internal: move diagnostics to a new crate

28 files changed, 612 insertions, 578 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 04c235341..55016ccf7 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -591,6 +591,7 @@ dependencies = [
  "ide_assists",
  "ide_completion",
  "ide_db",
+ "ide_diagnostics",
  "ide_ssr",
  "indexmap",
  "itertools",
@@ -671,6 +672,22 @@ dependencies = [
 [[package]]
 name = "ide_diagnostics"
 version = "0.0.0"
+dependencies = [
+ "cfg",
+ "cov-mark",
+ "either",
+ "expect-test",
+ "hir",
+ "ide_assists",
+ "ide_db",
+ "itertools",
+ "profile",
+ "rustc-hash",
+ "stdx",
+ "syntax",
+ "test_utils",
+ "text_edit",
+]
 
 [[package]]
 name = "ide_ssr"
diff --git a/crates/base_db/src/fixture.rs b/crates/base_db/src/fixture.rs
index da4afb5eb..1b17db102 100644
--- a/crates/base_db/src/fixture.rs
+++ b/crates/base_db/src/fixture.rs
@@ -24,6 +24,14 @@ pub trait WithFixture: Default + SourceDatabaseExt + 'static {
         (db, fixture.files[0])
     }
 
+    fn with_many_files(ra_fixture: &str) -> (Self, Vec<FileId>) {
+        let fixture = ChangeFixture::parse(ra_fixture);
+        let mut db = Self::default();
+        fixture.change.apply(&mut db);
+        assert!(fixture.file_position.is_none());
+        (db, fixture.files)
+    }
+
     fn with_files(ra_fixture: &str) -> Self {
         let fixture = ChangeFixture::parse(ra_fixture);
         let mut db = Self::default();
diff --git a/crates/ide/Cargo.toml b/crates/ide/Cargo.toml
index f12928225..0e8447394 100644
--- a/crates/ide/Cargo.toml
+++ b/crates/ide/Cargo.toml
@@ -29,6 +29,7 @@ ide_db = { path = "../ide_db", version = "0.0.0" }
 cfg = { path = "../cfg", version = "0.0.0" }
 profile = { path = "../profile", version = "0.0.0" }
 ide_assists = { path = "../ide_assists", version = "0.0.0" }
+ide_diagnostics = { path = "../ide_diagnostics", version = "0.0.0" }
 ide_ssr = { path = "../ide_ssr", version = "0.0.0" }
 ide_completion = { path = "../ide_completion", version = "0.0.0" }
 
diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
deleted file mode 100644
index 815a633e5..000000000
--- a/crates/ide/src/diagnostics.rs
+++ /dev/null
@@ -1,498 +0,0 @@
-//! Collects diagnostics & fixits  for a single file.
-//!
-//! The tricky bit here is that diagnostics are produced by hir in terms of
-//! macro-expanded files, but we need to present them to the users in terms of
-//! original files. So we need to map the ranges.
-
-mod break_outside_of_loop;
-mod inactive_code;
-mod incorrect_case;
-mod macro_error;
-mod mismatched_arg_count;
-mod missing_fields;
-mod missing_match_arms;
-mod missing_ok_or_some_in_tail_expr;
-mod missing_unsafe;
-mod no_such_field;
-mod remove_this_semicolon;
-mod replace_filter_map_next_with_find_map;
-mod unimplemented_builtin_macro;
-mod unlinked_file;
-mod unresolved_extern_crate;
-mod unresolved_import;
-mod unresolved_macro_call;
-mod unresolved_module;
-mod unresolved_proc_macro;
-
-mod field_shorthand;
-
-use hir::{diagnostics::AnyDiagnostic, Semantics};
-use ide_assists::AssistResolveStrategy;
-use ide_db::{base_db::SourceDatabase, RootDatabase};
-use itertools::Itertools;
-use rustc_hash::FxHashSet;
-use syntax::{
-    ast::{self, AstNode},
-    SyntaxNode, TextRange,
-};
-use text_edit::TextEdit;
-use unlinked_file::UnlinkedFile;
-
-use crate::{Assist, AssistId, AssistKind, FileId, Label, SourceChange};
-
-#[derive(Copy, Clone, Debug, PartialEq)]
-pub struct DiagnosticCode(pub &'static str);
-
-impl DiagnosticCode {
-    pub fn as_str(&self) -> &str {
-        self.0
-    }
-}
-
-#[derive(Debug)]
-pub struct Diagnostic {
-    pub code: DiagnosticCode,
-    pub message: String,
-    pub range: TextRange,
-    pub severity: Severity,
-    pub unused: bool,
-    pub experimental: bool,
-    pub fixes: Option<Vec<Assist>>,
-}
-
-impl Diagnostic {
-    fn new(code: &'static str, message: impl Into<String>, range: TextRange) -> Diagnostic {
-        let message = message.into();
-        Diagnostic {
-            code: DiagnosticCode(code),
-            message,
-            range,
-            severity: Severity::Error,
-            unused: false,
-            experimental: false,
-            fixes: None,
-        }
-    }
-
-    fn experimental(mut self) -> Diagnostic {
-        self.experimental = true;
-        self
-    }
-
-    fn severity(mut self, severity: Severity) -> Diagnostic {
-        self.severity = severity;
-        self
-    }
-
-    fn with_fixes(mut self, fixes: Option<Vec<Assist>>) -> Diagnostic {
-        self.fixes = fixes;
-        self
-    }
-
-    fn with_unused(mut self, unused: bool) -> Diagnostic {
-        self.unused = unused;
-        self
-    }
-}
-
-#[derive(Debug, Copy, Clone)]
-pub enum Severity {
-    Error,
-    WeakWarning,
-}
-
-#[derive(Default, Debug, Clone)]
-pub struct DiagnosticsConfig {
-    pub disable_experimental: bool,
-    pub disabled: FxHashSet<String>,
-}
-
-struct DiagnosticsContext<'a> {
-    config: &'a DiagnosticsConfig,
-    sema: Semantics<'a, RootDatabase>,
-    resolve: &'a AssistResolveStrategy,
-}
-
-pub(crate) fn diagnostics(
-    db: &RootDatabase,
-    config: &DiagnosticsConfig,
-    resolve: &AssistResolveStrategy,
-    file_id: FileId,
-) -> Vec<Diagnostic> {
-    let _p = profile::span("diagnostics");
-    let sema = Semantics::new(db);
-    let parse = db.parse(file_id);
-    let mut res = Vec::new();
-
-    // [#34344] Only take first 128 errors to prevent slowing down editor/ide, the number 128 is chosen arbitrarily.
-    res.extend(
-        parse.errors().iter().take(128).map(|err| {
-            Diagnostic::new("syntax-error", format!("Syntax Error: {}", err), err.range())
-        }),
-    );
-
-    for node in parse.tree().syntax().descendants() {
-        check_unnecessary_braces_in_use_statement(&mut res, file_id, &node);
-        field_shorthand::check(&mut res, file_id, &node);
-    }
-
-    let mut diags = Vec::new();
-    let module = sema.to_module_def(file_id);
-    if let Some(m) = module {
-        m.diagnostics(db, &mut diags)
-    }
-
-    let ctx = DiagnosticsContext { config, sema, resolve };
-    if module.is_none() {
-        let d = UnlinkedFile { file: file_id };
-        let d = unlinked_file::unlinked_file(&ctx, &d);
-        res.push(d)
-    }
-
-    for diag in diags {
-        #[rustfmt::skip]
-        let d = match diag {
-            AnyDiagnostic::BreakOutsideOfLoop(d) => break_outside_of_loop::break_outside_of_loop(&ctx, &d),
-            AnyDiagnostic::IncorrectCase(d) => incorrect_case::incorrect_case(&ctx, &d),
-            AnyDiagnostic::MacroError(d) => macro_error::macro_error(&ctx, &d),
-            AnyDiagnostic::MismatchedArgCount(d) => mismatched_arg_count::mismatched_arg_count(&ctx, &d),
-            AnyDiagnostic::MissingFields(d) => missing_fields::missing_fields(&ctx, &d),
-            AnyDiagnostic::MissingMatchArms(d) => missing_match_arms::missing_match_arms(&ctx, &d),
-            AnyDiagnostic::MissingOkOrSomeInTailExpr(d) => missing_ok_or_some_in_tail_expr::missing_ok_or_some_in_tail_expr(&ctx, &d),
-            AnyDiagnostic::MissingUnsafe(d) => missing_unsafe::missing_unsafe(&ctx, &d),
-            AnyDiagnostic::NoSuchField(d) => no_such_field::no_such_field(&ctx, &d),
-            AnyDiagnostic::RemoveThisSemicolon(d) => remove_this_semicolon::remove_this_semicolon(&ctx, &d),
-            AnyDiagnostic::ReplaceFilterMapNextWithFindMap(d) => replace_filter_map_next_with_find_map::replace_filter_map_next_with_find_map(&ctx, &d),
-            AnyDiagnostic::UnimplementedBuiltinMacro(d) => unimplemented_builtin_macro::unimplemented_builtin_macro(&ctx, &d),
-            AnyDiagnostic::UnresolvedExternCrate(d) => unresolved_extern_crate::unresolved_extern_crate(&ctx, &d),
-            AnyDiagnostic::UnresolvedImport(d) => unresolved_import::unresolved_import(&ctx, &d),
-            AnyDiagnostic::UnresolvedMacroCall(d) => unresolved_macro_call::unresolved_macro_call(&ctx, &d),
-            AnyDiagnostic::UnresolvedModule(d) => unresolved_module::unresolved_module(&ctx, &d),
-            AnyDiagnostic::UnresolvedProcMacro(d) => unresolved_proc_macro::unresolved_proc_macro(&ctx, &d),
-
-            AnyDiagnostic::InactiveCode(d) => match inactive_code::inactive_code(&ctx, &d) {
-                Some(it) => it,
-                None => continue,
-            }
-        };
-        res.push(d)
-    }
-
-    res.retain(|d| {
-        !ctx.config.disabled.contains(d.code.as_str())
-            && !(ctx.config.disable_experimental && d.experimental)
-    });
-
-    res
-}
-
-fn check_unnecessary_braces_in_use_statement(
-    acc: &mut Vec<Diagnostic>,
-    file_id: FileId,
-    node: &SyntaxNode,
-) -> Option<()> {
-    let use_tree_list = ast::UseTreeList::cast(node.clone())?;
-    if let Some((single_use_tree,)) = use_tree_list.use_trees().collect_tuple() {
-        // If there is a comment inside the bracketed `use`,
-        // assume it is a commented out module path and don't show diagnostic.
-        if use_tree_list.has_inner_comment() {
-            return Some(());
-        }
-
-        let use_range = use_tree_list.syntax().text_range();
-        let edit =
-            text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(&single_use_tree)
-                .unwrap_or_else(|| {
-                    let to_replace = single_use_tree.syntax().text().to_string();
-                    let mut edit_builder = TextEdit::builder();
-                    edit_builder.delete(use_range);
-                    edit_builder.insert(use_range.start(), to_replace);
-                    edit_builder.finish()
-                });
-
-        acc.push(
-            Diagnostic::new(
-                "unnecessary-braces",
-                "Unnecessary braces in use statement".to_string(),
-                use_range,
-            )
-            .severity(Severity::WeakWarning)
-            .with_fixes(Some(vec![fix(
-                "remove_braces",
-                "Remove unnecessary braces",
-                SourceChange::from_text_edit(file_id, edit),
-                use_range,
-            )])),
-        );
-    }
-
-    Some(())
-}
-
-fn text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(
-    single_use_tree: &ast::UseTree,
-) -> Option<TextEdit> {
-    let use_tree_list_node = single_use_tree.syntax().parent()?;
-    if single_use_tree.path()?.segment()?.self_token().is_some() {
-        let start = use_tree_list_node.prev_sibling_or_token()?.text_range().start();
-        let end = use_tree_list_node.text_range().end();
-        return Some(TextEdit::delete(TextRange::new(start, end)));
-    }
-    None
-}
-
-fn fix(id: &'static str, label: &str, source_change: SourceChange, target: TextRange) -> Assist {
-    let mut res = unresolved_fix(id, label, target);
-    res.source_change = Some(source_change);
-    res
-}
-
-fn unresolved_fix(id: &'static str, label: &str, target: TextRange) -> Assist {
-    assert!(!id.contains(' '));
-    Assist {
-        id: AssistId(id, AssistKind::QuickFix),
-        label: Label::new(label),
-        group: None,
-        target,
-        source_change: None,
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use expect_test::Expect;
-    use ide_assists::AssistResolveStrategy;
-    use stdx::trim_indent;
-    use test_utils::{assert_eq_text, extract_annotations};
-
-    use crate::{fixture, DiagnosticsConfig};
-
-    /// Takes a multi-file input fixture with annotated cursor positions,
-    /// and checks that:
-    ///  * a diagnostic is produced
-    ///  * the first diagnostic fix trigger range touches the input cursor position
-    ///  * that the contents of the file containing the cursor match `after` after the diagnostic fix is applied
-    #[track_caller]
-    pub(crate) fn check_fix(ra_fixture_before: &str, ra_fixture_after: &str) {
-        check_nth_fix(0, ra_fixture_before, ra_fixture_after);
-    }
-    /// Takes a multi-file input fixture with annotated cursor positions,
-    /// and checks that:
-    ///  * a diagnostic is produced
-    ///  * every diagnostic fixes trigger range touches the input cursor position
-    ///  * that the contents of the file containing the cursor match `after` after each diagnostic fix is applied
-    pub(crate) fn check_fixes(ra_fixture_before: &str, ra_fixtures_after: Vec<&str>) {
-        for (i, ra_fixture_after) in ra_fixtures_after.iter().enumerate() {
-            check_nth_fix(i, ra_fixture_before, ra_fixture_after)
-        }
-    }
-
-    #[track_caller]
-    fn check_nth_fix(nth: usize, ra_fixture_before: &str, ra_fixture_after: &str) {
-        let after = trim_indent(ra_fixture_after);
-
-        let (analysis, file_position) = fixture::position(ra_fixture_before);
-        let diagnostic = analysis
-            .diagnostics(
-                &DiagnosticsConfig::default(),
-                AssistResolveStrategy::All,
-                file_position.file_id,
-            )
-            .unwrap()
-            .pop()
-            .expect("no diagnostics");
-        let fix = &diagnostic.fixes.expect("diagnostic misses fixes")[nth];
-        let actual = {
-            let source_change = fix.source_change.as_ref().unwrap();
-            let file_id = *source_change.source_file_edits.keys().next().unwrap();
-            let mut actual = analysis.file_text(file_id).unwrap().to_string();
-
-            for edit in source_change.source_file_edits.values() {
-                edit.apply(&mut actual);
-            }
-            actual
-        };
-
-        assert_eq_text!(&after, &actual);
-        assert!(
-            fix.target.contains_inclusive(file_position.offset),
-            "diagnostic fix range {:?} does not touch cursor position {:?}",
-            fix.target,
-            file_position.offset
-        );
-    }
-
-    /// Checks that there's a diagnostic *without* fix at `$0`.
-    pub(crate) fn check_no_fix(ra_fixture: &str) {
-        let (analysis, file_position) = fixture::position(ra_fixture);
-        let diagnostic = analysis
-            .diagnostics(
-                &DiagnosticsConfig::default(),
-                AssistResolveStrategy::All,
-                file_position.file_id,
-            )
-            .unwrap()
-            .pop()
-            .unwrap();
-        assert!(diagnostic.fixes.is_none(), "got a fix when none was expected: {:?}", diagnostic);
-    }
-
-    pub(crate) fn check_expect(ra_fixture: &str, expect: Expect) {
-        let (analysis, file_id) = fixture::file(ra_fixture);
-        let diagnostics = analysis
-            .diagnostics(&DiagnosticsConfig::default(), AssistResolveStrategy::All, file_id)
-            .unwrap();
-        expect.assert_debug_eq(&diagnostics)
-    }
-
-    #[track_caller]
-    pub(crate) fn check_diagnostics(ra_fixture: &str) {
-        let mut config = DiagnosticsConfig::default();
-        config.disabled.insert("inactive-code".to_string());
-        check_diagnostics_with_config(config, ra_fixture)
-    }
-
-    #[track_caller]
-    pub(crate) fn check_diagnostics_with_config(config: DiagnosticsConfig, ra_fixture: &str) {
-        let (analysis, files) = fixture::files(ra_fixture);
-        for file_id in files {
-            let diagnostics =
-                analysis.diagnostics(&config, AssistResolveStrategy::All, file_id).unwrap();
-
-            let expected = extract_annotations(&*analysis.file_text(file_id).unwrap());
-            let mut actual =
-                diagnostics.into_iter().map(|d| (d.range, d.message)).collect::<Vec<_>>();
-            actual.sort_by_key(|(range, _)| range.start());
-            assert_eq!(expected, actual);
-        }
-    }
-
-    #[test]
-    fn test_check_unnecessary_braces_in_use_statement() {
-        check_diagnostics(
-            r#"
-use a;
-use a::{c, d::e};
-
-mod a {
-    mod c {}
-    mod d {
-        mod e {}
-    }
-}
-"#,
-        );
-        check_diagnostics(
-            r#"
-use a;
-use a::{
-    c,
-    // d::e
-};
-
-mod a {
-    mod c {}
-    mod d {
-        mod e {}
-    }
-}
-"#,
-        );
-        check_fix(
-            r"
-            mod b {}
-            use {$0b};
-            ",
-            r"
-            mod b {}
-            use b;
-            ",
-        );
-        check_fix(
-            r"
-            mod b {}
-            use {b$0};
-            ",
-            r"
-            mod b {}
-            use b;
-            ",
-        );
-        check_fix(
-            r"
-            mod a { mod c {} }
-            use a::{c$0};
-            ",
-            r"
-            mod a { mod c {} }
-            use a::c;
-            ",
-        );
-        check_fix(
-            r"
-            mod a {}
-            use a::{self$0};
-            ",
-            r"
-            mod a {}
-            use a;
-            ",
-        );
-        check_fix(
-            r"
-            mod a { mod c {} mod d { mod e {} } }
-            use a::{c, d::{e$0}};
-            ",
-            r"
-            mod a { mod c {} mod d { mod e {} } }
-            use a::{c, d::e};
-            ",
-        );
-    }
-
-    #[test]
-    fn test_disabled_diagnostics() {
-        let mut config = DiagnosticsConfig::default();
-        config.disabled.insert("unresolved-module".into());
-
-        let (analysis, file_id) = fixture::file(r#"mod foo;"#);
-
-        let diagnostics =
-            analysis.diagnostics(&config, AssistResolveStrategy::All, file_id).unwrap();
-        assert!(diagnostics.is_empty());
-
-        let diagnostics = analysis
-            .diagnostics(&DiagnosticsConfig::default(), AssistResolveStrategy::All, file_id)
-            .unwrap();
-        assert!(!diagnostics.is_empty());
-    }
-
-    #[test]
-    fn import_extern_crate_clash_with_inner_item() {
-        // This is more of a resolver test, but doesn't really work with the hir_def testsuite.
-
-        check_diagnostics(
-            r#"
-//- /lib.rs crate:lib deps:jwt
-mod permissions;
-
-use permissions::jwt;
-
-fn f() {
-    fn inner() {}
-    jwt::Claims {}; // should resolve to the local one with 0 fields, and not get a diagnostic
-}
-
-//- /permissions.rs
-pub mod jwt  {
-    pub struct Claims {}
-}
-
-//- /jwt/lib.rs crate:jwt
-pub struct Claims {
-    field: u8,
-}
-        "#,
-        );
-    }
-}
diff --git a/crates/ide/src/fixture.rs b/crates/ide/src/fixture.rs
index 38e2e866b..cf679edd3 100644
--- a/crates/ide/src/fixture.rs
+++ b/crates/ide/src/fixture.rs
@@ -12,14 +12,6 @@ pub(crate) fn file(ra_fixture: &str) -> (Analysis, FileId) {
     (host.analysis(), change_fixture.files[0])
 }
 
-/// Creates analysis for many files.
-pub(crate) fn files(ra_fixture: &str) -> (Analysis, Vec<FileId>) {
-    let mut host = AnalysisHost::default();
-    let change_fixture = ChangeFixture::parse(ra_fixture);
-    host.db.apply_change(change_fixture.change);
-    (host.analysis(), change_fixture.files)
-}
-
 /// Creates analysis from a multi-file fixture, returns positions marked with $0.
 pub(crate) fn position(ra_fixture: &str) -> (Analysis, FilePosition) {
     let mut host = AnalysisHost::default();
diff --git a/crates/ide/src/lib.rs b/crates/ide/src/lib.rs
index 0511efae3..0019b7ba5 100644
--- a/crates/ide/src/lib.rs
+++ b/crates/ide/src/lib.rs
@@ -24,7 +24,6 @@ mod display;
 
 mod annotations;
 mod call_hierarchy;
-mod diagnostics;
 mod expand_macro;
 mod extend_selection;
 mod file_structure;
@@ -71,7 +70,6 @@ use crate::display::ToNav;
 pub use crate::{
     annotations::{Annotation, AnnotationConfig, AnnotationKind},
     call_hierarchy::CallItem,
-    diagnostics::{Diagnostic, DiagnosticsConfig, Severity},
     display::navigation_target::NavigationTarget,
     expand_macro::ExpandedMacro,
     file_structure::{StructureNode, StructureNodeKind},
@@ -109,6 +107,7 @@ pub use ide_db::{
     symbol_index::Query,
     RootDatabase, SymbolKind,
 };
+pub use ide_diagnostics::{Diagnostic, DiagnosticsConfig, Severity};
 pub use ide_ssr::SsrError;
 pub use syntax::{TextRange, TextSize};
 pub use text_edit::{Indel, TextEdit};
@@ -549,7 +548,7 @@ impl Analysis {
         resolve: AssistResolveStrategy,
         file_id: FileId,
     ) -> Cancellable<Vec<Diagnostic>> {
-        self.with_db(|db| diagnostics::diagnostics(db, config, &resolve, file_id))
+        self.with_db(|db| ide_diagnostics::diagnostics(db, config, &resolve, file_id))
     }
 
     /// Convenience function to return assists + quick fixes for diagnostics
@@ -568,7 +567,7 @@ impl Analysis {
         self.with_db(|db| {
             let ssr_assists = ssr::ssr_assists(db, &resolve, frange);
             let diagnostic_assists = if include_fixes {
-                diagnostics::diagnostics(db, diagnostics_config, &resolve, frange.file_id)
+                ide_diagnostics::diagnostics(db, diagnostics_config, &resolve, frange.file_id)
                     .into_iter()
                     .flat_map(|it| it.fixes.unwrap_or_default())
                     .filter(|it| it.target.intersect(frange.range).is_some())
diff --git a/crates/ide_diagnostics/Cargo.toml b/crates/ide_diagnostics/Cargo.toml
index 11cd8d570..738fca14e 100644
--- a/crates/ide_diagnostics/Cargo.toml
+++ b/crates/ide_diagnostics/Cargo.toml
@@ -10,3 +10,21 @@ edition = "2018"
 doctest = false
 
 [dependencies]
+cov-mark = "2.0.0-pre.1"
+itertools = "0.10.0"
+rustc-hash = "1.1.0"
+either = "1.5.3"
+
+profile = { path = "../profile", version = "0.0.0" }
+stdx = { path = "../stdx", version = "0.0.0" }
+syntax = { path = "../syntax", version = "0.0.0" }
+text_edit = { path = "../text_edit", version = "0.0.0" }
+cfg = { path = "../cfg", version = "0.0.0" }
+hir = { path = "../hir", version = "0.0.0" }
+ide_db = { path = "../ide_db", version = "0.0.0" }
+ide_assists = { path = "../ide_assists", version = "0.0.0" }
+
+[dev-dependencies]
+expect-test = "1.1"
+
+test_utils = { path = "../test_utils" }
diff --git a/crates/ide/src/diagnostics/break_outside_of_loop.rs b/crates/ide_diagnostics/src/break_outside_of_loop.rs
index 80e68f3cc..79e8cea37 100644
--- a/crates/ide/src/diagnostics/break_outside_of_loop.rs
+++ b/crates/ide_diagnostics/src/break_outside_of_loop.rs
@@ -1,4 +1,4 @@
-use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+use crate::{Diagnostic, DiagnosticsContext};
 
 // Diagnostic: break-outside-of-loop
 //
@@ -16,7 +16,7 @@ pub(super) fn break_outside_of_loop(
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::check_diagnostics;
+    use crate::tests::check_diagnostics;
 
     #[test]
     fn break_outside_of_loop() {
diff --git a/crates/ide/src/diagnostics/field_shorthand.rs b/crates/ide_diagnostics/src/field_shorthand.rs
index c7f4dab8e..0b6af9965 100644
--- a/crates/ide/src/diagnostics/field_shorthand.rs
+++ b/crates/ide_diagnostics/src/field_shorthand.rs
@@ -5,7 +5,7 @@ use ide_db::{base_db::FileId, source_change::SourceChange};
 use syntax::{ast, match_ast, AstNode, SyntaxNode};
 use text_edit::TextEdit;
 
-use crate::{diagnostics::fix, Diagnostic, Severity};
+use crate::{fix, Diagnostic, Severity};
 
 pub(super) fn check(acc: &mut Vec<Diagnostic>, file_id: FileId, node: &SyntaxNode) {
     match_ast! {
@@ -101,7 +101,7 @@ fn check_pat_field_shorthand(
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::{check_diagnostics, check_fix};
+    use crate::tests::{check_diagnostics, check_fix};
 
     #[test]
     fn test_check_expr_field_shorthand() {
diff --git a/crates/ide/src/diagnostics/inactive_code.rs b/crates/ide_diagnostics/src/inactive_code.rs
index d9d3e88c1..34837cc0d 100644
--- a/crates/ide/src/diagnostics/inactive_code.rs
+++ b/crates/ide_diagnostics/src/inactive_code.rs
@@ -1,10 +1,7 @@
 use cfg::DnfExpr;
 use stdx::format_to;
 
-use crate::{
-    diagnostics::{Diagnostic, DiagnosticsContext},
-    Severity,
-};
+use crate::{Diagnostic, DiagnosticsContext, Severity};
 
 // Diagnostic: inactive-code
 //
@@ -37,7 +34,7 @@ pub(super) fn inactive_code(
 
 #[cfg(test)]
 mod tests {
-    use crate::{diagnostics::tests::check_diagnostics_with_config, DiagnosticsConfig};
+    use crate::{tests::check_diagnostics_with_config, DiagnosticsConfig};
 
     pub(crate) fn check(ra_fixture: &str) {
         let config = DiagnosticsConfig::default();
diff --git a/crates/ide/src/diagnostics/incorrect_case.rs b/crates/ide_diagnostics/src/incorrect_case.rs
index 832394400..04fc779ce 100644
--- a/crates/ide/src/diagnostics/incorrect_case.rs
+++ b/crates/ide_diagnostics/src/incorrect_case.rs
@@ -4,8 +4,10 @@ use ide_db::base_db::FilePosition;
 use syntax::AstNode;
 
 use crate::{
-    diagnostics::{unresolved_fix, Diagnostic, DiagnosticsContext},
-    references::rename::rename_with_semantics,
+    // references::rename::rename_with_semantics,
+    unresolved_fix,
+    Diagnostic,
+    DiagnosticsContext,
     Severity,
 };
 
@@ -26,28 +28,34 @@ pub(super) fn incorrect_case(ctx: &DiagnosticsContext<'_>, d: &hir::IncorrectCas
 }
 
 fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::IncorrectCase) -> Option<Vec<Assist>> {
+    if true {
+        return None;
+    }
+
     let root = ctx.sema.db.parse_or_expand(d.file)?;
     let name_node = d.ident.to_node(&root);
 
     let name_node = InFile::new(d.file, name_node.syntax());
     let frange = name_node.original_file_range(ctx.sema.db);
-    let file_position = FilePosition { file_id: frange.file_id, offset: frange.range.start() };
+    let _file_position = FilePosition { file_id: frange.file_id, offset: frange.range.start() };
 
     let label = format!("Rename to {}", d.suggested_text);
-    let mut res = unresolved_fix("change_case", &label, frange.range);
+    let res = unresolved_fix("change_case", &label, frange.range);
     if ctx.resolve.should_resolve(&res.id) {
-        let source_change = rename_with_semantics(&ctx.sema, file_position, &d.suggested_text);
-        res.source_change = Some(source_change.ok().unwrap_or_default());
+        //let source_change = rename_with_semantics(&ctx.sema, file_position, &d.suggested_text);
+        //res.source_change = Some(source_change.ok().unwrap_or_default());
+        todo!()
     }
 
     Some(vec![res])
 }
 
-#[cfg(test)]
+#[cfg(TODO)]
 mod change_case {
     use crate::{
-        diagnostics::tests::{check_diagnostics, check_fix},
-        fixture, AssistResolveStrategy, DiagnosticsConfig,
+        fixture,
+        tests::{check_diagnostics, check_fix},
+        AssistResolveStrategy, DiagnosticsConfig,
     };
 
     #[test]
diff --git a/crates/ide_diagnostics/src/lib.rs b/crates/ide_diagnostics/src/lib.rs
index e69de29bb..a104a702d 100644
--- a/crates/ide_diagnostics/src/lib.rs
+++ b/crates/ide_diagnostics/src/lib.rs
@@ -0,0 +1,510 @@
+//! Collects diagnostics & fixits  for a single file.
+//!
+//! The tricky bit here is that diagnostics are produced by hir in terms of
+//! macro-expanded files, but we need to present them to the users in terms of
+//! original files. So we need to map the ranges.
+
+mod break_outside_of_loop;
+mod inactive_code;
+mod incorrect_case;
+mod macro_error;
+mod mismatched_arg_count;
+mod missing_fields;
+mod missing_match_arms;
+mod missing_ok_or_some_in_tail_expr;
+mod missing_unsafe;
+mod no_such_field;
+mod remove_this_semicolon;
+mod replace_filter_map_next_with_find_map;
+mod unimplemented_builtin_macro;
+mod unlinked_file;
+mod unresolved_extern_crate;
+mod unresolved_import;
+mod unresolved_macro_call;
+mod unresolved_module;
+mod unresolved_proc_macro;
+
+mod field_shorthand;
+
+use hir::{diagnostics::AnyDiagnostic, Semantics};
+use ide_assists::AssistResolveStrategy;
+use ide_db::{
+    base_db::{FileId, SourceDatabase},
+    label::Label,
+    source_change::SourceChange,
+    RootDatabase,
+};
+use itertools::Itertools;
+use rustc_hash::FxHashSet;
+use syntax::{
+    ast::{self, AstNode},
+    SyntaxNode, TextRange,
+};
+use text_edit::TextEdit;
+use unlinked_file::UnlinkedFile;
+
+use ide_assists::{Assist, AssistId, AssistKind};
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub struct DiagnosticCode(pub &'static str);
+
+impl DiagnosticCode {
+    pub fn as_str(&self) -> &str {
+        self.0
+    }
+}
+
+#[derive(Debug)]
+pub struct Diagnostic {
+    pub code: DiagnosticCode,
+    pub message: String,
+    pub range: TextRange,
+    pub severity: Severity,
+    pub unused: bool,
+    pub experimental: bool,
+    pub fixes: Option<Vec<Assist>>,
+}
+
+impl Diagnostic {
+    fn new(code: &'static str, message: impl Into<String>, range: TextRange) -> Diagnostic {
+        let message = message.into();
+        Diagnostic {
+            code: DiagnosticCode(code),
+            message,
+            range,
+            severity: Severity::Error,
+            unused: false,
+            experimental: false,
+            fixes: None,
+        }
+    }
+
+    fn experimental(mut self) -> Diagnostic {
+        self.experimental = true;
+        self
+    }
+
+    fn severity(mut self, severity: Severity) -> Diagnostic {
+        self.severity = severity;
+        self
+    }
+
+    fn with_fixes(mut self, fixes: Option<Vec<Assist>>) -> Diagnostic {
+        self.fixes = fixes;
+        self
+    }
+
+    fn with_unused(mut self, unused: bool) -> Diagnostic {
+        self.unused = unused;
+        self
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+pub enum Severity {
+    Error,
+    WeakWarning,
+}
+
+#[derive(Default, Debug, Clone)]
+pub struct DiagnosticsConfig {
+    pub disable_experimental: bool,
+    pub disabled: FxHashSet<String>,
+}
+
+struct DiagnosticsContext<'a> {
+    config: &'a DiagnosticsConfig,
+    sema: Semantics<'a, RootDatabase>,
+    resolve: &'a AssistResolveStrategy,
+}
+
+pub fn diagnostics(
+    db: &RootDatabase,
+    config: &DiagnosticsConfig,
+    resolve: &AssistResolveStrategy,
+    file_id: FileId,
+) -> Vec<Diagnostic> {
+    let _p = profile::span("diagnostics");
+    let sema = Semantics::new(db);
+    let parse = db.parse(file_id);
+    let mut res = Vec::new();
+
+    // [#34344] Only take first 128 errors to prevent slowing down editor/ide, the number 128 is chosen arbitrarily.
+    res.extend(
+        parse.errors().iter().take(128).map(|err| {
+            Diagnostic::new("syntax-error", format!("Syntax Error: {}", err), err.range())
+        }),
+    );
+
+    for node in parse.tree().syntax().descendants() {
+        check_unnecessary_braces_in_use_statement(&mut res, file_id, &node);
+        field_shorthand::check(&mut res, file_id, &node);
+    }
+
+    let mut diags = Vec::new();
+    let module = sema.to_module_def(file_id);
+    if let Some(m) = module {
+        m.diagnostics(db, &mut diags)
+    }
+
+    let ctx = DiagnosticsContext { config, sema, resolve };
+    if module.is_none() {
+        let d = UnlinkedFile { file: file_id };
+        let d = unlinked_file::unlinked_file(&ctx, &d);
+        res.push(d)
+    }
+
+    for diag in diags {
+        #[rustfmt::skip]
+        let d = match diag {
+            AnyDiagnostic::BreakOutsideOfLoop(d) => break_outside_of_loop::break_outside_of_loop(&ctx, &d),
+            AnyDiagnostic::IncorrectCase(d) => incorrect_case::incorrect_case(&ctx, &d),
+            AnyDiagnostic::MacroError(d) => macro_error::macro_error(&ctx, &d),
+            AnyDiagnostic::MismatchedArgCount(d) => mismatched_arg_count::mismatched_arg_count(&ctx, &d),
+            AnyDiagnostic::MissingFields(d) => missing_fields::missing_fields(&ctx, &d),
+            AnyDiagnostic::MissingMatchArms(d) => missing_match_arms::missing_match_arms(&ctx, &d),
+            AnyDiagnostic::MissingOkOrSomeInTailExpr(d) => missing_ok_or_some_in_tail_expr::missing_ok_or_some_in_tail_expr(&ctx, &d),
+            AnyDiagnostic::MissingUnsafe(d) => missing_unsafe::missing_unsafe(&ctx, &d),
+            AnyDiagnostic::NoSuchField(d) => no_such_field::no_such_field(&ctx, &d),
+            AnyDiagnostic::RemoveThisSemicolon(d) => remove_this_semicolon::remove_this_semicolon(&ctx, &d),
+            AnyDiagnostic::ReplaceFilterMapNextWithFindMap(d) => replace_filter_map_next_with_find_map::replace_filter_map_next_with_find_map(&ctx, &d),
+            AnyDiagnostic::UnimplementedBuiltinMacro(d) => unimplemented_builtin_macro::unimplemented_builtin_macro(&ctx, &d),
+            AnyDiagnostic::UnresolvedExternCrate(d) => unresolved_extern_crate::unresolved_extern_crate(&ctx, &d),
+            AnyDiagnostic::UnresolvedImport(d) => unresolved_import::unresolved_import(&ctx, &d),
+            AnyDiagnostic::UnresolvedMacroCall(d) => unresolved_macro_call::unresolved_macro_call(&ctx, &d),
+            AnyDiagnostic::UnresolvedModule(d) => unresolved_module::unresolved_module(&ctx, &d),
+            AnyDiagnostic::UnresolvedProcMacro(d) => unresolved_proc_macro::unresolved_proc_macro(&ctx, &d),
+
+            AnyDiagnostic::InactiveCode(d) => match inactive_code::inactive_code(&ctx, &d) {
+                Some(it) => it,
+                None => continue,
+            }
+        };
+        res.push(d)
+    }
+
+    res.retain(|d| {
+        !ctx.config.disabled.contains(d.code.as_str())
+            && !(ctx.config.disable_experimental && d.experimental)
+    });
+
+    res
+}
+
+fn check_unnecessary_braces_in_use_statement(
+    acc: &mut Vec<Diagnostic>,
+    file_id: FileId,
+    node: &SyntaxNode,
+) -> Option<()> {
+    let use_tree_list = ast::UseTreeList::cast(node.clone())?;
+    if let Some((single_use_tree,)) = use_tree_list.use_trees().collect_tuple() {
+        // If there is a comment inside the bracketed `use`,
+        // assume it is a commented out module path and don't show diagnostic.
+        if use_tree_list.has_inner_comment() {
+            return Some(());
+        }
+
+        let use_range = use_tree_list.syntax().text_range();
+        let edit =
+            text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(&single_use_tree)
+                .unwrap_or_else(|| {
+                    let to_replace = single_use_tree.syntax().text().to_string();
+                    let mut edit_builder = TextEdit::builder();
+                    edit_builder.delete(use_range);
+                    edit_builder.insert(use_range.start(), to_replace);
+                    edit_builder.finish()
+                });
+
+        acc.push(
+            Diagnostic::new(
+                "unnecessary-braces",
+                "Unnecessary braces in use statement".to_string(),
+                use_range,
+            )
+            .severity(Severity::WeakWarning)
+            .with_fixes(Some(vec![fix(
+                "remove_braces",
+                "Remove unnecessary braces",
+                SourceChange::from_text_edit(file_id, edit),
+                use_range,
+            )])),
+        );
+    }
+
+    Some(())
+}
+
+fn text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(
+    single_use_tree: &ast::UseTree,
+) -> Option<TextEdit> {
+    let use_tree_list_node = single_use_tree.syntax().parent()?;
+    if single_use_tree.path()?.segment()?.self_token().is_some() {
+        let start = use_tree_list_node.prev_sibling_or_token()?.text_range().start();
+        let end = use_tree_list_node.text_range().end();
+        return Some(TextEdit::delete(TextRange::new(start, end)));
+    }
+    None
+}
+
+fn fix(id: &'static str, label: &str, source_change: SourceChange, target: TextRange) -> Assist {
+    let mut res = unresolved_fix(id, label, target);
+    res.source_change = Some(source_change);
+    res
+}
+
+fn unresolved_fix(id: &'static str, label: &str, target: TextRange) -> Assist {
+    assert!(!id.contains(' '));
+    Assist {
+        id: AssistId(id, AssistKind::QuickFix),
+        label: Label::new(label),
+        group: None,
+        target,
+        source_change: None,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::Expect;
+    use ide_assists::AssistResolveStrategy;
+    use ide_db::{
+        base_db::{fixture::WithFixture, SourceDatabaseExt},
+        RootDatabase,
+    };
+    use stdx::trim_indent;
+    use test_utils::{assert_eq_text, extract_annotations};
+
+    use crate::DiagnosticsConfig;
+
+    /// Takes a multi-file input fixture with annotated cursor positions,
+    /// and checks that:
+    ///  * a diagnostic is produced
+    ///  * the first diagnostic fix trigger range touches the input cursor position
+    ///  * that the contents of the file containing the cursor match `after` after the diagnostic fix is applied
+    #[track_caller]
+    pub(crate) fn check_fix(ra_fixture_before: &str, ra_fixture_after: &str) {
+        check_nth_fix(0, ra_fixture_before, ra_fixture_after);
+    }
+    /// Takes a multi-file input fixture with annotated cursor positions,
+    /// and checks that:
+    ///  * a diagnostic is produced
+    ///  * every diagnostic fixes trigger range touches the input cursor position
+    ///  * that the contents of the file containing the cursor match `after` after each diagnostic fix is applied
+    pub(crate) fn check_fixes(ra_fixture_before: &str, ra_fixtures_after: Vec<&str>) {
+        for (i, ra_fixture_after) in ra_fixtures_after.iter().enumerate() {
+            check_nth_fix(i, ra_fixture_before, ra_fixture_after)
+        }
+    }
+
+    #[track_caller]
+    fn check_nth_fix(nth: usize, ra_fixture_before: &str, ra_fixture_after: &str) {
+        let after = trim_indent(ra_fixture_after);
+
+        let (db, file_position) = RootDatabase::with_position(ra_fixture_before);
+        let diagnostic = super::diagnostics(
+            &db,
+            &DiagnosticsConfig::default(),
+            &AssistResolveStrategy::All,
+            file_position.file_id,
+        )
+        .pop()
+        .expect("no diagnostics");
+        let fix = &diagnostic.fixes.expect("diagnostic misses fixes")[nth];
+        let actual = {
+            let source_change = fix.source_change.as_ref().unwrap();
+            let file_id = *source_change.source_file_edits.keys().next().unwrap();
+            let mut actual = db.file_text(file_id).to_string();
+
+            for edit in source_change.source_file_edits.values() {
+                edit.apply(&mut actual);
+            }
+            actual
+        };
+
+        assert_eq_text!(&after, &actual);
+        assert!(
+            fix.target.contains_inclusive(file_position.offset),
+            "diagnostic fix range {:?} does not touch cursor position {:?}",
+            fix.target,
+            file_position.offset
+        );
+    }
+
+    /// Checks that there's a diagnostic *without* fix at `$0`.
+    pub(crate) fn check_no_fix(ra_fixture: &str) {
+        let (db, file_position) = RootDatabase::with_position(ra_fixture);
+        let diagnostic = super::diagnostics(
+            &db,
+            &DiagnosticsConfig::default(),
+            &AssistResolveStrategy::All,
+            file_position.file_id,
+        )
+        .pop()
+        .unwrap();
+        assert!(diagnostic.fixes.is_none(), "got a fix when none was expected: {:?}", diagnostic);
+    }
+
+    pub(crate) fn check_expect(ra_fixture: &str, expect: Expect) {
+        let (db, file_id) = RootDatabase::with_single_file(ra_fixture);
+        let diagnostics = super::diagnostics(
+            &db,
+            &DiagnosticsConfig::default(),
+            &AssistResolveStrategy::All,
+            file_id,
+        );
+        expect.assert_debug_eq(&diagnostics)
+    }
+
+    #[track_caller]
+    pub(crate) fn check_diagnostics(ra_fixture: &str) {
+        let mut config = DiagnosticsConfig::default();
+        config.disabled.insert("inactive-code".to_string());
+        check_diagnostics_with_config(config, ra_fixture)
+    }
+
+    #[track_caller]
+    pub(crate) fn check_diagnostics_with_config(config: DiagnosticsConfig, ra_fixture: &str) {
+        let (db, files) = RootDatabase::with_many_files(ra_fixture);
+        for file_id in files {
+            let diagnostics =
+                super::diagnostics(&db, &config, &AssistResolveStrategy::All, file_id);
+
+            let expected = extract_annotations(&*db.file_text(file_id));
+            let mut actual =
+                diagnostics.into_iter().map(|d| (d.range, d.message)).collect::<Vec<_>>();
+            actual.sort_by_key(|(range, _)| range.start());
+            assert_eq!(expected, actual);
+        }
+    }
+
+    #[test]
+    fn test_check_unnecessary_braces_in_use_statement() {
+        check_diagnostics(
+            r#"
+use a;
+use a::{c, d::e};
+
+mod a {
+    mod c {}
+    mod d {
+        mod e {}
+    }
+}
+"#,
+        );
+        check_diagnostics(
+            r#"
+use a;
+use a::{
+    c,
+    // d::e
+};
+
+mod a {
+    mod c {}
+    mod d {
+        mod e {}
+    }
+}
+"#,
+        );
+        check_fix(
+            r"
+            mod b {}
+            use {$0b};
+            ",
+            r"
+            mod b {}
+            use b;
+            ",
+        );
+        check_fix(
+            r"
+            mod b {}
+            use {b$0};
+            ",
+            r"
+            mod b {}
+            use b;
+            ",
+        );
+        check_fix(
+            r"
+            mod a { mod c {} }
+            use a::{c$0};
+            ",
+            r"
+            mod a { mod c {} }
+            use a::c;
+            ",
+        );
+        check_fix(
+            r"
+            mod a {}
+            use a::{self$0};
+            ",
+            r"
+            mod a {}
+            use a;
+            ",
+        );
+        check_fix(
+            r"
+            mod a { mod c {} mod d { mod e {} } }
+            use a::{c, d::{e$0}};
+            ",
+            r"
+            mod a { mod c {} mod d { mod e {} } }
+            use a::{c, d::e};
+            ",
+        );
+    }
+
+    #[test]
+    fn test_disabled_diagnostics() {
+        let mut config = DiagnosticsConfig::default();
+        config.disabled.insert("unresolved-module".into());
+
+        let (db, file_id) = RootDatabase::with_single_file(r#"mod foo;"#);
+
+        let diagnostics = super::diagnostics(&db, &config, &AssistResolveStrategy::All, file_id);
+        assert!(diagnostics.is_empty());
+
+        let diagnostics = super::diagnostics(
+            &db,
+            &DiagnosticsConfig::default(),
+            &AssistResolveStrategy::All,
+            file_id,
+        );
+        assert!(!diagnostics.is_empty());
+    }
+
+    #[test]
+    fn import_extern_crate_clash_with_inner_item() {
+        // This is more of a resolver test, but doesn't really work with the hir_def testsuite.
+
+        check_diagnostics(
+            r#"
+//- /lib.rs crate:lib deps:jwt
+mod permissions;
+
+use permissions::jwt;
+
+fn f() {
+    fn inner() {}
+    jwt::Claims {}; // should resolve to the local one with 0 fields, and not get a diagnostic
+}
+
+//- /permissions.rs
+pub mod jwt  {
+    pub struct Claims {}
+}
+
+//- /jwt/lib.rs crate:jwt
+pub struct Claims {
+    field: u8,
+}
+        "#,
+        );
+    }
+}
diff --git a/crates/ide/src/diagnostics/macro_error.rs b/crates/ide_diagnostics/src/macro_error.rs
index 5f97f190d..180f297eb 100644
--- a/crates/ide/src/diagnostics/macro_error.rs
+++ b/crates/ide_diagnostics/src/macro_error.rs
@@ -1,4 +1,4 @@
-use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+use crate::{Diagnostic, DiagnosticsContext};
 
 // Diagnostic: macro-error
 //
@@ -15,7 +15,7 @@ pub(super) fn macro_error(ctx: &DiagnosticsContext<'_>, d: &hir::MacroError) ->
 #[cfg(test)]
 mod tests {
     use crate::{
-        diagnostics::tests::{check_diagnostics, check_diagnostics_with_config},
+        tests::{check_diagnostics, check_diagnostics_with_config},
         DiagnosticsConfig,
     };
 
diff --git a/crates/ide/src/diagnostics/mismatched_arg_count.rs b/crates/ide_diagnostics/src/mismatched_arg_count.rs
index 08e1cfa5f..c5749c8a6 100644
--- a/crates/ide/src/diagnostics/mismatched_arg_count.rs
+++ b/crates/ide_diagnostics/src/mismatched_arg_count.rs
@@ -1,4 +1,4 @@
-use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+use crate::{Diagnostic, DiagnosticsContext};
 
 // Diagnostic: mismatched-arg-count
 //
@@ -18,7 +18,7 @@ pub(super) fn mismatched_arg_count(
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::check_diagnostics;
+    use crate::tests::check_diagnostics;
 
     #[test]
     fn simple_free_fn_zero() {
diff --git a/crates/ide/src/diagnostics/missing_fields.rs b/crates/ide_diagnostics/src/missing_fields.rs
index d01f05041..f242ee481 100644
--- a/crates/ide/src/diagnostics/missing_fields.rs
+++ b/crates/ide_diagnostics/src/missing_fields.rs
@@ -6,7 +6,7 @@ use stdx::format_to;
 use syntax::{algo, ast::make, AstNode, SyntaxNodePtr};
 use text_edit::TextEdit;
 
-use crate::diagnostics::{fix, Diagnostic, DiagnosticsContext};
+use crate::{fix, Diagnostic, DiagnosticsContext};
 
 // Diagnostic: missing-fields
 //
@@ -77,7 +77,7 @@ fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::MissingFields) -> Option<Vec<Ass
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::{check_diagnostics, check_fix};
+    use crate::tests::{check_diagnostics, check_fix};
 
     #[test]
     fn missing_record_pat_field_diagnostic() {
diff --git a/crates/ide/src/diagnostics/missing_match_arms.rs b/crates/ide_diagnostics/src/missing_match_arms.rs
index b636489b3..c83155d2f 100644
--- a/crates/ide/src/diagnostics/missing_match_arms.rs
+++ b/crates/ide_diagnostics/src/missing_match_arms.rs
@@ -1,6 +1,6 @@
 use hir::InFile;
 
-use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+use crate::{Diagnostic, DiagnosticsContext};
 
 // Diagnostic: missing-match-arm
 //
@@ -18,11 +18,11 @@ pub(super) fn missing_match_arms(
 
 #[cfg(test)]
 pub(super) mod tests {
-    use crate::diagnostics::tests::check_diagnostics;
+    use crate::tests::check_diagnostics;
 
     fn check_diagnostics_no_bails(ra_fixture: &str) {
         cov_mark::check_count!(validate_match_bailed_out, 0);
-        crate::diagnostics::tests::check_diagnostics(ra_fixture)
+        crate::tests::check_diagnostics(ra_fixture)
     }
 
     #[test]
diff --git a/crates/ide/src/diagnostics/missing_ok_or_some_in_tail_expr.rs b/crates/ide_diagnostics/src/missing_ok_or_some_in_tail_expr.rs
index 06005d156..9e36ca296 100644
--- a/crates/ide/src/diagnostics/missing_ok_or_some_in_tail_expr.rs
+++ b/crates/ide_diagnostics/src/missing_ok_or_some_in_tail_expr.rs
@@ -4,7 +4,7 @@ use ide_db::source_change::SourceChange;
 use syntax::AstNode;
 use text_edit::TextEdit;
 
-use crate::diagnostics::{fix, Diagnostic, DiagnosticsContext};
+use crate::{fix, Diagnostic, DiagnosticsContext};
 
 // Diagnostic: missing-ok-or-some-in-tail-expr
 //
@@ -44,7 +44,7 @@ fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::MissingOkOrSomeInTailExpr) -> Op
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::{check_diagnostics, check_fix};
+    use crate::tests::{check_diagnostics, check_fix};
 
     #[test]
     fn test_wrap_return_type_option() {
diff --git a/crates/ide/src/diagnostics/missing_unsafe.rs b/crates/ide_diagnostics/src/missing_unsafe.rs
index 5c47e8d0a..f5f38a0d3 100644
--- a/crates/ide/src/diagnostics/missing_unsafe.rs
+++ b/crates/ide_diagnostics/src/missing_unsafe.rs
@@ -1,4 +1,4 @@
-use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+use crate::{Diagnostic, DiagnosticsContext};
 
 // Diagnostic: missing-unsafe
 //
@@ -13,7 +13,7 @@ pub(super) fn missing_unsafe(ctx: &DiagnosticsContext<'_>, d: &hir::MissingUnsaf
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::check_diagnostics;
+    use crate::tests::check_diagnostics;
 
     #[test]
     fn missing_unsafe_diagnostic_with_raw_ptr() {
diff --git a/crates/ide/src/diagnostics/no_such_field.rs b/crates/ide_diagnostics/src/no_such_field.rs
index edc63c246..c4fa387ca 100644
--- a/crates/ide/src/diagnostics/no_such_field.rs
+++ b/crates/ide_diagnostics/src/no_such_field.rs
@@ -6,10 +6,7 @@ use syntax::{
 };
 use text_edit::TextEdit;
 
-use crate::{
-    diagnostics::{fix, Diagnostic, DiagnosticsContext},
-    Assist,
-};
+use crate::{fix, Assist, Diagnostic, DiagnosticsContext};
 
 // Diagnostic: no-such-field
 //
@@ -112,7 +109,7 @@ fn missing_record_expr_field_fixes(
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::{check_diagnostics, check_fix};
+    use crate::tests::{check_diagnostics, check_fix};
 
     #[test]
     fn no_such_field_diagnostics() {
diff --git a/crates/ide/src/diagnostics/remove_this_semicolon.rs b/crates/ide_diagnostics/src/remove_this_semicolon.rs
index 814cb0f8c..dc6c9c083 100644
--- a/crates/ide/src/diagnostics/remove_this_semicolon.rs
+++ b/crates/ide_diagnostics/src/remove_this_semicolon.rs
@@ -3,10 +3,7 @@ use ide_db::source_change::SourceChange;
 use syntax::{ast, AstNode};
 use text_edit::TextEdit;
 
-use crate::{
-    diagnostics::{fix, Diagnostic, DiagnosticsContext},
-    Assist,
-};
+use crate::{fix, Assist, Diagnostic, DiagnosticsContext};
 
 // Diagnostic: remove-this-semicolon
 //
@@ -45,7 +42,7 @@ fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::RemoveThisSemicolon) -> Option<V
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::{check_diagnostics, check_fix};
+    use crate::tests::{check_diagnostics, check_fix};
 
     #[test]
     fn missing_semicolon() {
diff --git a/crates/ide/src/diagnostics/replace_filter_map_next_with_find_map.rs b/crates/ide_diagnostics/src/replace_filter_map_next_with_find_map.rs
index f3b011495..775c350d2 100644
--- a/crates/ide/src/diagnostics/replace_filter_map_next_with_find_map.rs
+++ b/crates/ide_diagnostics/src/replace_filter_map_next_with_find_map.rs
@@ -6,10 +6,7 @@ use syntax::{
 };
 use text_edit::TextEdit;
 
-use crate::{
-    diagnostics::{fix, Diagnostic, DiagnosticsContext},
-    Assist, Severity,
-};
+use crate::{fix, Assist, Diagnostic, DiagnosticsContext, Severity};
 
 // Diagnostic: replace-filter-map-next-with-find-map
 //
@@ -58,7 +55,7 @@ fn fixes(
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::check_fix;
+    use crate::tests::check_fix;
 
     // Register the required standard library types to make the tests work
     #[track_caller]
@@ -86,7 +83,7 @@ pub mod iter {
     }
 }
 "#;
-        crate::diagnostics::tests::check_diagnostics(&format!("{}{}{}", prefix, ra_fixture, suffix))
+        crate::tests::check_diagnostics(&format!("{}{}{}", prefix, ra_fixture, suffix))
     }
 
     #[test]
diff --git a/crates/ide/src/diagnostics/unimplemented_builtin_macro.rs b/crates/ide_diagnostics/src/unimplemented_builtin_macro.rs
index 09faa3bbc..a600544f0 100644
--- a/crates/ide/src/diagnostics/unimplemented_builtin_macro.rs
+++ b/crates/ide_diagnostics/src/unimplemented_builtin_macro.rs
@@ -1,7 +1,4 @@
-use crate::{
-    diagnostics::{Diagnostic, DiagnosticsContext},
-    Severity,
-};
+use crate::{Diagnostic, DiagnosticsContext, Severity};
 
 // Diagnostic: unimplemented-builtin-macro
 //
diff --git a/crates/ide/src/diagnostics/unlinked_file.rs b/crates/ide_diagnostics/src/unlinked_file.rs
index a5b2e3399..424532e3a 100644
--- a/crates/ide/src/diagnostics/unlinked_file.rs
+++ b/crates/ide_diagnostics/src/unlinked_file.rs
@@ -12,10 +12,7 @@ use syntax::{
 };
 use text_edit::TextEdit;
 
-use crate::{
-    diagnostics::{fix, DiagnosticsContext},
-    Assist, Diagnostic,
-};
+use crate::{fix, Assist, Diagnostic, DiagnosticsContext};
 
 #[derive(Debug)]
 pub(crate) struct UnlinkedFile {
@@ -164,7 +161,7 @@ fn make_fixes(
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::{check_diagnostics, check_fix, check_fixes, check_no_fix};
+    use crate::tests::{check_diagnostics, check_fix, check_fixes, check_no_fix};
 
     #[test]
     fn unlinked_file_prepend_first_item() {
diff --git a/crates/ide/src/diagnostics/unresolved_extern_crate.rs b/crates/ide_diagnostics/src/unresolved_extern_crate.rs
index 2ea79c2ee..69f07d0b0 100644
--- a/crates/ide/src/diagnostics/unresolved_extern_crate.rs
+++ b/crates/ide_diagnostics/src/unresolved_extern_crate.rs
@@ -1,4 +1,4 @@
-use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+use crate::{Diagnostic, DiagnosticsContext};
 
 // Diagnostic: unresolved-extern-crate
 //
@@ -16,7 +16,7 @@ pub(super) fn unresolved_extern_crate(
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::check_diagnostics;
+    use crate::tests::check_diagnostics;
 
     #[test]
     fn unresolved_extern_crate() {
diff --git a/crates/ide/src/diagnostics/unresolved_import.rs b/crates/ide_diagnostics/src/unresolved_import.rs
index 1cbf96ba1..7779033d4 100644
--- a/crates/ide/src/diagnostics/unresolved_import.rs
+++ b/crates/ide_diagnostics/src/unresolved_import.rs
@@ -1,4 +1,4 @@
-use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+use crate::{Diagnostic, DiagnosticsContext};
 
 // Diagnostic: unresolved-import
 //
@@ -22,7 +22,7 @@ pub(super) fn unresolved_import(
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::check_diagnostics;
+    use crate::tests::check_diagnostics;
 
     #[test]
     fn unresolved_import() {
diff --git a/crates/ide/src/diagnostics/unresolved_macro_call.rs b/crates/ide_diagnostics/src/unresolved_macro_call.rs
index 15b6a2730..88133d0f3 100644
--- a/crates/ide/src/diagnostics/unresolved_macro_call.rs
+++ b/crates/ide_diagnostics/src/unresolved_macro_call.rs
@@ -1,7 +1,7 @@
 use hir::{db::AstDatabase, InFile};
 use syntax::{AstNode, SyntaxNodePtr};
 
-use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+use crate::{Diagnostic, DiagnosticsContext};
 
 // Diagnostic: unresolved-macro-call
 //
@@ -32,7 +32,7 @@ pub(super) fn unresolved_macro_call(
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::check_diagnostics;
+    use crate::tests::check_diagnostics;
 
     #[test]
     fn unresolved_macro_diag() {
diff --git a/crates/ide/src/diagnostics/unresolved_module.rs b/crates/ide_diagnostics/src/unresolved_module.rs
index 977b46414..b11e71b3e 100644
--- a/crates/ide/src/diagnostics/unresolved_module.rs
+++ b/crates/ide_diagnostics/src/unresolved_module.rs
@@ -3,7 +3,7 @@ use ide_assists::Assist;
 use ide_db::{base_db::AnchoredPathBuf, source_change::FileSystemEdit};
 use syntax::AstNode;
 
-use crate::diagnostics::{fix, Diagnostic, DiagnosticsContext};
+use crate::{fix, Diagnostic, DiagnosticsContext};
 
 // Diagnostic: unresolved-module
 //
@@ -42,7 +42,7 @@ fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::UnresolvedModule) -> Option<Vec<
 mod tests {
     use expect_test::expect;
 
-    use crate::diagnostics::tests::{check_diagnostics, check_expect};
+    use crate::tests::{check_diagnostics, check_expect};
 
     #[test]
     fn unresolved_module() {
diff --git a/crates/ide/src/diagnostics/unresolved_proc_macro.rs b/crates/ide_diagnostics/src/unresolved_proc_macro.rs
index 3dc6ab451..744cce508 100644
--- a/crates/ide/src/diagnostics/unresolved_proc_macro.rs
+++ b/crates/ide_diagnostics/src/unresolved_proc_macro.rs
@@ -1,7 +1,4 @@
-use crate::{
-    diagnostics::{Diagnostic, DiagnosticsContext},
-    Severity,
-};
+use crate::{Diagnostic, DiagnosticsContext, Severity};
 
 // Diagnostic: unresolved-proc-macro
 //