Rollup merge of #101161 - ldm0:ldm_fix_diagnostic, r=cjgillot

Fix uintended diagnostic caused by `drain(..)`

Calling `drain(..)` makes later `suggestable_variants.is_empty()` always true, which makes the diagnostics unintended.

compiler/rustc_resolve/src/late/diagnostics.rs

@@ -1792,7 +1792,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                 }
             };
 
-            let mut suggestable_variants = variants
+            let suggestable_variants = variants
                 .iter()
                 .filter(|(_, def_id, kind)| !needs_placeholder(*def_id, *kind))
                 .map(|(variant, _, kind)| (path_names_to_string(variant), kind))
@@ -1802,8 +1802,9 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                     CtorKind::Fictive => format!("({} {{}})", variant),
                 })
                 .collect::<Vec<_>>();
+            let no_suggestable_variant = suggestable_variants.is_empty();
 
-            if !suggestable_variants.is_empty() {
+            if !no_suggestable_variant {
                 let msg = if suggestable_variants.len() == 1 {
                     "you might have meant to use the following enum variant"
                 } else {
@@ -1813,7 +1814,7 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                 err.span_suggestions(
                     span,
                     msg,
-                    suggestable_variants.drain(..),
+                    suggestable_variants.into_iter(),
                     Applicability::MaybeIncorrect,
                 );
             }
@@ -1830,15 +1831,15 @@ impl<'a: 'ast, 'ast> LateResolutionVisitor<'a, '_, 'ast> {
                 .collect::<Vec<_>>();
 
             if !suggestable_variants_with_placeholders.is_empty() {
-                let msg = match (
+                let msg =
-                    suggestable_variants.is_empty(),
+                    match (no_suggestable_variant, suggestable_variants_with_placeholders.len()) {
-                    suggestable_variants_with_placeholders.len(),
+                        (true, 1) => "the following enum variant is available",
-                ) {
+                        (true, _) => "the following enum variants are available",
-                    (true, 1) => "the following enum variant is available",
+                        (false, 1) => "alternatively, the following enum variant is available",
-                    (true, _) => "the following enum variants are available",
+                        (false, _) => {
-                    (false, 1) => "alternatively, the following enum variant is available",
+                            "alternatively, the following enum variants are also available"
-                    (false, _) => "alternatively, the following enum variants are also available",
+                        }
-                };
+                    };
 
                 err.span_suggestions(
                     span,

src/test/ui/resolve/issue-73427.rs

@@ -22,6 +22,10 @@ enum D {
     Unit,
 }
 
+enum E {
+    TupleWithFields(()),
+}
+
 fn main() {
     // Only variants without fields are suggested (and others mentioned in a note) where an enum
     // is used rather than a variant.
@@ -34,6 +38,8 @@ fn main() {
     //~^ ERROR expected value, found enum `C`
     D.foo();
     //~^ ERROR expected value, found enum `D`
+    E.foo();
+    //~^ ERROR expected value, found enum `E`
 
     // Only tuple variants are suggested in calls or tuple struct pattern matching.
 

src/test/ui/resolve/issue-73427.stderr

@@ -1,5 +1,5 @@
 error[E0423]: expected value, found enum `A`
-  --> $DIR/issue-73427.rs:29:5
+  --> $DIR/issue-73427.rs:33:5
    |
 LL |     A.foo();
    |     ^
@@ -23,7 +23,7 @@ LL |     (A::Tuple()).foo();
    |     ~~~~~~~~~~~~
 LL |     A::Unit.foo();
    |     ~~~~~~~
-help: the following enum variants are available
+help: alternatively, the following enum variants are also available
    |
 LL |     (A::StructWithFields { /* fields */ }).foo();
    |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -31,7 +31,7 @@ LL |     (A::TupleWithFields(/* fields */)).foo();
    |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 error[E0423]: expected value, found enum `B`
-  --> $DIR/issue-73427.rs:31:5
+  --> $DIR/issue-73427.rs:35:5
    |
 LL |     B.foo();
    |     ^
@@ -52,7 +52,7 @@ LL |     (B::TupleWithFields(/* fields */)).foo();
    |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 error[E0423]: expected value, found enum `C`
-  --> $DIR/issue-73427.rs:33:5
+  --> $DIR/issue-73427.rs:37:5
    |
 LL |     C.foo();
    |     ^
@@ -70,7 +70,7 @@ help: you might have meant to use the following enum variant
    |
 LL |     C::Unit.foo();
    |     ~~~~~~~
-help: the following enum variants are available
+help: alternatively, the following enum variants are also available
    |
 LL |     (C::StructWithFields { /* fields */ }).foo();
    |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -78,7 +78,7 @@ LL |     (C::TupleWithFields(/* fields */)).foo();
    |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 error[E0423]: expected value, found enum `D`
-  --> $DIR/issue-73427.rs:35:5
+  --> $DIR/issue-73427.rs:39:5
    |
 LL |     D.foo();
    |     ^
@@ -95,13 +95,37 @@ help: you might have meant to use the following enum variant
    |
 LL |     D::Unit.foo();
    |     ~~~~~~~
-help: the following enum variant is available
+help: alternatively, the following enum variant is available
    |
 LL |     (D::TupleWithFields(/* fields */)).foo();
    |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
+error[E0423]: expected value, found enum `E`
+  --> $DIR/issue-73427.rs:41:5
+   |
+LL |     E.foo();
+   |     ^
+   |
+note: the enum is defined here
+  --> $DIR/issue-73427.rs:25:1
+   |
+LL | / enum E {
+LL | |     TupleWithFields(()),
+LL | | }
+   | |_^
+help: the following enum variant is available
+   |
+LL |     (E::TupleWithFields(/* fields */)).foo();
+   |     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+help: consider importing one of these items instead
+   |
+LL | use std::f32::consts::E;
+   |
+LL | use std::f64::consts::E;
+   |
+
 error[E0423]: expected function, tuple struct or tuple variant, found enum `A`
-  --> $DIR/issue-73427.rs:40:13
+  --> $DIR/issue-73427.rs:46:13
    |
 LL |     let x = A(3);
    |             ^
@@ -126,7 +150,7 @@ LL |     let x = A::TupleWithFields(3);
    |             ~~~~~~~~~~~~~~~~~~
 
 error[E0532]: expected tuple struct or tuple variant, found enum `A`
-  --> $DIR/issue-73427.rs:42:12
+  --> $DIR/issue-73427.rs:48:12
    |
 LL |     if let A(3) = x { }
    |            ^
@@ -150,7 +174,7 @@ LL |     if let A::Tuple(3) = x { }
 LL |     if let A::TupleWithFields(3) = x { }
    |            ~~~~~~~~~~~~~~~~~~
 
-error: aborting due to 6 previous errors
+error: aborting due to 7 previous errors
 
 Some errors have detailed explanations: E0423, E0532.
 For more information about an error, try `rustc --explain E0423`.

src/test/ui/resolve/privacy-enum-ctor.stderr

@@ -19,7 +19,7 @@ help: you might have meant to use the following enum variant
    |
 LL |         m::Z::Unit;
    |         ~~~~~~~~~~
-help: the following enum variants are available
+help: alternatively, the following enum variants are also available
    |
 LL |         (m::Z::Fn(/* fields */));
    |         ~~~~~~~~~~~~~~~~~~~~~~~~
@@ -47,7 +47,7 @@ help: you might have meant to use the following enum variant
    |
 LL |         m::Z::Unit;
    |         ~~~~~~~~~~
-help: the following enum variants are available
+help: alternatively, the following enum variants are also available
    |
 LL |         (m::Z::Fn(/* fields */));
    |         ~~~~~~~~~~~~~~~~~~~~~~~~
@@ -89,7 +89,7 @@ help: you might have meant to use the following enum variant
    |
 LL |     let _: E = E::Unit;
    |                ~~~~~~~
-help: the following enum variants are available
+help: alternatively, the following enum variants are also available
    |
 LL |     let _: E = (E::Fn(/* fields */));
    |                ~~~~~~~~~~~~~~~~~~~~~
@@ -143,7 +143,7 @@ help: you might have meant to use the following enum variant
    |
 LL |     let _: E = E::Unit;
    |                ~~~~~~~
-help: the following enum variants are available
+help: alternatively, the following enum variants are also available
    |
 LL |     let _: E = (E::Fn(/* fields */));
    |                ~~~~~~~~~~~~~~~~~~~~~
@@ -203,7 +203,7 @@ help: you might have meant to use the following enum variant
    |
 LL |     let _: Z = m::Z::Unit;
    |                ~~~~~~~~~~
-help: the following enum variants are available
+help: alternatively, the following enum variants are also available
    |
 LL |     let _: Z = (m::Z::Fn(/* fields */));
    |                ~~~~~~~~~~~~~~~~~~~~~~~~