Completion frequently needs manual trigger with app code using gtk-rs

[YaLTeR]

I'm writing an app using gtk-rs. Even though the app is still pretty small and I have a high-end machine (Ryzen 5900X, 32 GB of RAM), I frequently get dumb completions in VSCode which I need to manually Escape out of and Ctrl-Space to manually trigger rust-analyzer ones. Then when narrowing down, the r-a completions frequently disappear, requiring another Escape and Ctrl-Space.

Here's a demonstration:

out.mp4

Every pause is intentional by me, so it's not like something happens automatically after a while. I'm just waiting to show what happens, and then manually pressing Escape and Ctrl-Space.

I can reproduce it on a clean checkout of my project:

1. git clone https://github.com/YaLTeR/plitki.git && cd plitki && git checkout 0a33e2994b8dc1fcc964ff1f23629e0f3ef49cda
2. Open plitki-gtk in VSCode.
3. Open main.rs, wait for rust-analyzer to finish loading.
4. Try typing something in on_activate like I do on the video, or maybe in some other files.

Completions seemed to work fine on an empty project with gtk4 added. However I really cannot call the project above anywhere close to complicated: it only contains a single window and two custom widgets.

Fedora 35 Silverblue, rust-analyzer version: 183ef04 2021-11-22 stable, VSCode 1.61.2 from Flathub opening the project in a toolbox container which works through VSCode's "Remote Container" extension.

[jhgg]

This is most likely #10369 - when completions take too long to compute vscode does not show them anymore unless you manually trigger them.

[YaLTeR]

when completions take too long to compute vscode does not show them anymore unless you manually trigger them

I see; what about completions disappearing when narrowing down? E.g. when I typed conne and triggered completions, then typed ct_ac and completions disappeared.

[YaLTeR]

Not sure I'm doing this right, but I set RA_PROFILE=* and got output when typing just a single letter (window.connect + _):

  140ms - handle_completion
       93ms - CompletionContext::new
           92ms - descend_into_macros
               92ms - Semantics::analyze_impl
                    9ms - SourceBinder::to_module_def
                        9ms - crate_def_map:wait
                        0   - relevant_crates (1 calls)
                        0   - ???
                   83ms - infer:wait @ on_activate
                       83ms - infer_query
                           81ms - trait_solve::wait
                            0   - crate_def_map:wait (13 calls)
                            0   - deref (1 calls)
                            0   - deref_by_trait (1 calls)
                            0   - resolve_obligations_as_possible (24 calls)
                            0   - trait_solve::wait (4 calls)
                            1ms - ???
                        0   - ???
                    0   - body_with_source_map_query (1 calls)
                    0   - crate_def_map:wait (2 calls)
                    0   - ???
                0   - ???
            0   - Semantics::analyze_impl (3 calls)
            0   - SourceBinder::to_module_def (3 calls)
            0   - crate_def_map:wait (2 calls)
            0   - ???
       27ms - iterate_method_candidates
            0   - crate_def_map:wait (402 calls)
            0   - deref (1 calls)
            6ms - render_method (400 calls)
            1ms - trait_solve::wait (324 calls)
           19ms - ???
       19ms - import_on_the_fly @ connect_
           19ms - import_assets::search_for_imports
               19ms - import_assets::search_for
                   18ms - import_assets::trait_applicable_items
                       14ms - items_with_name @ Name: connect_, crate: AssocItemsOnly, assoc items: Some("plitki_gtk"), limit: Some(40)
                           14ms - find_items
                               13ms - query_external_importables
                                   13ms - search_dependencies @ Query { query: "connect_", lowercased: "connect_", name_only: true, assoc_items_only: true, search_mode: Fuzzy, case_sensitive: false, limit: 40, exclude_import_kinds: {} }
                                        0   - fst_path (126 calls)
                                        0   - import_map::Query::import_matches (57 calls)
                                       13ms - ???
                                    0   - ???
                                0   - crate_symbols (1 calls)
                                0   - ???
                            0   - ???
                        4ms - iterate_method_candidates
                            0   - deref (1 calls)
                            0   - find_path_prefixed (8 calls)
                            0   - trait_solve::wait (23 calls)
                            4ms - ???
                        0   - applicable_inherent_traits (1 calls)
                        0   - deref (1 calls)
                        0   - ???
                    0   - import_assets::scope_definitions (1 calls)
                    0   - ???
                0   - ???
            0   - Semantics::analyze_impl (1 calls)
            0   - ???
        0   - Semantics::analyze_impl (2 calls)
        0   - complete_unqualified_path (1 calls)
        0   - crate_def_map:wait (58 calls)
        0   - deref (1 calls)
        0   - item::Builder::build (13 calls)
        0   - trait_solve::wait (2 calls)
        0   - ???

[Veykril]

Closing this as the main problem here is us being too slow with completions at times which is tracked in #7542