1 files changed, 47 insertions, 10 deletions

diff --git a/crates/hir_ty/src/diagnostics/expr.rs b/crates/hir_ty/src/diagnostics/expr.rs
index 849415706..107417c27 100644
--- a/crates/hir_ty/src/diagnostics/expr.rs
+++ b/crates/hir_ty/src/diagnostics/expr.rs
@@ -11,8 +11,8 @@ use crate::{
     db::HirDatabase,
     diagnostics::{
         match_check::{is_useful, MatchCheckCtx, Matrix, PatStack, Usefulness},
-        MismatchedArgCount, MissingFields, MissingMatchArms, MissingOkInTailExpr, MissingPatFields,
-        RemoveThisSemicolon,
+        MismatchedArgCount, MissingFields, MissingMatchArms, MissingOkOrSomeInTailExpr,
+        MissingPatFields, RemoveThisSemicolon,
     },
     utils::variant_data,
     ApplicationTy, InferenceResult, Ty, TypeCtor,
@@ -156,7 +156,7 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
         // FIXME: Due to shortcomings in the current type system implementation, only emit this
         // diagnostic if there are no type mismatches in the containing function.
         if self.infer.type_mismatches.iter().next().is_some() {
-            return Some(());
+            return None;
         }
 
         let is_method_call = matches!(expr, Expr::MethodCall { .. });
@@ -170,6 +170,14 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
                 let mut args = args.clone();
                 args.insert(0, *receiver);
 
+                let receiver = &self.infer.type_of_expr[*receiver];
+                if receiver.strip_references().is_unknown() {
+                    // if the receiver is of unknown type, it's very likely we
+                    // don't know enough to correctly resolve the method call.
+                    // This is kind of a band-aid for #6975.
+                    return None;
+                }
+
                 // FIXME: note that we erase information about substs here. This
                 // is not right, but, luckily, doesn't matter as we care only
                 // about the number of params
@@ -298,27 +306,40 @@ impl<'a, 'b> ExprValidator<'a, 'b> {
         };
 
         let core_result_path = path![core::result::Result];
+        let core_option_path = path![core::option::Option];
 
         let resolver = self.owner.resolver(db.upcast());
         let core_result_enum = match resolver.resolve_known_enum(db.upcast(), &core_result_path) {
             Some(it) => it,
             _ => return,
         };
+        let core_option_enum = match resolver.resolve_known_enum(db.upcast(), &core_option_path) {
+            Some(it) => it,
+            _ => return,
+        };
 
         let core_result_ctor = TypeCtor::Adt(AdtId::EnumId(core_result_enum));
-        let params = match &mismatch.expected {
+        let core_option_ctor = TypeCtor::Adt(AdtId::EnumId(core_option_enum));
+
+        let (params, required) = match &mismatch.expected {
             Ty::Apply(ApplicationTy { ctor, parameters }) if ctor == &core_result_ctor => {
-                parameters
+                (parameters, "Ok".to_string())
+            }
+            Ty::Apply(ApplicationTy { ctor, parameters }) if ctor == &core_option_ctor => {
+                (parameters, "Some".to_string())
             }
             _ => return,
         };
 
-        if params.len() == 2 && params[0] == mismatch.actual {
+        if params.len() > 0 && params[0] == mismatch.actual {
             let (_, source_map) = db.body_with_source_map(self.owner.into());
 
             if let Ok(source_ptr) = source_map.expr_syntax(id) {
-                self.sink
-                    .push(MissingOkInTailExpr { file: source_ptr.file_id, expr: source_ptr.value });
+                self.sink.push(MissingOkOrSomeInTailExpr {
+                    file: source_ptr.file_id,
+                    expr: source_ptr.value,
+                    required,
+                });
             }
         }
     }
@@ -358,7 +379,7 @@ pub fn record_literal_missing_fields(
     id: ExprId,
     expr: &Expr,
 ) -> Option<(VariantId, Vec<LocalFieldId>, /*exhaustive*/ bool)> {
-    let (fields, exhausitve) = match expr {
+    let (fields, exhaustive) = match expr {
         Expr::RecordLit { path: _, fields, spread } => (fields, spread.is_none()),
         _ => return None,
     };
@@ -379,7 +400,7 @@ pub fn record_literal_missing_fields(
     if missed_fields.is_empty() {
         return None;
     }
-    Some((variant_def, missed_fields, exhausitve))
+    Some((variant_def, missed_fields, exhaustive))
 }
 
 pub fn record_pattern_missing_fields(
@@ -505,6 +526,22 @@ fn f() {
     }
 
     #[test]
+    fn method_unknown_receiver() {
+        // note: this is incorrect code, so there might be errors on this in the
+        // future, but we shouldn't emit an argument count diagnostic here
+        check_diagnostics(
+            r#"
+trait Foo { fn method(&self, arg: usize) {} }
+
+fn f() {
+    let x;
+    x.method();
+}
+"#,
+        );
+    }
+
+    #[test]
     fn tuple_struct() {
         check_diagnostics(
             r#"