Auto merge of #49799 - hdhoang:46205_deny_incoherent_fundamental_impls, r=nikomatsakis

lint: convert incoherent_fundamental_impls into hard error

*Summary for affected authors:* If your crate depends on one of the following crates, please upgrade to a newer version:
- gtk-rs: upgrade to at least 0.4
- rusqlite: upgrade to at least 0.14
- nalgebra: upgrade to at least 0.15, or the last patch version of 0.14
- spade: upgrade or refresh the Cargo.lock file to use version 1.7
- imageproc: upgrade to at least 0.16 (newer versions no longer use nalgebra)

implement #46205

r? @nikomatsakis

src/doc/rustc/src/lints/groups.md

@@ -21,9 +21,9 @@ Here's a list of each lint group, and the lints that they are made up of:
 | edition-2018        | Lints that will be turned into errors in Rust 2018            | tyvar-behind-raw-pointer                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
 | rust-2018-idioms    | Lints to nudge you toward idiomatic features of Rust 2018     | bare-trait-object, unreachable-pub                                                                                                                                                                                                                                                                                                                                                                                                                                                     |
 | unused              | These lints detect things being declared but not used         | unused-imports, unused-variables, unused-assignments, dead-code, unused-mut, unreachable-code, unreachable-patterns, unused-must-use, unused-unsafe, path-statements, unused-attributes, unused-macros, unused-allocation, unused-doc-comment, unused-extern-crates, unused-features, unused-parens                                                                                                                                                                                    |
-| future-incompatible | Lints that detect code that has future-compatibility problems | private-in-public, pub-use-of-private-extern-crate, patterns-in-fns-without-body, safe-extern-statics, invalid-type-param-default, legacy-directory-ownership, legacy-imports, legacy-constructor-visibility, missing-fragment-specifier, illegal-floating-point-literal-pattern, anonymous-parameters, parenthesized-params-in-types-and-modules, late-bound-lifetime-arguments, safe-packed-borrows, incoherent-fundamental-impls, tyvar-behind-raw-pointer, unstable-name-collision |
+| future-incompatible | Lints that detect code that has future-compatibility problems | private-in-public, pub-use-of-private-extern-crate, patterns-in-fns-without-body, safe-extern-statics, invalid-type-param-default, legacy-directory-ownership, legacy-imports, legacy-constructor-visibility, missing-fragment-specifier, illegal-floating-point-literal-pattern, anonymous-parameters, parenthesized-params-in-types-and-modules, late-bound-lifetime-arguments, safe-packed-borrows, tyvar-behind-raw-pointer, unstable-name-collision |
 
 Additionally, there's a `bad-style` lint group that's a deprecated alias for `nonstandard-style`.
 
 Finally, you can also see the table above by invoking `rustc -W help`. This will give you the exact values for the specific
-compiler you have installed.
+compiler you have installed.

src/doc/rustc/src/lints/listing/deny-by-default.md

@@ -222,44 +222,3 @@ error: invalid `crate_type` value
   | ^^^^^^^^^^^^^^^^^^^^
   |
 ```
-
-## incoherent-fundamental-impls
-
-This lint detects potentially-conflicting impls that were erroneously allowed. Some
-example code that triggers this lint:
-
-```rust,ignore
-pub trait Trait1<X> {
-    type Output;
-}
-
-pub trait Trait2<X> {}
-
-pub struct A;
-
-impl<X, T> Trait1<X> for T where T: Trait2<X> {
-    type Output = ();
-}
-
-impl<X> Trait1<Box<X>> for A {
-    type Output = i32;
-}
-```
-
-This will produce:
-
-```text
-error: conflicting implementations of trait `Trait1<std::boxed::Box<_>>` for type `A`: (E0119)
-  --> src/main.rs:13:1
-   |
-9  | impl<X, T> Trait1<X> for T where T: Trait2<X> {
-   | --------------------------------------------- first implementation here
-...
-13 | impl<X> Trait1<Box<X>> for A {
-   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `A`
-   |
-   = note: #[deny(incoherent_fundamental_impls)] on by default
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #46205 <https://github.com/rust-lang/rust/issues/46205>
-   = note: downstream crates may implement trait `Trait2<std::boxed::Box<_>>` for type `A`
-```

src/librustc/lint/builtin.rs

@@ -198,12 +198,6 @@ declare_lint! {
     "detects generic lifetime arguments in path segments with late bound lifetime parameters"
 }
 
-declare_lint! {
-    pub INCOHERENT_FUNDAMENTAL_IMPLS,
-    Deny,
-    "potentially-conflicting impls were erroneously allowed"
-}
-
 declare_lint! {
     pub ORDER_DEPENDENT_TRAIT_OBJECTS,
     Deny,
@@ -428,7 +422,6 @@ declare_lint_pass! {
         MISSING_FRAGMENT_SPECIFIER,
         PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES,
         LATE_BOUND_LIFETIME_ARGUMENTS,
-        INCOHERENT_FUNDAMENTAL_IMPLS,
         ORDER_DEPENDENT_TRAIT_OBJECTS,
         DEPRECATED,
         UNUSED_UNSAFE,

src/librustc/traits/specialize/mod.rs

@@ -319,29 +319,34 @@ pub(super) fn specialization_graph_provider<'a, 'tcx>(
                         String::new(), |ty| {
                             format!(" for type `{}`", ty)
                         }),
-                    if used_to_be_allowed.is_some() { " (E0119)" } else { "" }
+                    match used_to_be_allowed {
+                        Some(FutureCompatOverlapErrorKind::Issue33140) => " (E0119)",
+                        _ => "",
+                    }
                 );
                 let impl_span = tcx.sess.source_map().def_span(
                     tcx.span_of_impl(impl_def_id).unwrap()
                 );
-                let mut err = if let Some(kind) = used_to_be_allowed {
+                let mut err = match used_to_be_allowed {
-                    let lint = match kind {
+                    Some(FutureCompatOverlapErrorKind::Issue43355) | None =>
-                        FutureCompatOverlapErrorKind::Issue43355 =>
+                        struct_span_err!(tcx.sess,
-                            lint::builtin::INCOHERENT_FUNDAMENTAL_IMPLS,
+                                         impl_span,
-                        FutureCompatOverlapErrorKind::Issue33140 =>
+                                         E0119,
-                            lint::builtin::ORDER_DEPENDENT_TRAIT_OBJECTS,
+                                         "{}",
-                    };
+                                         msg),
-                    tcx.struct_span_lint_hir(
+                    Some(kind) => {
-                        lint,
+                        let lint = match kind {
-                        tcx.hir().as_local_hir_id(impl_def_id).unwrap(),
+                            FutureCompatOverlapErrorKind::Issue43355 =>
-                        impl_span,
+                                unreachable!("converted to hard error above"),
-                        &msg)
+                            FutureCompatOverlapErrorKind::Issue33140 =>
-                } else {
+                                lint::builtin::ORDER_DEPENDENT_TRAIT_OBJECTS,
-                    struct_span_err!(tcx.sess,
+                        };
-                                     impl_span,
+                        tcx.struct_span_lint_hir(
-                                     E0119,
+                            lint,
-                                     "{}",
+                            tcx.hir().as_local_hir_id(impl_def_id).unwrap(),
-                                     msg)
+                            impl_span,
+                            &msg)
+                    }
                 };
 
                 match tcx.span_of_impl(overlap.with_impl) {

src/librustc_lint/lib.rs

@@ -371,11 +371,6 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
             reference: "issue #46043 <https://github.com/rust-lang/rust/issues/46043>",
             edition: None,
         },
-        FutureIncompatibleInfo {
-            id: LintId::of(INCOHERENT_FUNDAMENTAL_IMPLS),
-            reference: "issue #46205 <https://github.com/rust-lang/rust/issues/46205>",
-            edition: None,
-        },
         FutureIncompatibleInfo {
             id: LintId::of(ORDER_DEPENDENT_TRAIT_OBJECTS),
             reference: "issue #56484 <https://github.com/rust-lang/rust/issues/56484>",
@@ -491,6 +486,8 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
         "replaced with a generic attribute input check");
     store.register_removed("duplicate_matcher_binding_name",
         "converted into hard error, see https://github.com/rust-lang/rust/issues/57742");
+    store.register_removed("incoherent_fundamental_impls",
+        "converted into hard error, see https://github.com/rust-lang/rust/issues/46205");
 }
 
 pub fn register_internals(store: &mut lint::LintStore, sess: Option<&Session>) {

src/librustc_typeck/coherence/inherent_impls_overlap.rs

@@ -5,8 +5,6 @@ use rustc::hir::itemlikevisit::ItemLikeVisitor;
 use rustc::traits::{self, IntercrateMode};
 use rustc::ty::TyCtxt;
 
-use crate::lint;
-
 pub fn crate_inherent_impls_overlap_check<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                                     crate_num: CrateNum) {
     assert_eq!(crate_num, LOCAL_CRATE);
@@ -20,8 +18,7 @@ struct InherentOverlapChecker<'a, 'tcx: 'a> {
 
 impl<'a, 'tcx> InherentOverlapChecker<'a, 'tcx> {
     fn check_for_common_items_in_impls(&self, impl1: DefId, impl2: DefId,
-                                       overlap: traits::OverlapResult<'_>,
+                                       overlap: traits::OverlapResult<'_>) {
-                                       used_to_be_allowed: bool) {
 
         let name_and_namespace = |def_id| {
             let item = self.tcx.associated_item(def_id);
@@ -36,22 +33,12 @@ impl<'a, 'tcx> InherentOverlapChecker<'a, 'tcx> {
 
             for &item2 in &impl_items2[..] {
                 if (name, namespace) == name_and_namespace(item2) {
-                    let hir_id = self.tcx.hir().as_local_hir_id(impl1);
+                    let mut err =
-                    let mut err = if used_to_be_allowed && hir_id.is_some() {
-                        self.tcx.struct_span_lint_hir(
-                            lint::builtin::INCOHERENT_FUNDAMENTAL_IMPLS,
-                            hir_id.unwrap(),
-                            self.tcx.span_of_impl(item1).unwrap(),
-                            &format!("duplicate definitions with name `{}` (E0592)", name)
-                        )
-                    } else {
                         struct_span_err!(self.tcx.sess,
                                          self.tcx.span_of_impl(item1).unwrap(),
                                          E0592,
                                          "duplicate definitions with name `{}`",
-                                         name)
+                                         name);
-                    };
-
                     err.span_label(self.tcx.span_of_impl(item1).unwrap(),
                                    format!("duplicate definitions for `{}`", name));
                     err.span_label(self.tcx.span_of_impl(item2).unwrap(),
@@ -76,7 +63,7 @@ impl<'a, 'tcx> InherentOverlapChecker<'a, 'tcx> {
 
         for (i, &impl1_def_id) in impls.iter().enumerate() {
             for &impl2_def_id in &impls[(i + 1)..] {
-                let used_to_be_allowed = traits::overlapping_impls(
+                traits::overlapping_impls(
                     self.tcx,
                     impl1_def_id,
                     impl2_def_id,
@@ -86,28 +73,11 @@ impl<'a, 'tcx> InherentOverlapChecker<'a, 'tcx> {
                             impl1_def_id,
                             impl2_def_id,
                             overlap,
-                            false,
                         );
                         false
                     },
                     || true,
                 );
-
-                if used_to_be_allowed {
-                    traits::overlapping_impls(
-                        self.tcx,
-                        impl1_def_id,
-                        impl2_def_id,
-                        IntercrateMode::Fixed,
-                        |overlap| self.check_for_common_items_in_impls(
-                            impl1_def_id,
-                            impl2_def_id,
-                            overlap,
-                            true,
-                        ),
-                        || (),
-                    );
-                }
             }
         }
     }

src/test/ui/issues/issue-43355.rs

@@ -12,7 +12,6 @@ impl<X, T> Trait1<X> for T where T: Trait2<X> {
 
 impl<X> Trait1<Box<X>> for A {
 //~^ ERROR conflicting implementations of trait
-//~| hard error
 //~| downstream crates may implement trait `Trait2<std::boxed::Box<_>>` for type `A`
     type Output = i32;
 }

src/test/ui/issues/issue-43355.stderr

@@ -1,4 +1,4 @@
-error: conflicting implementations of trait `Trait1<std::boxed::Box<_>>` for type `A`: (E0119)
+error[E0119]: conflicting implementations of trait `Trait1<std::boxed::Box<_>>` for type `A`:
   --> $DIR/issue-43355.rs:13:1
    |
 LL | impl<X, T> Trait1<X> for T where T: Trait2<X> {
@@ -7,10 +7,8 @@ LL | impl<X, T> Trait1<X> for T where T: Trait2<X> {
 LL | impl<X> Trait1<Box<X>> for A {
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `A`
    |
-   = note: #[deny(incoherent_fundamental_impls)] on by default
-   = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
-   = note: for more information, see issue #46205 <https://github.com/rust-lang/rust/issues/46205>
    = note: downstream crates may implement trait `Trait2<std::boxed::Box<_>>` for type `A`
 
 error: aborting due to previous error
 
+For more information about this error, try `rustc --explain E0119`.