unable to build doge API!

[shreyarastogi]

I am trying to implement the doge API and this is the code that I am implementing:

use crate::dom::bindings::cell::DomRefCell;
use crate::dom::bindings::codegen::Bindings::DogeBinding::{DogeMethods, DogeInit, Wrap as DogeWrap};
use crate::dom::bindings::error::{Error, Fallible};
use crate::dom::bindings::GlobalScope;
use crate::dom::bindings::root;
use crate::dom::bindings::reflector::{Reflector, reflect_dom_object};
use crate::dom::bindings::str::DOMString;
use crate::rand;
use crate::rand::Rng;
extern crate rand;

#[dom_struct]
pub struct Doge {
reflector_: Reflector,
such_list: DOMRefCell<Vec>,
}

impl Doge{

pub fn new_inherited() -> Doge {
Doge {
reflector_: Reflector::new(),
such_list: DomRefCell::new(vec![]),
}
}

pub fn new(global: &GlobalScope) -> Root {
reflect_dom_object(Box::Doge::new_inherited(), global, DogeWrap)
}

// https://jeenalee.github.io/doge-standard/#dom-doge
pub fn Constructor(global: &GlobalScope, init: Option) -> Fallible<Root> {
// Step 1
let doge = Doge::new(global);
// Step 2
if let Some(i) = init {
for word in i {
doge.Append(word);
}
}
// Step 3
Ok(doge)
}
}

impl DogeMethods for Doge{

// https://jeenalee.github.io/doge-standard/#dom-doge-append
fn Append(&self, word: DOMString) -> () {
self.such_list.borrow_mut().push(word);
}

fn Random(&self) -> Fallible {
// Step 1
let list = self.such_list.borrow();
// Step 2
if list.len() == 0 {
return Err(Error::Type("Such list is empty".to_string()));
} else {
// Step 3
let random_index = servo_rand::thread_rng().gen_range(0, list.len());
return Ok(list[random_index].clone());
}
}
}

These are the errors that I am facing:
$ ./mach build --dev
Blocking waiting for file lock on package cache
Blocking waiting for file lock on package cache
Blocking waiting for file lock on package cache
Compiling script v0.0.1 (C:\Users\shrey\servo\components\script)
warning: Error finalizing incremental compilation session directory \\?\C:\Users\shrey\servo\target\debug\incremental\canvas_traits-aj1987kq9sua\s-fkbu5d627i-159yjr0-working: Access is denied. (os error 5)

Completed script v0.0.1 custom-build (run) in 13.6s
error[E0432]: unresolved import crate::dom::bindings::GlobalScope
--> components\script\dom\doge.rs:4:5
|
4 | use crate::dom::bindings::GlobalScope;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ no GlobalScope in dom::bindings

error[E0432]: unresolved import crate::rand
--> components\script\dom\doge.rs:8:5
|
8 | use crate::rand;
| ^^^^^^^^^^^ no rand in the root

error[E0432]: unresolved import crate::rand
--> components\script\dom\doge.rs:9:12
|
9 | use crate::rand::Rng;
| ^^^^
| |
| unresolved import
| help: a similar path exists: crate::dom::doge::rand

error: cannot find attribute dom_struct in this scope
--> components\script\dom\doge.rs:12:3
|
12 | #[dom_struct]
| ^^^^^^^^^^

error[E0412]: cannot find type DOMRefCell in this scope
--> components\script\dom\doge.rs:15:16
|
15 | such_list: DOMRefCell<Vec>,
| ^^^^^^^^^^ help: a struct with a similar name exists: DomRefCell
|
::: components\script\dom\bindings\cell.rs:21:1
|
21 | / pub struct DomRefCell {
22 | | value: RefCell,
23 | | }
| |_- similarly named struct DomRefCell defined here

error[E0412]: cannot find type Root in this scope
--> components\script\dom\doge.rs:27:37
|
27 | pub fn new(global: &GlobalScope) -> Root {
| ^^^^ not found in this scope
|
help: possible candidate is found in another module, you can import it into scope
|
1 | use crate::dom::bindings::root::Root;
|

error[E0412]: cannot find type Root in this scope
--> components\script\dom\doge.rs:32:78
|
32 | pub fn Constructor(global: &GlobalScope, init: Option) -> Fallible<Root> {
| ^^^^ not found in this scope
|
help: possible candidate is found in another module, you can import it into scope
|
1 | use crate::dom::bindings::root::Root;
|

warning: unused import: crate::dom::bindings::root
--> components\script\dom\doge.rs:5:5
|
5 | use crate::dom::bindings::root;
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: #[warn(unused_imports)] on by default

error[E0277]: the trait bound dom::doge::Doge: dom::bindings::reflector::DomObject is not satisfied
--> C:\Users\shrey\servo\target\debug\build\script-0fc8d3571dfd85fa\out/Bindings\DogeBinding.rs:666:1
|
666 | / pub unsafe fn Wrap(cx: SafeJSContext, scope: &GlobalScope, object: Box) -> DomRoot {
667 | | let scope = scope.reflector().get_jsobject();
668 | | assert!(!scope.get().is_null());
669 | | assert!(((*get_object_class(scope.get())).flags & JSCLASS_IS_GLOBAL) != 0);
... |
689 | | DomRoot::from_ref(&*raw)
690 | | }
| |_^ the trait dom::bindings::reflector::DomObject is not implemented for dom::doge::Doge
|
::: components\script\dom\bindings\root.rs:50:1
|
50 | pub struct Root<T: StableTraceObject> {
| ------------------------------------- required by dom::bindings::root::Root
|
= note: required because of the requirements on the impl of dom::bindings::root::StableTraceObject for dom::bindings::root::Dom<dom::doge::Doge>

error: aborting due to 8 previous errors

Some errors have detailed explanations: E0277, E0412, E0432.
For more information about an error, try rustc --explain E0277.
error: could not compile script.

To learn more, run the command again with --verbose.
Build FAILED in 0:01:26

Made some changes in the original code that has been provided in the guide. Still these errors persist. What more changes should I do?

[kunalmohan]

Few corrections that should remove most of the errors:

1. It's DomRefCell and not DOMRefCell.
2. GlobalScope is present in components/script/dom/globalscope.rs and should be imported from there (like use crate::dom::globalscope::GlobalScope;.
3. Remove crate:: from statements while importing rand (since its not present inside script crate).
4. Root should be imported like use crate::dom::bindings::root::Root; as suggested in the error logs.

[shreyarastogi]

Hey! those inputs were really helpful, but I am still getting these errors:

shrey@LAPTOP-L08HN83K MINGW64 /c/Users/shrey/servo (master)
$ ./mach build --dev
Blocking waiting for file lock on package cache
Blocking waiting for file lock on package cache
Blocking waiting for file lock on package cache
Compiling script v0.0.1 (C:\Users\shrey\servo\components\script)
warning: Error finalizing incremental compilation session directory \\?\C:\Users\shrey\servo\target\debug\incremental\canvas_traits-aj1987kq9sua\s-fkbu5d627i-159yjr0-working: Access is denied. (os error 5)

Completed script v0.0.1 custom-build (run) in 15.9s
error: cannot find attribute dom_struct in this scope
--> components\script\dom\doge.rs:12:3
|
12 | #[dom_struct]
| ^^^^^^^^^^

error[E0277]: the trait bound dom::doge::Doge: dom::bindings::reflector::DomObject is not satisfied
--> C:\Users\shrey\servo\target\debug\build\script-0fc8d3571dfd85fa\out/Bindings\DogeBinding.rs:666:1
|
666 | / pub unsafe fn Wrap(cx: SafeJSContext, scope: &GlobalScope, object: Box) -> DomRoot {
667 | | let scope = scope.reflector().get_jsobject();
668 | | assert!(!scope.get().is_null());
669 | | assert!(((*get_object_class(scope.get())).flags & JSCLASS_IS_GLOBAL) != 0);
... |
689 | | DomRoot::from_ref(&*raw)
690 | | }
| |_^ the trait dom::bindings::reflector::DomObject is not implemented for dom::doge::Doge
|
::: components\script\dom\bindings\root.rs:50:1
|
50 | pub struct Root<T: StableTraceObject> {
| ------------------------------------- required by dom::bindings::root::Root
|
= note: required because of the requirements on the impl of dom::bindings::root::StableTraceObject for dom::bindings::root::Dom<dom::doge::Doge>

error[E0277]: the trait bound dom::doge::Doge: dom::bindings::root::StableTraceObject is not satisfied
--> components\script\dom\doge.rs:27:1
|
27 | / pub fn new(global: &GlobalScope) -> Root {
28 | | reflect_dom_object(Box::Doge::new_inherited(), global, DogeWrap)
29 | | }
| |_^ the trait dom::bindings::root::StableTraceObject is not implemented for dom::doge::Doge
|
::: components\script\dom\bindings\root.rs:50:1
|
50 | pub struct Root<T: StableTraceObject> {
| ------------------------------------- required by dom::bindings::root::Root

error[E0277]: the trait bound dom::doge::Doge: dom::bindings::root::StableTraceObject is not satisfied
--> components\script\dom\doge.rs:32:1
|
32 | / pub fn Constructor(global: &GlobalScope, init: Option) -> Fallible<Root> {
33 | | // Step 1
34 | | let doge = Doge::new(global);
35 | | // Step 2
... |
42 | | Ok(doge)
43 | | }
| |_^ the trait dom::bindings::root::StableTraceObject is not implemented for dom::doge::Doge
|
::: components\script\dom\bindings\root.rs:50:1
|
50 | pub struct Root<T: StableTraceObject> {
| ------------------------------------- required by dom::bindings::root::Root

error: aborting due to 4 previous errors

For more information about this error, try rustc --explain E0277.
error: could not compile script.

To learn more, run the command again with --verbose.
Build FAILED in 0:01:44

[kunalmohan]

Ah, I missed that. You forgot to import dom_struct (use dom_struct::dom_struct;). Also, the new fn should return DomRoot<Doge> instead of Root and the Constructor should return Fallible<DomRoot<Doge>>. Don't forget to import DomRoot; present in the same file as Root.

[shreyarastogi]

made these changes as well, thank you. But still facing 2 more errors:

shrey@LAPTOP-L08HN83K MINGW64 /c/Users/shrey/servo (master)
$ ./mach build --dev
Blocking waiting for file lock on package cache
Blocking waiting for file lock on package cache
Blocking waiting for file lock on package cache
Compiling script v0.0.1 (C:\Users\shrey\servo\components\script)
warning: Error finalizing incremental compilation session directory \\?\C:\Users\shrey\servo\target\debug\incremental\canvas_traits-aj1987kq9sua\s-fkbu5d627i-159yjr0-working: Access is denied. (os error 5)

Completed script v0.0.1 custom-build (run) in 7.0s
error[E0433]: failed to resolve: use of undeclared type or module Trait
--> components\script\dom\doge.rs:30:47
|
30 | reflect_dom_object(<std::boxed::Box<_> as Trait>::Doge::new_inherited(), global, DogeWrap)
| ^^^^^ use of undeclared type or module Trait

error[E0053]: method Random has an incompatible type for trait
--> components\script\dom\doge.rs:55:21
|
55 | fn Random(&self) -> Fallible {
| ^^^^^^^^^^^^^^^^^^^ expected struct dom::bindings::str::DOMString, found enum std::result::Result
|
::: C:\Users\shrey\servo\target\debug\build\script-0fc8d3571dfd85fa\out/Bindings\DogeBinding.rs:707:25
|
707 | fn Random(&self) -> DOMString;
| --------- type in trait
|
= note: expected fn pointer fn(&dom::doge::Doge) -> dom::bindings::str::DOMString
found fn pointer fn(&dom::doge::Doge) -> std::result::Result<dom::bindings::str::DOMString, dom::bindings::error::Error>

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0053, E0433.
For more information about an error, try rustc --explain E0053.
error: could not compile script.

To learn more, run the command again with --verbose.
Build FAILED in 0:01:34

[kunalmohan]

In the new function, the first argument should be Box::new(Doge::new_inherited()). The second error occurs because according to webidl spec Random should return DOMString. Currently, you are returning Fallible which by itself doesn't make any sense. So change that to Fallible<DOMString> and in the Doge.webidl, edit the line defining Random function to [Throws] DOMString random(); (See #25376 (comment) for reference)

[shreyarastogi]

Build completed, thank you so much for your help!!

[jdm]

I'll update the original instructions to incorporate the appropriate code changes. Thanks for asking these questions @shreyarastogi, and thanks for answering them @kunalmohan!