Delay function resolution error until typeck

Author: compiler-errors

compiler/rustc_errors/src/lib.rs

@@ -460,6 +460,7 @@ pub enum StashKey {
     ItemNoType,
     UnderscoreForArrayLengths,
     EarlySyntaxWarning,
+    CallIntoMethod,
 }
 
 fn default_track_diagnostic(_: &Diagnostic) {}

compiler/rustc_hir_analysis/src/check/callee.rs

@@ -2,7 +2,7 @@ use super::method::MethodCallee;
 use super::{DefIdOrName, Expectation, FnCtxt, TupleArgumentsFlag};
 use crate::type_error_struct;
 
-use rustc_errors::{struct_span_err, Applicability, Diagnostic};
+use rustc_errors::{struct_span_err, Applicability, Diagnostic, StashKey};
 use rustc_hir as hir;
 use rustc_hir::def::{self, Namespace, Res};
 use rustc_hir::def_id::DefId;
@@ -60,6 +60,7 @@ pub fn check_legal_trait_for_method_call(
     }
 }
 
+#[derive(Debug)]
 enum CallStep<'tcx> {
     Builtin(Ty<'tcx>),
     DeferredClosure(LocalDefId, ty::FnSig<'tcx>),
@@ -188,6 +189,10 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 return None;
             }
 
+            ty::Error(_) => {
+                return None;
+            }
+
             _ => {}
         }
 
@@ -394,6 +399,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             }
             ty::FnPtr(sig) => (sig, None),
             _ => {
+                if let hir::ExprKind::Path(hir::QPath::Resolved(_, path)) = &callee_expr.kind
+                    && let [segment] = path.segments
+                    && let Some(mut diag) = self
+                        .tcx
+                        .sess
+                        .diagnostic()
+                        .steal_diagnostic(segment.ident.span, StashKey::CallIntoMethod)
+                {
+                    diag.emit();
+                }
+
                 self.report_invalid_callee(call_expr, callee_expr, callee_ty, arg_exprs);
 
                 // This is the "default" function signature, used in case of error.

compiler/rustc_resolve/src/diagnostics.rs

@@ -120,14 +120,15 @@ impl<'a> Resolver<'a> {
     }
 
     fn report_with_use_injections(&mut self, krate: &Crate) {
-        for UseError { mut err, candidates, def_id, instead, suggestion, path } in
+        for UseError { mut err, candidates, def_id, instead, suggestion, path, is_call } in
             self.use_injections.drain(..)
         {
             let (span, found_use) = if let Some(def_id) = def_id.as_local() {
                 UsePlacementFinder::check(krate, self.def_id_to_node_id[def_id])
             } else {
                 (None, FoundUse::No)
             };
+
             if !candidates.is_empty() {
                 show_candidates(
                     &self.session,
@@ -140,10 +141,15 @@ impl<'a> Resolver<'a> {
                     IsPattern::No,
                     path,
                 );
+                err.emit();
             } else if let Some((span, msg, sugg, appl)) = suggestion {
                 err.span_suggestion(span, msg, sugg, appl);
+                err.emit();
+            } else if let [segment] = path.as_slice() && is_call {
+                err.stash(segment.ident.span, rustc_errors::StashKey::CallIntoMethod);
+            } else {
+                err.emit();
             }
-            err.emit();
         }
     }
 

compiler/rustc_resolve/src/late.rs

@@ -3263,6 +3263,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                     instead,
                     suggestion,
                     path: path.into(),
+                    is_call: source.is_call(),
                 });
             }
 
@@ -3327,6 +3328,7 @@ impl<'a: 'ast, 'b, 'ast> LateResolutionVisitor<'a, 'b, 'ast> {
                     instead: false,
                     suggestion: None,
                     path: path.into(),
+                    is_call: source.is_call(),
                 });
             } else {
                 err.cancel();

compiler/rustc_resolve/src/lib.rs

@@ -674,6 +674,8 @@ struct UseError<'a> {
     /// Path `Segment`s at the place of use that failed. Used for accurate suggestion after telling
     /// the user to import the item directly.
     path: Vec<Segment>,
+    /// Whether the expected source is a call
+    is_call: bool,
 }
 
 #[derive(Clone, Copy, PartialEq, Debug)]

src/test/ui/did_you_mean/issue-43871-enum-instead-of-variant.stderr

@@ -1,11 +1,3 @@
-error[E0423]: expected function, tuple struct or tuple variant, found enum `Option`
-  --> $DIR/issue-43871-enum-instead-of-variant.rs:19:13
-   |
-LL |     let x = Option(1);
-   |             ^^^^^^ help: try to construct one of the enum's variants: `std::option::Option::Some`
-   |
-   = help: you might have meant to construct the enum's non-tuple variant
-
 error[E0532]: expected tuple struct or tuple variant, found enum `Option`
   --> $DIR/issue-43871-enum-instead-of-variant.rs:21:12
    |
@@ -27,6 +19,14 @@ note: the enum is defined here
 LL | enum Example { Ex(String), NotEx }
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
+error[E0423]: expected function, tuple struct or tuple variant, found enum `Option`
+  --> $DIR/issue-43871-enum-instead-of-variant.rs:19:13
+   |
+LL |     let x = Option(1);
+   |             ^^^^^^ help: try to construct one of the enum's variants: `std::option::Option::Some`
+   |
+   = help: you might have meant to construct the enum's non-tuple variant
+
 error[E0423]: expected function, tuple struct or tuple variant, found enum `Void`
   --> $DIR/issue-43871-enum-instead-of-variant.rs:31:13
    |

src/test/ui/empty/empty-struct-braces-expr.stderr

@@ -21,29 +21,6 @@ help: a unit struct with a similar name exists
 LL |     let e1 = XEmpty2;
    |              ~~~~~~~
 
-error[E0423]: expected function, tuple struct or tuple variant, found struct `Empty1`
-  --> $DIR/empty-struct-braces-expr.rs:16:14
-   |
-LL | struct Empty1 {}
-   | ---------------- `Empty1` defined here
-...
-LL |     let e1 = Empty1();
-   |              ^^^^^^^^
-   |
-  ::: $DIR/auxiliary/empty-struct.rs:2:1
-   |
-LL | pub struct XEmpty2;
-   | ------------------ similarly named unit struct `XEmpty2` defined here
-   |
-help: use struct literal syntax instead
-   |
-LL |     let e1 = Empty1 {};
-   |              ~~~~~~~~~
-help: a unit struct with a similar name exists
-   |
-LL |     let e1 = XEmpty2();
-   |              ~~~~~~~
-
 error[E0423]: expected value, found struct variant `E::Empty3`
   --> $DIR/empty-struct-braces-expr.rs:18:14
    |
@@ -84,6 +61,29 @@ help: a unit struct with a similar name exists
 LL |     let xe1 = XEmpty2;
    |               ~~~~~~~
 
+error[E0423]: expected function, tuple struct or tuple variant, found struct `Empty1`
+  --> $DIR/empty-struct-braces-expr.rs:16:14
+   |
+LL | struct Empty1 {}
+   | ---------------- `Empty1` defined here
+...
+LL |     let e1 = Empty1();
+   |              ^^^^^^^^
+   |
+  ::: $DIR/auxiliary/empty-struct.rs:2:1
+   |
+LL | pub struct XEmpty2;
+   | ------------------ similarly named unit struct `XEmpty2` defined here
+   |
+help: use struct literal syntax instead
+   |
+LL |     let e1 = Empty1 {};
+   |              ~~~~~~~~~
+help: a unit struct with a similar name exists
+   |
+LL |     let e1 = XEmpty2();
+   |              ~~~~~~~
+
 error[E0423]: expected function, tuple struct or tuple variant, found struct `XEmpty1`
   --> $DIR/empty-struct-braces-expr.rs:23:15
    |

src/test/ui/error-codes/E0423.stderr

@@ -26,6 +26,17 @@ help: surround the struct literal with parentheses
 LL |     for _ in (std::ops::Range { start: 0, end: 10 }) {}
    |              +                                     +
 
+error[E0423]: expected value, found struct `T`
+  --> $DIR/E0423.rs:14:8
+   |
+LL |     if T {} == T {} { println!("Ok"); }
+   |        ^ not a value
+   |
+help: surround the struct literal with parentheses
+   |
+LL |     if (T {}) == T {} { println!("Ok"); }
+   |        +    +
+
 error[E0423]: expected function, tuple struct or tuple variant, found struct `Foo`
   --> $DIR/E0423.rs:4:13
    |
@@ -47,17 +58,6 @@ help: a function with a similar name exists
 LL |     let f = foo();
    |             ~~~
 
-error[E0423]: expected value, found struct `T`
-  --> $DIR/E0423.rs:14:8
-   |
-LL |     if T {} == T {} { println!("Ok"); }
-   |        ^ not a value
-   |
-help: surround the struct literal with parentheses
-   |
-LL |     if (T {}) == T {} { println!("Ok"); }
-   |        +    +
-
 error: aborting due to 5 previous errors
 
 For more information about this error, try `rustc --explain E0423`.

src/test/ui/issues/issue-58022.stderr

@@ -1,9 +1,3 @@
-error[E0423]: expected function, tuple struct or tuple variant, found trait `Foo`
-  --> $DIR/issue-58022.rs:14:9
-   |
-LL |         Foo(Box::new(*slice))
-   |         ^^^ not a function, tuple struct or tuple variant
-
 error[E0790]: cannot refer to the associated constant on trait without specifying the corresponding `impl` type
   --> $DIR/issue-58022.rs:4:25
    |
@@ -13,6 +7,12 @@ LL |
 LL |     fn new(slice: &[u8; Foo::SIZE]) -> Self;
    |                         ^^^^^^^^^ cannot refer to the associated constant of trait
 
+error[E0423]: expected function, tuple struct or tuple variant, found trait `Foo`
+  --> $DIR/issue-58022.rs:14:9
+   |
+LL |         Foo(Box::new(*slice))
+   |         ^^^ not a function, tuple struct or tuple variant
+
 error: aborting due to 2 previous errors
 
 Some errors have detailed explanations: E0423, E0790.

src/test/ui/lang-items/issue-83471.stderr

@@ -4,12 +4,6 @@ error[E0573]: expected type, found built-in attribute `export_name`
 LL |     fn call(export_name);
    |             ^^^^^^^^^^^ not a type
 
-error[E0425]: cannot find function `a` in this scope
-  --> $DIR/issue-83471.rs:21:5
-   |
-LL |     a()
-   |     ^ not found in this scope
-
 error[E0658]: language items are subject to change
   --> $DIR/issue-83471.rs:7:1
    |
@@ -45,6 +39,12 @@ LL | #[lang = "fn"]
 LL | trait Fn {
    |         - this trait has 0 generic arguments
 
+error[E0425]: cannot find function `a` in this scope
+  --> $DIR/issue-83471.rs:21:5
+   |
+LL |     a()
+   |     ^ not found in this scope
+
 error: aborting due to 5 previous errors; 1 warning emitted
 
 Some errors have detailed explanations: E0425, E0573, E0658, E0718.