change to a struct variant

[rust.git] / compiler / rustc_typeck / src / check / fn_ctxt / checks.rs

diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
index c39199f84b527d210dc90de342cabbe9ba4ed1ab..d05dd517f1ea32ab68d9737805309b5680d9dbcc 100644 (file)
--- a/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/checks.rs
@@ -28,6 +28,11 @@
 use std::iter;
 use std::slice;
 
+struct FnArgsAsTuple<'hir> {
+    first: &'hir hir::Expr<'hir>,
+    last: &'hir hir::Expr<'hir>,
+}
+
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
     pub(in super::super) fn check_casts(&self) {
         let mut deferred_cast_checks = self.deferred_cast_checks.borrow_mut();
@@ -127,8 +132,8 @@ pub(in super::super) fn check_argument_types(
 
         let expected_arg_count = formal_input_tys.len();
 
-        // expected_count, arg_count, error_code, sugg_unit
-        let mut error: Option<(usize, usize, &str, bool)> = None;
+        // expected_count, arg_count, error_code, sugg_unit, sugg_tuple_wrap_args
+        let mut error: Option<(usize, usize, &str, bool, Option<FnArgsAsTuple<'_>>)> = None;
 
         // If the arguments should be wrapped in a tuple (ex: closures), unwrap them here
         let (formal_input_tys, expected_input_tys) = if tuple_arguments == TupleArguments {
@@ -138,7 +143,7 @@ pub(in super::super) fn check_argument_types(
                 ty::Tuple(arg_types) => {
                     // Argument length differs
                     if arg_types.len() != provided_args.len() {
-                        error = Some((arg_types.len(), provided_args.len(), "E0057", false));
+                        error = Some((arg_types.len(), provided_args.len(), "E0057", false, None));
                     }
                     let expected_input_tys = match expected_input_tys.get(0) {
                         Some(&ty) => match ty.kind() {
@@ -169,7 +174,7 @@ pub(in super::super) fn check_argument_types(
             if supplied_arg_count >= expected_arg_count {
                 (formal_input_tys.to_vec(), expected_input_tys)
             } else {
-                error = Some((expected_arg_count, supplied_arg_count, "E0060", false));
+                error = Some((expected_arg_count, supplied_arg_count, "E0060", false, None));
                 (self.err_args(supplied_arg_count), vec![])
             }
         } else {
@@ -181,7 +186,25 @@ pub(in super::super) fn check_argument_types(
             } else {
                 false
             };
-            error = Some((expected_arg_count, supplied_arg_count, "E0061", sugg_unit));
+
+            // are we passing elements of a tuple without the tuple parentheses?
+            let expected_input_tys = if expected_input_tys.is_empty() {
+                // In most cases we can use expected_input_tys, but some callers won't have the type
+                // information, in which case we fall back to the types from the input expressions.
+                formal_input_tys
+            } else {
+                &*expected_input_tys
+            };
+
+            let sugg_tuple_wrap_args = self.suggested_tuple_wrap(expected_input_tys, provided_args);
+
+            error = Some((
+                expected_arg_count,
+                supplied_arg_count,
+                "E0061",
+                sugg_unit,
+                sugg_tuple_wrap_args,
+            ));
             (self.err_args(supplied_arg_count), vec![])
         };
 
@@ -305,7 +328,8 @@ pub(in super::super) fn check_argument_types(
         }
 
         // If there was an error in parameter count, emit that here
-        if let Some((expected_count, arg_count, err_code, sugg_unit)) = error {
+        if let Some((expected_count, arg_count, err_code, sugg_unit, sugg_tuple_wrap_args)) = error
+        {
             let (span, start_span, args, ctor_of) = match &call_expr.kind {
                 hir::ExprKind::Call(
                     hir::Expr {
@@ -408,6 +432,15 @@ pub(in super::super) fn check_argument_types(
                     String::from("()"),
                     Applicability::MachineApplicable,
                 );
+            } else if let Some(FnArgsAsTuple { first, last }) = sugg_tuple_wrap_args {
+                err.multipart_suggestion(
+                    "use parentheses to construct a tuple",
+                    vec![
+                        (first.span.shrink_to_lo(), '('.to_string()),
+                        (last.span.shrink_to_hi(), ')'.to_string()),
+                    ],
+                    Applicability::MachineApplicable,
+                );
             } else {
                 err.span_label(
                     span,
@@ -457,6 +490,35 @@ fn variadic_error<'tcx>(sess: &Session, span: Span, ty: Ty<'tcx>, cast_ty: &str)
         }
     }
 
+    fn suggested_tuple_wrap(
+        &self,
+        expected_input_tys: &[Ty<'tcx>],
+        provided_args: &'tcx [hir::Expr<'tcx>],
+    ) -> Option<FnArgsAsTuple<'_>> {
+        let [expected_arg_type] = &expected_input_tys[..] else { return None };
+
+        let ty::Tuple(expected_elems) = self.resolve_vars_if_possible(*expected_arg_type).kind()
+            else { return None };
+
+        let expected_types: Vec<_> = expected_elems.iter().map(|k| k.expect_ty()).collect();
+        let supplied_types: Vec<_> = provided_args.iter().map(|arg| self.check_expr(arg)).collect();
+
+        let all_match = iter::zip(expected_types, supplied_types)
+            .all(|(expected, supplied)| self.can_eq(self.param_env, expected, supplied).is_ok());
+
+        if all_match {
+            match provided_args {
+                [] => None,
+                [_] => unreachable!(
+                    "shouldn't reach here - need count mismatch between 1-tuple and 1-argument"
+                ),
+                [first, .., last] => Some(FnArgsAsTuple { first, last }),
+            }
+        } else {
+            None
+        }
+    }
+
     // AST fragment checking
     pub(in super::super) fn check_lit(
         &self,
@@ -516,7 +578,7 @@ pub fn check_struct_path(
                 _ => bug!("unexpected type: {:?}", ty),
             },
             Res::Def(DefKind::Struct | DefKind::Union | DefKind::TyAlias | DefKind::AssocTy, _)
-            | Res::SelfTy(..) => match ty.kind() {
+            | Res::SelfTy { .. } => match ty.kind() {
                 ty::Adt(adt, substs) if !adt.is_enum() => {
                     Some((adt.non_enum_variant(), adt.did, substs))
                 }
@@ -1021,7 +1083,7 @@ fn unpeel_to_top(
                 ObligationCauseCode::BuiltinDerivedObligation(code) |
                 ObligationCauseCode::ImplDerivedObligation(code) |
                 ObligationCauseCode::DerivedObligation(code) => {
-                    code.parent_trait_ref.self_ty().skip_binder().into()
+                    code.parent_trait_pred.self_ty().skip_binder().into()
                 }
                 _ if let ty::PredicateKind::Trait(predicate) =
                     error.obligation.predicate.kind().skip_binder() => {