Fix private fields diagnostics and improve error messages

compiler/rustc_hir_typeck/src/expr.rs

@@ -2439,25 +2439,28 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             })
             .partition(|field| field.2);
         err.span_labels(used_private_fields.iter().map(|(_, span, _)| *span), "private field");
-        if !remaining_private_fields.is_empty() {
-            let names = if remaining_private_fields.len() > 6 {
-                String::new()
-            } else {
-                format!(
-                    "{} ",
-                    listify(&remaining_private_fields, |(name, _, _)| format!("`{name}`"))
-                        .expect("expected at least one private field to report")
-                )
-            };
-            err.note(format!(
-                "{}private field{s} {names}that {were} not provided",
-                if used_fields.is_empty() { "" } else { "...and other " },
-                s = pluralize!(remaining_private_fields.len()),
-                were = pluralize!("was", remaining_private_fields.len()),
-            ));
-        }
 
         if let ty::Adt(def, _) = adt_ty.kind() {
+            if (def.did().is_local() || !used_fields.is_empty())
+                && !remaining_private_fields.is_empty()
+            {
+                let names = if remaining_private_fields.len() > 6 {
+                    String::new()
+                } else {
+                    format!(
+                        "{} ",
+                        listify(&remaining_private_fields, |(name, _, _)| format!("`{name}`"))
+                            .expect("expected at least one private field to report")
+                    )
+                };
+                err.note(format!(
+                    "{}private field{s} {names}that {were} not provided",
+                    if used_fields.is_empty() { "" } else { "...and other " },
+                    s = pluralize!(remaining_private_fields.len()),
+                    were = pluralize!("was", remaining_private_fields.len()),
+                ));
+            }
+
             let def_id = def.did();
             let mut items = self
                 .tcx

tests/ui/privacy/auxiliary/private-fields-diagnostic-aux-issue-151408.rs

@@ -0,0 +1,24 @@
+pub struct Named {
+    hidden: u8,
+}
+
+impl Named {
+    pub fn new() -> Self {
+        Self { hidden: 0 }
+    }
+}
+
+pub struct NamedWithMultipleFields {
+    hidden: u8,
+    pub visible: u8,
+}
+
+struct PrivateInner;
+
+pub struct PublicTuple(PrivateInner);
+
+impl PublicTuple {
+    pub fn new() -> Self {
+        Self(PrivateInner)
+    }
+}

tests/ui/privacy/private-fields-diagnostic-issue-151408.rs

@@ -0,0 +1,20 @@
+//@ aux-build:private-fields-diagnostic-aux-issue-151408.rs
+
+extern crate private_fields_diagnostic_aux_issue_151408 as aux;
+
+use aux::{Named, NamedWithMultipleFields, PublicTuple};
+
+fn main() {
+    let _ = Named {};
+    //~^ ERROR cannot construct `aux::Named` with struct literal syntax due to private fields
+
+    let _ = PublicTuple();
+    //~^ ERROR cannot initialize a tuple struct which contains private fields [E0423]
+
+    // Keep the private-field note when the user already wrote part of the struct literal.
+    let _ = NamedWithMultipleFields { visible: 1 };
+    //~^ ERROR cannot construct `NamedWithMultipleFields` with struct literal syntax due to private fields
+
+    let _ = NamedWithMultipleFields {};
+    //~^ ERROR cannot construct `NamedWithMultipleFields` with struct literal syntax due to private fields
+}

tests/ui/privacy/private-fields-diagnostic-issue-151408.stderr

@@ -0,0 +1,45 @@
+error: cannot construct `aux::Named` with struct literal syntax due to private fields
+  --> $DIR/private-fields-diagnostic-issue-151408.rs:8:13
+   |
+LL |     let _ = Named {};
+   |             ^^^^^
+   |
+help: you might have meant to use the `new` associated function
+   |
+LL -     let _ = Named {};
+LL +     let _ = Named::new();
+   |
+
+error[E0423]: cannot initialize a tuple struct which contains private fields
+  --> $DIR/private-fields-diagnostic-issue-151408.rs:11:13
+   |
+LL |     let _ = PublicTuple();
+   |             ^^^^^^^^^^^
+   |
+note: constructor is not visible here due to private fields
+  --> $DIR/auxiliary/private-fields-diagnostic-aux-issue-151408.rs:18:24
+   |
+LL | pub struct PublicTuple(PrivateInner);
+   |                        ^^^^^^^^^^^^ private field
+help: you might have meant to use the `new` associated function
+   |
+LL |     let _ = PublicTuple::new();
+   |                        +++++
+
+error: cannot construct `NamedWithMultipleFields` with struct literal syntax due to private fields
+  --> $DIR/private-fields-diagnostic-issue-151408.rs:15:13
+   |
+LL |     let _ = NamedWithMultipleFields { visible: 1 };
+   |             ^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = note: ...and other private field `hidden` that was not provided
+
+error: cannot construct `NamedWithMultipleFields` with struct literal syntax due to private fields
+  --> $DIR/private-fields-diagnostic-issue-151408.rs:18:13
+   |
+LL |     let _ = NamedWithMultipleFields {};
+   |             ^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0423`.

tests/ui/privacy/suggest-box-new.stderr

@@ -81,7 +81,6 @@ error: cannot construct `HashMap<_, _, _, _>` with struct literal syntax due to
 LL |     let _ = std::collections::HashMap {};
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: private field `base` that was not provided
 help: you might have meant to use an associated function to build this type
    |
 LL -     let _ = std::collections::HashMap {};
@@ -109,7 +108,6 @@ error: cannot construct `Box<_, _>` with struct literal syntax due to private fi
 LL |     let _ = Box {};
    |             ^^^
    |
-   = note: private fields `0` and `1` that were not provided
 help: you might have meant to use an associated function to build this type
    |
 LL -     let _ = Box {};
@@ -137,7 +135,6 @@ error: cannot construct `Box<i32>` with struct literal syntax due to private fie
 LL |     let _ = Box::<i32> {};
    |             ^^^^^^^^^^
    |
-   = note: private fields `0` and `1` that were not provided
 help: you might have meant to use an associated function to build this type
    |
 LL -     let _ = Box::<i32> {};

tests/ui/suggestions/multi-suggestion.ascii.stderr

@@ -81,7 +81,6 @@ error: cannot construct `HashMap<_, _, _, _>` with struct literal syntax due to
 LL |     let _ = std::collections::HashMap {};
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^
    |
-   = note: private field `base` that was not provided
 help: you might have meant to use an associated function to build this type
    |
 LL -     let _ = std::collections::HashMap {};
@@ -109,7 +108,6 @@ error: cannot construct `Box<_, _>` with struct literal syntax due to private fi
 LL |     let _ = Box {};
    |             ^^^
    |
-   = note: private fields `0` and `1` that were not provided
 help: you might have meant to use an associated function to build this type
    |
 LL -     let _ = Box {};

tests/ui/suggestions/multi-suggestion.unicode.stderr

@@ -80,8 +80,7 @@ error: cannot construct `HashMap<_, _, _, _>` with struct literal syntax due to
    │
 LL │     let _ = std::collections::HashMap {};
    │             ━━━━━━━━━━━━━━━━━━━━━━━━━
-   │
-   ╰ note: private field `base` that was not provided
+   ╰╴
 help: you might have meant to use an associated function to build this type
    ╭╴
 LL -     let _ = std::collections::HashMap {};
@@ -108,8 +107,7 @@ error: cannot construct `Box<_, _>` with struct literal syntax due to private fi
    │
 LL │     let _ = Box {};
    │             ━━━
-   │
-   ╰ note: private fields `0` and `1` that were not provided
+   ╰╴
 help: you might have meant to use an associated function to build this type
    ╭╴
 LL -     let _ = Box {};