4 files changed, 534 insertions, 585 deletions

diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
index f084f7b06..7978c1fc2 100644
--- a/crates/ide/src/diagnostics.rs
+++ b/crates/ide/src/diagnostics.rs
@@ -16,20 +16,19 @@ mod no_such_field;
 mod remove_this_semicolon;
 mod replace_filter_map_next_with_find_map;
 mod unimplemented_builtin_macro;
+mod unlinked_file;
 mod unresolved_extern_crate;
 mod unresolved_import;
 mod unresolved_macro_call;
 mod unresolved_module;
 mod unresolved_proc_macro;
 
-mod fixes;
 mod field_shorthand;
-mod unlinked_file;
 
 use std::cell::RefCell;
 
 use hir::{
-    diagnostics::{AnyDiagnostic, Diagnostic as _, DiagnosticCode, DiagnosticSinkBuilder},
+    diagnostics::{AnyDiagnostic, DiagnosticCode, DiagnosticSinkBuilder},
     Semantics,
 };
 use ide_assists::AssistResolveStrategy;
@@ -38,15 +37,13 @@ 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(Debug)]
 pub struct Diagnostic {
     // pub name: Option<String>,
@@ -165,19 +162,6 @@ pub(crate) fn diagnostics(
     }
     let res = RefCell::new(res);
     let sink_builder = DiagnosticSinkBuilder::new()
-        .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())),
-            );
-        })
         // 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()));
@@ -197,11 +181,9 @@ pub(crate) fn diagnostics(
 
     let mut diags = Vec::new();
     let internal_diagnostics = cfg!(test);
-    match sema.to_module_def(file_id) {
-        Some(m) => diags = m.diagnostics(db, &mut sink, internal_diagnostics),
-        None => {
-            sink.push(UnlinkedFile { file_id, node: SyntaxNodePtr::new(parse.tree().syntax()) });
-        }
+    let module = sema.to_module_def(file_id);
+    if let Some(m) = module {
+        diags = m.diagnostics(db, &mut sink, internal_diagnostics)
     }
 
     drop(sink);
@@ -209,6 +191,12 @@ pub(crate) fn diagnostics(
     let mut res = 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)
+    }
+
     for diag in diags {
         #[rustfmt::skip]
         let d = match diag {
@@ -234,16 +222,20 @@ pub(crate) fn diagnostics(
                 None => continue,
             }
         };
+        res.push(d)
+    }
+
+    res.retain(|d| {
         if let Some(code) = d.code {
             if ctx.config.disabled.contains(code.as_str()) {
-                continue;
+                return false;
             }
         }
         if ctx.config.disable_experimental && d.experimental {
-            continue;
+            return false;
         }
-        res.push(d)
-    }
+        true
+    });
 
     res
 }
@@ -378,8 +370,9 @@ 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(
@@ -524,142 +517,6 @@ 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
-
-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
-"#,
-            r#"
-mod foo;
-"#,
-        );
-    }
-
-    #[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;
-
-//- /foo.rs
-$0
-"#,
-        );
-    }
-
-    #[test]
-    fn unlinked_file_with_cfg_on() {
-        check_diagnostics(
-            r#"
-//- /main.rs
-#[cfg(not(never))]
-mod foo;
-
-//- /foo.rs
-"#,
-        );
-    }
-
-    #[test]
     fn import_extern_crate_clash_with_inner_item() {
         // This is more of a resolver test, but doesn't really work with the hir_def testsuite.
 
@@ -1595,330 +1452,3 @@ fn main() {
         }
     }
 }
-
-#[cfg(test)]
-mod decl_check_tests {
-    use crate::diagnostics::tests::check_diagnostics;
-
-    #[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() {
-        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;
-    "#,
-        );
-    }
-
-    #[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]
-    #[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 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]
-    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): _) {}"#)
-    }
-}
diff --git a/crates/ide/src/diagnostics/fixes.rs b/crates/ide/src/diagnostics/fixes.rs
deleted file mode 100644
index d763dca93..000000000
--- a/crates/ide/src/diagnostics/fixes.rs
+++ /dev/null
@@ -1,24 +0,0 @@
-//! Provides a way to attach fixes to the diagnostics.
-//! The same module also has all curret custom fixes for the diagnostics implemented.
-
-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/incorrect_case.rs b/crates/ide/src/diagnostics/incorrect_case.rs
index 56283b58b..832394400 100644
--- a/crates/ide/src/diagnostics/incorrect_case.rs
+++ b/crates/ide/src/diagnostics/incorrect_case.rs
@@ -163,4 +163,326 @@ impl TestStruct {
 
         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/unlinked_file.rs b/crates/ide/src/diagnostics/unlinked_file.rs
index 51fe0f360..a5b2e3399 100644
--- a/crates/ide/src/diagnostics/unlinked_file.rs
+++ b/crates/ide/src/diagnostics/unlinked_file.rs
@@ -1,11 +1,6 @@
 //! Diagnostic emitted for files that aren't part of any crate.
 
-use hir::{
-    db::DefDatabase,
-    diagnostics::{Diagnostic, DiagnosticCode},
-    InFile,
-};
-use ide_assists::AssistResolveStrategy;
+use hir::db::DefDatabase;
 use ide_db::{
     base_db::{FileId, FileLoader, SourceDatabase, SourceDatabaseExt},
     source_change::SourceChange,
@@ -13,92 +8,77 @@ use ide_db::{
 };
 use syntax::{
     ast::{self, ModuleItemOwner, NameOwner},
-    AstNode, SyntaxNodePtr,
+    AstNode, TextRange, TextSize,
 };
 use text_edit::TextEdit;
 
 use crate::{
-    diagnostics::{fix, fixes::DiagnosticWithFixes},
-    Assist,
+    diagnostics::{fix, DiagnosticsContext},
+    Assist, Diagnostic,
 };
 
+#[derive(Debug)]
+pub(crate) struct UnlinkedFile {
+    pub(crate) file: FileId,
+}
+
 // Diagnostic: unlinked-file
 //
 // This diagnostic is shown for files that are not included in any crate, or files that are part of
 // crates rust-analyzer failed to discover. The file will not have IDE features available.
-#[derive(Debug)]
-pub(crate) struct UnlinkedFile {
-    pub(crate) file_id: FileId,
-    pub(crate) node: SyntaxNodePtr,
+pub(super) fn unlinked_file(ctx: &DiagnosticsContext, d: &UnlinkedFile) -> Diagnostic {
+    // 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 = ctx.sema.db.parse(d.file).syntax_node().text_range();
+    // FIXME: This is wrong if one of the first three characters is not ascii: `//Ы`.
+    let range = range.intersect(TextRange::up_to(TextSize::of("..."))).unwrap_or(range);
+
+    Diagnostic::new("unlinked-file", "file not included in module tree", range)
+        .with_fixes(fixes(ctx, d))
 }
 
-impl Diagnostic for UnlinkedFile {
-    fn code(&self) -> DiagnosticCode {
-        DiagnosticCode("unlinked-file")
-    }
+fn fixes(ctx: &DiagnosticsContext, d: &UnlinkedFile) -> Option<Vec<Assist>> {
+    // If there's an existing module that could add `mod` or `pub mod` items to include the unlinked file,
+    // suggest that as a fix.
 
-    fn message(&self) -> String {
-        "file not included in module tree".to_string()
-    }
+    let source_root = ctx.sema.db.source_root(ctx.sema.db.file_source_root(d.file));
+    let our_path = source_root.path_for_file(&d.file)?;
+    let module_name = our_path.name_and_extension()?.0;
 
-    fn display_source(&self) -> InFile<SyntaxNodePtr> {
-        InFile::new(self.file_id.into(), self.node.clone())
-    }
+    // Candidates to look for:
+    // - `mod.rs` in the same folder
+    //   - we also check `main.rs` and `lib.rs`
+    // - `$dir.rs` in the parent folder, where `$dir` is the directory containing `self.file_id`
+    let parent = our_path.parent()?;
+    let mut paths = vec![parent.join("mod.rs")?, parent.join("lib.rs")?, parent.join("main.rs")?];
 
-    fn as_any(&self) -> &(dyn std::any::Any + Send + 'static) {
-        self
+    // `submod/bla.rs` -> `submod.rs`
+    if let Some(newmod) = (|| {
+        let name = parent.name_and_extension()?.0;
+        parent.parent()?.join(&format!("{}.rs", name))
+    })() {
+        paths.push(newmod);
     }
-}
 
-impl DiagnosticWithFixes for UnlinkedFile {
-    fn fixes(
-        &self,
-        sema: &hir::Semantics<RootDatabase>,
-        _resolve: &AssistResolveStrategy,
-    ) -> Option<Vec<Assist>> {
-        // If there's an existing module that could add `mod` or `pub mod` items to include the unlinked file,
-        // suggest that as a fix.
-
-        let source_root = sema.db.source_root(sema.db.file_source_root(self.file_id));
-        let our_path = source_root.path_for_file(&self.file_id)?;
-        let module_name = our_path.name_and_extension()?.0;
-
-        // Candidates to look for:
-        // - `mod.rs` in the same folder
-        //   - we also check `main.rs` and `lib.rs`
-        // - `$dir.rs` in the parent folder, where `$dir` is the directory containing `self.file_id`
-        let parent = our_path.parent()?;
-        let mut paths =
-            vec![parent.join("mod.rs")?, parent.join("lib.rs")?, parent.join("main.rs")?];
-
-        // `submod/bla.rs` -> `submod.rs`
-        if let Some(newmod) = (|| {
-            let name = parent.name_and_extension()?.0;
-            parent.parent()?.join(&format!("{}.rs", name))
-        })() {
-            paths.push(newmod);
-        }
+    for path in &paths {
+        if let Some(parent_id) = source_root.file_for_path(path) {
+            for krate in ctx.sema.db.relevant_crates(*parent_id).iter() {
+                let crate_def_map = ctx.sema.db.crate_def_map(*krate);
+                for (_, module) in crate_def_map.modules() {
+                    if module.origin.is_inline() {
+                        // We don't handle inline `mod parent {}`s, they use different paths.
+                        continue;
+                    }
 
-        for path in &paths {
-            if let Some(parent_id) = source_root.file_for_path(path) {
-                for krate in sema.db.relevant_crates(*parent_id).iter() {
-                    let crate_def_map = sema.db.crate_def_map(*krate);
-                    for (_, module) in crate_def_map.modules() {
-                        if module.origin.is_inline() {
-                            // We don't handle inline `mod parent {}`s, they use different paths.
-                            continue;
-                        }
-
-                        if module.origin.file_id() == Some(*parent_id) {
-                            return make_fixes(sema.db, *parent_id, module_name, self.file_id);
-                        }
+                    if module.origin.file_id() == Some(*parent_id) {
+                        return make_fixes(ctx.sema.db, *parent_id, module_name, d.file);
                     }
                 }
             }
         }
-
-        None
     }
+
+    None
 }
 
 fn make_fixes(
@@ -181,3 +161,144 @@ fn make_fixes(
         ),
     ])
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::diagnostics::tests::{check_diagnostics, check_fix, check_fixes, check_no_fix};
+
+    #[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
+
+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
+"#,
+            r#"
+mod foo;
+"#,
+        );
+    }
+
+    #[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;
+
+//- /foo.rs
+$0
+"#,
+        );
+    }
+
+    #[test]
+    fn unlinked_file_with_cfg_on() {
+        check_diagnostics(
+            r#"
+//- /main.rs
+#[cfg(not(never))]
+mod foo;
+
+//- /foo.rs
+"#,
+        );
+    }
+}