zig/build/stage3/lib/zig/std/Thread.zig:510:13: 0x6ceee70 in callFn__anon_195317 (std.zig)
            @call(.auto, f, args);
            ^
/home/erez/src/zig/build/stage3/lib/zig/std/Thread.zig:782:30: 0x6796989 in entryFn (std.zig)
                return callFn(f, args_ptr.*);
                             ^
???:?:?: 0x7febab69a7bd in ??? (libc.so.6)
Unwind information for `libc.so.6:0x7febab69a7bd` was not available, trace may be incomplete

Expected Behavior

No compiler crash