Auto merge of #157487 - CrooseGit:dev/reucru01/only, r=<try>

crater: reserve `only` keyword

Author: bors

.gitmodules

@@ -4,7 +4,7 @@
 	shallow = true
 [submodule "src/tools/cargo"]
 	path = src/tools/cargo
-	url = https://github.com/rust-lang/cargo.git
+	url = https://github.com/lqd/cargo.git
 	shallow = true
 [submodule "src/doc/reference"]
 	path = src/doc/reference

compiler/rustc_ast/src/ast.rs

@@ -3179,6 +3179,8 @@ pub enum BoundPolarity {
     Negative(Span),
     /// `Type: ?Trait`
     Maybe(Span),
+    /// `Type: only Trait`,
+    Only(Span),
 }
 
 impl BoundPolarity {
@@ -3187,6 +3189,7 @@ impl BoundPolarity {
             Self::Positive => "",
             Self::Negative(_) => "!",
             Self::Maybe(_) => "?",
+            Self::Only(_) => "only",
         }
     }
 }

compiler/rustc_ast_lowering/src/lib.rs

@@ -2778,6 +2778,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
             BoundPolarity::Positive => BoundPolarity::Positive,
             BoundPolarity::Negative(span) => BoundPolarity::Negative(self.lower_span(span)),
             BoundPolarity::Maybe(span) => BoundPolarity::Maybe(self.lower_span(span)),
+            BoundPolarity::Only(span) => BoundPolarity::Only(self.lower_span(span)),
         };
         hir::TraitBoundModifiers { constness, polarity }
     }

compiler/rustc_ast_pretty/src/pprust/state.rs

@@ -1478,7 +1478,9 @@ impl<'a> State<'a> {
         }
         match polarity {
             ast::BoundPolarity::Positive => {}
-            ast::BoundPolarity::Negative(_) | ast::BoundPolarity::Maybe(_) => {
+            ast::BoundPolarity::Negative(_)
+            | ast::BoundPolarity::Maybe(_)
+            | ast::BoundPolarity::Only(_) => {
                 self.word(polarity.as_str());
             }
         }

compiler/rustc_attr_parsing/src/session_diagnostics.rs

@@ -331,7 +331,7 @@ pub(crate) struct EmptyConfusables {
 }
 
 #[derive(Diagnostic)]
-#[help("`#[{$name}{$attribute_args}]` can {$only}be applied to {$applied}")]
+#[help("`#[{$name}{$attribute_args}]` can {$only_prefix}be applied to {$applied}")]
 #[diag("`#[{$name}{$attribute_args}]` attribute cannot be used on {$target}")]
 pub(crate) struct InvalidTarget {
     #[primary_span]
@@ -345,7 +345,7 @@ pub(crate) struct InvalidTarget {
     pub name: AttrPath,
     pub target: &'static str,
     pub applied: DiagArgValue,
-    pub only: &'static str,
+    pub only_prefix: &'static str,
     pub attribute_args: &'static str,
     #[subdiagnostic]
     pub help: Option<InvalidTargetHelp>,

compiler/rustc_attr_parsing/src/target_checking.rs

@@ -128,12 +128,13 @@ impl<'sess> AttributeParser<'sess> {
         }
 
         let allowed_targets = allowed_targets.allowed_targets();
-        let (applied, only) = allowed_targets_applied(allowed_targets, cx.target, cx.features);
+        let (applied, only_prefix) =
+            allowed_targets_applied(allowed_targets, cx.target, cx.features);
         let diag = InvalidTarget {
             span: cx.attr_span.clone(),
             name: cx.attr_path.clone(),
             target: cx.target.plural_name(),
-            only: if only { "only " } else { "" },
+            only_prefix: if only_prefix { "only " } else { "" },
             applied: DiagArgValue::StrListSepByAnd(applied.into_iter().map(Cow::Owned).collect()),
             attribute_args,
             help: Self::target_checking_help(attribute_args, cx),

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -1430,7 +1430,7 @@ impl<'infcx, 'tcx> MirBorrowckCtxt<'_, 'infcx, 'tcx> {
                 span.push_span_label(expr.span, "you could clone this value");
                 let types: Vec<_> = types.into_iter().collect();
                 let msg = match &types[..] {
-                    [only] => format!("`{only}`"),
+                    [single] => format!("`{single}`"),
                     [head @ .., last] => format!(
                         "{} and `{last}`",
                         head.iter().map(|t| format!("`{t}`")).collect::<Vec<_>>().join(", ")

compiler/rustc_hir_analysis/src/hir_ty_lowering/bounds.rs

@@ -31,6 +31,8 @@ struct CollectedBound {
     maybe: bool,
     /// `!Trait`
     negative: bool,
+    /// `only Trait`
+    only_modifier: bool,
 }
 
 impl CollectedBound {
@@ -112,6 +114,7 @@ fn collect_bounds<'a, 'tcx>(
         match ptr.modifiers.polarity {
             hir::BoundPolarity::Maybe(_) => collect_into.maybe = true,
             hir::BoundPolarity::Negative(_) => collect_into.negative = true,
+            hir::BoundPolarity::Only(_) => collect_into.only_modifier = true,
             hir::BoundPolarity::Positive => collect_into.positive = true,
         }
     });

compiler/rustc_hir_analysis/src/hir_ty_lowering/mod.rs

@@ -986,13 +986,14 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
                 self.require_bound_to_relax_default_trait(trait_ref, span);
                 true
             }
+            hir::BoundPolarity::Only(_) => true,
         };
         let bounds = if transient { &mut Vec::new() } else { bounds };
 
         let polarity = match polarity {
-            hir::BoundPolarity::Positive | hir::BoundPolarity::Maybe(_) => {
-                ty::PredicatePolarity::Positive
-            }
+            hir::BoundPolarity::Positive
+            | hir::BoundPolarity::Maybe(_)
+            | hir::BoundPolarity::Only(_) => ty::PredicatePolarity::Positive,
             hir::BoundPolarity::Negative(_) => ty::PredicatePolarity::Negative,
         };
 

compiler/rustc_hir_pretty/src/lib.rs

@@ -824,6 +824,7 @@ impl<'a> State<'a> {
             hir::BoundPolarity::Positive => {}
             hir::BoundPolarity::Negative(_) => self.word("!"),
             hir::BoundPolarity::Maybe(_) => self.word("?"),
+            hir::BoundPolarity::Only(_) => self.word_space("only"),
         }
         self.print_formal_generic_params(t.bound_generic_params);
         self.print_trait_ref(&t.trait_ref);