1 files changed, 530 insertions, 0 deletions

diff --git a/crates/ide_diagnostics/src/lib.rs b/crates/ide_diagnostics/src/lib.rs
new file mode 100644
index 000000000..88037be5a
--- /dev/null
+++ b/crates/ide_diagnostics/src/lib.rs
@@ -0,0 +1,530 @@
+//! Diagnostics rendering and fixits.
+//!
+//! Most of the diagnostics originate from the dark depth of the compiler, and
+//! are originally expressed in term of IR. When we emit the diagnostic, we are
+//! usually not in the position to decide how to best "render" it in terms of
+//! user-authored source code. We are especially not in the position to offer
+//! fixits, as the compiler completely lacks the infrastructure to edit the
+//! source code.
+//!
+//! Instead, we "bubble up" raw, structured diagnostics until the `hir` crate,
+//! where we "cook" them so that each diagnostic is formulated in terms of `hir`
+//! types. Well, at least that's the aspiration, the "cooking" is somewhat
+//! ad-hoc at the moment. Anyways, we get a bunch of ide-friendly diagnostic
+//! structs from hir, and we want to render them to unified serializable
+//! representation (span, level, message) here. If we can, we also provide
+//! fixits. By the way, that's why we want to keep diagnostics structured
+//! internally -- so that we have all the info to make fixes.
+//!
+//! We have one "handler" module per diagnostic code. Such a module contains
+//! rendering, optional fixes and tests. It's OK if some low-level compiler
+//! functionality ends up being tested via a diagnostic.
+//!
+//! There are also a couple of ad-hoc diagnostics implemented directly here, we
+//! don't yet have a great pattern for how to do them properly.
+
+mod handlers {
+    pub(crate) mod break_outside_of_loop;
+    pub(crate) mod inactive_code;
+    pub(crate) mod incorrect_case;
+    pub(crate) mod macro_error;
+    pub(crate) mod mismatched_arg_count;
+    pub(crate) mod missing_fields;
+    pub(crate) mod missing_match_arms;
+    pub(crate) mod missing_ok_or_some_in_tail_expr;
+    pub(crate) mod missing_unsafe;
+    pub(crate) mod no_such_field;
+    pub(crate) mod remove_this_semicolon;
+    pub(crate) mod replace_filter_map_next_with_find_map;
+    pub(crate) mod unimplemented_builtin_macro;
+    pub(crate) mod unlinked_file;
+    pub(crate) mod unresolved_extern_crate;
+    pub(crate) mod unresolved_import;
+    pub(crate) mod unresolved_macro_call;
+    pub(crate) mod unresolved_module;
+    pub(crate) mod unresolved_proc_macro;
+}
+
+mod field_shorthand;
+
+use hir::{diagnostics::AnyDiagnostic, Semantics};
+use ide_db::{
+    assists::{Assist, AssistId, AssistKind, AssistResolveStrategy},
+    base_db::{FileId, SourceDatabase},
+    label::Label,
+    source_change::SourceChange,
+    RootDatabase,
+};
+use itertools::Itertools;
+use rustc_hash::FxHashSet;
+use syntax::{
+    ast::{self, AstNode},
+    SyntaxNode, TextRange,
+};
+use text_edit::TextEdit;
+
+use crate::handlers::unlinked_file::UnlinkedFile;
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub struct DiagnosticCode(pub &'static str);
+
+impl DiagnosticCode {
+    pub fn as_str(&self) -> &str {
+        self.0
+    }
+}
+
+#[derive(Debug)]
+pub struct Diagnostic {
+    pub code: DiagnosticCode,
+    pub message: String,
+    pub range: TextRange,
+    pub severity: Severity,
+    pub unused: bool,
+    pub experimental: bool,
+    pub fixes: Option<Vec<Assist>>,
+}
+
+impl Diagnostic {
+    fn new(code: &'static str, message: impl Into<String>, range: TextRange) -> Diagnostic {
+        let message = message.into();
+        Diagnostic {
+            code: DiagnosticCode(code),
+            message,
+            range,
+            severity: Severity::Error,
+            unused: false,
+            experimental: false,
+            fixes: None,
+        }
+    }
+
+    fn experimental(mut self) -> Diagnostic {
+        self.experimental = true;
+        self
+    }
+
+    fn severity(mut self, severity: Severity) -> Diagnostic {
+        self.severity = severity;
+        self
+    }
+
+    fn with_fixes(mut self, fixes: Option<Vec<Assist>>) -> Diagnostic {
+        self.fixes = fixes;
+        self
+    }
+
+    fn with_unused(mut self, unused: bool) -> Diagnostic {
+        self.unused = unused;
+        self
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+pub enum Severity {
+    Error,
+    WeakWarning,
+}
+
+#[derive(Default, Debug, Clone)]
+pub struct DiagnosticsConfig {
+    pub disable_experimental: bool,
+    pub disabled: FxHashSet<String>,
+}
+
+struct DiagnosticsContext<'a> {
+    config: &'a DiagnosticsConfig,
+    sema: Semantics<'a, RootDatabase>,
+    resolve: &'a AssistResolveStrategy,
+}
+
+pub fn diagnostics(
+    db: &RootDatabase,
+    config: &DiagnosticsConfig,
+    resolve: &AssistResolveStrategy,
+    file_id: FileId,
+) -> Vec<Diagnostic> {
+    let _p = profile::span("diagnostics");
+    let sema = Semantics::new(db);
+    let parse = db.parse(file_id);
+    let mut res = Vec::new();
+
+    // [#34344] Only take first 128 errors to prevent slowing down editor/ide, the number 128 is chosen arbitrarily.
+    res.extend(
+        parse.errors().iter().take(128).map(|err| {
+            Diagnostic::new("syntax-error", format!("Syntax Error: {}", err), err.range())
+        }),
+    );
+
+    for node in parse.tree().syntax().descendants() {
+        check_unnecessary_braces_in_use_statement(&mut res, file_id, &node);
+        field_shorthand::check(&mut res, file_id, &node);
+    }
+
+    let mut diags = Vec::new();
+    let module = sema.to_module_def(file_id);
+    if let Some(m) = module {
+        m.diagnostics(db, &mut diags)
+    }
+
+    let ctx = DiagnosticsContext { config, sema, resolve };
+    if module.is_none() {
+        let d = UnlinkedFile { file: file_id };
+        let d = handlers::unlinked_file::unlinked_file(&ctx, &d);
+        res.push(d)
+    }
+
+    for diag in diags {
+        #[rustfmt::skip]
+        let d = match diag {
+            AnyDiagnostic::BreakOutsideOfLoop(d) => handlers::break_outside_of_loop::break_outside_of_loop(&ctx, &d),
+            AnyDiagnostic::IncorrectCase(d) => handlers::incorrect_case::incorrect_case(&ctx, &d),
+            AnyDiagnostic::MacroError(d) => handlers::macro_error::macro_error(&ctx, &d),
+            AnyDiagnostic::MismatchedArgCount(d) => handlers::mismatched_arg_count::mismatched_arg_count(&ctx, &d),
+            AnyDiagnostic::MissingFields(d) => handlers::missing_fields::missing_fields(&ctx, &d),
+            AnyDiagnostic::MissingMatchArms(d) => handlers::missing_match_arms::missing_match_arms(&ctx, &d),
+            AnyDiagnostic::MissingOkOrSomeInTailExpr(d) => handlers::missing_ok_or_some_in_tail_expr::missing_ok_or_some_in_tail_expr(&ctx, &d),
+            AnyDiagnostic::MissingUnsafe(d) => handlers::missing_unsafe::missing_unsafe(&ctx, &d),
+            AnyDiagnostic::NoSuchField(d) => handlers::no_such_field::no_such_field(&ctx, &d),
+            AnyDiagnostic::RemoveThisSemicolon(d) => handlers::remove_this_semicolon::remove_this_semicolon(&ctx, &d),
+            AnyDiagnostic::ReplaceFilterMapNextWithFindMap(d) => handlers::replace_filter_map_next_with_find_map::replace_filter_map_next_with_find_map(&ctx, &d),
+            AnyDiagnostic::UnimplementedBuiltinMacro(d) => handlers::unimplemented_builtin_macro::unimplemented_builtin_macro(&ctx, &d),
+            AnyDiagnostic::UnresolvedExternCrate(d) => handlers::unresolved_extern_crate::unresolved_extern_crate(&ctx, &d),
+            AnyDiagnostic::UnresolvedImport(d) => handlers::unresolved_import::unresolved_import(&ctx, &d),
+            AnyDiagnostic::UnresolvedMacroCall(d) => handlers::unresolved_macro_call::unresolved_macro_call(&ctx, &d),
+            AnyDiagnostic::UnresolvedModule(d) => handlers::unresolved_module::unresolved_module(&ctx, &d),
+            AnyDiagnostic::UnresolvedProcMacro(d) => handlers::unresolved_proc_macro::unresolved_proc_macro(&ctx, &d),
+
+            AnyDiagnostic::InactiveCode(d) => match handlers::inactive_code::inactive_code(&ctx, &d) {
+                Some(it) => it,
+                None => continue,
+            }
+        };
+        res.push(d)
+    }
+
+    res.retain(|d| {
+        !ctx.config.disabled.contains(d.code.as_str())
+            && !(ctx.config.disable_experimental && d.experimental)
+    });
+
+    res
+}
+
+fn check_unnecessary_braces_in_use_statement(
+    acc: &mut Vec<Diagnostic>,
+    file_id: FileId,
+    node: &SyntaxNode,
+) -> Option<()> {
+    let use_tree_list = ast::UseTreeList::cast(node.clone())?;
+    if let Some((single_use_tree,)) = use_tree_list.use_trees().collect_tuple() {
+        // If there is a comment inside the bracketed `use`,
+        // assume it is a commented out module path and don't show diagnostic.
+        if use_tree_list.has_inner_comment() {
+            return Some(());
+        }
+
+        let use_range = use_tree_list.syntax().text_range();
+        let edit =
+            text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(&single_use_tree)
+                .unwrap_or_else(|| {
+                    let to_replace = single_use_tree.syntax().text().to_string();
+                    let mut edit_builder = TextEdit::builder();
+                    edit_builder.delete(use_range);
+                    edit_builder.insert(use_range.start(), to_replace);
+                    edit_builder.finish()
+                });
+
+        acc.push(
+            Diagnostic::new(
+                "unnecessary-braces",
+                "Unnecessary braces in use statement".to_string(),
+                use_range,
+            )
+            .severity(Severity::WeakWarning)
+            .with_fixes(Some(vec![fix(
+                "remove_braces",
+                "Remove unnecessary braces",
+                SourceChange::from_text_edit(file_id, edit),
+                use_range,
+            )])),
+        );
+    }
+
+    Some(())
+}
+
+fn text_edit_for_remove_unnecessary_braces_with_self_in_use_statement(
+    single_use_tree: &ast::UseTree,
+) -> Option<TextEdit> {
+    let use_tree_list_node = single_use_tree.syntax().parent()?;
+    if single_use_tree.path()?.segment()?.self_token().is_some() {
+        let start = use_tree_list_node.prev_sibling_or_token()?.text_range().start();
+        let end = use_tree_list_node.text_range().end();
+        return Some(TextEdit::delete(TextRange::new(start, end)));
+    }
+    None
+}
+
+fn fix(id: &'static str, label: &str, source_change: SourceChange, target: TextRange) -> Assist {
+    let mut res = unresolved_fix(id, label, target);
+    res.source_change = Some(source_change);
+    res
+}
+
+fn unresolved_fix(id: &'static str, label: &str, target: TextRange) -> Assist {
+    assert!(!id.contains(' '));
+    Assist {
+        id: AssistId(id, AssistKind::QuickFix),
+        label: Label::new(label),
+        group: None,
+        target,
+        source_change: None,
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::Expect;
+    use ide_db::{
+        assists::AssistResolveStrategy,
+        base_db::{fixture::WithFixture, SourceDatabaseExt},
+        RootDatabase,
+    };
+    use stdx::trim_indent;
+    use test_utils::{assert_eq_text, extract_annotations};
+
+    use crate::DiagnosticsConfig;
+
+    /// Takes a multi-file input fixture with annotated cursor positions,
+    /// and checks that:
+    ///  * a diagnostic is produced
+    ///  * the first diagnostic fix trigger range touches the input cursor position
+    ///  * that the contents of the file containing the cursor match `after` after the diagnostic fix is applied
+    #[track_caller]
+    pub(crate) fn check_fix(ra_fixture_before: &str, ra_fixture_after: &str) {
+        check_nth_fix(0, ra_fixture_before, ra_fixture_after);
+    }
+    /// Takes a multi-file input fixture with annotated cursor positions,
+    /// and checks that:
+    ///  * a diagnostic is produced
+    ///  * every diagnostic fixes trigger range touches the input cursor position
+    ///  * that the contents of the file containing the cursor match `after` after each diagnostic fix is applied
+    pub(crate) fn check_fixes(ra_fixture_before: &str, ra_fixtures_after: Vec<&str>) {
+        for (i, ra_fixture_after) in ra_fixtures_after.iter().enumerate() {
+            check_nth_fix(i, ra_fixture_before, ra_fixture_after)
+        }
+    }
+
+    #[track_caller]
+    fn check_nth_fix(nth: usize, ra_fixture_before: &str, ra_fixture_after: &str) {
+        let after = trim_indent(ra_fixture_after);
+
+        let (db, file_position) = RootDatabase::with_position(ra_fixture_before);
+        let diagnostic = super::diagnostics(
+            &db,
+            &DiagnosticsConfig::default(),
+            &AssistResolveStrategy::All,
+            file_position.file_id,
+        )
+        .pop()
+        .expect("no diagnostics");
+        let fix = &diagnostic.fixes.expect("diagnostic misses fixes")[nth];
+        let actual = {
+            let source_change = fix.source_change.as_ref().unwrap();
+            let file_id = *source_change.source_file_edits.keys().next().unwrap();
+            let mut actual = db.file_text(file_id).to_string();
+
+            for edit in source_change.source_file_edits.values() {
+                edit.apply(&mut actual);
+            }
+            actual
+        };
+
+        assert_eq_text!(&after, &actual);
+        assert!(
+            fix.target.contains_inclusive(file_position.offset),
+            "diagnostic fix range {:?} does not touch cursor position {:?}",
+            fix.target,
+            file_position.offset
+        );
+    }
+
+    /// Checks that there's a diagnostic *without* fix at `$0`.
+    pub(crate) fn check_no_fix(ra_fixture: &str) {
+        let (db, file_position) = RootDatabase::with_position(ra_fixture);
+        let diagnostic = super::diagnostics(
+            &db,
+            &DiagnosticsConfig::default(),
+            &AssistResolveStrategy::All,
+            file_position.file_id,
+        )
+        .pop()
+        .unwrap();
+        assert!(diagnostic.fixes.is_none(), "got a fix when none was expected: {:?}", diagnostic);
+    }
+
+    pub(crate) fn check_expect(ra_fixture: &str, expect: Expect) {
+        let (db, file_id) = RootDatabase::with_single_file(ra_fixture);
+        let diagnostics = super::diagnostics(
+            &db,
+            &DiagnosticsConfig::default(),
+            &AssistResolveStrategy::All,
+            file_id,
+        );
+        expect.assert_debug_eq(&diagnostics)
+    }
+
+    #[track_caller]
+    pub(crate) fn check_diagnostics(ra_fixture: &str) {
+        let mut config = DiagnosticsConfig::default();
+        config.disabled.insert("inactive-code".to_string());
+        check_diagnostics_with_config(config, ra_fixture)
+    }
+
+    #[track_caller]
+    pub(crate) fn check_diagnostics_with_config(config: DiagnosticsConfig, ra_fixture: &str) {
+        let (db, files) = RootDatabase::with_many_files(ra_fixture);
+        for file_id in files {
+            let diagnostics =
+                super::diagnostics(&db, &config, &AssistResolveStrategy::All, file_id);
+
+            let expected = extract_annotations(&*db.file_text(file_id));
+            let mut actual =
+                diagnostics.into_iter().map(|d| (d.range, d.message)).collect::<Vec<_>>();
+            actual.sort_by_key(|(range, _)| range.start());
+            assert_eq!(expected, actual);
+        }
+    }
+
+    #[test]
+    fn test_check_unnecessary_braces_in_use_statement() {
+        check_diagnostics(
+            r#"
+use a;
+use a::{c, d::e};
+
+mod a {
+    mod c {}
+    mod d {
+        mod e {}
+    }
+}
+"#,
+        );
+        check_diagnostics(
+            r#"
+use a;
+use a::{
+    c,
+    // d::e
+};
+
+mod a {
+    mod c {}
+    mod d {
+        mod e {}
+    }
+}
+"#,
+        );
+        check_fix(
+            r"
+            mod b {}
+            use {$0b};
+            ",
+            r"
+            mod b {}
+            use b;
+            ",
+        );
+        check_fix(
+            r"
+            mod b {}
+            use {b$0};
+            ",
+            r"
+            mod b {}
+            use b;
+            ",
+        );
+        check_fix(
+            r"
+            mod a { mod c {} }
+            use a::{c$0};
+            ",
+            r"
+            mod a { mod c {} }
+            use a::c;
+            ",
+        );
+        check_fix(
+            r"
+            mod a {}
+            use a::{self$0};
+            ",
+            r"
+            mod a {}
+            use a;
+            ",
+        );
+        check_fix(
+            r"
+            mod a { mod c {} mod d { mod e {} } }
+            use a::{c, d::{e$0}};
+            ",
+            r"
+            mod a { mod c {} mod d { mod e {} } }
+            use a::{c, d::e};
+            ",
+        );
+    }
+
+    #[test]
+    fn test_disabled_diagnostics() {
+        let mut config = DiagnosticsConfig::default();
+        config.disabled.insert("unresolved-module".into());
+
+        let (db, file_id) = RootDatabase::with_single_file(r#"mod foo;"#);
+
+        let diagnostics = super::diagnostics(&db, &config, &AssistResolveStrategy::All, file_id);
+        assert!(diagnostics.is_empty());
+
+        let diagnostics = super::diagnostics(
+            &db,
+            &DiagnosticsConfig::default(),
+            &AssistResolveStrategy::All,
+            file_id,
+        );
+        assert!(!diagnostics.is_empty());
+    }
+
+    #[test]
+    fn import_extern_crate_clash_with_inner_item() {
+        // This is more of a resolver test, but doesn't really work with the hir_def testsuite.
+
+        check_diagnostics(
+            r#"
+//- /lib.rs crate:lib deps:jwt
+mod permissions;
+
+use permissions::jwt;
+
+fn f() {
+    fn inner() {}
+    jwt::Claims {}; // should resolve to the local one with 0 fields, and not get a diagnostic
+}
+
+//- /permissions.rs
+pub mod jwt  {
+    pub struct Claims {}
+}
+
+//- /jwt/lib.rs crate:jwt
+pub struct Claims {
+    field: u8,
+}
+        "#,
+        );
+    }
+}