1 files changed, 326 insertions, 0 deletions

diff --git a/crates/ide_diagnostics/src/handlers/missing_fields.rs b/crates/ide_diagnostics/src/handlers/missing_fields.rs
new file mode 100644
index 000000000..bc82c0e4a
--- /dev/null
+++ b/crates/ide_diagnostics/src/handlers/missing_fields.rs
@@ -0,0 +1,326 @@
+use either::Either;
+use hir::{db::AstDatabase, InFile};
+use ide_db::{assists::Assist, source_change::SourceChange};
+use stdx::format_to;
+use syntax::{algo, ast::make, AstNode, SyntaxNodePtr};
+use text_edit::TextEdit;
+
+use crate::{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(crate) 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::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: (),
+    };
+}
+"#,
+        );
+    }
+}