Merge #8302

8302: Allow multiple modules from the same crate in fixtures r=SomeoneToIgnore a=SomeoneToIgnore

A tiny step towards #6633

As discussed in [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Fwg-rls-2.2E0/topic/Completion.20benchmarks), we would need to have a generated code for the completions benchmark.
To better represent a real project, we'd better allow to specify multiple modules in a crate within a single fixture.

Co-authored-by: Kirill Bulatov <mail4score@gmail.com>

crates/base_db/src/fixture.rs

@@ -57,7 +57,7 @@
 //! fn insert_source_code_here() {}
 //! "
 //! ```
-use std::{mem, str::FromStr, sync::Arc};
+use std::{mem, str::FromStr, sync::Arc, collections::hash_map::Entry};
 
 use cfg::CfgOptions;
 use rustc_hash::FxHashMap;
@@ -175,19 +175,34 @@ impl ChangeFixture {
 
             if let Some(krate) = meta.krate {
                 let crate_name = CrateName::normalize_dashes(&krate);
-                let crate_id = crate_graph.add_crate_root(
-                    file_id,
-                    meta.edition,
-                    Some(crate_name.clone().into()),
-                    meta.cfg,
-                    meta.env,
-                    Default::default(),
-                );
-                let prev = crates.insert(crate_name.clone(), crate_id);
-                assert!(prev.is_none());
-                for dep in meta.deps {
-                    let dep = CrateName::normalize_dashes(&dep);
-                    crate_deps.push((crate_name.clone(), dep))
+                match crates.entry(crate_name.clone()) {
+                    Entry::Occupied(_) => {
+                        assert_eq!(
+                            crate_deps,
+                            meta.deps
+                                .iter()
+                                .map(|dep| (crate_name.clone(), CrateName::normalize_dashes(dep)))
+                                .collect::<Vec<_>>(),
+                            "Crate {} has two modules with different dependencies in metadata",
+                            krate,
+                        )
+                    }
+                    Entry::Vacant(v) => {
+                        let new_crate_id = crate_graph.add_crate_root(
+                            file_id,
+                            meta.edition,
+                            Some(crate_name.clone().into()),
+                            meta.cfg,
+                            meta.env,
+                            Default::default(),
+                        );
+                        v.insert(new_crate_id);
+
+                        for dep in meta.deps {
+                            let dep = CrateName::normalize_dashes(&dep);
+                            crate_deps.push((crate_name.clone(), dep))
+                        }
+                    }
                 }
             } else if meta.path == "/main.rs" || meta.path == "/lib.rs" {
                 assert!(default_crate_root.is_none());

crates/ide_assists/src/handlers/auto_import.rs

@@ -918,6 +918,9 @@ fn main() {
             auto_import,
             r"
 //- /lib.rs crate:dep
+pub mod formatters;
+
+//- /formatters.rs crate:dep
 pub struct FMT;
 pub struct fmt;
 
@@ -926,7 +929,7 @@ fn main() {
     FMT$0;
 }
 ",
-            r"use dep::FMT;
+            r"use dep::formatters::FMT;
 
 fn main() {
     FMT;