47 files changed, 4749 insertions, 1771 deletions

diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index d5c954b8b..815a633e5 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -4,69 +4,94 @@
 //! 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 fixes;
-mod field_shorthand;
+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;
 
-use std::cell::RefCell;
+mod field_shorthand;
 
-use hir::{
-    db::AstDatabase,
-    diagnostics::{Diagnostic as _, DiagnosticCode, DiagnosticSinkBuilder},
-    InFile, Semantics,
-};
+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, SyntaxNodePtr, TextRange, TextSize,
+    SyntaxNode, TextRange,
 };
 use text_edit::TextEdit;
 use unlinked_file::UnlinkedFile;
 
 use crate::{Assist, AssistId, AssistKind, FileId, Label, SourceChange};
 
-use self::fixes::DiagnosticWithFixes;
+#[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 name: Option<String>,
+    pub code: DiagnosticCode,
     pub message: String,
     pub range: TextRange,
     pub severity: Severity,
-    pub fixes: Option<Vec<Assist>>,
     pub unused: bool,
-    pub code: Option<DiagnosticCode>,
+    pub experimental: bool,
+    pub fixes: Option<Vec<Assist>>,
 }
 
 impl Diagnostic {
-    fn error(range: TextRange, message: String) -> Self {
-        Self { message, range, severity: Severity::Error, fixes: None, unused: false, code: None }
-    }
-
-    fn hint(range: TextRange, message: String) -> Self {
-        Self {
+    fn new(code: &'static str, message: impl Into<String>, range: TextRange) -> Diagnostic {
+        let message = message.into();
+        Diagnostic {
+            code: DiagnosticCode(code),
             message,
             range,
-            severity: Severity::WeakWarning,
-            fixes: None,
+            severity: Severity::Error,
             unused: false,
-            code: None,
+            experimental: false,
+            fixes: None,
         }
     }
 
-    fn with_fixes(self, fixes: Option<Vec<Assist>>) -> Self {
-        Self { fixes, ..self }
+    fn experimental(mut self) -> Diagnostic {
+        self.experimental = true;
+        self
+    }
+
+    fn severity(mut self, severity: Severity) -> Diagnostic {
+        self.severity = severity;
+        self
     }
 
-    fn with_unused(self, unused: bool) -> Self {
-        Self { unused, ..self }
+    fn with_fixes(mut self, fixes: Option<Vec<Assist>>) -> Diagnostic {
+        self.fixes = fixes;
+        self
     }
 
-    fn with_code(self, code: Option<DiagnosticCode>) -> Self {
-        Self { code, ..self }
+    fn with_unused(mut self, unused: bool) -> Diagnostic {
+        self.unused = unused;
+        self
     }
 }
 
@@ -82,6 +107,12 @@ pub struct DiagnosticsConfig {
     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,
@@ -95,144 +126,64 @@ pub(crate) fn diagnostics(
 
     // [#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::error(err.range(), format!("Syntax Error: {}", err))),
+        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 res = RefCell::new(res);
-    let sink_builder = DiagnosticSinkBuilder::new()
-        .on::<hir::diagnostics::UnresolvedModule, _>(|d| {
-            res.borrow_mut().push(diagnostic_with_fix(d, &sema, resolve));
-        })
-        .on::<hir::diagnostics::MissingFields, _>(|d| {
-            res.borrow_mut().push(diagnostic_with_fix(d, &sema, resolve));
-        })
-        .on::<hir::diagnostics::MissingOkOrSomeInTailExpr, _>(|d| {
-            res.borrow_mut().push(diagnostic_with_fix(d, &sema, resolve));
-        })
-        .on::<hir::diagnostics::NoSuchField, _>(|d| {
-            res.borrow_mut().push(diagnostic_with_fix(d, &sema, resolve));
-        })
-        .on::<hir::diagnostics::RemoveThisSemicolon, _>(|d| {
-            res.borrow_mut().push(diagnostic_with_fix(d, &sema, resolve));
-        })
-        .on::<hir::diagnostics::IncorrectCase, _>(|d| {
-            res.borrow_mut().push(warning_with_fix(d, &sema, resolve));
-        })
-        .on::<hir::diagnostics::ReplaceFilterMapNextWithFindMap, _>(|d| {
-            res.borrow_mut().push(warning_with_fix(d, &sema, resolve));
-        })
-        .on::<hir::diagnostics::InactiveCode, _>(|d| {
-            // If there's inactive code somewhere in a macro, don't propagate to the call-site.
-            if d.display_source().file_id.expansion_info(db).is_some() {
-                return;
-            }
 
-            // Override severity and mark as unused.
-            res.borrow_mut().push(
-                Diagnostic::hint(
-                    sema.diagnostics_display_range(d.display_source()).range,
-                    d.message(),
-                )
-                .with_unused(true)
-                .with_code(Some(d.code())),
-            );
-        })
-        .on::<UnlinkedFile, _>(|d| {
-            // Limit diagnostic to the first few characters in the file. This matches how VS Code
-            // renders it with the full span, but on other editors, and is less invasive.
-            let range = sema.diagnostics_display_range(d.display_source()).range;
-            let range = range.intersect(TextRange::up_to(TextSize::of("..."))).unwrap_or(range);
-
-            // Override severity and mark as unused.
-            res.borrow_mut().push(
-                Diagnostic::hint(range, d.message())
-                    .with_fixes(d.fixes(&sema, resolve))
-                    .with_code(Some(d.code())),
-            );
-        })
-        .on::<hir::diagnostics::UnresolvedProcMacro, _>(|d| {
-            // Use more accurate position if available.
-            let display_range = d
-                .precise_location
-                .unwrap_or_else(|| sema.diagnostics_display_range(d.display_source()).range);
-
-            // FIXME: it would be nice to tell the user whether proc macros are currently disabled
-            res.borrow_mut()
-                .push(Diagnostic::hint(display_range, d.message()).with_code(Some(d.code())));
-        })
-        .on::<hir::diagnostics::UnresolvedMacroCall, _>(|d| {
-            let last_path_segment = sema.db.parse_or_expand(d.file).and_then(|root| {
-                d.node
-                    .to_node(&root)
-                    .path()
-                    .and_then(|it| it.segment())
-                    .and_then(|it| it.name_ref())
-                    .map(|it| InFile::new(d.file, SyntaxNodePtr::new(it.syntax())))
-            });
-            let diagnostics = last_path_segment.unwrap_or_else(|| d.display_source());
-            let display_range = sema.diagnostics_display_range(diagnostics).range;
-            res.borrow_mut()
-                .push(Diagnostic::error(display_range, d.message()).with_code(Some(d.code())));
-        })
-        .on::<hir::diagnostics::UnimplementedBuiltinMacro, _>(|d| {
-            let display_range = sema.diagnostics_display_range(d.display_source()).range;
-            res.borrow_mut()
-                .push(Diagnostic::hint(display_range, d.message()).with_code(Some(d.code())));
-        })
-        // Only collect experimental diagnostics when they're enabled.
-        .filter(|diag| !(diag.is_experimental() && config.disable_experimental))
-        .filter(|diag| !config.disabled.contains(diag.code().as_str()));
-
-    // Finalize the `DiagnosticSink` building process.
-    let mut sink = sink_builder
-        // Diagnostics not handled above get no fix and default treatment.
-        .build(|d| {
-            res.borrow_mut().push(
-                Diagnostic::error(
-                    sema.diagnostics_display_range(d.display_source()).range,
-                    d.message(),
-                )
-                .with_code(Some(d.code())),
-            );
-        });
-
-    match sema.to_module_def(file_id) {
-        Some(m) => m.diagnostics(db, &mut sink),
-        None => {
-            sink.push(UnlinkedFile { file_id, node: SyntaxNodePtr::new(&parse.tree().syntax()) });
-        }
+    let mut diags = Vec::new();
+    let module = sema.to_module_def(file_id);
+    if let Some(m) = module {
+        m.diagnostics(db, &mut diags)
     }
 
-    drop(sink);
-    res.into_inner()
-}
+    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)
+    }
 
-fn diagnostic_with_fix<D: DiagnosticWithFixes>(
-    d: &D,
-    sema: &Semantics<RootDatabase>,
-    resolve: &AssistResolveStrategy,
-) -> Diagnostic {
-    Diagnostic::error(sema.diagnostics_display_range(d.display_source()).range, d.message())
-        .with_fixes(d.fixes(&sema, resolve))
-        .with_code(Some(d.code()))
-}
+    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)
+    }
 
-fn warning_with_fix<D: DiagnosticWithFixes>(
-    d: &D,
-    sema: &Semantics<RootDatabase>,
-    resolve: &AssistResolveStrategy,
-) -> Diagnostic {
-    Diagnostic::hint(sema.diagnostics_display_range(d.display_source()).range, d.message())
-        .with_fixes(d.fixes(&sema, resolve))
-        .with_code(Some(d.code()))
+    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(
@@ -260,13 +211,18 @@ fn check_unnecessary_braces_in_use_statement(
                 });
 
         acc.push(
-            Diagnostic::hint(use_range, "Unnecessary braces in use statement".to_string())
-                .with_fixes(Some(vec![fix(
-                    "remove_braces",
-                    "Remove unnecessary braces",
-                    SourceChange::from_text_edit(file_id, edit),
-                    use_range,
-                )])),
+            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,
+            )])),
         );
     }
 
@@ -344,8 +300,8 @@ mod tests {
             )
             .unwrap()
             .pop()
-            .unwrap();
-        let fix = &diagnostic.fixes.unwrap()[nth];
+            .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();
@@ -365,8 +321,9 @@ mod tests {
             file_position.offset
         );
     }
+
     /// Checks that there's a diagnostic *without* fix at `$0`.
-    fn check_no_fix(ra_fixture: &str) {
+    pub(crate) fn check_no_fix(ra_fixture: &str) {
         let (analysis, file_position) = fixture::position(ra_fixture);
         let diagnostic = analysis
             .diagnostics(
@@ -380,21 +337,6 @@ mod tests {
         assert!(diagnostic.fixes.is_none(), "got a fix when none was expected: {:?}", diagnostic);
     }
 
-    /// Takes a multi-file input fixture with annotated cursor position and checks that no diagnostics
-    /// apply to the file containing the cursor.
-    pub(crate) fn check_no_diagnostics(ra_fixture: &str) {
-        let (analysis, files) = fixture::files(ra_fixture);
-        let diagnostics = files
-            .into_iter()
-            .flat_map(|file_id| {
-                analysis
-                    .diagnostics(&DiagnosticsConfig::default(), AssistResolveStrategy::All, file_id)
-                    .unwrap()
-            })
-            .collect::<Vec<_>>();
-        assert_eq!(diagnostics.len(), 0, "unexpected diagnostics:\n{:#?}", diagnostics);
-    }
-
     pub(crate) fn check_expect(ra_fixture: &str, expect: Expect) {
         let (analysis, file_id) = fixture::file(ra_fixture);
         let diagnostics = analysis
@@ -403,90 +345,31 @@ mod tests {
         expect.assert_debug_eq(&diagnostics)
     }
 
+    #[track_caller]
     pub(crate) fn check_diagnostics(ra_fixture: &str) {
-        let (analysis, file_id) = fixture::file(ra_fixture);
-        let diagnostics = analysis
-            .diagnostics(&DiagnosticsConfig::default(), AssistResolveStrategy::All, file_id)
-            .unwrap();
-
-        let expected = extract_annotations(&*analysis.file_text(file_id).unwrap());
-        let actual = diagnostics.into_iter().map(|d| (d.range, d.message)).collect::<Vec<_>>();
-        assert_eq!(expected, actual);
-    }
-
-    #[test]
-    fn test_unresolved_macro_range() {
-        check_diagnostics(
-            r#"
-foo::bar!(92);
-   //^^^ unresolved macro `foo::bar!`
-"#,
-        );
-    }
-
-    #[test]
-    fn unresolved_import_in_use_tree() {
-        // Only the relevant part of a nested `use` item should be highlighted.
-        check_diagnostics(
-            r#"
-use does_exist::{Exists, DoesntExist};
-                       //^^^^^^^^^^^ unresolved import
-
-use {does_not_exist::*, does_exist};
-   //^^^^^^^^^^^^^^^^^ unresolved import
-
-use does_not_exist::{
-    a,
-  //^ unresolved import
-    b,
-  //^ unresolved import
-    c,
-  //^ unresolved import
-};
-
-mod does_exist {
-    pub struct Exists;
-}
-"#,
-        );
+        let mut config = DiagnosticsConfig::default();
+        config.disabled.insert("inactive-code".to_string());
+        check_diagnostics_with_config(config, ra_fixture)
     }
 
-    #[test]
-    fn range_mapping_out_of_macros() {
-        // FIXME: this is very wrong, but somewhat tricky to fix.
-        check_fix(
-            r#"
-fn some() {}
-fn items() {}
-fn here() {}
-
-macro_rules! id { ($($tt:tt)*) => { $($tt)*}; }
-
-fn main() {
-    let _x = id![Foo { a: $042 }];
-}
-
-pub struct Foo { pub a: i32, pub b: i32 }
-"#,
-            r#"
-fn some(, b: () ) {}
-fn items() {}
-fn here() {}
-
-macro_rules! id { ($($tt:tt)*) => { $($tt)*}; }
-
-fn main() {
-    let _x = id![Foo { a: 42 }];
-}
-
-pub struct Foo { pub a: i32, pub b: i32 }
-"#,
-        );
+    #[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_no_diagnostics(
+        check_diagnostics(
             r#"
 use a;
 use a::{c, d::e};
@@ -499,7 +382,7 @@ mod a {
 }
 "#,
         );
-        check_no_diagnostics(
+        check_diagnostics(
             r#"
 use a;
 use a::{
@@ -585,138 +468,31 @@ mod a {
     }
 
     #[test]
-    fn unlinked_file_prepend_first_item() {
-        cov_mark::check!(unlinked_file_prepend_before_first_item);
-        // Only tests the first one for `pub mod` since the rest are the same
-        check_fixes(
-            r#"
-//- /main.rs
-fn f() {}
-//- /foo.rs
-$0
-"#,
-            vec![
-                r#"
-mod foo;
-
-fn f() {}
-"#,
-                r#"
-pub mod foo;
-
-fn f() {}
-"#,
-            ],
-        );
-    }
-
-    #[test]
-    fn unlinked_file_append_mod() {
-        cov_mark::check!(unlinked_file_append_to_existing_mods);
-        check_fix(
-            r#"
-//- /main.rs
-//! Comment on top
-
-mod preexisting;
-
-mod preexisting2;
-
-struct S;
-
-mod preexisting_bottom;)
-//- /foo.rs
-$0
-"#,
-            r#"
-//! Comment on top
+    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.
 
-mod preexisting;
-
-mod preexisting2;
-mod foo;
-
-struct S;
-
-mod preexisting_bottom;)
-"#,
-        );
-    }
-
-    #[test]
-    fn unlinked_file_insert_in_empty_file() {
-        cov_mark::check!(unlinked_file_empty_file);
-        check_fix(
-            r#"
-//- /main.rs
-//- /foo.rs
-$0
-"#,
-            r#"
-mod foo;
-"#,
-        );
-    }
-
-    #[test]
-    fn unlinked_file_old_style_modrs() {
-        check_fix(
-            r#"
-//- /main.rs
-mod submod;
-//- /submod/mod.rs
-// in mod.rs
-//- /submod/foo.rs
-$0
-"#,
-            r#"
-// in mod.rs
-mod foo;
-"#,
-        );
-    }
-
-    #[test]
-    fn unlinked_file_new_style_mod() {
-        check_fix(
-            r#"
-//- /main.rs
-mod submod;
-//- /submod.rs
-//- /submod/foo.rs
-$0
-"#,
+        check_diagnostics(
             r#"
-mod foo;
-"#,
-        );
-    }
+//- /lib.rs crate:lib deps:jwt
+mod permissions;
 
-    #[test]
-    fn unlinked_file_with_cfg_off() {
-        cov_mark::check!(unlinked_file_skip_fix_when_mod_already_exists);
-        check_no_fix(
-            r#"
-//- /main.rs
-#[cfg(never)]
-mod foo;
+use permissions::jwt;
 
-//- /foo.rs
-$0
-"#,
-        );
-    }
+fn f() {
+    fn inner() {}
+    jwt::Claims {}; // should resolve to the local one with 0 fields, and not get a diagnostic
+}
 
-    #[test]
-    fn unlinked_file_with_cfg_on() {
-        check_no_diagnostics(
-            r#"
-//- /main.rs
-#[cfg(not(never))]
-mod foo;
+//- /permissions.rs
+pub mod jwt  {
+    pub struct Claims {}
+}
 
-//- /foo.rs
-"#,
+//- /jwt/lib.rs crate:jwt
+pub struct Claims {
+    field: u8,
+}
+        "#,
         );
     }
 }
diff --git a/crates/ide/src/diagnostics/break_outside_of_loop.rs b/crates/ide/src/diagnostics/break_outside_of_loop.rs
new file mode 100644
index 000000000..80e68f3cc
--- /dev/null
+++ b/crates/ide/src/diagnostics/break_outside_of_loop.rs
@@ -0,0 +1,30 @@
+use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+
+// Diagnostic: break-outside-of-loop
+//
+// This diagnostic is triggered if the `break` keyword is used outside of a loop.
+pub(super) fn break_outside_of_loop(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::BreakOutsideOfLoop,
+) -> Diagnostic {
+    Diagnostic::new(
+        "break-outside-of-loop",
+        "break outside of loop",
+        ctx.sema.diagnostics_display_range(d.expr.clone().map(|it| it.into())).range,
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostics::tests::check_diagnostics;
+
+    #[test]
+    fn break_outside_of_loop() {
+        check_diagnostics(
+            r#"
+fn foo() { break; }
+         //^^^^^ break outside of loop
+"#,
+        );
+    }
+}
diff --git a/crates/ide/src/diagnostics/field_shorthand.rs b/crates/ide/src/diagnostics/field_shorthand.rs
index 01bd2dba6..c7f4dab8e 100644
--- a/crates/ide/src/diagnostics/field_shorthand.rs
+++ b/crates/ide/src/diagnostics/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};
+use crate::{diagnostics::fix, Diagnostic, Severity};
 
 pub(super) fn check(acc: &mut Vec<Diagnostic>, file_id: FileId, node: &SyntaxNode) {
     match_ast! {
@@ -46,7 +46,8 @@ fn check_expr_field_shorthand(
 
         let field_range = record_field.syntax().text_range();
         acc.push(
-            Diagnostic::hint(field_range, "Shorthand struct initialization".to_string())
+            Diagnostic::new("use-field-shorthand", "Shorthand struct initialization", field_range)
+                .severity(Severity::WeakWarning)
                 .with_fixes(Some(vec![fix(
                     "use_expr_field_shorthand",
                     "Use struct shorthand initialization",
@@ -85,30 +86,32 @@ fn check_pat_field_shorthand(
         let edit = edit_builder.finish();
 
         let field_range = record_pat_field.syntax().text_range();
-        acc.push(Diagnostic::hint(field_range, "Shorthand struct pattern".to_string()).with_fixes(
-            Some(vec![fix(
-                "use_pat_field_shorthand",
-                "Use struct field shorthand",
-                SourceChange::from_text_edit(file_id, edit),
-                field_range,
-            )]),
-        ));
+        acc.push(
+            Diagnostic::new("use-field-shorthand", "Shorthand struct pattern", field_range)
+                .severity(Severity::WeakWarning)
+                .with_fixes(Some(vec![fix(
+                    "use_pat_field_shorthand",
+                    "Use struct field shorthand",
+                    SourceChange::from_text_edit(file_id, edit),
+                    field_range,
+                )])),
+        );
     }
 }
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::{check_fix, check_no_diagnostics};
+    use crate::diagnostics::tests::{check_diagnostics, check_fix};
 
     #[test]
     fn test_check_expr_field_shorthand() {
-        check_no_diagnostics(
+        check_diagnostics(
             r#"
 struct A { a: &'static str }
 fn main() { A { a: "hello" } }
 "#,
         );
-        check_no_diagnostics(
+        check_diagnostics(
             r#"
 struct A(usize);
 fn main() { A { 0: 0 } }
@@ -154,13 +157,13 @@ fn main() {
 
     #[test]
     fn test_check_pat_field_shorthand() {
-        check_no_diagnostics(
+        check_diagnostics(
             r#"
 struct A { a: &'static str }
 fn f(a: A) { let A { a: hello } = a; }
 "#,
         );
-        check_no_diagnostics(
+        check_diagnostics(
             r#"
 struct A(usize);
 fn f(a: A) { let A { 0: 0 } = a; }
diff --git a/crates/ide/src/diagnostics/fixes.rs b/crates/ide/src/diagnostics/fixes.rs
deleted file mode 100644
index 258ac6974..000000000
--- a/crates/ide/src/diagnostics/fixes.rs
+++ /dev/null
@@ -1,31 +0,0 @@
-//! Provides a way to attach fixes to the diagnostics.
-//! The same module also has all curret custom fixes for the diagnostics implemented.
-mod change_case;
-mod create_field;
-mod fill_missing_fields;
-mod remove_semicolon;
-mod replace_with_find_map;
-mod unresolved_module;
-mod wrap_tail_expr;
-
-use hir::{diagnostics::Diagnostic, Semantics};
-use ide_assists::AssistResolveStrategy;
-use ide_db::RootDatabase;
-
-use crate::Assist;
-
-/// A [Diagnostic] that potentially has some fixes available.
-///
-/// [Diagnostic]: hir::diagnostics::Diagnostic
-pub(crate) trait DiagnosticWithFixes: Diagnostic {
-    /// `resolve` determines if the diagnostic should fill in the `edit` field
-    /// of the assist.
-    ///
-    /// If `resolve` is false, the edit will be computed later, on demand, and
-    /// can be omitted.
-    fn fixes(
-        &self,
-        sema: &Semantics<RootDatabase>,
-        _resolve: &AssistResolveStrategy,
-    ) -> Option<Vec<Assist>>;
-}
diff --git a/crates/ide/src/diagnostics/fixes/change_case.rs b/crates/ide/src/diagnostics/fixes/change_case.rs
deleted file mode 100644
index 42be3375f..000000000
--- a/crates/ide/src/diagnostics/fixes/change_case.rs
+++ /dev/null
@@ -1,155 +0,0 @@
-use hir::{db::AstDatabase, diagnostics::IncorrectCase, InFile, Semantics};
-use ide_assists::{Assist, AssistResolveStrategy};
-use ide_db::{base_db::FilePosition, RootDatabase};
-use syntax::AstNode;
-
-use crate::{
-    diagnostics::{unresolved_fix, DiagnosticWithFixes},
-    references::rename::rename_with_semantics,
-};
-
-impl DiagnosticWithFixes for IncorrectCase {
-    fn fixes(
-        &self,
-        sema: &Semantics<RootDatabase>,
-        resolve: &AssistResolveStrategy,
-    ) -> Option<Vec<Assist>> {
-        let root = sema.db.parse_or_expand(self.file)?;
-        let name_node = self.ident.to_node(&root);
-
-        let name_node = InFile::new(self.file, name_node.syntax());
-        let frange = name_node.original_file_range(sema.db);
-        let file_position = FilePosition { file_id: frange.file_id, offset: frange.range.start() };
-
-        let label = format!("Rename to {}", self.suggested_text);
-        let mut res = unresolved_fix("change_case", &label, frange.range);
-        if resolve.should_resolve(&res.id) {
-            let source_change = rename_with_semantics(sema, file_position, &self.suggested_text);
-            res.source_change = Some(source_change.ok().unwrap_or_default());
-        }
-
-        Some(vec![res])
-    }
-}
-
-#[cfg(test)]
-mod change_case {
-    use crate::{
-        diagnostics::tests::{check_fix, check_no_diagnostics},
-        fixture, AssistResolveStrategy, DiagnosticsConfig,
-    };
-
-    #[test]
-    fn test_rename_incorrect_case() {
-        check_fix(
-            r#"
-pub struct test_struct$0 { one: i32 }
-
-pub fn some_fn(val: test_struct) -> test_struct {
-    test_struct { one: val.one + 1 }
-}
-"#,
-            r#"
-pub struct TestStruct { one: i32 }
-
-pub fn some_fn(val: TestStruct) -> TestStruct {
-    TestStruct { one: val.one + 1 }
-}
-"#,
-        );
-
-        check_fix(
-            r#"
-pub fn some_fn(NonSnakeCase$0: u8) -> u8 {
-    NonSnakeCase
-}
-"#,
-            r#"
-pub fn some_fn(non_snake_case: u8) -> u8 {
-    non_snake_case
-}
-"#,
-        );
-
-        check_fix(
-            r#"
-pub fn SomeFn$0(val: u8) -> u8 {
-    if val != 0 { SomeFn(val - 1) } else { val }
-}
-"#,
-            r#"
-pub fn some_fn(val: u8) -> u8 {
-    if val != 0 { some_fn(val - 1) } else { val }
-}
-"#,
-        );
-
-        check_fix(
-            r#"
-fn some_fn() {
-    let whatAWeird_Formatting$0 = 10;
-    another_func(whatAWeird_Formatting);
-}
-"#,
-            r#"
-fn some_fn() {
-    let what_a_weird_formatting = 10;
-    another_func(what_a_weird_formatting);
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn test_uppercase_const_no_diagnostics() {
-        check_no_diagnostics(
-            r#"
-fn foo() {
-    const ANOTHER_ITEM$0: &str = "some_item";
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn test_rename_incorrect_case_struct_method() {
-        check_fix(
-            r#"
-pub struct TestStruct;
-
-impl TestStruct {
-    pub fn SomeFn$0() -> TestStruct {
-        TestStruct
-    }
-}
-"#,
-            r#"
-pub struct TestStruct;
-
-impl TestStruct {
-    pub fn some_fn() -> TestStruct {
-        TestStruct
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn test_single_incorrect_case_diagnostic_in_function_name_issue_6970() {
-        let input = r#"fn FOO$0() {}"#;
-        let expected = r#"fn foo() {}"#;
-
-        let (analysis, file_position) = fixture::position(input);
-        let diagnostics = analysis
-            .diagnostics(
-                &DiagnosticsConfig::default(),
-                AssistResolveStrategy::All,
-                file_position.file_id,
-            )
-            .unwrap();
-        assert_eq!(diagnostics.len(), 1);
-
-        check_fix(input, expected);
-    }
-}
diff --git a/crates/ide/src/diagnostics/fixes/fill_missing_fields.rs b/crates/ide/src/diagnostics/fixes/fill_missing_fields.rs
deleted file mode 100644
index b5dd64c08..000000000
--- a/crates/ide/src/diagnostics/fixes/fill_missing_fields.rs
+++ /dev/null
@@ -1,217 +0,0 @@
-use hir::{db::AstDatabase, diagnostics::MissingFields, Semantics};
-use ide_assists::AssistResolveStrategy;
-use ide_db::{source_change::SourceChange, RootDatabase};
-use syntax::{algo, ast::make, AstNode};
-use text_edit::TextEdit;
-
-use crate::{
-    diagnostics::{fix, fixes::DiagnosticWithFixes},
-    Assist,
-};
-
-impl DiagnosticWithFixes for MissingFields {
-    fn fixes(
-        &self,
-        sema: &Semantics<RootDatabase>,
-        _resolve: &AssistResolveStrategy,
-    ) -> Option<Vec<Assist>> {
-        // Note that although we could add a diagnostics to
-        // fill the missing tuple field, e.g :
-        // `struct A(usize);`
-        // `let a = A { 0: () }`
-        // but it is uncommon usage and it should not be encouraged.
-        if self.missed_fields.iter().any(|it| it.as_tuple_index().is_some()) {
-            return None;
-        }
-
-        let root = sema.db.parse_or_expand(self.file)?;
-        let field_list_parent = self.field_list_parent.to_node(&root);
-        let old_field_list = field_list_parent.record_expr_field_list()?;
-        let new_field_list = old_field_list.clone_for_update();
-        for f in self.missed_fields.iter() {
-            let field =
-                make::record_expr_field(make::name_ref(&f.to_string()), Some(make::expr_unit()))
-                    .clone_for_update();
-            new_field_list.add_field(field);
-        }
-
-        let edit = {
-            let mut builder = TextEdit::builder();
-            algo::diff(&old_field_list.syntax(), &new_field_list.syntax())
-                .into_text_edit(&mut builder);
-            builder.finish()
-        };
-        Some(vec![fix(
-            "fill_missing_fields",
-            "Fill struct fields",
-            SourceChange::from_text_edit(self.file.original_file(sema.db), edit),
-            sema.original_range(&field_list_parent.syntax()).range,
-        )])
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::diagnostics::tests::{check_fix, check_no_diagnostics};
-
-    #[test]
-    fn test_fill_struct_fields_empty() {
-        check_fix(
-            r#"
-struct TestStruct { one: i32, two: i64 }
-
-fn test_fn() {
-    let s = TestStruct {$0};
-}
-"#,
-            r#"
-struct TestStruct { one: i32, two: i64 }
-
-fn test_fn() {
-    let s = TestStruct { one: (), two: () };
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn test_fill_struct_fields_self() {
-        check_fix(
-            r#"
-struct TestStruct { one: i32 }
-
-impl TestStruct {
-    fn test_fn() { let s = Self {$0}; }
-}
-"#,
-            r#"
-struct TestStruct { one: i32 }
-
-impl TestStruct {
-    fn test_fn() { let s = Self { one: () }; }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn test_fill_struct_fields_enum() {
-        check_fix(
-            r#"
-enum Expr {
-    Bin { lhs: Box<Expr>, rhs: Box<Expr> }
-}
-
-impl Expr {
-    fn new_bin(lhs: Box<Expr>, rhs: Box<Expr>) -> Expr {
-        Expr::Bin {$0 }
-    }
-}
-"#,
-            r#"
-enum Expr {
-    Bin { lhs: Box<Expr>, rhs: Box<Expr> }
-}
-
-impl Expr {
-    fn new_bin(lhs: Box<Expr>, rhs: Box<Expr>) -> Expr {
-        Expr::Bin { lhs: (), rhs: () }
-    }
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn test_fill_struct_fields_partial() {
-        check_fix(
-            r#"
-struct TestStruct { one: i32, two: i64 }
-
-fn test_fn() {
-    let s = TestStruct{ two: 2$0 };
-}
-"#,
-            r"
-struct TestStruct { one: i32, two: i64 }
-
-fn test_fn() {
-    let s = TestStruct{ two: 2, one: () };
-}
-",
-        );
-    }
-
-    #[test]
-    fn test_fill_struct_fields_raw_ident() {
-        check_fix(
-            r#"
-struct TestStruct { r#type: u8 }
-
-fn test_fn() {
-    TestStruct { $0 };
-}
-"#,
-            r"
-struct TestStruct { r#type: u8 }
-
-fn test_fn() {
-    TestStruct { r#type: ()  };
-}
-",
-        );
-    }
-
-    #[test]
-    fn test_fill_struct_fields_no_diagnostic() {
-        check_no_diagnostics(
-            r#"
-struct TestStruct { one: i32, two: i64 }
-
-fn test_fn() {
-    let one = 1;
-    let s = TestStruct{ one, two: 2 };
-}
-        "#,
-        );
-    }
-
-    #[test]
-    fn test_fill_struct_fields_no_diagnostic_on_spread() {
-        check_no_diagnostics(
-            r#"
-struct TestStruct { one: i32, two: i64 }
-
-fn test_fn() {
-    let one = 1;
-    let s = TestStruct{ ..a };
-}
-"#,
-        );
-    }
-
-    #[test]
-    fn test_fill_struct_fields_blank_line() {
-        check_fix(
-            r#"
-struct S { a: (), b: () }
-
-fn f() {
-    S {
-        $0
-    };
-}
-"#,
-            r#"
-struct S { a: (), b: () }
-
-fn f() {
-    S {
-        a: (),
-        b: (),
-    };
-}
-"#,
-        );
-    }
-}
diff --git a/crates/ide/src/diagnostics/fixes/remove_semicolon.rs b/crates/ide/src/diagnostics/fixes/remove_semicolon.rs
deleted file mode 100644
index f1724d479..000000000
--- a/crates/ide/src/diagnostics/fixes/remove_semicolon.rs
+++ /dev/null
@@ -1,41 +0,0 @@
-use hir::{db::AstDatabase, diagnostics::RemoveThisSemicolon, Semantics};
-use ide_assists::{Assist, AssistResolveStrategy};
-use ide_db::{source_change::SourceChange, RootDatabase};
-use syntax::{ast, AstNode};
-use text_edit::TextEdit;
-
-use crate::diagnostics::{fix, DiagnosticWithFixes};
-
-impl DiagnosticWithFixes for RemoveThisSemicolon {
-    fn fixes(
-        &self,
-        sema: &Semantics<RootDatabase>,
-        _resolve: &AssistResolveStrategy,
-    ) -> Option<Vec<Assist>> {
-        let root = sema.db.parse_or_expand(self.file)?;
-
-        let semicolon = self
-            .expr
-            .to_node(&root)
-            .syntax()
-            .parent()
-            .and_then(ast::ExprStmt::cast)
-            .and_then(|expr| expr.semicolon_token())?
-            .text_range();
-
-        let edit = TextEdit::delete(semicolon);
-        let source_change = SourceChange::from_text_edit(self.file.original_file(sema.db), edit);
-
-        Some(vec![fix("remove_semicolon", "Remove this semicolon", source_change, semicolon)])
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::diagnostics::tests::check_fix;
-
-    #[test]
-    fn remove_semicolon() {
-        check_fix(r#"fn f() -> i32 { 92$0; }"#, r#"fn f() -> i32 { 92 }"#);
-    }
-}
diff --git a/crates/ide/src/diagnostics/fixes/replace_with_find_map.rs b/crates/ide/src/diagnostics/fixes/replace_with_find_map.rs
deleted file mode 100644
index 444bf563b..000000000
--- a/crates/ide/src/diagnostics/fixes/replace_with_find_map.rs
+++ /dev/null
@@ -1,84 +0,0 @@
-use hir::{db::AstDatabase, diagnostics::ReplaceFilterMapNextWithFindMap, Semantics};
-use ide_assists::{Assist, AssistResolveStrategy};
-use ide_db::{source_change::SourceChange, RootDatabase};
-use syntax::{
-    ast::{self, ArgListOwner},
-    AstNode, TextRange,
-};
-use text_edit::TextEdit;
-
-use crate::diagnostics::{fix, DiagnosticWithFixes};
-
-impl DiagnosticWithFixes for ReplaceFilterMapNextWithFindMap {
-    fn fixes(
-        &self,
-        sema: &Semantics<RootDatabase>,
-        _resolve: &AssistResolveStrategy,
-    ) -> Option<Vec<Assist>> {
-        let root = sema.db.parse_or_expand(self.file)?;
-        let next_expr = self.next_expr.to_node(&root);
-        let next_call = ast::MethodCallExpr::cast(next_expr.syntax().clone())?;
-
-        let filter_map_call = ast::MethodCallExpr::cast(next_call.receiver()?.syntax().clone())?;
-        let filter_map_name_range = filter_map_call.name_ref()?.ident_token()?.text_range();
-        let filter_map_args = filter_map_call.arg_list()?;
-
-        let range_to_replace =
-            TextRange::new(filter_map_name_range.start(), next_expr.syntax().text_range().end());
-        let replacement = format!("find_map{}", filter_map_args.syntax().text());
-        let trigger_range = next_expr.syntax().text_range();
-
-        let edit = TextEdit::replace(range_to_replace, replacement);
-
-        let source_change = SourceChange::from_text_edit(self.file.original_file(sema.db), edit);
-
-        Some(vec![fix(
-            "replace_with_find_map",
-            "Replace filter_map(..).next() with find_map()",
-            source_change,
-            trigger_range,
-        )])
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::diagnostics::tests::check_fix;
-
-    #[test]
-    fn replace_with_wind_map() {
-        check_fix(
-            r#"
-//- /main.rs crate:main deps:core
-use core::iter::Iterator;
-use core::option::Option::{self, Some, None};
-fn foo() {
-    let m = [1, 2, 3].iter().$0filter_map(|x| if *x == 2 { Some (4) } else { None }).next();
-}
-//- /core/lib.rs crate:core
-pub mod option {
-    pub enum Option<T> { Some(T), None }
-}
-pub mod iter {
-    pub trait Iterator {
-        type Item;
-        fn filter_map<B, F>(self, f: F) -> FilterMap where F: FnMut(Self::Item) -> Option<B> { FilterMap }
-        fn next(&mut self) -> Option<Self::Item>;
-    }
-    pub struct FilterMap {}
-    impl Iterator for FilterMap {
-        type Item = i32;
-        fn next(&mut self) -> i32 { 7 }
-    }
-}
-"#,
-            r#"
-use core::iter::Iterator;
-use core::option::Option::{self, Some, None};
-fn foo() {
-    let m = [1, 2, 3].iter().find_map(|x| if *x == 2 { Some (4) } else { None });
-}
-"#,
-        )
-    }
-}
diff --git a/crates/ide/src/diagnostics/inactive_code.rs b/crates/ide/src/diagnostics/inactive_code.rs
new file mode 100644
index 000000000..d9d3e88c1
--- /dev/null
+++ b/crates/ide/src/diagnostics/inactive_code.rs
@@ -0,0 +1,119 @@
+use cfg::DnfExpr;
+use stdx::format_to;
+
+use crate::{
+    diagnostics::{Diagnostic, DiagnosticsContext},
+    Severity,
+};
+
+// Diagnostic: inactive-code
+//
+// This diagnostic is shown for code with inactive `#[cfg]` attributes.
+pub(super) fn inactive_code(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::InactiveCode,
+) -> Option<Diagnostic> {
+    // If there's inactive code somewhere in a macro, don't propagate to the call-site.
+    if d.node.file_id.expansion_info(ctx.sema.db).is_some() {
+        return None;
+    }
+
+    let inactive = DnfExpr::new(d.cfg.clone()).why_inactive(&d.opts);
+    let mut message = "code is inactive due to #[cfg] directives".to_string();
+
+    if let Some(inactive) = inactive {
+        format_to!(message, ": {}", inactive);
+    }
+
+    let res = Diagnostic::new(
+        "inactive-code",
+        message,
+        ctx.sema.diagnostics_display_range(d.node.clone()).range,
+    )
+    .severity(Severity::WeakWarning)
+    .with_unused(true);
+    Some(res)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{diagnostics::tests::check_diagnostics_with_config, DiagnosticsConfig};
+
+    pub(crate) fn check(ra_fixture: &str) {
+        let config = DiagnosticsConfig::default();
+        check_diagnostics_with_config(config, ra_fixture)
+    }
+
+    #[test]
+    fn cfg_diagnostics() {
+        check(
+            r#"
+fn f() {
+    // The three g̶e̶n̶d̶e̶r̶s̶ statements:
+
+    #[cfg(a)] fn f() {}  // Item statement
+  //^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: a is disabled
+    #[cfg(a)] {}         // Expression statement
+  //^^^^^^^^^^^^ code is inactive due to #[cfg] directives: a is disabled
+    #[cfg(a)] let x = 0; // let statement
+  //^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: a is disabled
+
+    abc(#[cfg(a)] 0);
+      //^^^^^^^^^^^ code is inactive due to #[cfg] directives: a is disabled
+    let x = Struct {
+        #[cfg(a)] f: 0,
+      //^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: a is disabled
+    };
+    match () {
+        () => (),
+        #[cfg(a)] () => (),
+      //^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: a is disabled
+    }
+
+    #[cfg(a)] 0          // Trailing expression of block
+  //^^^^^^^^^^^ code is inactive due to #[cfg] directives: a is disabled
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn inactive_item() {
+        // Additional tests in `cfg` crate. This only tests disabled cfgs.
+
+        check(
+            r#"
+    #[cfg(no)] pub fn f() {}
+  //^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: no is disabled
+
+    #[cfg(no)] #[cfg(no2)] mod m;
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: no and no2 are disabled
+
+    #[cfg(all(not(a), b))] enum E {}
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: b is disabled
+
+    #[cfg(feature = "std")] use std;
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: feature = "std" is disabled
+"#,
+        );
+    }
+
+    /// Tests that `cfg` attributes behind `cfg_attr` is handled properly.
+    #[test]
+    fn inactive_via_cfg_attr() {
+        cov_mark::check!(cfg_attr_active);
+        check(
+            r#"
+    #[cfg_attr(not(never), cfg(no))] fn f() {}
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: no is disabled
+
+    #[cfg_attr(not(never), cfg(not(no)))] fn f() {}
+
+    #[cfg_attr(never, cfg(no))] fn g() {}
+
+    #[cfg_attr(not(never), inline, cfg(no))] fn h() {}
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ code is inactive due to #[cfg] directives: no is disabled
+"#,
+        );
+    }
+}
diff --git a/crates/ide/src/diagnostics/incorrect_case.rs b/crates/ide/src/diagnostics/incorrect_case.rs
new file mode 100644
index 000000000..832394400
--- /dev/null
+++ b/crates/ide/src/diagnostics/incorrect_case.rs
@@ -0,0 +1,488 @@
+use hir::{db::AstDatabase, InFile};
+use ide_assists::Assist;
+use ide_db::base_db::FilePosition;
+use syntax::AstNode;
+
+use crate::{
+    diagnostics::{unresolved_fix, Diagnostic, DiagnosticsContext},
+    references::rename::rename_with_semantics,
+    Severity,
+};
+
+// Diagnostic: incorrect-ident-case
+//
+// This diagnostic is triggered if an item name doesn't follow https://doc.rust-lang.org/1.0.0/style/style/naming/README.html[Rust naming convention].
+pub(super) fn incorrect_case(ctx: &DiagnosticsContext<'_>, d: &hir::IncorrectCase) -> Diagnostic {
+    Diagnostic::new(
+        "incorrect-ident-case",
+        format!(
+            "{} `{}` should have {} name, e.g. `{}`",
+            d.ident_type, d.ident_text, d.expected_case, d.suggested_text
+        ),
+        ctx.sema.diagnostics_display_range(InFile::new(d.file, d.ident.clone().into())).range,
+    )
+    .severity(Severity::WeakWarning)
+    .with_fixes(fixes(ctx, d))
+}
+
+fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::IncorrectCase) -> Option<Vec<Assist>> {
+    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 label = format!("Rename to {}", d.suggested_text);
+    let mut 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());
+    }
+
+    Some(vec![res])
+}
+
+#[cfg(test)]
+mod change_case {
+    use crate::{
+        diagnostics::tests::{check_diagnostics, check_fix},
+        fixture, AssistResolveStrategy, DiagnosticsConfig,
+    };
+
+    #[test]
+    fn test_rename_incorrect_case() {
+        check_fix(
+            r#"
+pub struct test_struct$0 { one: i32 }
+
+pub fn some_fn(val: test_struct) -> test_struct {
+    test_struct { one: val.one + 1 }
+}
+"#,
+            r#"
+pub struct TestStruct { one: i32 }
+
+pub fn some_fn(val: TestStruct) -> TestStruct {
+    TestStruct { one: val.one + 1 }
+}
+"#,
+        );
+
+        check_fix(
+            r#"
+pub fn some_fn(NonSnakeCase$0: u8) -> u8 {
+    NonSnakeCase
+}
+"#,
+            r#"
+pub fn some_fn(non_snake_case: u8) -> u8 {
+    non_snake_case
+}
+"#,
+        );
+
+        check_fix(
+            r#"
+pub fn SomeFn$0(val: u8) -> u8 {
+    if val != 0 { SomeFn(val - 1) } else { val }
+}
+"#,
+            r#"
+pub fn some_fn(val: u8) -> u8 {
+    if val != 0 { some_fn(val - 1) } else { val }
+}
+"#,
+        );
+
+        check_fix(
+            r#"
+fn some_fn() {
+    let whatAWeird_Formatting$0 = 10;
+    another_func(whatAWeird_Formatting);
+}
+"#,
+            r#"
+fn some_fn() {
+    let what_a_weird_formatting = 10;
+    another_func(what_a_weird_formatting);
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_uppercase_const_no_diagnostics() {
+        check_diagnostics(
+            r#"
+fn foo() {
+    const ANOTHER_ITEM$0: &str = "some_item";
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_rename_incorrect_case_struct_method() {
+        check_fix(
+            r#"
+pub struct TestStruct;
+
+impl TestStruct {
+    pub fn SomeFn$0() -> TestStruct {
+        TestStruct
+    }
+}
+"#,
+            r#"
+pub struct TestStruct;
+
+impl TestStruct {
+    pub fn some_fn() -> TestStruct {
+        TestStruct
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_single_incorrect_case_diagnostic_in_function_name_issue_6970() {
+        let input = r#"fn FOO$0() {}"#;
+        let expected = r#"fn foo() {}"#;
+
+        let (analysis, file_position) = fixture::position(input);
+        let diagnostics = analysis
+            .diagnostics(
+                &DiagnosticsConfig::default(),
+                AssistResolveStrategy::All,
+                file_position.file_id,
+            )
+            .unwrap();
+        assert_eq!(diagnostics.len(), 1);
+
+        check_fix(input, expected);
+    }
+
+    #[test]
+    fn incorrect_function_name() {
+        check_diagnostics(
+            r#"
+fn NonSnakeCaseName() {}
+// ^^^^^^^^^^^^^^^^ Function `NonSnakeCaseName` should have snake_case name, e.g. `non_snake_case_name`
+"#,
+        );
+    }
+
+    #[test]
+    fn incorrect_function_params() {
+        check_diagnostics(
+            r#"
+fn foo(SomeParam: u8) {}
+    // ^^^^^^^^^ Parameter `SomeParam` should have snake_case name, e.g. `some_param`
+
+fn foo2(ok_param: &str, CAPS_PARAM: u8) {}
+                     // ^^^^^^^^^^ Parameter `CAPS_PARAM` should have snake_case name, e.g. `caps_param`
+"#,
+        );
+    }
+
+    #[test]
+    fn incorrect_variable_names() {
+        check_diagnostics(
+            r#"
+fn foo() {
+    let SOME_VALUE = 10;
+     // ^^^^^^^^^^ Variable `SOME_VALUE` should have snake_case name, e.g. `some_value`
+    let AnotherValue = 20;
+     // ^^^^^^^^^^^^ Variable `AnotherValue` should have snake_case name, e.g. `another_value`
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn incorrect_struct_names() {
+        check_diagnostics(
+            r#"
+struct non_camel_case_name {}
+    // ^^^^^^^^^^^^^^^^^^^ Structure `non_camel_case_name` should have CamelCase name, e.g. `NonCamelCaseName`
+
+struct SCREAMING_CASE {}
+    // ^^^^^^^^^^^^^^ Structure `SCREAMING_CASE` should have CamelCase name, e.g. `ScreamingCase`
+"#,
+        );
+    }
+
+    #[test]
+    fn no_diagnostic_for_camel_cased_acronyms_in_struct_name() {
+        check_diagnostics(
+            r#"
+struct AABB {}
+"#,
+        );
+    }
+
+    #[test]
+    fn incorrect_struct_field() {
+        check_diagnostics(
+            r#"
+struct SomeStruct { SomeField: u8 }
+                 // ^^^^^^^^^ Field `SomeField` should have snake_case name, e.g. `some_field`
+"#,
+        );
+    }
+
+    #[test]
+    fn incorrect_enum_names() {
+        check_diagnostics(
+            r#"
+enum some_enum { Val(u8) }
+  // ^^^^^^^^^ Enum `some_enum` should have CamelCase name, e.g. `SomeEnum`
+
+enum SOME_ENUM {}
+  // ^^^^^^^^^ Enum `SOME_ENUM` should have CamelCase name, e.g. `SomeEnum`
+"#,
+        );
+    }
+
+    #[test]
+    fn no_diagnostic_for_camel_cased_acronyms_in_enum_name() {
+        check_diagnostics(
+            r#"
+enum AABB {}
+"#,
+        );
+    }
+
+    #[test]
+    fn incorrect_enum_variant_name() {
+        check_diagnostics(
+            r#"
+enum SomeEnum { SOME_VARIANT(u8) }
+             // ^^^^^^^^^^^^ Variant `SOME_VARIANT` should have CamelCase name, e.g. `SomeVariant`
+"#,
+        );
+    }
+
+    #[test]
+    fn incorrect_const_name() {
+        check_diagnostics(
+            r#"
+const some_weird_const: u8 = 10;
+   // ^^^^^^^^^^^^^^^^ Constant `some_weird_const` should have UPPER_SNAKE_CASE name, e.g. `SOME_WEIRD_CONST`
+"#,
+        );
+    }
+
+    #[test]
+    fn incorrect_static_name() {
+        check_diagnostics(
+            r#"
+static some_weird_const: u8 = 10;
+    // ^^^^^^^^^^^^^^^^ Static variable `some_weird_const` should have UPPER_SNAKE_CASE name, e.g. `SOME_WEIRD_CONST`
+"#,
+        );
+    }
+
+    #[test]
+    fn fn_inside_impl_struct() {
+        check_diagnostics(
+            r#"
+struct someStruct;
+    // ^^^^^^^^^^ Structure `someStruct` should have CamelCase name, e.g. `SomeStruct`
+
+impl someStruct {
+    fn SomeFunc(&self) {
+    // ^^^^^^^^ Function `SomeFunc` should have snake_case name, e.g. `some_func`
+        let WHY_VAR_IS_CAPS = 10;
+         // ^^^^^^^^^^^^^^^ Variable `WHY_VAR_IS_CAPS` should have snake_case name, e.g. `why_var_is_caps`
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn no_diagnostic_for_enum_varinats() {
+        check_diagnostics(
+            r#"
+enum Option { Some, None }
+
+fn main() {
+    match Option::None {
+        None => (),
+        Some => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn non_let_bind() {
+        check_diagnostics(
+            r#"
+enum Option { Some, None }
+
+fn main() {
+    match Option::None {
+        SOME_VAR @ None => (),
+     // ^^^^^^^^ Variable `SOME_VAR` should have snake_case name, e.g. `some_var`
+        Some => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn allow_attributes_crate_attr() {
+        check_diagnostics(
+            r#"
+#![allow(non_snake_case)]
+
+mod F {
+    fn CheckItWorksWithCrateAttr(BAD_NAME_HI: u8) {}
+}
+    "#,
+        );
+    }
+
+    #[test]
+    #[ignore]
+    fn bug_trait_inside_fn() {
+        // FIXME:
+        // This is broken, and in fact, should not even be looked at by this
+        // lint in the first place. There's weird stuff going on in the
+        // collection phase.
+        // It's currently being brought in by:
+        // * validate_func on `a` recursing into modules
+        // * then it finds the trait and then the function while iterating
+        //   through modules
+        // * then validate_func is called on Dirty
+        // * ... which then proceeds to look at some unknown module taking no
+        //   attrs from either the impl or the fn a, and then finally to the root
+        //   module
+        //
+        // It should find the attribute on the trait, but it *doesn't even see
+        // the trait* as far as I can tell.
+
+        check_diagnostics(
+            r#"
+trait T { fn a(); }
+struct U {}
+impl T for U {
+    fn a() {
+        // this comes out of bitflags, mostly
+        #[allow(non_snake_case)]
+        trait __BitFlags {
+            const HiImAlsoBad: u8 = 2;
+            #[inline]
+            fn Dirty(&self) -> bool {
+                false
+            }
+        }
+
+    }
+}
+    "#,
+        );
+    }
+
+    #[test]
+    fn infinite_loop_inner_items() {
+        check_diagnostics(
+            r#"
+fn qualify() {
+    mod foo {
+        use super::*;
+    }
+}
+            "#,
+        )
+    }
+
+    #[test] // Issue #8809.
+    fn parenthesized_parameter() {
+        check_diagnostics(r#"fn f((O): _) {}"#)
+    }
+
+    #[test]
+    fn ignores_extern_items() {
+        cov_mark::check!(extern_func_incorrect_case_ignored);
+        cov_mark::check!(extern_static_incorrect_case_ignored);
+        check_diagnostics(
+            r#"
+extern {
+    fn NonSnakeCaseName(SOME_VAR: u8) -> u8;
+    pub static SomeStatic: u8 = 10;
+}
+            "#,
+        );
+    }
+
+    #[test]
+    #[ignore]
+    fn bug_traits_arent_checked() {
+        // FIXME: Traits and functions in traits aren't currently checked by
+        // r-a, even though rustc will complain about them.
+        check_diagnostics(
+            r#"
+trait BAD_TRAIT {
+    // ^^^^^^^^^ Trait `BAD_TRAIT` should have CamelCase name, e.g. `BadTrait`
+    fn BAD_FUNCTION();
+    // ^^^^^^^^^^^^ Function `BAD_FUNCTION` should have snake_case name, e.g. `bad_function`
+    fn BadFunction();
+    // ^^^^^^^^^^^^ Function `BadFunction` should have snake_case name, e.g. `bad_function`
+}
+    "#,
+        );
+    }
+
+    #[test]
+    fn allow_attributes() {
+        check_diagnostics(
+            r#"
+#[allow(non_snake_case)]
+fn NonSnakeCaseName(SOME_VAR: u8) -> u8{
+    // cov_flags generated output from elsewhere in this file
+    extern "C" {
+        #[no_mangle]
+        static lower_case: u8;
+    }
+
+    let OtherVar = SOME_VAR + 1;
+    OtherVar
+}
+
+#[allow(nonstandard_style)]
+mod CheckNonstandardStyle {
+    fn HiImABadFnName() {}
+}
+
+#[allow(bad_style)]
+mod CheckBadStyle {
+    fn HiImABadFnName() {}
+}
+
+mod F {
+    #![allow(non_snake_case)]
+    fn CheckItWorksWithModAttr(BAD_NAME_HI: u8) {}
+}
+
+#[allow(non_snake_case, non_camel_case_types)]
+pub struct some_type {
+    SOME_FIELD: u8,
+    SomeField: u16,
+}
+
+#[allow(non_upper_case_globals)]
+pub const some_const: u8 = 10;
+
+#[allow(non_upper_case_globals)]
+pub static SomeStatic: u8 = 10;
+    "#,
+        );
+    }
+}
diff --git a/crates/ide/src/diagnostics/macro_error.rs b/crates/ide/src/diagnostics/macro_error.rs
new file mode 100644
index 000000000..5f97f190d
--- /dev/null
+++ b/crates/ide/src/diagnostics/macro_error.rs
@@ -0,0 +1,173 @@
+use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+
+// Diagnostic: macro-error
+//
+// This diagnostic is shown for macro expansion errors.
+pub(super) fn macro_error(ctx: &DiagnosticsContext<'_>, d: &hir::MacroError) -> Diagnostic {
+    Diagnostic::new(
+        "macro-error",
+        d.message.clone(),
+        ctx.sema.diagnostics_display_range(d.node.clone()).range,
+    )
+    .experimental()
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::{
+        diagnostics::tests::{check_diagnostics, check_diagnostics_with_config},
+        DiagnosticsConfig,
+    };
+
+    #[test]
+    fn builtin_macro_fails_expansion() {
+        check_diagnostics(
+            r#"
+#[rustc_builtin_macro]
+macro_rules! include { () => {} }
+
+  include!("doesntexist");
+//^^^^^^^^^^^^^^^^^^^^^^^^ failed to load file `doesntexist`
+            "#,
+        );
+    }
+
+    #[test]
+    fn include_macro_should_allow_empty_content() {
+        let mut config = DiagnosticsConfig::default();
+
+        // FIXME: This is a false-positive, the file is actually linked in via
+        // `include!` macro
+        config.disabled.insert("unlinked-file".to_string());
+
+        check_diagnostics_with_config(
+            config,
+            r#"
+//- /lib.rs
+#[rustc_builtin_macro]
+macro_rules! include { () => {} }
+
+include!("foo/bar.rs");
+//- /foo/bar.rs
+// empty
+"#,
+        );
+    }
+
+    #[test]
+    fn good_out_dir_diagnostic() {
+        check_diagnostics(
+            r#"
+#[rustc_builtin_macro]
+macro_rules! include { () => {} }
+#[rustc_builtin_macro]
+macro_rules! env { () => {} }
+#[rustc_builtin_macro]
+macro_rules! concat { () => {} }
+
+  include!(concat!(env!("OUT_DIR"), "/out.rs"));
+//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `OUT_DIR` not set, enable "run build scripts" to fix
+"#,
+        );
+    }
+
+    #[test]
+    fn register_attr_and_tool() {
+        cov_mark::check!(register_attr);
+        cov_mark::check!(register_tool);
+        check_diagnostics(
+            r#"
+#![register_tool(tool)]
+#![register_attr(attr)]
+
+#[tool::path]
+#[attr]
+struct S;
+"#,
+        );
+        // NB: we don't currently emit diagnostics here
+    }
+
+    #[test]
+    fn macro_diag_builtin() {
+        check_diagnostics(
+            r#"
+#[rustc_builtin_macro]
+macro_rules! env {}
+
+#[rustc_builtin_macro]
+macro_rules! include {}
+
+#[rustc_builtin_macro]
+macro_rules! compile_error {}
+
+#[rustc_builtin_macro]
+macro_rules! format_args { () => {} }
+
+fn main() {
+    // Test a handful of built-in (eager) macros:
+
+    include!(invalid);
+  //^^^^^^^^^^^^^^^^^ could not convert tokens
+    include!("does not exist");
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^ failed to load file `does not exist`
+
+    env!(invalid);
+  //^^^^^^^^^^^^^ could not convert tokens
+
+    env!("OUT_DIR");
+  //^^^^^^^^^^^^^^^ `OUT_DIR` not set, enable "run build scripts" to fix
+
+    compile_error!("compile_error works");
+  //^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ compile_error works
+
+    // Lazy:
+
+    format_args!();
+  //^^^^^^^^^^^^^^ no rule matches input tokens
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn macro_rules_diag() {
+        check_diagnostics(
+            r#"
+macro_rules! m {
+    () => {};
+}
+fn f() {
+    m!();
+
+    m!(hi);
+  //^^^^^^ leftover tokens
+}
+      "#,
+        );
+    }
+    #[test]
+    fn dollar_crate_in_builtin_macro() {
+        check_diagnostics(
+            r#"
+#[macro_export]
+#[rustc_builtin_macro]
+macro_rules! format_args {}
+
+#[macro_export]
+macro_rules! arg { () => {} }
+
+#[macro_export]
+macro_rules! outer {
+    () => {
+        $crate::format_args!( "", $crate::arg!(1) )
+    };
+}
+
+fn f() {
+    outer!();
+} //^^^^^^^^ leftover tokens
+"#,
+        )
+    }
+}
diff --git a/crates/ide/src/diagnostics/mismatched_arg_count.rs b/crates/ide/src/diagnostics/mismatched_arg_count.rs
new file mode 100644
index 000000000..08e1cfa5f
--- /dev/null
+++ b/crates/ide/src/diagnostics/mismatched_arg_count.rs
@@ -0,0 +1,272 @@
+use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+
+// Diagnostic: mismatched-arg-count
+//
+// This diagnostic is triggered if a function is invoked with an incorrect amount of arguments.
+pub(super) fn mismatched_arg_count(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::MismatchedArgCount,
+) -> Diagnostic {
+    let s = if d.expected == 1 { "" } else { "s" };
+    let message = format!("expected {} argument{}, found {}", d.expected, s, d.found);
+    Diagnostic::new(
+        "mismatched-arg-count",
+        message,
+        ctx.sema.diagnostics_display_range(d.call_expr.clone().map(|it| it.into())).range,
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostics::tests::check_diagnostics;
+
+    #[test]
+    fn simple_free_fn_zero() {
+        check_diagnostics(
+            r#"
+fn zero() {}
+fn f() { zero(1); }
+       //^^^^^^^ expected 0 arguments, found 1
+"#,
+        );
+
+        check_diagnostics(
+            r#"
+fn zero() {}
+fn f() { zero(); }
+"#,
+        );
+    }
+
+    #[test]
+    fn simple_free_fn_one() {
+        check_diagnostics(
+            r#"
+fn one(arg: u8) {}
+fn f() { one(); }
+       //^^^^^ expected 1 argument, found 0
+"#,
+        );
+
+        check_diagnostics(
+            r#"
+fn one(arg: u8) {}
+fn f() { one(1); }
+"#,
+        );
+    }
+
+    #[test]
+    fn method_as_fn() {
+        check_diagnostics(
+            r#"
+struct S;
+impl S { fn method(&self) {} }
+
+fn f() {
+    S::method();
+} //^^^^^^^^^^^ expected 1 argument, found 0
+"#,
+        );
+
+        check_diagnostics(
+            r#"
+struct S;
+impl S { fn method(&self) {} }
+
+fn f() {
+    S::method(&S);
+    S.method();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn method_with_arg() {
+        check_diagnostics(
+            r#"
+struct S;
+impl S { fn method(&self, arg: u8) {} }
+
+            fn f() {
+                S.method();
+            } //^^^^^^^^^^ expected 1 argument, found 0
+            "#,
+        );
+
+        check_diagnostics(
+            r#"
+struct S;
+impl S { fn method(&self, arg: u8) {} }
+
+fn f() {
+    S::method(&S, 0);
+    S.method(1);
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn method_unknown_receiver() {
+        // note: this is incorrect code, so there might be errors on this in the
+        // future, but we shouldn't emit an argument count diagnostic here
+        check_diagnostics(
+            r#"
+trait Foo { fn method(&self, arg: usize) {} }
+
+fn f() {
+    let x;
+    x.method();
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn tuple_struct() {
+        check_diagnostics(
+            r#"
+struct Tup(u8, u16);
+fn f() {
+    Tup(0);
+} //^^^^^^ expected 2 arguments, found 1
+"#,
+        )
+    }
+
+    #[test]
+    fn enum_variant() {
+        check_diagnostics(
+            r#"
+enum En { Variant(u8, u16), }
+fn f() {
+    En::Variant(0);
+} //^^^^^^^^^^^^^^ expected 2 arguments, found 1
+"#,
+        )
+    }
+
+    #[test]
+    fn enum_variant_type_macro() {
+        check_diagnostics(
+            r#"
+macro_rules! Type {
+    () => { u32 };
+}
+enum Foo {
+    Bar(Type![])
+}
+impl Foo {
+    fn new() {
+        Foo::Bar(0);
+        Foo::Bar(0, 1);
+      //^^^^^^^^^^^^^^ expected 1 argument, found 2
+        Foo::Bar();
+      //^^^^^^^^^^ expected 1 argument, found 0
+    }
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn varargs() {
+        check_diagnostics(
+            r#"
+extern "C" {
+    fn fixed(fixed: u8);
+    fn varargs(fixed: u8, ...);
+    fn varargs2(...);
+}
+
+fn f() {
+    unsafe {
+        fixed(0);
+        fixed(0, 1);
+      //^^^^^^^^^^^ expected 1 argument, found 2
+        varargs(0);
+        varargs(0, 1);
+        varargs2();
+        varargs2(0);
+        varargs2(0, 1);
+    }
+}
+        "#,
+        )
+    }
+
+    #[test]
+    fn arg_count_lambda() {
+        check_diagnostics(
+            r#"
+fn main() {
+    let f = |()| ();
+    f();
+  //^^^ expected 1 argument, found 0
+    f(());
+    f((), ());
+  //^^^^^^^^^ expected 1 argument, found 2
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn cfgd_out_call_arguments() {
+        check_diagnostics(
+            r#"
+struct C(#[cfg(FALSE)] ());
+impl C {
+    fn new() -> Self {
+        Self(
+            #[cfg(FALSE)]
+            (),
+        )
+    }
+
+    fn method(&self) {}
+}
+
+fn main() {
+    C::new().method(#[cfg(FALSE)] 0);
+}
+            "#,
+        );
+    }
+
+    #[test]
+    fn cfgd_out_fn_params() {
+        check_diagnostics(
+            r#"
+fn foo(#[cfg(NEVER)] x: ()) {}
+
+struct S;
+
+impl S {
+    fn method(#[cfg(NEVER)] self) {}
+    fn method2(#[cfg(NEVER)] self, arg: u8) {}
+    fn method3(self, #[cfg(NEVER)] arg: u8) {}
+}
+
+extern "C" {
+    fn fixed(fixed: u8, #[cfg(NEVER)] ...);
+    fn varargs(#[cfg(not(NEVER))] ...);
+}
+
+fn main() {
+    foo();
+    S::method();
+    S::method2(0);
+    S::method3(S);
+    S.method3();
+    unsafe {
+        fixed(0);
+        varargs(1, 2, 3);
+    }
+}
+            "#,
+        )
+    }
+}
diff --git a/crates/ide/src/diagnostics/missing_fields.rs b/crates/ide/src/diagnostics/missing_fields.rs
new file mode 100644
index 000000000..d01f05041
--- /dev/null
+++ b/crates/ide/src/diagnostics/missing_fields.rs
@@ -0,0 +1,327 @@
+use either::Either;
+use hir::{db::AstDatabase, InFile};
+use ide_assists::Assist;
+use ide_db::source_change::SourceChange;
+use stdx::format_to;
+use syntax::{algo, ast::make, AstNode, SyntaxNodePtr};
+use text_edit::TextEdit;
+
+use crate::diagnostics::{fix, Diagnostic, DiagnosticsContext};
+
+// Diagnostic: missing-fields
+//
+// This diagnostic is triggered if record lacks some fields that exist in the corresponding structure.
+//
+// Example:
+//
+// ```rust
+// struct A { a: u8, b: u8 }
+//
+// let a = A { a: 10 };
+// ```
+pub(super) fn missing_fields(ctx: &DiagnosticsContext<'_>, d: &hir::MissingFields) -> Diagnostic {
+    let mut message = String::from("Missing structure fields:\n");
+    for field in &d.missed_fields {
+        format_to!(message, "- {}\n", field);
+    }
+
+    let ptr = InFile::new(
+        d.file,
+        d.field_list_parent_path
+            .clone()
+            .map(SyntaxNodePtr::from)
+            .unwrap_or_else(|| d.field_list_parent.clone().either(|it| it.into(), |it| it.into())),
+    );
+
+    Diagnostic::new("missing-fields", message, ctx.sema.diagnostics_display_range(ptr).range)
+        .with_fixes(fixes(ctx, d))
+}
+
+fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::MissingFields) -> Option<Vec<Assist>> {
+    // Note that although we could add a diagnostics to
+    // fill the missing tuple field, e.g :
+    // `struct A(usize);`
+    // `let a = A { 0: () }`
+    // but it is uncommon usage and it should not be encouraged.
+    if d.missed_fields.iter().any(|it| it.as_tuple_index().is_some()) {
+        return None;
+    }
+
+    let root = ctx.sema.db.parse_or_expand(d.file)?;
+    let field_list_parent = match &d.field_list_parent {
+        Either::Left(record_expr) => record_expr.to_node(&root),
+        // FIXE: patterns should be fixable as well.
+        Either::Right(_) => return None,
+    };
+    let old_field_list = field_list_parent.record_expr_field_list()?;
+    let new_field_list = old_field_list.clone_for_update();
+    for f in d.missed_fields.iter() {
+        let field =
+            make::record_expr_field(make::name_ref(&f.to_string()), Some(make::expr_unit()))
+                .clone_for_update();
+        new_field_list.add_field(field);
+    }
+
+    let edit = {
+        let mut builder = TextEdit::builder();
+        algo::diff(old_field_list.syntax(), new_field_list.syntax()).into_text_edit(&mut builder);
+        builder.finish()
+    };
+    Some(vec![fix(
+        "fill_missing_fields",
+        "Fill struct fields",
+        SourceChange::from_text_edit(d.file.original_file(ctx.sema.db), edit),
+        ctx.sema.original_range(field_list_parent.syntax()).range,
+    )])
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostics::tests::{check_diagnostics, check_fix};
+
+    #[test]
+    fn missing_record_pat_field_diagnostic() {
+        check_diagnostics(
+            r#"
+struct S { foo: i32, bar: () }
+fn baz(s: S) {
+    let S { foo: _ } = s;
+      //^ Missing structure fields:
+      //| - bar
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn missing_record_pat_field_no_diagnostic_if_not_exhaustive() {
+        check_diagnostics(
+            r"
+struct S { foo: i32, bar: () }
+fn baz(s: S) -> i32 {
+    match s {
+        S { foo, .. } => foo,
+    }
+}
+",
+        )
+    }
+
+    #[test]
+    fn missing_record_pat_field_box() {
+        check_diagnostics(
+            r"
+struct S { s: Box<u32> }
+fn x(a: S) {
+    let S { box s } = a;
+}
+",
+        )
+    }
+
+    #[test]
+    fn missing_record_pat_field_ref() {
+        check_diagnostics(
+            r"
+struct S { s: u32 }
+fn x(a: S) {
+    let S { ref s } = a;
+}
+",
+        )
+    }
+
+    #[test]
+    fn range_mapping_out_of_macros() {
+        // FIXME: this is very wrong, but somewhat tricky to fix.
+        check_fix(
+            r#"
+fn some() {}
+fn items() {}
+fn here() {}
+
+macro_rules! id { ($($tt:tt)*) => { $($tt)*}; }
+
+fn main() {
+    let _x = id![Foo { a: $042 }];
+}
+
+pub struct Foo { pub a: i32, pub b: i32 }
+"#,
+            r#"
+fn some(, b: () ) {}
+fn items() {}
+fn here() {}
+
+macro_rules! id { ($($tt:tt)*) => { $($tt)*}; }
+
+fn main() {
+    let _x = id![Foo { a: 42 }];
+}
+
+pub struct Foo { pub a: i32, pub b: i32 }
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_empty() {
+        check_fix(
+            r#"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let s = TestStruct {$0};
+}
+"#,
+            r#"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let s = TestStruct { one: (), two: () };
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_self() {
+        check_fix(
+            r#"
+struct TestStruct { one: i32 }
+
+impl TestStruct {
+    fn test_fn() { let s = Self {$0}; }
+}
+"#,
+            r#"
+struct TestStruct { one: i32 }
+
+impl TestStruct {
+    fn test_fn() { let s = Self { one: () }; }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_enum() {
+        check_fix(
+            r#"
+enum Expr {
+    Bin { lhs: Box<Expr>, rhs: Box<Expr> }
+}
+
+impl Expr {
+    fn new_bin(lhs: Box<Expr>, rhs: Box<Expr>) -> Expr {
+        Expr::Bin {$0 }
+    }
+}
+"#,
+            r#"
+enum Expr {
+    Bin { lhs: Box<Expr>, rhs: Box<Expr> }
+}
+
+impl Expr {
+    fn new_bin(lhs: Box<Expr>, rhs: Box<Expr>) -> Expr {
+        Expr::Bin { lhs: (), rhs: () }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_partial() {
+        check_fix(
+            r#"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let s = TestStruct{ two: 2$0 };
+}
+"#,
+            r"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let s = TestStruct{ two: 2, one: () };
+}
+",
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_raw_ident() {
+        check_fix(
+            r#"
+struct TestStruct { r#type: u8 }
+
+fn test_fn() {
+    TestStruct { $0 };
+}
+"#,
+            r"
+struct TestStruct { r#type: u8 }
+
+fn test_fn() {
+    TestStruct { r#type: ()  };
+}
+",
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_no_diagnostic() {
+        check_diagnostics(
+            r#"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let one = 1;
+    let s = TestStruct{ one, two: 2 };
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_no_diagnostic_on_spread() {
+        check_diagnostics(
+            r#"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let one = 1;
+    let s = TestStruct{ ..a };
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_blank_line() {
+        check_fix(
+            r#"
+struct S { a: (), b: () }
+
+fn f() {
+    S {
+        $0
+    };
+}
+"#,
+            r#"
+struct S { a: (), b: () }
+
+fn f() {
+    S {
+        a: (),
+        b: (),
+    };
+}
+"#,
+        );
+    }
+}
diff --git a/crates/ide/src/diagnostics/missing_match_arms.rs b/crates/ide/src/diagnostics/missing_match_arms.rs
new file mode 100644
index 000000000..b636489b3
--- /dev/null
+++ b/crates/ide/src/diagnostics/missing_match_arms.rs
@@ -0,0 +1,929 @@
+use hir::InFile;
+
+use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+
+// Diagnostic: missing-match-arm
+//
+// This diagnostic is triggered if `match` block is missing one or more match arms.
+pub(super) fn missing_match_arms(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::MissingMatchArms,
+) -> Diagnostic {
+    Diagnostic::new(
+        "missing-match-arm",
+        "missing match arm",
+        ctx.sema.diagnostics_display_range(InFile::new(d.file, d.match_expr.clone().into())).range,
+    )
+}
+
+#[cfg(test)]
+pub(super) mod tests {
+    use crate::diagnostics::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)
+    }
+
+    #[test]
+    fn empty_tuple() {
+        check_diagnostics_no_bails(
+            r#"
+fn main() {
+    match () { }
+        //^^ missing match arm
+    match (()) { }
+        //^^^^ missing match arm
+
+    match () { _ => (), }
+    match () { () => (), }
+    match (()) { (()) => (), }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn tuple_of_two_empty_tuple() {
+        check_diagnostics_no_bails(
+            r#"
+fn main() {
+    match ((), ()) { }
+        //^^^^^^^^ missing match arm
+
+    match ((), ()) { ((), ()) => (), }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn boolean() {
+        check_diagnostics_no_bails(
+            r#"
+fn test_main() {
+    match false { }
+        //^^^^^ missing match arm
+    match false { true => (), }
+        //^^^^^ missing match arm
+    match (false, true) {}
+        //^^^^^^^^^^^^^ missing match arm
+    match (false, true) { (true, true) => (), }
+        //^^^^^^^^^^^^^ missing match arm
+    match (false, true) {
+        //^^^^^^^^^^^^^ missing match arm
+        (false, true) => (),
+        (false, false) => (),
+        (true, false) => (),
+    }
+    match (false, true) { (true, _x) => (), }
+        //^^^^^^^^^^^^^ missing match arm
+
+    match false { true => (), false => (), }
+    match (false, true) {
+        (false, _) => (),
+        (true, false) => (),
+        (_, true) => (),
+    }
+    match (false, true) {
+        (true, true) => (),
+        (true, false) => (),
+        (false, true) => (),
+        (false, false) => (),
+    }
+    match (false, true) {
+        (true, _x) => (),
+        (false, true) => (),
+        (false, false) => (),
+    }
+    match (false, true, false) {
+        (false, ..) => (),
+        (true, ..) => (),
+    }
+    match (false, true, false) {
+        (.., false) => (),
+        (.., true) => (),
+    }
+    match (false, true, false) { (..) => (), }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn tuple_of_tuple_and_bools() {
+        check_diagnostics_no_bails(
+            r#"
+fn main() {
+    match (false, ((), false)) {}
+        //^^^^^^^^^^^^^^^^^^^^ missing match arm
+    match (false, ((), false)) { (true, ((), true)) => (), }
+        //^^^^^^^^^^^^^^^^^^^^ missing match arm
+    match (false, ((), false)) { (true, _) => (), }
+        //^^^^^^^^^^^^^^^^^^^^ missing match arm
+
+    match (false, ((), false)) {
+        (true, ((), true)) => (),
+        (true, ((), false)) => (),
+        (false, ((), true)) => (),
+        (false, ((), false)) => (),
+    }
+    match (false, ((), false)) {
+        (true, ((), true)) => (),
+        (true, ((), false)) => (),
+        (false, _) => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn enums() {
+        check_diagnostics_no_bails(
+            r#"
+enum Either { A, B, }
+
+fn main() {
+    match Either::A { }
+        //^^^^^^^^^ missing match arm
+    match Either::B { Either::A => (), }
+        //^^^^^^^^^ missing match arm
+
+    match &Either::B {
+        //^^^^^^^^^^ missing match arm
+        Either::A => (),
+    }
+
+    match Either::B {
+        Either::A => (), Either::B => (),
+    }
+    match &Either::B {
+        Either::A => (), Either::B => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn enum_containing_bool() {
+        check_diagnostics_no_bails(
+            r#"
+enum Either { A(bool), B }
+
+fn main() {
+    match Either::B { }
+        //^^^^^^^^^ missing match arm
+    match Either::B {
+        //^^^^^^^^^ missing match arm
+        Either::A(true) => (), Either::B => ()
+    }
+
+    match Either::B {
+        Either::A(true) => (),
+        Either::A(false) => (),
+        Either::B => (),
+    }
+    match Either::B {
+        Either::B => (),
+        _ => (),
+    }
+    match Either::B {
+        Either::A(_) => (),
+        Either::B => (),
+    }
+
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn enum_different_sizes() {
+        check_diagnostics_no_bails(
+            r#"
+enum Either { A(bool), B(bool, bool) }
+
+fn main() {
+    match Either::A(false) {
+        //^^^^^^^^^^^^^^^^ missing match arm
+        Either::A(_) => (),
+        Either::B(false, _) => (),
+    }
+
+    match Either::A(false) {
+        Either::A(_) => (),
+        Either::B(true, _) => (),
+        Either::B(false, _) => (),
+    }
+    match Either::A(false) {
+        Either::A(true) | Either::A(false) => (),
+        Either::B(true, _) => (),
+        Either::B(false, _) => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn tuple_of_enum_no_diagnostic() {
+        check_diagnostics_no_bails(
+            r#"
+enum Either { A(bool), B(bool, bool) }
+enum Either2 { C, D }
+
+fn main() {
+    match (Either::A(false), Either2::C) {
+        (Either::A(true), _) | (Either::A(false), _) => (),
+        (Either::B(true, _), Either2::C) => (),
+        (Either::B(false, _), Either2::C) => (),
+        (Either::B(_, _), Either2::D) => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn or_pattern_no_diagnostic() {
+        check_diagnostics_no_bails(
+            r#"
+enum Either {A, B}
+
+fn main() {
+    match (Either::A, Either::B) {
+        (Either::A | Either::B, _) => (),
+    }
+}"#,
+        )
+    }
+
+    #[test]
+    fn mismatched_types() {
+        cov_mark::check_count!(validate_match_bailed_out, 4);
+        // Match statements with arms that don't match the
+        // expression pattern do not fire this diagnostic.
+        check_diagnostics(
+            r#"
+enum Either { A, B }
+enum Either2 { C, D }
+
+fn main() {
+    match Either::A {
+        Either2::C => (),
+        Either2::D => (),
+    }
+    match (true, false) {
+        (true, false, true) => (),
+        (true) => (),
+    }
+    match (true, false) { (true,) => {} }
+    match (0) { () => () }
+    match Unresolved::Bar { Unresolved::Baz => () }
+}
+        "#,
+        );
+    }
+
+    #[test]
+    fn mismatched_types_in_or_patterns() {
+        cov_mark::check_count!(validate_match_bailed_out, 2);
+        check_diagnostics(
+            r#"
+fn main() {
+    match false { true | () => {} }
+    match (false,) { (true | (),) => {} }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn malformed_match_arm_tuple_enum_missing_pattern() {
+        // We are testing to be sure we don't panic here when the match
+        // arm `Either::B` is missing its pattern.
+        check_diagnostics_no_bails(
+            r#"
+enum Either { A, B(u32) }
+
+fn main() {
+    match Either::A {
+        Either::A => (),
+        Either::B() => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn malformed_match_arm_extra_fields() {
+        cov_mark::check_count!(validate_match_bailed_out, 2);
+        check_diagnostics(
+            r#"
+enum A { B(isize, isize), C }
+fn main() {
+    match A::B(1, 2) {
+        A::B(_, _, _) => (),
+    }
+    match A::B(1, 2) {
+        A::C(_) => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn expr_diverges() {
+        cov_mark::check_count!(validate_match_bailed_out, 2);
+        check_diagnostics(
+            r#"
+enum Either { A, B }
+
+fn main() {
+    match loop {} {
+        Either::A => (),
+        Either::B => (),
+    }
+    match loop {} {
+        Either::A => (),
+    }
+    match loop { break Foo::A } {
+        //^^^^^^^^^^^^^^^^^^^^^ missing match arm
+        Either::A => (),
+    }
+    match loop { break Foo::A } {
+        Either::A => (),
+        Either::B => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn expr_partially_diverges() {
+        check_diagnostics_no_bails(
+            r#"
+enum Either<T> { A(T), B }
+
+fn foo() -> Either<!> { Either::B }
+fn main() -> u32 {
+    match foo() {
+        Either::A(val) => val,
+        Either::B => 0,
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn enum_record() {
+        check_diagnostics_no_bails(
+            r#"
+enum Either { A { foo: bool }, B }
+
+fn main() {
+    let a = Either::A { foo: true };
+    match a { }
+        //^ missing match arm
+    match a { Either::A { foo: true } => () }
+        //^ missing match arm
+    match a {
+        Either::A { } => (),
+      //^^^^^^^^^ Missing structure fields:
+      //        | - foo
+        Either::B => (),
+    }
+    match a {
+        //^ missing match arm
+        Either::A { } => (),
+    } //^^^^^^^^^ Missing structure fields:
+      //        | - foo
+
+    match a {
+        Either::A { foo: true } => (),
+        Either::A { foo: false } => (),
+        Either::B => (),
+    }
+    match a {
+        Either::A { foo: _ } => (),
+        Either::B => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn enum_record_fields_out_of_order() {
+        check_diagnostics_no_bails(
+            r#"
+enum Either {
+    A { foo: bool, bar: () },
+    B,
+}
+
+fn main() {
+    let a = Either::A { foo: true, bar: () };
+    match a {
+        //^ missing match arm
+        Either::A { bar: (), foo: false } => (),
+        Either::A { foo: true, bar: () } => (),
+    }
+
+    match a {
+        Either::A { bar: (), foo: false } => (),
+        Either::A { foo: true, bar: () } => (),
+        Either::B => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn enum_record_ellipsis() {
+        check_diagnostics_no_bails(
+            r#"
+enum Either {
+    A { foo: bool, bar: bool },
+    B,
+}
+
+fn main() {
+    let a = Either::B;
+    match a {
+        //^ missing match arm
+        Either::A { foo: true, .. } => (),
+        Either::B => (),
+    }
+    match a {
+        //^ missing match arm
+        Either::A { .. } => (),
+    }
+
+    match a {
+        Either::A { foo: true, .. } => (),
+        Either::A { foo: false, .. } => (),
+        Either::B => (),
+    }
+
+    match a {
+        Either::A { .. } => (),
+        Either::B => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn enum_tuple_partial_ellipsis() {
+        check_diagnostics_no_bails(
+            r#"
+enum Either {
+    A(bool, bool, bool, bool),
+    B,
+}
+
+fn main() {
+    match Either::B {
+        //^^^^^^^^^ missing match arm
+        Either::A(true, .., true) => (),
+        Either::A(true, .., false) => (),
+        Either::A(false, .., false) => (),
+        Either::B => (),
+    }
+    match Either::B {
+        //^^^^^^^^^ missing match arm
+        Either::A(true, .., true) => (),
+        Either::A(true, .., false) => (),
+        Either::A(.., true) => (),
+        Either::B => (),
+    }
+
+    match Either::B {
+        Either::A(true, .., true) => (),
+        Either::A(true, .., false) => (),
+        Either::A(false, .., true) => (),
+        Either::A(false, .., false) => (),
+        Either::B => (),
+    }
+    match Either::B {
+        Either::A(true, .., true) => (),
+        Either::A(true, .., false) => (),
+        Either::A(.., true) => (),
+        Either::A(.., false) => (),
+        Either::B => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn never() {
+        check_diagnostics_no_bails(
+            r#"
+enum Never {}
+
+fn enum_(never: Never) {
+    match never {}
+}
+fn enum_ref(never: &Never) {
+    match never {}
+        //^^^^^ missing match arm
+}
+fn bang(never: !) {
+    match never {}
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn unknown_type() {
+        cov_mark::check_count!(validate_match_bailed_out, 1);
+
+        check_diagnostics(
+            r#"
+enum Option<T> { Some(T), None }
+
+fn main() {
+    // `Never` is deliberately not defined so that it's an uninferred type.
+    match Option::<Never>::None {
+        None => (),
+        Some(never) => match never {},
+    }
+    match Option::<Never>::None {
+        //^^^^^^^^^^^^^^^^^^^^^ missing match arm
+        Option::Some(_never) => {},
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn tuple_of_bools_with_ellipsis_at_end_missing_arm() {
+        check_diagnostics_no_bails(
+            r#"
+fn main() {
+    match (false, true, false) {
+        //^^^^^^^^^^^^^^^^^^^^ missing match arm
+        (false, ..) => (),
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn tuple_of_bools_with_ellipsis_at_beginning_missing_arm() {
+        check_diagnostics_no_bails(
+            r#"
+fn main() {
+    match (false, true, false) {
+        //^^^^^^^^^^^^^^^^^^^^ missing match arm
+        (.., false) => (),
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn tuple_of_bools_with_ellipsis_in_middle_missing_arm() {
+        check_diagnostics_no_bails(
+            r#"
+fn main() {
+    match (false, true, false) {
+        //^^^^^^^^^^^^^^^^^^^^ missing match arm
+        (true, .., false) => (),
+    }
+}"#,
+        );
+    }
+
+    #[test]
+    fn record_struct() {
+        check_diagnostics_no_bails(
+            r#"struct Foo { a: bool }
+fn main(f: Foo) {
+    match f {}
+        //^ missing match arm
+    match f { Foo { a: true } => () }
+        //^ missing match arm
+    match &f { Foo { a: true } => () }
+        //^^ missing match arm
+    match f { Foo { a: _ } => () }
+    match f {
+        Foo { a: true } => (),
+        Foo { a: false } => (),
+    }
+    match &f {
+        Foo { a: true } => (),
+        Foo { a: false } => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn tuple_struct() {
+        check_diagnostics_no_bails(
+            r#"struct Foo(bool);
+fn main(f: Foo) {
+    match f {}
+        //^ missing match arm
+    match f { Foo(true) => () }
+        //^ missing match arm
+    match f {
+        Foo(true) => (),
+        Foo(false) => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn unit_struct() {
+        check_diagnostics_no_bails(
+            r#"struct Foo;
+fn main(f: Foo) {
+    match f {}
+        //^ missing match arm
+    match f { Foo => () }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn record_struct_ellipsis() {
+        check_diagnostics_no_bails(
+            r#"struct Foo { foo: bool, bar: bool }
+fn main(f: Foo) {
+    match f { Foo { foo: true, .. } => () }
+        //^ missing match arm
+    match f {
+        //^ missing match arm
+        Foo { foo: true, .. } => (),
+        Foo { bar: false, .. } => ()
+    }
+    match f { Foo { .. } => () }
+    match f {
+        Foo { foo: true, .. } => (),
+        Foo { foo: false, .. } => ()
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn internal_or() {
+        check_diagnostics_no_bails(
+            r#"
+fn main() {
+    enum Either { A(bool), B }
+    match Either::B {
+        //^^^^^^^^^ missing match arm
+        Either::A(true | false) => (),
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn no_panic_at_unimplemented_subpattern_type() {
+        cov_mark::check_count!(validate_match_bailed_out, 1);
+
+        check_diagnostics(
+            r#"
+struct S { a: char}
+fn main(v: S) {
+    match v { S{ a }      => {} }
+    match v { S{ a: _x }  => {} }
+    match v { S{ a: 'a' } => {} }
+    match v { S{..}       => {} }
+    match v { _           => {} }
+    match v { }
+        //^ missing match arm
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn binding() {
+        check_diagnostics_no_bails(
+            r#"
+fn main() {
+    match true {
+        _x @ true => {}
+        false     => {}
+    }
+    match true { _x @ true => {} }
+        //^^^^ missing match arm
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn binding_ref_has_correct_type() {
+        cov_mark::check_count!(validate_match_bailed_out, 1);
+
+        // Asserts `PatKind::Binding(ref _x): bool`, not &bool.
+        // If that's not true match checking will panic with "incompatible constructors"
+        // FIXME: make facilities to test this directly like `tests::check_infer(..)`
+        check_diagnostics(
+            r#"
+enum Foo { A }
+fn main() {
+    // FIXME: this should not bail out but current behavior is such as the old algorithm.
+    // ExprValidator::validate_match(..) checks types of top level patterns incorrecly.
+    match Foo::A {
+        ref _x => {}
+        Foo::A => {}
+    }
+    match (true,) {
+        (ref _x,) => {}
+        (true,) => {}
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn enum_non_exhaustive() {
+        check_diagnostics_no_bails(
+            r#"
+//- /lib.rs crate:lib
+#[non_exhaustive]
+pub enum E { A, B }
+fn _local() {
+    match E::A { _ => {} }
+    match E::A {
+        E::A => {}
+        E::B => {}
+    }
+    match E::A {
+        E::A | E::B => {}
+    }
+}
+
+//- /main.rs crate:main deps:lib
+use lib::E;
+fn main() {
+    match E::A { _ => {} }
+    match E::A {
+        //^^^^ missing match arm
+        E::A => {}
+        E::B => {}
+    }
+    match E::A {
+        //^^^^ missing match arm
+        E::A | E::B => {}
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn match_guard() {
+        check_diagnostics_no_bails(
+            r#"
+fn main() {
+    match true {
+        true if false => {}
+        true          => {}
+        false         => {}
+    }
+    match true {
+        //^^^^ missing match arm
+        true if false => {}
+        false         => {}
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn pattern_type_is_of_substitution() {
+        cov_mark::check!(match_check_wildcard_expanded_to_substitutions);
+        check_diagnostics_no_bails(
+            r#"
+struct Foo<T>(T);
+struct Bar;
+fn main() {
+    match Foo(Bar) {
+        _ | Foo(Bar) => {}
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn record_struct_no_such_field() {
+        cov_mark::check_count!(validate_match_bailed_out, 1);
+
+        check_diagnostics(
+            r#"
+struct Foo { }
+fn main(f: Foo) {
+    match f { Foo { bar } => () }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn match_ergonomics_issue_9095() {
+        check_diagnostics_no_bails(
+            r#"
+enum Foo<T> { A(T) }
+fn main() {
+    match &Foo::A(true) {
+        _ => {}
+        Foo::A(_) => {}
+    }
+}
+"#,
+        );
+    }
+
+    mod false_negatives {
+        //! The implementation of match checking here is a work in progress. As we roll this out, we
+        //! prefer false negatives to false positives (ideally there would be no false positives). This
+        //! test module should document known false negatives. Eventually we will have a complete
+        //! implementation of match checking and this module will be empty.
+        //!
+        //! The reasons for documenting known false negatives:
+        //!
+        //!   1. It acts as a backlog of work that can be done to improve the behavior of the system.
+        //!   2. It ensures the code doesn't panic when handling these cases.
+        use super::*;
+
+        #[test]
+        fn integers() {
+            cov_mark::check_count!(validate_match_bailed_out, 1);
+
+            // We don't currently check integer exhaustiveness.
+            check_diagnostics(
+                r#"
+fn main() {
+    match 5 {
+        10 => (),
+        11..20 => (),
+    }
+}
+"#,
+            );
+        }
+
+        #[test]
+        fn reference_patterns_at_top_level() {
+            cov_mark::check_count!(validate_match_bailed_out, 1);
+
+            check_diagnostics(
+                r#"
+fn main() {
+    match &false {
+        &true => {}
+    }
+}
+            "#,
+            );
+        }
+
+        #[test]
+        fn reference_patterns_in_fields() {
+            cov_mark::check_count!(validate_match_bailed_out, 2);
+
+            check_diagnostics(
+                r#"
+fn main() {
+    match (&false,) {
+        (true,) => {}
+    }
+    match (&false,) {
+        (&true,) => {}
+    }
+}
+            "#,
+            );
+        }
+    }
+}
diff --git a/crates/ide/src/diagnostics/fixes/wrap_tail_expr.rs b/crates/ide/src/diagnostics/missing_ok_or_some_in_tail_expr.rs
index 715a403b9..06005d156 100644
--- a/crates/ide/src/diagnostics/fixes/wrap_tail_expr.rs
+++ b/crates/ide/src/diagnostics/missing_ok_or_some_in_tail_expr.rs
@@ -1,31 +1,50 @@
-use hir::{db::AstDatabase, diagnostics::MissingOkOrSomeInTailExpr, Semantics};
-use ide_assists::{Assist, AssistResolveStrategy};
-use ide_db::{source_change::SourceChange, RootDatabase};
+use hir::db::AstDatabase;
+use ide_assists::Assist;
+use ide_db::source_change::SourceChange;
 use syntax::AstNode;
 use text_edit::TextEdit;
 
-use crate::diagnostics::{fix, DiagnosticWithFixes};
-
-impl DiagnosticWithFixes for MissingOkOrSomeInTailExpr {
-    fn fixes(
-        &self,
-        sema: &Semantics<RootDatabase>,
-        _resolve: &AssistResolveStrategy,
-    ) -> Option<Vec<Assist>> {
-        let root = sema.db.parse_or_expand(self.file)?;
-        let tail_expr = self.expr.to_node(&root);
-        let tail_expr_range = tail_expr.syntax().text_range();
-        let replacement = format!("{}({})", self.required, tail_expr.syntax());
-        let edit = TextEdit::replace(tail_expr_range, replacement);
-        let source_change = SourceChange::from_text_edit(self.file.original_file(sema.db), edit);
-        let name = if self.required == "Ok" { "Wrap with Ok" } else { "Wrap with Some" };
-        Some(vec![fix("wrap_tail_expr", name, source_change, tail_expr_range)])
-    }
+use crate::diagnostics::{fix, Diagnostic, DiagnosticsContext};
+
+// Diagnostic: missing-ok-or-some-in-tail-expr
+//
+// This diagnostic is triggered if a block that should return `Result` returns a value not wrapped in `Ok`,
+// or if a block that should return `Option` returns a value not wrapped in `Some`.
+//
+// Example:
+//
+// ```rust
+// fn foo() -> Result<u8, ()> {
+//     10
+// }
+// ```
+pub(super) fn missing_ok_or_some_in_tail_expr(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::MissingOkOrSomeInTailExpr,
+) -> Diagnostic {
+    Diagnostic::new(
+        "missing-ok-or-some-in-tail-expr",
+        format!("wrap return expression in {}", d.required),
+        ctx.sema.diagnostics_display_range(d.expr.clone().map(|it| it.into())).range,
+    )
+    .with_fixes(fixes(ctx, d))
+}
+
+fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::MissingOkOrSomeInTailExpr) -> Option<Vec<Assist>> {
+    let root = ctx.sema.db.parse_or_expand(d.expr.file_id)?;
+    let tail_expr = d.expr.value.to_node(&root);
+    let tail_expr_range = tail_expr.syntax().text_range();
+    let replacement = format!("{}({})", d.required, tail_expr.syntax());
+    let edit = TextEdit::replace(tail_expr_range, replacement);
+    let source_change =
+        SourceChange::from_text_edit(d.expr.file_id.original_file(ctx.sema.db), edit);
+    let name = if d.required == "Ok" { "Wrap with Ok" } else { "Wrap with Some" };
+    Some(vec![fix("wrap_tail_expr", name, source_change, tail_expr_range)])
 }
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::{check_fix, check_no_diagnostics};
+    use crate::diagnostics::tests::{check_diagnostics, check_fix};
 
     #[test]
     fn test_wrap_return_type_option() {
@@ -169,7 +188,7 @@ fn div(x: i32, y: i32) -> MyResult<i32> {
 
     #[test]
     fn test_wrap_return_type_not_applicable_when_expr_type_does_not_match_ok_type() {
-        check_no_diagnostics(
+        check_diagnostics(
             r#"
 //- /main.rs crate:main deps:core
 use core::result::Result::{self, Ok, Err};
@@ -189,7 +208,7 @@ pub mod option {
 
     #[test]
     fn test_wrap_return_type_not_applicable_when_return_type_is_not_result_or_option() {
-        check_no_diagnostics(
+        check_diagnostics(
             r#"
 //- /main.rs crate:main deps:core
 use core::result::Result::{self, Ok, Err};
diff --git a/crates/ide/src/diagnostics/missing_unsafe.rs b/crates/ide/src/diagnostics/missing_unsafe.rs
new file mode 100644
index 000000000..5c47e8d0a
--- /dev/null
+++ b/crates/ide/src/diagnostics/missing_unsafe.rs
@@ -0,0 +1,101 @@
+use crate::diagnostics::{Diagnostic, DiagnosticsContext};
+
+// Diagnostic: missing-unsafe
+//
+// This diagnostic is triggered if an operation marked as `unsafe` is used outside of an `unsafe` function or block.
+pub(super) fn missing_unsafe(ctx: &DiagnosticsContext<'_>, d: &hir::MissingUnsafe) -> Diagnostic {
+    Diagnostic::new(
+        "missing-unsafe",
+        "this operation is unsafe and requires an unsafe function or block",
+        ctx.sema.diagnostics_display_range(d.expr.clone().map(|it| it.into())).range,
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostics::tests::check_diagnostics;
+
+    #[test]
+    fn missing_unsafe_diagnostic_with_raw_ptr() {
+        check_diagnostics(
+            r#"
+fn main() {
+    let x = &5 as *const usize;
+    unsafe { let y = *x; }
+    let z = *x;
+}         //^^ this operation is unsafe and requires an unsafe function or block
+"#,
+        )
+    }
+
+    #[test]
+    fn missing_unsafe_diagnostic_with_unsafe_call() {
+        check_diagnostics(
+            r#"
+struct HasUnsafe;
+
+impl HasUnsafe {
+    unsafe fn unsafe_fn(&self) {
+        let x = &5 as *const usize;
+        let y = *x;
+    }
+}
+
+unsafe fn unsafe_fn() {
+    let x = &5 as *const usize;
+    let y = *x;
+}
+
+fn main() {
+    unsafe_fn();
+  //^^^^^^^^^^^ this operation is unsafe and requires an unsafe function or block
+    HasUnsafe.unsafe_fn();
+  //^^^^^^^^^^^^^^^^^^^^^ this operation is unsafe and requires an unsafe function or block
+    unsafe {
+        unsafe_fn();
+        HasUnsafe.unsafe_fn();
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn missing_unsafe_diagnostic_with_static_mut() {
+        check_diagnostics(
+            r#"
+struct Ty {
+    a: u8,
+}
+
+static mut STATIC_MUT: Ty = Ty { a: 0 };
+
+fn main() {
+    let x = STATIC_MUT.a;
+          //^^^^^^^^^^ this operation is unsafe and requires an unsafe function or block
+    unsafe {
+        let x = STATIC_MUT.a;
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn no_missing_unsafe_diagnostic_with_safe_intrinsic() {
+        check_diagnostics(
+            r#"
+extern "rust-intrinsic" {
+    pub fn bitreverse(x: u32) -> u32; // Safe intrinsic
+    pub fn floorf32(x: f32) -> f32; // Unsafe intrinsic
+}
+
+fn main() {
+    let _ = bitreverse(12);
+    let _ = floorf32(12.0);
+          //^^^^^^^^^^^^^^ this operation is unsafe and requires an unsafe function or block
+}
+"#,
+        );
+    }
+}
diff --git a/crates/ide/src/diagnostics/fixes/create_field.rs b/crates/ide/src/diagnostics/no_such_field.rs
index a5f457dce..edc63c246 100644
--- a/crates/ide/src/diagnostics/fixes/create_field.rs
+++ b/crates/ide/src/diagnostics/no_such_field.rs
@@ -1,4 +1,4 @@
-use hir::{db::AstDatabase, diagnostics::NoSuchField, HasSource, HirDisplay, Semantics};
+use hir::{db::AstDatabase, HasSource, HirDisplay, Semantics};
 use ide_db::{base_db::FileId, source_change::SourceChange, RootDatabase};
 use syntax::{
     ast::{self, edit::IndentLevel, make},
@@ -7,22 +7,29 @@ use syntax::{
 use text_edit::TextEdit;
 
 use crate::{
-    diagnostics::{fix, DiagnosticWithFixes},
-    Assist, AssistResolveStrategy,
+    diagnostics::{fix, Diagnostic, DiagnosticsContext},
+    Assist,
 };
-impl DiagnosticWithFixes for NoSuchField {
-    fn fixes(
-        &self,
-        sema: &Semantics<RootDatabase>,
-        _resolve: &AssistResolveStrategy,
-    ) -> Option<Vec<Assist>> {
-        let root = sema.db.parse_or_expand(self.file)?;
-        missing_record_expr_field_fixes(
-            &sema,
-            self.file.original_file(sema.db),
-            &self.field.to_node(&root),
-        )
-    }
+
+// Diagnostic: no-such-field
+//
+// This diagnostic is triggered if created structure does not have field provided in record.
+pub(super) fn no_such_field(ctx: &DiagnosticsContext<'_>, d: &hir::NoSuchField) -> Diagnostic {
+    Diagnostic::new(
+        "no-such-field",
+        "no such field",
+        ctx.sema.diagnostics_display_range(d.field.clone().map(|it| it.into())).range,
+    )
+    .with_fixes(fixes(ctx, d))
+}
+
+fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::NoSuchField) -> Option<Vec<Assist>> {
+    let root = ctx.sema.db.parse_or_expand(d.field.file_id)?;
+    missing_record_expr_field_fixes(
+        &ctx.sema,
+        d.field.file_id.original_file(ctx.sema.db),
+        &d.field.value.to_node(&root),
+    )
 }
 
 fn missing_record_expr_field_fixes(
@@ -105,7 +112,130 @@ fn missing_record_expr_field_fixes(
 
 #[cfg(test)]
 mod tests {
-    use crate::diagnostics::tests::check_fix;
+    use crate::diagnostics::tests::{check_diagnostics, check_fix};
+
+    #[test]
+    fn no_such_field_diagnostics() {
+        check_diagnostics(
+            r#"
+struct S { foo: i32, bar: () }
+impl S {
+    fn new() -> S {
+        S {
+      //^ Missing structure fields:
+      //|    - bar
+            foo: 92,
+            baz: 62,
+          //^^^^^^^ no such field
+        }
+    }
+}
+"#,
+        );
+    }
+    #[test]
+    fn no_such_field_with_feature_flag_diagnostics() {
+        check_diagnostics(
+            r#"
+//- /lib.rs crate:foo cfg:feature=foo
+struct MyStruct {
+    my_val: usize,
+    #[cfg(feature = "foo")]
+    bar: bool,
+}
+
+impl MyStruct {
+    #[cfg(feature = "foo")]
+    pub(crate) fn new(my_val: usize, bar: bool) -> Self {
+        Self { my_val, bar }
+    }
+    #[cfg(not(feature = "foo"))]
+    pub(crate) fn new(my_val: usize, _bar: bool) -> Self {
+        Self { my_val }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn no_such_field_enum_with_feature_flag_diagnostics() {
+        check_diagnostics(
+            r#"
+//- /lib.rs crate:foo cfg:feature=foo
+enum Foo {
+    #[cfg(not(feature = "foo"))]
+    Buz,
+    #[cfg(feature = "foo")]
+    Bar,
+    Baz
+}
+
+fn test_fn(f: Foo) {
+    match f {
+        Foo::Bar => {},
+        Foo::Baz => {},
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn no_such_field_with_feature_flag_diagnostics_on_struct_lit() {
+        check_diagnostics(
+            r#"
+//- /lib.rs crate:foo cfg:feature=foo
+struct S {
+    #[cfg(feature = "foo")]
+    foo: u32,
+    #[cfg(not(feature = "foo"))]
+    bar: u32,
+}
+
+impl S {
+    #[cfg(feature = "foo")]
+    fn new(foo: u32) -> Self {
+        Self { foo }
+    }
+    #[cfg(not(feature = "foo"))]
+    fn new(bar: u32) -> Self {
+        Self { bar }
+    }
+    fn new2(bar: u32) -> Self {
+        #[cfg(feature = "foo")]
+        { Self { foo: bar } }
+        #[cfg(not(feature = "foo"))]
+        { Self { bar } }
+    }
+    fn new2(val: u32) -> Self {
+        Self {
+            #[cfg(feature = "foo")]
+            foo: val,
+            #[cfg(not(feature = "foo"))]
+            bar: val,
+        }
+    }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn no_such_field_with_type_macro() {
+        check_diagnostics(
+            r#"
+macro_rules! Type { () => { u32 }; }
+struct Foo { bar: Type![] }
+
+impl Foo {
+    fn new() -> Self {
+        Foo { bar: 0 }
+    }
+}
+"#,
+        );
+    }
 
     #[test]
     fn test_add_field_from_usage() {
diff --git a/crates/ide/src/diagnostics/remove_this_semicolon.rs b/crates/ide/src/diagnostics/remove_this_semicolon.rs
new file mode 100644
index 000000000..814cb0f8c
--- /dev/null
+++ b/crates/ide/src/diagnostics/remove_this_semicolon.rs
@@ -0,0 +1,64 @@
+use hir::db::AstDatabase;
+use ide_db::source_change::SourceChange;
+use syntax::{ast, AstNode};
+use text_edit::TextEdit;
+
+use crate::{
+    diagnostics::{fix, Diagnostic, DiagnosticsContext},
+    Assist,
+};
+
+// Diagnostic: remove-this-semicolon
+//
+// This diagnostic is triggered when there's an erroneous `;` at the end of the block.
+pub(super) fn remove_this_semicolon(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::RemoveThisSemicolon,
+) -> Diagnostic {
+    Diagnostic::new(
+        "remove-this-semicolon",
+        "remove this semicolon",
+        ctx.sema.diagnostics_display_range(d.expr.clone().map(|it| it.into())).range,
+    )
+    .with_fixes(fixes(ctx, d))
+}
+
+fn fixes(ctx: &DiagnosticsContext<'_>, d: &hir::RemoveThisSemicolon) -> Option<Vec<Assist>> {
+    let root = ctx.sema.db.parse_or_expand(d.expr.file_id)?;
+
+    let semicolon = d
+        .expr
+        .value
+        .to_node(&root)
+        .syntax()
+        .parent()
+        .and_then(ast::ExprStmt::cast)
+        .and_then(|expr| expr.semicolon_token())?
+        .text_range();
+
+    let edit = TextEdit::delete(semicolon);
+    let source_change =
+        SourceChange::from_text_edit(d.expr.file_id.original_file(ctx.sema.db), edit);
+
+    Some(vec![fix("remove_semicolon", "Remove this semicolon", source_change, semicolon)])
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostics::tests::{check_diagnostics, check_fix};
+
+    #[test]
+    fn missing_semicolon() {
+        check_diagnostics(
+            r#"
+fn test() -> i32 { 123; }
+                 //^^^ remove this semicolon
+"#,
+        );
+    }
+
+    #[test]
+    fn remove_semicolon() {
+        check_fix(r#"fn f() -> i32 { 92$0; }"#, r#"fn f() -> i32 { 92 }"#);
+    }
+}
diff --git a/crates/ide/src/diagnostics/replace_filter_map_next_with_find_map.rs b/crates/ide/src/diagnostics/replace_filter_map_next_with_find_map.rs
new file mode 100644
index 000000000..f3b011495
--- /dev/null
+++ b/crates/ide/src/diagnostics/replace_filter_map_next_with_find_map.rs
@@ -0,0 +1,182 @@
+use hir::{db::AstDatabase, InFile};
+use ide_db::source_change::SourceChange;
+use syntax::{
+    ast::{self, ArgListOwner},
+    AstNode, TextRange,
+};
+use text_edit::TextEdit;
+
+use crate::{
+    diagnostics::{fix, Diagnostic, DiagnosticsContext},
+    Assist, Severity,
+};
+
+// Diagnostic: replace-filter-map-next-with-find-map
+//
+// This diagnostic is triggered when `.filter_map(..).next()` is used, rather than the more concise `.find_map(..)`.
+pub(super) fn replace_filter_map_next_with_find_map(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::ReplaceFilterMapNextWithFindMap,
+) -> Diagnostic {
+    Diagnostic::new(
+        "replace-filter-map-next-with-find-map",
+        "replace filter_map(..).next() with find_map(..)",
+        ctx.sema.diagnostics_display_range(InFile::new(d.file, d.next_expr.clone().into())).range,
+    )
+    .severity(Severity::WeakWarning)
+    .with_fixes(fixes(ctx, d))
+}
+
+fn fixes(
+    ctx: &DiagnosticsContext<'_>,
+    d: &hir::ReplaceFilterMapNextWithFindMap,
+) -> Option<Vec<Assist>> {