Simplify checking return type, add new test

Author: theotherphil

crates/ra_hir/src/expr/validation.rs

@@ -6,12 +6,11 @@ use ra_syntax::ast::{AstNode, RecordLit};
 use super::{Expr, ExprId, RecordLitField};
 use crate::{
     adt::AdtDef,
-    code_model::Enum,
     diagnostics::{DiagnosticSink, MissingFields, MissingOkInTailExpr},
     expr::AstPtr,
     name,
     path::{PathKind, PathSegment},
-    ty::{InferenceResult, Ty, TypeCtor},
+    ty::{ApplicationTy, InferenceResult, Ty, TypeCtor},
     Function, HasSource, HirDatabase, ModuleDef, Name, Path, PerNs, Resolution,
 };
 use ra_syntax::ast;
@@ -120,28 +119,12 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
                 _ => return,
             };
 
-        let std_result_type = std_result_enum.ty(db);
-
-        fn enum_from_type(ty: &Ty) -> Option<Enum> {
-            match ty {
-                Ty::Apply(t) => match t.ctor {
-                    TypeCtor::Adt(AdtDef::Enum(e)) => Some(e),
-                    _ => None,
-                },
-                _ => None,
-            }
-        }
-
-        if enum_from_type(&mismatch.expected) != enum_from_type(&std_result_type) {
-            return;
-        }
-
-        let ret = match &mismatch.expected {
-            Ty::Apply(t) => t,
+        let std_result_ctor = TypeCtor::Adt(AdtDef::Enum(std_result_enum));
+        let params = match &mismatch.expected {
+            Ty::Apply(ApplicationTy { ctor, parameters }) if ctor == &std_result_ctor => parameters,
             _ => return,
         };
 
-        let params = &ret.parameters;
         if params.len() == 2 && &params[0] == &mismatch.actual {
             let source_map = self.func.body_source_map(db);
             let file_id = self.func.source(db).file_id;

crates/ra_ide_api/src/diagnostics.rs

@@ -79,7 +79,7 @@ pub(crate) fn diagnostics(db: &RootDatabase, file_id: FileId) -> Vec<Diagnostic>
     .on::<hir::diagnostics::MissingOkInTailExpr, _>(|d| {
         let node = d.ast(db);
         let mut builder = TextEditBuilder::default();
-        let replacement = format!("Ok({})", node.syntax().text());
+        let replacement = format!("Ok({})", node.syntax());
         builder.replace(node.syntax().text_range(), replacement);
         let fix = SourceChange::source_file_edit_from("wrap with ok", file_id, builder.finish());
         res.borrow_mut().push(Diagnostic {
@@ -353,7 +353,7 @@ fn div(x: i32, y: i32) -> MyResult<i32> {
     }
 
     #[test]
-    fn test_wrap_return_type_not_applicable() {
+    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}};
@@ -373,6 +373,32 @@ fn div(x: i32, y: i32) -> MyResult<i32> {
         check_no_diagnostic_for_target_file("/main.rs", 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("/main.rs", content);
+    }
+
     #[test]
     fn test_fill_struct_fields_empty() {
         let before = r"