proc_macro_attribute input has invalid span for various input.

[thiolliere]

Context:

input of proc_macro_attribute have invalid (null) span for some input.
I test spans with this code:

#[proc_macro_attribute]
pub fn bar(_attr: proc_macro::TokenStream, item: proc_macro::TokenStream) -> proc_macro::TokenStream {
	for tt in item.clone().into_iter() {
		println!("tt: {}: {:?}", tt, tt.span());
	}
	item
}

Failing inputs:

1- inner doc (this is fixed by #76130 )

#[ressai_proc::bar]
pub mod inner_doc {
	//! With this documentation line removed span are working.
}

prints

tt: pub: #0 bytes(0..0)
tt: mod: #0 bytes(0..0)
tt: inner_doc: #0 bytes(0..0)
tt: {
    //! With this documentation line removed span are working.

}: #0 bytes(0..0)

removing the inner doc makes the token tree having non-null spans.

2- another path attribute (with two path segment) (this one is now fixed in rustc 1.49.0-nightly (ffa2e7a 2020-10-24))

#[ressai_proc::bar]
#[ressai_proc::bar]
pub mod another_attribute {
}

prints

tt: #: #0 bytes(0..0)
tt: [ressai_proc :: bar]: #0 bytes(0..0)
tt: pub: #0 bytes(0..0)
tt: mod: #0 bytes(0..0)
tt: another_attribute: #0 bytes(0..0)
tt: { }: #0 bytes(0..0)
tt: pub: #0 bytes(0..0)
tt: mod: #0 bytes(0..0)
tt: another_attribute: #0 bytes(0..0)
tt: { }: #0 bytes(0..0)

note that this slightly modified input will give non-null spans:

use ressai_proc::bar;
#[ressai_proc::bar]
#[bar]
pub mod another_attribute_but_successful {
}

3 - some method on associated type: (this is fixed by #78980)

#[ressai_proc::bar]
mod foo {
	trait Config {
		type Origin: From<u32>;
	}

	struct A<T>(T);

	impl<T: Config> A<T> {
		fn foo() {
			<T as Config>::Origin::from(3);
		}
	}
}

This will output:

   Compiling ressai-proc v0.1.0 (/home/thiolliere/Developpement/ressai-procedural/ressai-proc)
tt: mod: #0 bytes(0..0)
tt: foo: #0 bytes(0..0)
tt: {
    trait Config { type Origin : From < u32 > ; } struct A < T > (T) ; impl <
    T : Config > A < T > { fn foo() { < T as Config > :: from(3) ; } }
}: #0 bytes(0..0)
error[E0576]: cannot find method or associated constant `from` in trait `Config`

So the rust error message is not pointing the failing code. All span are 0.

Meta

cargo rustc -- --version --verbose:

rustc 1.49.0-nightly (ffa2e7ae8 2020-10-24)
binary: rustc
commit-hash: ffa2e7ae8fbf9badc035740db949b9dae271c29f
commit-date: 2020-10-24
host: x86_64-unknown-linux-gnu
release: 1.49.0-nightly
LLVM version: 11.0

EDIT: related #43081

[Aaron1011]

Both of these issues will be fixed by #76130

[thiolliere]

update:

• I added another failing input.
• the second input is not failing anymore
• Also I tried to check if [WIP] Token-based outer attributes handling #76130 fix all of them, so I compiled with channel=dev, extended=true and tools=["cargo"] and then used build/x86_64-unknown-linux-gnu/stage1-tools-bin/cargo but the span are still wrong for all input (1 and 3). I guess there should be something wrong in my setup though as Aaron1011 tends to imply otherwise
  sorry my setup was wrong, aaron1011 branch indeed fix the first example. Thus only the 3, latest added one, is still failing with his branch

[thiolliere]

the third input should be fixed by #78980

[thiolliere]

the inner doc issue is remaining but it is a duplicate of #43081