1 files changed, 652 insertions, 0 deletions

diff --git a/crates/ra_ide/src/diagnostics.rs b/crates/ra_ide/src/diagnostics.rs
new file mode 100644
index 000000000..cc1ccab4b
--- /dev/null
+++ b/crates/ra_ide/src/diagnostics.rs
@@ -0,0 +1,652 @@
+//! FIXME: write short doc here
+
+use std::cell::RefCell;
+
+use hir::diagnostics::{AstDiagnostic, Diagnostic as _, DiagnosticSink};
+use itertools::Itertools;
+use ra_db::{RelativePath, SourceDatabase, SourceDatabaseExt};
+use ra_prof::profile;
+use ra_syntax::{
+    algo,
+    ast::{self, make, AstNode},
+    Location, SyntaxNode, TextRange, T,
+};
+use ra_text_edit::{TextEdit, TextEditBuilder};
+
+use crate::{db::RootDatabase, Diagnostic, FileId, FileSystemEdit, SourceChange, SourceFileEdit};
+
+#[derive(Debug, Copy, Clone)]
+pub enum Severity {
+    Error,
+    WeakWarning,
+}
+
+pub(crate) fn diagnostics(db: &RootDatabase, file_id: FileId) -> Vec<Diagnostic> {
+    let _p = profile("diagnostics");
+    let parse = db.parse(file_id);
+    let mut res = Vec::new();
+
+    res.extend(parse.errors().iter().map(|err| Diagnostic {
+        range: location_to_range(err.location()),
+        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 mut sink = DiagnosticSink::new(|d| {
+        res.borrow_mut().push(Diagnostic {
+            message: d.message(),
+            range: d.highlight_range(),
+            severity: Severity::Error,
+            fix: None,
+        })
+    })
+    .on::<hir::diagnostics::UnresolvedModule, _>(|d| {
+        let original_file = d.source().file_id.original_file(db);
+        let source_root = db.file_source_root(original_file);
+        let path = db
+            .file_relative_path(original_file)
+            .parent()
+            .unwrap_or_else(|| RelativePath::new(""))
+            .join(&d.candidate);
+        let create_file = FileSystemEdit::CreateFile { source_root, path };
+        let fix = SourceChange::file_system_edit("create module", create_file);
+        res.borrow_mut().push(Diagnostic {
+            range: d.highlight_range(),
+            message: d.message(),
+            severity: Severity::Error,
+            fix: Some(fix),
+        })
+    })
+    .on::<hir::diagnostics::MissingFields, _>(|d| {
+        let mut field_list = d.ast(db);
+        for f in d.missed_fields.iter() {
+            let field = make::record_field(make::name_ref(&f.to_string()), Some(make::expr_unit()));
+            field_list = field_list.append_field(&field);
+        }
+
+        let mut builder = TextEditBuilder::default();
+        algo::diff(&d.ast(db).syntax(), &field_list.syntax()).into_text_edit(&mut builder);
+
+        let fix =
+            SourceChange::source_file_edit_from("fill struct fields", file_id, builder.finish());
+        res.borrow_mut().push(Diagnostic {
+            range: d.highlight_range(),
+            message: d.message(),
+            severity: Severity::Error,
+            fix: Some(fix),
+        })
+    })
+    .on::<hir::diagnostics::MissingOkInTailExpr, _>(|d| {
+        let node = d.ast(db);
+        let replacement = format!("Ok({})", node.syntax());
+        let edit = TextEdit::replace(node.syntax().text_range(), replacement);
+        let fix = SourceChange::source_file_edit_from("wrap with ok", file_id, edit);
+        res.borrow_mut().push(Diagnostic {
+            range: d.highlight_range(),
+            message: d.message(),
+            severity: Severity::Error,
+            fix: Some(fix),
+        })
+    });
+    let source_file = db.parse(file_id).tree();
+    let src =
+        hir::Source { file_id: file_id.into(), value: hir::ModuleSource::SourceFile(source_file) };
+    if let Some(m) = hir::Module::from_definition(db, src) {
+        m.diagnostics(db, &mut sink);
+    };
+    drop(sink);
+    res.into_inner()
+}
+fn location_to_range(location: Location) -> TextRange {
+    match location {
+        Location::Offset(offset) => TextRange::offset_len(offset, 1.into()),
+        Location::Range(range) => range,
+    }
+}
+
+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 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 = TextEditBuilder::default();
+                    edit_builder.delete(range);
+                    edit_builder.insert(range.start(), to_replace);
+                    edit_builder.finish()
+                });
+
+        acc.push(Diagnostic {
+            range,
+            message: "Unnecessary braces in use statement".to_string(),
+            severity: Severity::WeakWarning,
+            fix: Some(SourceChange::source_file_edit(
+                "Remove unnecessary braces",
+                SourceFileEdit { file_id, edit },
+            )),
+        });
+    }
+
+    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();
+        let range = TextRange::from_to(start, end);
+        return Some(TextEdit::delete(range));
+    }
+    None
+}
+
+fn check_struct_shorthand_initialization(
+    acc: &mut Vec<Diagnostic>,
+    file_id: FileId,
+    node: &SyntaxNode,
+) -> Option<()> {
+    let record_lit = ast::RecordLit::cast(node.clone())?;
+    let record_field_list = record_lit.record_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();
+            if field_name == field_expr {
+                let mut edit_builder = TextEditBuilder::default();
+                edit_builder.delete(record_field.syntax().text_range());
+                edit_builder.insert(record_field.syntax().text_range().start(), field_name);
+                let edit = edit_builder.finish();
+
+                acc.push(Diagnostic {
+                    range: record_field.syntax().text_range(),
+                    message: "Shorthand struct initialization".to_string(),
+                    severity: Severity::WeakWarning,
+                    fix: Some(SourceChange::source_file_edit(
+                        "use struct shorthand initialization",
+                        SourceFileEdit { file_id, edit },
+                    )),
+                });
+            }
+        }
+    }
+    Some(())
+}
+
+#[cfg(test)]
+mod tests {
+    use insta::assert_debug_snapshot;
+    use join_to_string::join;
+    use ra_syntax::SourceFile;
+    use test_utils::assert_eq_text;
+
+    use crate::mock_analysis::{analysis_and_position, single_file};
+
+    use super::*;
+
+    type DiagnosticChecker = fn(&mut Vec<Diagnostic>, FileId, &SyntaxNode) -> Option<()>;
+
+    fn check_not_applicable(code: &str, func: DiagnosticChecker) {
+        let parse = SourceFile::parse(code);
+        let mut diagnostics = Vec::new();
+        for node in parse.tree().syntax().descendants() {
+            func(&mut diagnostics, FileId(0), &node);
+        }
+        assert!(diagnostics.is_empty());
+    }
+
+    fn check_apply(before: &str, after: &str, func: DiagnosticChecker) {
+        let parse = SourceFile::parse(before);
+        let mut diagnostics = Vec::new();
+        for node in parse.tree().syntax().descendants() {
+            func(&mut diagnostics, FileId(0), &node);
+        }
+        let diagnostic =
+            diagnostics.pop().unwrap_or_else(|| panic!("no diagnostics for:\n{}\n", before));
+        let mut fix = diagnostic.fix.unwrap();
+        let edit = fix.source_file_edits.pop().unwrap().edit;
+        let actual = edit.apply(&before);
+        assert_eq_text!(after, &actual);
+    }
+
+    /// Takes a multi-file input fixture with annotated cursor positions,
+    /// and checks that:
+    ///  * a diagnostic is produced
+    ///  * this diagnostic touches the input cursor position
+    ///  * that the contents of the file containing the cursor match `after` after the diagnostic fix is applied
+    fn check_apply_diagnostic_fix_from_position(fixture: &str, after: &str) {
+        let (analysis, file_position) = analysis_and_position(fixture);
+        let diagnostic = analysis.diagnostics(file_position.file_id).unwrap().pop().unwrap();
+        let mut fix = diagnostic.fix.unwrap();
+        let edit = fix.source_file_edits.pop().unwrap().edit;
+        let target_file_contents = analysis.file_text(file_position.file_id).unwrap();
+        let actual = edit.apply(&target_file_contents);
+
+        // Strip indent and empty lines from `after`, to match the behaviour of
+        // `parse_fixture` called from `analysis_and_position`.
+        let margin = fixture
+            .lines()
+            .filter(|it| it.trim_start().starts_with("//-"))
+            .map(|it| it.len() - it.trim_start().len())
+            .next()
+            .expect("empty fixture");
+        let after = join(after.lines().filter_map(|line| {
+            if line.len() > margin {
+                Some(&line[margin..])
+            } else {
+                None
+            }
+        }))
+        .separator("\n")
+        .suffix("\n")
+        .to_string();
+
+        assert_eq_text!(&after, &actual);
+        assert!(
+            diagnostic.range.start() <= file_position.offset
+                && diagnostic.range.end() >= file_position.offset,
+            "diagnostic range {} does not touch cursor position {}",
+            diagnostic.range,
+            file_position.offset
+        );
+    }
+
+    fn check_apply_diagnostic_fix(before: &str, after: &str) {
+        let (analysis, file_id) = single_file(before);
+        let diagnostic = analysis.diagnostics(file_id).unwrap().pop().unwrap();
+        let mut fix = diagnostic.fix.unwrap();
+        let edit = fix.source_file_edits.pop().unwrap().edit;
+        let actual = edit.apply(&before);
+        assert_eq_text!(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_diagnostic_for_target_file(fixture: &str) {
+        let (analysis, file_position) = analysis_and_position(fixture);
+        let diagnostics = analysis.diagnostics(file_position.file_id).unwrap();
+        assert_eq!(diagnostics.len(), 0);
+    }
+
+    fn check_no_diagnostic(content: &str) {
+        let (analysis, file_id) = single_file(content);
+        let diagnostics = analysis.diagnostics(file_id).unwrap();
+        assert_eq!(diagnostics.len(), 0);
+    }
+
+    #[test]
+    fn test_wrap_return_type() {
+        let before = r#"
+            //- /main.rs
+            use std::{string::String, result::Result::{self, Ok, Err}};
+
+            fn div(x: i32, y: i32) -> Result<i32, String> {
+                if y == 0 {
+                    return Err("div by zero".into());
+                }
+                x / y<|>
+            }
+
+            //- /std/lib.rs
+            pub mod string {
+                pub struct String { }
+            }
+            pub mod result {
+                pub enum Result<T, E> { Ok(T), Err(E) }
+            }
+        "#;
+        let after = r#"
+            use std::{string::String, result::Result::{self, Ok, Err}};
+
+            fn div(x: i32, y: i32) -> Result<i32, String> {
+                if y == 0 {
+                    return Err("div by zero".into());
+                }
+                Ok(x / y)
+            }
+        "#;
+        check_apply_diagnostic_fix_from_position(before, after);
+    }
+
+    #[test]
+    fn test_wrap_return_type_handles_generic_functions() {
+        let before = r#"
+            //- /main.rs
+            use std::result::Result::{self, Ok, Err};
+
+            fn div<T>(x: T) -> Result<T, i32> {
+                if x == 0 {
+                    return Err(7);
+                }
+                <|>x
+            }
+
+            //- /std/lib.rs
+            pub mod result {
+                pub enum Result<T, E> { Ok(T), Err(E) }
+            }
+        "#;
+        let after = r#"
+            use std::result::Result::{self, Ok, Err};
+
+            fn div<T>(x: T) -> Result<T, i32> {
+                if x == 0 {
+                    return Err(7);
+                }
+                Ok(x)
+            }
+        "#;
+        check_apply_diagnostic_fix_from_position(before, after);
+    }
+
+    #[test]
+    fn test_wrap_return_type_handles_type_aliases() {
+        let before = r#"
+            //- /main.rs
+            use std::{string::String, result::Result::{self, Ok, Err}};
+
+            type MyResult<T> = Result<T, String>;
+
+            fn div(x: i32, y: i32) -> MyResult<i32> {
+                if y == 0 {
+                    return Err("div by zero".into());
+                }
+                x <|>/ y
+            }
+
+            //- /std/lib.rs
+            pub mod string {
+                pub struct String { }
+            }
+            pub mod result {
+                pub enum Result<T, E> { Ok(T), Err(E) }
+            }
+        "#;
+        let after = r#"
+            use std::{string::String, result::Result::{self, Ok, Err}};
+
+            type MyResult<T> = Result<T, String>;
+            fn div(x: i32, y: i32) -> MyResult<i32> {
+                if y == 0 {
+                    return Err("div by zero".into());
+                }
+                Ok(x / y)
+            }
+        "#;
+        check_apply_diagnostic_fix_from_position(before, after);
+    }
+
+    #[test]
+    fn test_wrap_return_type_not_applicable_when_expr_type_does_not_match_ok_type() {
+        let content = r#"
+            //- /main.rs
+            use std::{string::String, result::Result::{self, Ok, Err}};
+
+            fn foo() -> Result<String, i32> {
+                0<|>
+            }
+
+            //- /std/lib.rs
+            pub mod string {
+                pub struct String { }
+            }
+            pub mod result {
+                pub enum Result<T, E> { Ok(T), Err(E) }
+            }
+        "#;
+        check_no_diagnostic_for_target_file(content);
+    }
+
+    #[test]
+    fn test_wrap_return_type_not_applicable_when_return_type_is_not_result() {
+        let content = r#"
+            //- /main.rs
+            use std::{string::String, result::Result::{self, Ok, Err}};
+
+            enum SomeOtherEnum {
+                Ok(i32),
+                Err(String),
+            }
+
+            fn foo() -> SomeOtherEnum {
+                0<|>
+            }
+
+            //- /std/lib.rs
+            pub mod string {
+                pub struct String { }
+            }
+            pub mod result {
+                pub enum Result<T, E> { Ok(T), Err(E) }
+            }
+        "#;
+        check_no_diagnostic_for_target_file(content);
+    }
+
+    #[test]
+    fn test_fill_struct_fields_empty() {
+        let before = r"
+            struct TestStruct {
+                one: i32,
+                two: i64,
+            }
+
+            fn test_fn() {
+                let s = TestStruct{};
+            }
+        ";
+        let after = r"
+            struct TestStruct {
+                one: i32,
+                two: i64,
+            }
+
+            fn test_fn() {
+                let s = TestStruct{ one: (), two: ()};
+            }
+        ";
+        check_apply_diagnostic_fix(before, after);
+    }
+
+    #[test]
+    fn test_fill_struct_fields_partial() {
+        let before = r"
+            struct TestStruct {
+                one: i32,
+                two: i64,
+            }
+
+            fn test_fn() {
+                let s = TestStruct{ two: 2 };
+            }
+        ";
+        let after = r"
+            struct TestStruct {
+                one: i32,
+                two: i64,
+            }
+
+            fn test_fn() {
+                let s = TestStruct{ two: 2, one: () };
+            }
+        ";
+        check_apply_diagnostic_fix(before, after);
+    }
+
+    #[test]
+    fn test_fill_struct_fields_no_diagnostic() {
+        let content = r"
+            struct TestStruct {
+                one: i32,
+                two: i64,
+            }
+
+            fn test_fn() {
+                let one = 1;
+                let s = TestStruct{ one, two: 2 };
+            }
+        ";
+
+        check_no_diagnostic(content);
+    }
+
+    #[test]
+    fn test_fill_struct_fields_no_diagnostic_on_spread() {
+        let content = r"
+            struct TestStruct {
+                one: i32,
+                two: i64,
+            }
+
+            fn test_fn() {
+                let one = 1;
+                let s = TestStruct{ ..a };
+            }
+        ";
+
+        check_no_diagnostic(content);
+    }
+
+    #[test]
+    fn test_unresolved_module_diagnostic() {
+        let (analysis, file_id) = single_file("mod foo;");
+        let diagnostics = analysis.diagnostics(file_id).unwrap();
+        assert_debug_snapshot!(diagnostics, @r###"
+        [
+            Diagnostic {
+                message: "unresolved module",
+                range: [0; 8),
+                fix: Some(
+                    SourceChange {
+                        label: "create module",
+                        source_file_edits: [],
+                        file_system_edits: [
+                            CreateFile {
+                                source_root: SourceRootId(
+                                    0,
+                                ),
+                                path: "foo.rs",
+                            },
+                        ],
+                        cursor_position: None,
+                    },
+                ),
+                severity: Error,
+            },
+        ]
+        "###);
+    }
+
+    #[test]
+    fn test_check_unnecessary_braces_in_use_statement() {
+        check_not_applicable(
+            "
+            use a;
+            use a::{c, d::e};
+        ",
+            check_unnecessary_braces_in_use_statement,
+        );
+        check_apply("use {b};", "use b;", check_unnecessary_braces_in_use_statement);
+        check_apply("use a::{c};", "use a::c;", check_unnecessary_braces_in_use_statement);
+        check_apply("use a::{self};", "use a;", check_unnecessary_braces_in_use_statement);
+        check_apply(
+            "use a::{c, d::{e}};",
+            "use a::{c, d::e};",
+            check_unnecessary_braces_in_use_statement,
+        );
+    }
+
+    #[test]
+    fn test_check_struct_shorthand_initialization() {
+        check_not_applicable(
+            r#"
+            struct A {
+                a: &'static str
+            }
+
+            fn main() {
+                A {
+                    a: "hello"
+                }
+            }
+        "#,
+            check_struct_shorthand_initialization,
+        );
+
+        check_apply(
+            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_struct_shorthand_initialization,
+        );
+
+        check_apply(
+            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
+    }
+}
+        "#,
+            check_struct_shorthand_initialization,
+        );
+    }
+}