How to use Semantics::resolve_path correctly

[nicola-gigante]

Hi all,

I'm progressing in my attempts at using Rust Analyzer crates for my project but I cannot make Semantics::resolve_path work correctly.

Recap of my problem:

1. I load the workspace with load_workspace_at() and look for a specific hir::Crate filtering Crate::all(db).
2. I instantiate a Semantics object with Semantics::new(db).
3. I start from the root module of the crate and traverse all submodules and all ADTs declared in the module
4. For each Adt, say a hir::Struct, for my task I need to go down to the syntax level to check some things on the ast::Struct returned by the struct's source(), which in particular include resolving ast::Path objects found in the struct, e.g. in types of the fields.
5. When I run the whole thing I get this panic:

thread 'main' (3210306) panicked at /Users/gigabytes/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/ra_ap_hir-0.0.312/src/semantics.rs:2155:13:


Failed to lookup [email protected] in this Semantics.
Make sure to only query nodes derived from this instance of Semantics.
root node:   [email protected]
known nodes: 

A second attempt was this:

1. instead of loading the root module from the hir::Crate I get the base_db::Crate from db.all_crates() and get its root_file_id()
2. call sema.parse(file_id) to get a SourceFile and iterate over its items().
3. when I find a ast::Item::Module(module) I ask sema.to_module_def(module) and go to its definition_source() to get again a ast::Module or an act::SourceFile to iterate over the items().

In the second attempt resolve_path() works but only for the paths found in the root file of the crate (those that I passed directly to parse()), and not for submodules located in other files, getting the same panic as above.

So it seems that in both cases I miss how to link the Semantics instance to the files I'm traversing.

What am I doing wrong and how do I fix the issue?

Any help is appreciated! :)

[ChayimFriedman2]

A crucial part of working with semantics is to only get AST through it. That means you need to call the Semantics' source() method and not the type's, otherwise you get a panic like the one you got.

[nicola-gigante]

Oh I had completely missed that method! It fixed everything!

Thanks!