lint: convert incoherent_fundamental_impls into hard error

implement #46205

Author: hdhoang

src/librustc/lint/builtin.rs

@@ -206,12 +206,6 @@ declare_lint! {
     "detects generic lifetime arguments in path segments with late bound lifetime parameters"
 }
 
-declare_lint! {
-    pub INCOHERENT_FUNDAMENTAL_IMPLS,
-    Warn,
-    "potentially-conflicting impls were erroneously allowed"
-}
-
 declare_lint! {
     pub DEPRECATED,
     Warn,
@@ -306,7 +300,6 @@ impl LintPass for HardwiredLints {
             MISSING_FRAGMENT_SPECIFIER,
             PARENTHESIZED_PARAMS_IN_TYPES_AND_MODULES,
             LATE_BOUND_LIFETIME_ARGUMENTS,
-            INCOHERENT_FUNDAMENTAL_IMPLS,
             DEPRECATED,
             UNUSED_UNSAFE,
             UNUSED_MUT,

src/librustc/traits/specialize/mod.rs

@@ -32,8 +32,6 @@ use ty::{self, TyCtxt, TypeFoldable};
 use syntax_pos::DUMMY_SP;
 use rustc_data_structures::sync::Lrc;
 
-use lint;
-
 pub mod specialization_graph;
 
 /// Information pertinent to an overlapping impl error.
@@ -329,36 +327,21 @@ pub(super) fn specialization_graph_provider<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx
             // This is where impl overlap checking happens:
             let insert_result = sg.insert(tcx, impl_def_id);
             // Report error if there was one.
-            let (overlap, used_to_be_allowed) = match insert_result {
-                Err(overlap) => (Some(overlap), false),
-                Ok(opt_overlap) => (opt_overlap, true)
-            };
-
-            if let Some(overlap) = overlap {
-                let msg = format!("conflicting implementations of trait `{}`{}:{}",
+            if let Some(overlap) = match insert_result {
+                Err(overlap) => Some(overlap),
+                Ok(opt_overlap) => opt_overlap,
+            } {
+                let msg = format!("conflicting implementations of trait `{}`{}:",
                     overlap.trait_desc,
                     overlap.self_desc.clone().map_or(
                         String::new(), |ty| {
                             format!(" for type `{}`", ty)
                         }),
-                    if used_to_be_allowed { " (E0119)" } else { "" }
                 );
                 let impl_span = tcx.sess.codemap().def_span(
                     tcx.span_of_impl(impl_def_id).unwrap()
                 );
-                let mut err = if used_to_be_allowed {
-                    tcx.struct_span_lint_node(
-                        lint::builtin::INCOHERENT_FUNDAMENTAL_IMPLS,
-                        tcx.hir.as_local_node_id(impl_def_id).unwrap(),
-                        impl_span,
-                        &msg)
-                } else {
-                    struct_span_err!(tcx.sess,
-                                     impl_span,
-                                     E0119,
-                                     "{}",
-                                     msg)
-                };
+                let mut err = struct_span_err!(tcx.sess, impl_span, E0119, "{}", msg);
 
                 match tcx.span_of_impl(overlap.with_impl) {
                     Ok(span) => {

src/librustc_lint/lib.rs

@@ -262,11 +262,6 @@ 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(TYVAR_BEHIND_RAW_POINTER),
             reference: "issue #46906 <https://github.com/rust-lang/rust/issues/46906>",
@@ -314,4 +309,6 @@ pub fn register_builtins(store: &mut lint::LintStore, sess: Option<&Session>) {
         "converted into hard error, see https://github.com/rust-lang/rust/issues/48950");
     store.register_removed("resolve_trait_on_defaulted_unit",
         "converted into hard error, see https://github.com/rust-lang/rust/issues/48950");
+    store.register_removed("incoherent_fundamental_impls",
+        "converted into hard error, see https://github.com/rust-lang/rust/issues/46205");
 }

src/librustc_typeck/coherence/inherent_impls_overlap.rs

@@ -15,8 +15,6 @@ use rustc::hir::itemlikevisit::ItemLikeVisitor;
 use rustc::traits::{self, IntercrateMode};
 use rustc::ty::TyCtxt;
 
-use lint;
-
 pub fn crate_inherent_impls_overlap_check<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
                                                     crate_num: CrateNum) {
     assert_eq!(crate_num, LOCAL_CRATE);
@@ -30,8 +28,7 @@ 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,
-                                       used_to_be_allowed: bool) {
+                                       overlap: traits::OverlapResult) {
 
         let name_and_namespace = |def_id| {
             let item = self.tcx.associated_item(def_id);
@@ -46,21 +43,13 @@ impl<'a, 'tcx> InherentOverlapChecker<'a, 'tcx> {
 
             for &item2 in &impl_items2[..] {
                 if (name, namespace) == name_and_namespace(item2) {
-                    let node_id = self.tcx.hir.as_local_node_id(impl1);
-                    let mut err = if used_to_be_allowed && node_id.is_some() {
-                        self.tcx.struct_span_lint_node(
-                            lint::builtin::INCOHERENT_FUNDAMENTAL_IMPLS,
-                            node_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)
-                    };
+                    let mut err = struct_span_err!(
+                        self.tcx.sess,
+                        self.tcx.span_of_impl(item1).unwrap(),
+                        E0592,
+                        "duplicate definitions with name `{}`",
+                        name
+                    );
 
                     err.span_label(self.tcx.span_of_impl(item1).unwrap(),
                                    format!("duplicate definitions for `{}`", name));
@@ -82,38 +71,16 @@ 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,
                     IntercrateMode::Issue43355,
                     |overlap| {
-                        self.check_for_common_items_in_impls(
-                            impl1_def_id,
-                            impl2_def_id,
-                            overlap,
-                            false,
-                        );
-                        false
+                        self.check_for_common_items_in_impls(impl1_def_id, impl2_def_id, overlap)
                     },
-                    || 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/compile-fail/issue-43355.rs

@@ -8,8 +8,6 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
-#![deny(incoherent_fundamental_impls)]
-
 pub trait Trait1<X> {
     type Output;
 }
@@ -24,7 +22,6 @@ 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;
 }