hash_const_val doesn't support bound functions

[daurnimator]

I was experimenting with the following function to get return types of both functions and bound functions:

fn ReturnType(func: var) type {
    return switch(@typeInfo(@typeOf(func))) {
        .Fn => |info| info,
        .BoundFn => |info| info,
        else => @compileError("attempt to get return type of non-function"),
    }.return_type;
}

And I hit:

Unreachable at zig/src/analyze.cpp:5201 in hash_const_val. This is a bug in the Zig compiler.

Traceback:

#4  0x00005555556c4ae1 in hash_const_val (const_val=0x555556be5b38) at /home/daurnimator/src/zig/src/analyze.cpp:5201
#5  0x00005555556c525a in fn_eval_hash (scope=0x555556be5d70) at /home/daurnimator/src/zig/src/analyze.cpp:5384
#6  0x0000555555683d85 in HashMap<Scope*, ConstExprValue*, &(fn_eval_hash(Scope*)), &(fn_eval_eql(Scope*, Scope*))>::key_to_index (this=0x55555581f080, key=@0x7fffffffa248: 0x555556be5d70) at /home/daurnimator/src/zig/src/hash_map.hpp:238
#7  0x0000555555682cc7 in HashMap<Scope*, ConstExprValue*, &(fn_eval_hash(Scope*)), &(fn_eval_eql(Scope*, Scope*))>::internal_get (this=0x55555581f080, key=@0x7fffffffa248: 0x555556be5d70) at /home/daurnimator/src/zig/src/hash_map.hpp:223
#8  0x0000555555682047 in HashMap<Scope*, ConstExprValue*, &(fn_eval_hash(Scope*)), &(fn_eval_eql(Scope*, Scope*))>::maybe_get (this=0x55555581f080, key=@0x7fffffffa248: 0x555556be5d70) at /home/daurnimator/src/zig/src/hash_map.hpp:81
#9  0x000055555564a724 in ir_analyze_fn_call (ira=0x555556bdfcc0, call_instruction=0x555556bdf220, fn_entry=0x555556be0100, fn_type=0x555556be0470, fn_ref=0x555556be0850, first_arg_ptr=0x0, comptime_fn_call=true, fn_inline=FnInlineAuto) at /home/daurnimator/src/zig/src/ir.cpp:16771
#10 0x000055555564c848 in ir_analyze_instruction_call (ira=0x555556bdfcc0, call_instruction=0x555556bdf220) at /home/daurnimator/src/zig/src/ir.cpp:17253

[andrewrk]

Related: #141