Move trait impl modifier errors to parsing

camsteffen · fmease · commit d7c736ad78e2 · 2025-08-12T02:32:51.000+02:00
This is a technically a breaking change for what can be parsed in
`#[cfg(false)]`.
diff --git a/compiler/rustc_ast_passes/messages.ftl b/compiler/rustc_ast_passes/messages.ftl
@@ -175,11 +175,6 @@ ast_passes_generic_default_trailing = generic parameters with a default must be
 ast_passes_incompatible_features = `{$f1}` and `{$f2}` are incompatible, using them at the same time is not allowed
     .help = remove one of these features
 
-ast_passes_inherent_cannot_be = inherent impls cannot be {$annotation}
-    .because = {$annotation} because of this
-    .type = inherent impl for this type
-    .only_trait = only trait implementations may be annotated with {$annotation}
-
 ast_passes_item_invalid_safety = items outside of `unsafe extern {"{ }"}` cannot be declared with `safe` safety qualifier
     .suggestion = remove safe from this item
 
diff --git a/compiler/rustc_ast_passes/src/ast_validation.rs b/compiler/rustc_ast_passes/src/ast_validation.rs
@@ -26,7 +26,7 @@ use rustc_ast::visit::{AssocCtxt, BoundKind, FnCtxt, FnKind, Visitor, walk_list}
 use rustc_ast::*;
 use rustc_ast_pretty::pprust::{self, State};
 use rustc_data_structures::fx::FxIndexMap;
-use rustc_errors::{DiagCtxtHandle, E0197};
+use rustc_errors::DiagCtxtHandle;
 use rustc_feature::Features;
 use rustc_parse::validate_attr;
 use rustc_session::Session;
@@ -993,49 +993,20 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                 });
             }
             ItemKind::Impl(box Impl {
-                safety,
-                polarity,
-                defaultness,
-                constness,
+                safety: _,
+                polarity: _,
+                defaultness: _,
+                constness: _,
                 generics,
                 of_trait: None,
                 self_ty,
                 items,
             }) => {
-                let error = |annotation_span, annotation, only_trait| errors::InherentImplCannot {
-                    span: self_ty.span,
-                    annotation_span,
-                    annotation,
-                    self_ty: self_ty.span,
-                    only_trait,
-                };
-
                 self.visit_attrs_vis(&item.attrs, &item.vis);
                 self.visibility_not_permitted(
                     &item.vis,
                     errors::VisibilityNotPermittedNote::IndividualImplItems,
                 );
-                if let &Safety::Unsafe(span) = safety {
-                    self.dcx()
-                        .create_err(errors::InherentImplCannot {
-                            span: self_ty.span,
-                            annotation_span: span,
-                            annotation: "unsafe",
-                            self_ty: self_ty.span,
-                            only_trait: true,
-                        })
-                        .with_code(E0197)
-                        .emit();
-                }
-                if let &ImplPolarity::Negative(span) = polarity {
-                    self.dcx().emit_err(error(span, "negative", false));
-                }
-                if let &Defaultness::Default(def_span) = defaultness {
-                    self.dcx().emit_err(error(def_span, "`default`", true));
-                }
-                if let &Const::Yes(span) = constness {
-                    self.dcx().emit_err(error(span, "`const`", true));
-                }
 
                 self.with_tilde_const(Some(TildeConstReason::Impl { span: item.span }), |this| {
                     this.visit_generics(generics)
diff --git a/compiler/rustc_ast_passes/src/errors.rs b/compiler/rustc_ast_passes/src/errors.rs
@@ -464,20 +464,6 @@ pub(crate) struct UnsafeNegativeImpl {
     pub r#unsafe: Span,
 }
 
-#[derive(Diagnostic)]
-#[diag(ast_passes_inherent_cannot_be)]
-pub(crate) struct InherentImplCannot<'a> {
-    #[primary_span]
-    pub span: Span,
-    #[label(ast_passes_because)]
-    pub annotation_span: Span,
-    pub annotation: &'a str,
-    #[label(ast_passes_type)]
-    pub self_ty: Span,
-    #[note(ast_passes_only_trait)]
-    pub only_trait: bool,
-}
-
 #[derive(Diagnostic)]
 #[diag(ast_passes_unsafe_item)]
 pub(crate) struct UnsafeItem {
diff --git a/compiler/rustc_parse/messages.ftl b/compiler/rustc_parse/messages.ftl
@@ -869,6 +869,11 @@ parse_trait_alias_cannot_be_auto = trait aliases cannot be `auto`
 parse_trait_alias_cannot_be_const = trait aliases cannot be `const`
 parse_trait_alias_cannot_be_unsafe = trait aliases cannot be `unsafe`
 
+parse_trait_impl_modifier_in_inherent_impl = inherent impls cannot be {$annotation}
+    .because = {$annotation} because of this
+    .type = inherent impl for this type
+    .only_trait = only trait implementations may be annotated with {$annotation}
+
 parse_transpose_dyn_or_impl = `for<...>` expected after `{$kw}`, not before
     .suggestion = move `{$kw}` before the `for<...>`
 
diff --git a/compiler/rustc_parse/src/errors.rs b/compiler/rustc_parse/src/errors.rs
@@ -71,6 +71,20 @@ pub(crate) struct BadQPathStage2 {
     pub wrap: WrapType,
 }
 
+#[derive(Diagnostic)]
+#[diag(parse_trait_impl_modifier_in_inherent_impl)]
+pub(crate) struct TraitImplModifierInInherentImpl<'a> {
+    #[primary_span]
+    pub span: Span,
+    #[label(parse_because)]
+    pub annotation_span: Span,
+    pub annotation: &'a str,
+    #[label(parse_type)]
+    pub self_ty: Span,
+    #[note(parse_only_trait)]
+    pub only_trait: bool,
+}
+
 #[derive(Subdiagnostic)]
 #[multipart_suggestion(parse_suggestion, applicability = "machine-applicable")]
 pub(crate) struct WrapType {
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
@@ -665,7 +665,41 @@ impl<'a> Parser<'a> {
 
                 (Some(trait_ref), ty_second)
             }
-            None => (None, ty_first), // impl Type
+            None => {
+                let self_ty = ty_first;
+                let error = |annotation_span, annotation, only_trait| {
+                    errors::TraitImplModifierInInherentImpl {
+                        span: self_ty.span,
+                        annotation_span,
+                        annotation,
+                        self_ty: self_ty.span,
+                        only_trait,
+                    }
+                };
+
+                if let Safety::Unsafe(span) = safety {
+                    self.dcx()
+                        .create_err(errors::TraitImplModifierInInherentImpl {
+                            span: self_ty.span,
+                            annotation_span: span,
+                            annotation: "unsafe",
+                            self_ty: self_ty.span,
+                            only_trait: true,
+                        })
+                        .with_code(E0197)
+                        .emit();
+                }
+                if let ImplPolarity::Negative(span) = polarity {
+                    self.dcx().emit_err(error(span, "negative", false));
+                }
+                if let Defaultness::Default(def_span) = defaultness {
+                    self.dcx().emit_err(error(def_span, "`default`", true));
+                }
+                if let Const::Yes(span) = constness {
+                    self.dcx().emit_err(error(span, "`const`", true));
+                }
+                (None, self_ty)
+            }
         };
         Ok(ItemKind::Impl(Box::new(Impl {
             safety,
diff --git a/tests/ui/parser/default-on-wrong-item-kind.rs b/tests/ui/parser/default-on-wrong-item-kind.rs
@@ -19,7 +19,7 @@ mod free_items {
     default union foo {} //~ ERROR a union cannot be `default`
     default trait foo {} //~ ERROR a trait cannot be `default`
     default trait foo = Ord; //~ ERROR a trait alias cannot be `default`
-    default impl foo {}
+    default impl foo {} //~ ERROR inherent impls cannot be `default`
     default!();
     default::foo::bar!();
     default default!(); //~ ERROR an item macro invocation cannot be `default`
@@ -53,7 +53,7 @@ extern "C" {
     //~^ ERROR trait is not supported in `extern` blocks
     default trait foo = Ord; //~ ERROR a trait alias cannot be `default`
     //~^ ERROR trait alias is not supported in `extern` blocks
-    default impl foo {}
+    default impl foo {} //~ ERROR inherent impls cannot be `default`
     //~^ ERROR implementation is not supported in `extern` blocks
     default!();
     default::foo::bar!();
@@ -90,7 +90,7 @@ impl S {
     //~^ ERROR trait is not supported in `trait`s or `impl`s
     default trait foo = Ord; //~ ERROR a trait alias cannot be `default`
     //~^ ERROR trait alias is not supported in `trait`s or `impl`s
-    default impl foo {}
+    default impl foo {} //~ ERROR inherent impls cannot be `default`
     //~^ ERROR implementation is not supported in `trait`s or `impl`s
     default!();
     default::foo::bar!();
@@ -127,7 +127,7 @@ trait T {
     //~^ ERROR trait is not supported in `trait`s or `impl`s
     default trait foo = Ord; //~ ERROR a trait alias cannot be `default`
     //~^ ERROR trait alias is not supported in `trait`s or `impl`s
-    default impl foo {}
+    default impl foo {} //~ ERROR inherent impls cannot be `default`
     //~^ ERROR implementation is not supported in `trait`s or `impl`s
     default!();
     default::foo::bar!();
diff --git a/tests/ui/parser/default-on-wrong-item-kind.stderr b/tests/ui/parser/default-on-wrong-item-kind.stderr
@@ -78,6 +78,16 @@ LL |     default trait foo = Ord;
    |
    = note: only associated `fn`, `const`, and `type` items can be `default`
 
+error: inherent impls cannot be `default`
+  --> $DIR/default-on-wrong-item-kind.rs:22:18
+   |
+LL |     default impl foo {}
+   |     -------      ^^^ inherent impl for this type
+   |     |
+   |     `default` because of this
+   |
+   = note: only trait implementations may be annotated with `default`
+
 error: an item macro invocation cannot be `default`
   --> $DIR/default-on-wrong-item-kind.rs:25:5
    |
@@ -275,6 +285,16 @@ LL |     default trait foo = Ord;
    |
    = help: consider moving the trait alias out to a nearby module scope
 
+error: inherent impls cannot be `default`
+  --> $DIR/default-on-wrong-item-kind.rs:56:18
+   |
+LL |     default impl foo {}
+   |     -------      ^^^ inherent impl for this type
+   |     |
+   |     `default` because of this
+   |
+   = note: only trait implementations may be annotated with `default`
+
 error: implementation is not supported in `extern` blocks
   --> $DIR/default-on-wrong-item-kind.rs:56:5
    |
@@ -489,6 +509,16 @@ LL |     default trait foo = Ord;
    |
    = help: consider moving the trait alias out to a nearby module scope
 
+error: inherent impls cannot be `default`
+  --> $DIR/default-on-wrong-item-kind.rs:93:18
+   |
+LL |     default impl foo {}
+   |     -------      ^^^ inherent impl for this type
+   |     |
+   |     `default` because of this
+   |
+   = note: only trait implementations may be annotated with `default`
+
 error: implementation is not supported in `trait`s or `impl`s
   --> $DIR/default-on-wrong-item-kind.rs:93:5
    |
@@ -703,6 +733,16 @@ LL |     default trait foo = Ord;
    |
    = help: consider moving the trait alias out to a nearby module scope
 
+error: inherent impls cannot be `default`
+  --> $DIR/default-on-wrong-item-kind.rs:130:18
+   |
+LL |     default impl foo {}
+   |     -------      ^^^ inherent impl for this type
+   |     |
+   |     `default` because of this
+   |
+   = note: only trait implementations may be annotated with `default`
+
 error: implementation is not supported in `trait`s or `impl`s
   --> $DIR/default-on-wrong-item-kind.rs:130:5
    |
@@ -759,5 +799,5 @@ LL |     default macro_rules! foo {}
    |
    = help: consider moving the macro definition out to a nearby module scope
 
-error: aborting due to 95 previous errors
+error: aborting due to 99 previous errors
 
diff --git a/tests/ui/traits/const-traits/macro-const-trait-bound-theoretical-regression.stderr b/tests/ui/traits/const-traits/macro-const-trait-bound-theoretical-regression.stderr
@@ -1,14 +1,3 @@
-error: macro expansion ignores keyword `dyn` and any tokens following
-  --> $DIR/macro-const-trait-bound-theoretical-regression.rs:14:31
-   |
-LL |     (dyn $c:ident Trait) => { dyn $c Trait {} };
-   |                               ^^^
-...
-LL | demo! { dyn const Trait }
-   | ------------------------- caused by the macro expansion here
-   |
-   = note: the usage of `demo!` is likely invalid in item context
-
 error: inherent impls cannot be `const`
   --> $DIR/macro-const-trait-bound-theoretical-regression.rs:10:40
    |
@@ -24,6 +13,17 @@ LL | demo! { impl const Trait }
    = note: only trait implementations may be annotated with `const`
    = note: this error originates in the macro `demo` (in Nightly builds, run with -Z macro-backtrace for more info)
 
+error: macro expansion ignores keyword `dyn` and any tokens following
+  --> $DIR/macro-const-trait-bound-theoretical-regression.rs:14:31
+   |
+LL |     (dyn $c:ident Trait) => { dyn $c Trait {} };
+   |                               ^^^
+...
+LL | demo! { dyn const Trait }
+   | ------------------------- caused by the macro expansion here
+   |
+   = note: the usage of `demo!` is likely invalid in item context
+
 error[E0658]: const trait impls are experimental
   --> $DIR/macro-const-trait-bound-theoretical-regression.rs:17:14
    |
diff --git a/tests/ui/traits/syntax-trait-polarity.stderr b/tests/ui/traits/syntax-trait-polarity.stderr
@@ -6,6 +6,14 @@ LL | impl !TestType {}
    |      |
    |      negative because of this
 
+error: inherent impls cannot be negative
+  --> $DIR/syntax-trait-polarity.rs:18:10
+   |
+LL | impl<T> !TestType2<T> {}
+   |         -^^^^^^^^^^^^ inherent impl for this type
+   |         |
+   |         negative because of this
+
 error[E0198]: negative impls cannot be unsafe
   --> $DIR/syntax-trait-polarity.rs:12:13
    |
@@ -15,14 +23,6 @@ LL | unsafe impl !Send for TestType {}
    | |           negative because of this
    | unsafe because of this
 
-error: inherent impls cannot be negative
-  --> $DIR/syntax-trait-polarity.rs:18:10
-   |
-LL | impl<T> !TestType2<T> {}
-   |         -^^^^^^^^^^^^ inherent impl for this type
-   |         |
-   |         negative because of this
-
 error[E0198]: negative impls cannot be unsafe
   --> $DIR/syntax-trait-polarity.rs:21:16
    |
