non-byte-aligned packed struct field passed as generic fn parameter causes invalid LLVM IR

[andrewrk]

const P = packed struct {
    b: u5,
    g: u5,
    r: u5,
    a: u1,
};

fn genericFn(ptr: var) void {}

test "" {
    var p: P = undefined;
    genericFn(&p.b);
}

broken LLVM module found: Call parameter type does not match function signature!
  %12 = getelementptr inbounds %P, %P* %p, i32 0, i32 0, !dbg !1162
 i16*  call fastcc void @genericFn([2 x i8]* %12), !dbg !1163