1 files changed, 746 insertions, 0 deletions

diff --git a/crates/ide/src/diagnostics.rs b/crates/ide/src/diagnostics.rs
new file mode 100644
index 000000000..b2b972b02
--- /dev/null
+++ b/crates/ide/src/diagnostics.rs
@@ -0,0 +1,746 @@
+//! Collects diagnostics & fixits  for a single file.
+//!
+//! The tricky bit here is that diagnostics are produced by hir in terms of
+//! macro-expanded files, but we need to present them to the users in terms of
+//! original files. So we need to map the ranges.
+
+mod fixes;
+
+use std::cell::RefCell;
+
+use base_db::SourceDatabase;
+use hir::{diagnostics::DiagnosticSinkBuilder, Semantics};
+use ide_db::RootDatabase;
+use itertools::Itertools;
+use rustc_hash::FxHashSet;
+use syntax::{
+    ast::{self, AstNode},
+    SyntaxNode, TextRange, T,
+};
+use text_edit::TextEdit;
+
+use crate::{FileId, Label, SourceChange, SourceFileEdit};
+
+use self::fixes::DiagnosticWithFix;
+
+#[derive(Debug)]
+pub struct Diagnostic {
+    // pub name: Option<String>,
+    pub message: String,
+    pub range: TextRange,
+    pub severity: Severity,
+    pub fix: Option<Fix>,
+}
+
+#[derive(Debug)]
+pub struct Fix {
+    pub label: Label,
+    pub source_change: SourceChange,
+    /// Allows to trigger the fix only when the caret is in the range given
+    pub fix_trigger_range: TextRange,
+}
+
+impl Fix {
+    fn new(label: &str, source_change: SourceChange, fix_trigger_range: TextRange) -> Self {
+        let label = Label::new(label);
+        Self { label, source_change, fix_trigger_range }
+    }
+}
+
+#[derive(Debug, Copy, Clone)]
+pub enum Severity {
+    Error,
+    WeakWarning,
+}
+
+#[derive(Default, Debug, Clone)]
+pub struct DiagnosticsConfig {
+    pub disable_experimental: bool,
+    pub disabled: FxHashSet<String>,
+}
+
+pub(crate) fn diagnostics(
+    db: &RootDatabase,
+    config: &DiagnosticsConfig,
+    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 {
+        // name: None,
+        range: err.range(),
+        message: format!("Syntax Error: {}", err),
+        severity: Severity::Error,
+        fix: None,
+    }));
+
+    for node in parse.tree().syntax().descendants() {
+        check_unnecessary_braces_in_use_statement(&mut res, file_id, &node);
+        check_struct_shorthand_initialization(&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));
+        })
+        .on::<hir::diagnostics::MissingFields, _>(|d| {
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+        })
+        .on::<hir::diagnostics::MissingOkInTailExpr, _>(|d| {
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+        })
+        .on::<hir::diagnostics::NoSuchField, _>(|d| {
+            res.borrow_mut().push(diagnostic_with_fix(d, &sema));
+        })
+        // 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 {
+                // name: Some(d.name().into()),
+                message: d.message(),
+                range: sema.diagnostics_display_range(d).range,
+                severity: Severity::Error,
+                fix: None,
+            })
+        });
+
+    if let Some(m) = sema.to_module_def(file_id) {
+        m.diagnostics(db, &mut sink);
+    };
+    drop(sink);
+    res.into_inner()
+}
+
+fn diagnostic_with_fix<D: DiagnosticWithFix>(d: &D, sema: &Semantics<RootDatabase>) -> Diagnostic {
+    Diagnostic {
+        // name: Some(d.name().into()),
+        range: sema.diagnostics_display_range(d).range,
+        message: d.message(),
+        severity: Severity::Error,
+        fix: d.fix(&sema),
+    }
+}
+
+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() {
+        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 {
+            // name: None,
+            range: use_range,
+            message: "Unnecessary braces in use statement".to_string(),
+            severity: Severity::WeakWarning,
+            fix: Some(Fix::new(
+                "Remove unnecessary braces",
+                SourceFileEdit { file_id, edit }.into(),
+                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()?.syntax().first_child_or_token()?.kind() == T![self] {
+        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 check_struct_shorthand_initialization(
+    acc: &mut Vec<Diagnostic>,
+    file_id: FileId,
+    node: &SyntaxNode,
+) -> Option<()> {
+    let record_lit = ast::RecordExpr::cast(node.clone())?;
+    let record_field_list = record_lit.record_expr_field_list()?;
+    for record_field in record_field_list.fields() {
+        if let (Some(name_ref), Some(expr)) = (record_field.name_ref(), record_field.expr()) {
+            let field_name = name_ref.syntax().text().to_string();
+            let field_expr = expr.syntax().text().to_string();
+            let field_name_is_tup_index = name_ref.as_tuple_field().is_some();
+            if field_name == field_expr && !field_name_is_tup_index {
+                let mut edit_builder = TextEdit::builder();
+                edit_builder.delete(record_field.syntax().text_range());
+                edit_builder.insert(record_field.syntax().text_range().start(), field_name);
+                let edit = edit_builder.finish();
+
+                let field_range = record_field.syntax().text_range();
+                acc.push(Diagnostic {
+                    // name: None,
+                    range: field_range,
+                    message: "Shorthand struct initialization".to_string(),
+                    severity: Severity::WeakWarning,
+                    fix: Some(Fix::new(
+                        "Use struct shorthand initialization",
+                        SourceFileEdit { file_id, edit }.into(),
+                        field_range,
+                    )),
+                });
+            }
+        }
+    }
+    Some(())
+}
+
+#[cfg(test)]
+mod tests {
+    use expect_test::{expect, Expect};
+    use stdx::trim_indent;
+    use test_utils::assert_eq_text;
+
+    use crate::{
+        mock_analysis::{analysis_and_position, single_file, MockAnalysis},
+        DiagnosticsConfig,
+    };
+
+    /// Takes a multi-file input fixture with annotated cursor positions,
+    /// and checks that:
+    ///  * a diagnostic is produced
+    ///  * this 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
+    fn check_fix(ra_fixture_before: &str, ra_fixture_after: &str) {
+        let after = trim_indent(ra_fixture_after);
+
+        let (analysis, file_position) = analysis_and_position(ra_fixture_before);
+        let diagnostic = analysis
+            .diagnostics(&DiagnosticsConfig::default(), file_position.file_id)
+            .unwrap()
+            .pop()
+            .unwrap();
+        let mut fix = diagnostic.fix.unwrap();
+        let edit = fix.source_change.source_file_edits.pop().unwrap().edit;
+        let target_file_contents = analysis.file_text(file_position.file_id).unwrap();
+        let actual = {
+            let mut actual = target_file_contents.to_string();
+            edit.apply(&mut actual);
+            actual
+        };
+
+        assert_eq_text!(&after, &actual);
+        assert!(
+            fix.fix_trigger_range.start() <= file_position.offset
+                && fix.fix_trigger_range.end() >= file_position.offset,
+            "diagnostic fix range {:?} does not touch cursor position {:?}",
+            fix.fix_trigger_range,
+            file_position.offset
+        );
+    }
+
+    /// Checks that a diagnostic applies to the file containing the `<|>` cursor marker
+    /// which has a fix that can apply to other files.
+    fn check_apply_diagnostic_fix_in_other_file(ra_fixture_before: &str, ra_fixture_after: &str) {
+        let ra_fixture_after = &trim_indent(ra_fixture_after);
+        let (analysis, file_pos) = analysis_and_position(ra_fixture_before);
+        let current_file_id = file_pos.file_id;
+        let diagnostic = analysis
+            .diagnostics(&DiagnosticsConfig::default(), current_file_id)
+            .unwrap()
+            .pop()
+            .unwrap();
+        let mut fix = diagnostic.fix.unwrap();
+        let edit = fix.source_change.source_file_edits.pop().unwrap();
+        let changed_file_id = edit.file_id;
+        let before = analysis.file_text(changed_file_id).unwrap();
+        let actual = {
+            let mut actual = before.to_string();
+            edit.edit.apply(&mut actual);
+            actual
+        };
+        assert_eq_text!(ra_fixture_after, &actual);
+    }
+
+    /// Takes a multi-file input fixture with annotated cursor position and checks that no diagnostics
+    /// apply to the file containing the cursor.
+    fn check_no_diagnostics(ra_fixture: &str) {
+        let mock = MockAnalysis::with_files(ra_fixture);
+        let files = mock.files().map(|(it, _)| it).collect::<Vec<_>>();
+        let analysis = mock.analysis();
+        let diagnostics = files
+            .into_iter()
+            .flat_map(|file_id| {
+                analysis.diagnostics(&DiagnosticsConfig::default(), file_id).unwrap()
+            })
+            .collect::<Vec<_>>();
+        assert_eq!(diagnostics.len(), 0, "unexpected diagnostics:\n{:#?}", diagnostics);
+    }
+
+    fn check_expect(ra_fixture: &str, expect: Expect) {
+        let (analysis, file_id) = single_file(ra_fixture);
+        let diagnostics = analysis.diagnostics(&DiagnosticsConfig::default(), file_id).unwrap();
+        expect.assert_debug_eq(&diagnostics)
+    }
+
+    #[test]
+    fn test_wrap_return_type() {
+        check_fix(
+            r#"
+//- /main.rs
+use core::result::Result::{self, Ok, Err};
+
+fn div(x: i32, y: i32) -> Result<i32, ()> {
+    if y == 0 {
+        return Err(());
+    }
+    x / y<|>
+}
+//- /core/lib.rs
+pub mod result {
+    pub enum Result<T, E> { Ok(T), Err(E) }
+}
+"#,
+            r#"
+use core::result::Result::{self, Ok, Err};
+
+fn div(x: i32, y: i32) -> Result<i32, ()> {
+    if y == 0 {
+        return Err(());
+    }
+    Ok(x / y)
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_wrap_return_type_handles_generic_functions() {
+        check_fix(
+            r#"
+//- /main.rs
+use core::result::Result::{self, Ok, Err};
+
+fn div<T>(x: T) -> Result<T, i32> {
+    if x == 0 {
+        return Err(7);
+    }
+    <|>x
+}
+//- /core/lib.rs
+pub mod result {
+    pub enum Result<T, E> { Ok(T), Err(E) }
+}
+"#,
+            r#"
+use core::result::Result::{self, Ok, Err};
+
+fn div<T>(x: T) -> Result<T, i32> {
+    if x == 0 {
+        return Err(7);
+    }
+    Ok(x)
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_wrap_return_type_handles_type_aliases() {
+        check_fix(
+            r#"
+//- /main.rs
+use core::result::Result::{self, Ok, Err};
+
+type MyResult<T> = Result<T, ()>;
+
+fn div(x: i32, y: i32) -> MyResult<i32> {
+    if y == 0 {
+        return Err(());
+    }
+    x <|>/ y
+}
+//- /core/lib.rs
+pub mod result {
+    pub enum Result<T, E> { Ok(T), Err(E) }
+}
+"#,
+            r#"
+use core::result::Result::{self, Ok, Err};
+
+type MyResult<T> = Result<T, ()>;
+
+fn div(x: i32, y: i32) -> MyResult<i32> {
+    if y == 0 {
+        return Err(());
+    }
+    Ok(x / y)
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_wrap_return_type_not_applicable_when_expr_type_does_not_match_ok_type() {
+        check_no_diagnostics(
+            r#"
+//- /main.rs
+use core::result::Result::{self, Ok, Err};
+
+fn foo() -> Result<(), i32> { 0 }
+
+//- /core/lib.rs
+pub mod result {
+    pub enum Result<T, E> { Ok(T), Err(E) }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_wrap_return_type_not_applicable_when_return_type_is_not_result() {
+        check_no_diagnostics(
+            r#"
+//- /main.rs
+use core::result::Result::{self, Ok, Err};
+
+enum SomeOtherEnum { Ok(i32), Err(String) }
+
+fn foo() -> SomeOtherEnum { 0 }
+
+//- /core/lib.rs
+pub mod result {
+    pub enum Result<T, E> { Ok(T), Err(E) }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_fill_struct_fields_empty() {
+        check_fix(
+            r#"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let s = TestStruct {<|>};
+}
+"#,
+            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 {<|>}; }
+}
+"#,
+            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 {<|> }
+    }
+}
+"#,
+            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<|> };
+}
+"#,
+            r"
+struct TestStruct { one: i32, two: i64 }
+
+fn test_fn() {
+    let s = TestStruct{ two: 2, one: () };
+}
+",
+        );
+    }
+
+    #[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_unresolved_module_diagnostic() {
+        check_expect(
+            r#"mod foo;"#,
+            expect![[r#"
+                [
+                    Diagnostic {
+                        message: "unresolved module",
+                        range: 0..8,
+                        severity: Error,
+                        fix: Some(
+                            Fix {
+                                label: "Create module",
+                                source_change: SourceChange {
+                                    source_file_edits: [],
+                                    file_system_edits: [
+                                        CreateFile {
+                                            anchor: FileId(
+                                                1,
+                                            ),
+                                            dst: "foo.rs",
+                                        },
+                                    ],
+                                    is_snippet: false,
+                                },
+                                fix_trigger_range: 0..8,
+                            },
+                        ),
+                    },
+                ]
+            "#]],
+        );
+    }
+
+    #[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: <|>42 }];
+}
+
+pub struct Foo { pub a: i32, pub b: i32 }
+"#,
+            r#"
+fn {a:42, 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_check_unnecessary_braces_in_use_statement() {
+        check_no_diagnostics(
+            r#"
+use a;
+use a::{c, d::e};
+"#,
+        );
+        check_fix(r#"use {<|>b};"#, r#"use b;"#);
+        check_fix(r#"use {b<|>};"#, r#"use b;"#);
+        check_fix(r#"use a::{c<|>};"#, r#"use a::c;"#);
+        check_fix(r#"use a::{self<|>};"#, r#"use a;"#);
+        check_fix(r#"use a::{c, d::{e<|>}};"#, r#"use a::{c, d::e};"#);
+    }
+
+    #[test]
+    fn test_check_struct_shorthand_initialization() {
+        check_no_diagnostics(
+            r#"
+struct A { a: &'static str }
+fn main() { A { a: "hello" } }
+"#,
+        );
+        check_no_diagnostics(
+            r#"
+struct A(usize);
+fn main() { A { 0: 0 } }
+"#,
+        );
+
+        check_fix(
+            r#"
+struct A { a: &'static str }
+fn main() {
+    let a = "haha";
+    A { a<|>: a }
+}
+"#,
+            r#"
+struct A { a: &'static str }
+fn main() {
+    let a = "haha";
+    A { a }
+}
+"#,
+        );
+
+        check_fix(
+            r#"
+struct A { a: &'static str, b: &'static str }
+fn main() {
+    let a = "haha";
+    let b = "bb";
+    A { a<|>: a, b }
+}
+"#,
+            r#"
+struct A { a: &'static str, b: &'static str }
+fn main() {
+    let a = "haha";
+    let b = "bb";
+    A { a, b }
+}
+"#,
+        );
+    }
+
+    #[test]
+    fn test_add_field_from_usage() {
+        check_fix(
+            r"
+fn main() {
+    Foo { bar: 3, baz<|>: false};
+}
+struct Foo {
+    bar: i32
+}
+",
+            r"
+fn main() {
+    Foo { bar: 3, baz: false};
+}
+struct Foo {
+    bar: i32,
+    baz: bool
+}
+",
+        )
+    }
+
+    #[test]
+    fn test_add_field_in_other_file_from_usage() {
+        check_apply_diagnostic_fix_in_other_file(
+            r"
+            //- /main.rs
+            mod foo;
+
+            fn main() {
+                <|>foo::Foo { bar: 3, baz: false};
+            }
+            //- /foo.rs
+            struct Foo {
+                bar: i32
+            }
+            ",
+            r"
+            struct Foo {
+                bar: i32,
+                pub(crate) baz: bool
+            }
+            ",
+        )
+    }
+
+    #[test]
+    fn test_disabled_diagnostics() {
+        let mut config = DiagnosticsConfig::default();
+        config.disabled.insert("unresolved-module".into());
+
+        let (analysis, file_id) = single_file(r#"mod foo;"#);
+
+        let diagnostics = analysis.diagnostics(&config, file_id).unwrap();
+        assert!(diagnostics.is_empty());
+
+        let diagnostics = analysis.diagnostics(&DiagnosticsConfig::default(), file_id).unwrap();
+        assert!(!diagnostics.is_empty());
+    }
+}