Auto merge of #145640 - estebank:point-at-impl-e0277, r=nnethercote

When a trait isn't implemented, but another similar impl is found, point at it ``` error[E0277]: the trait bound `u32: Trait` is not satisfied --> $DIR/trait_objects_fail.rs:26:9 | LL | foo(&10_u32); | ^^^^^^^ the trait `Trait` is not implemented for `u32` | help: the trait `Trait<12>` is not implemented for `u32` but trait `Trait<2>` is implemented for it --> $DIR/trait_objects_fail.rs:7:1 | LL | impl Trait<2> for u32 {} | ^^^^^^^^^^^^^^^^^^^^^ = note: required for the cast from `&u32` to `&dyn Trait` ``` Pointing at the `impl` definition that *could* apply given a different self type is *particularly* useful when it has a blanket self type, as it might not be obvious and is not trivially greppable: ``` error[E0277]: the trait bound `RawImpl<_>: Raw<_>` is not satisfied --> $DIR/issue-62742.rs:4:5 | LL | WrongImpl::foo(0i32); | ^^^^^^^^^ unsatisfied trait bound | help: the trait `Raw<_>` is not implemented for `RawImpl<_>` but trait `Raw<[_]>` is implemented for it --> $DIR/issue-62742.rs:29:1 | LL | impl<T> Raw<[T]> for RawImpl<T> { | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ note: required by a bound in `SafeImpl` --> $DIR/issue-62742.rs:33:35 | LL | pub struct SafeImpl<T: ?Sized, A: Raw<T>>(PhantomData<(A, T)>); | ^^^^^^ required by this bound in `SafeImpl` ```

Author: bors

compiler/rustc_errors/src/emitter.rs

@@ -1523,16 +1523,17 @@ impl HumanEmitter {
  label_width += 2;
  }
  let mut line = 0;
+ let mut pad = false;
  for (text, style) in msgs.iter() {
  let text =
  self.translator.translate_message(text, args).map_err(Report::new).unwrap();
  // Account for newlines to align output to its label.
- for text in normalize_whitespace(&text).lines() {
+ for text in normalize_whitespace(&text).split('\n') {
  buffer.append(
  line,
  &format!(
  "{}{}",
- if line == 0 { String::new() } else { " ".repeat(label_width) },
+ if pad { " ".repeat(label_width) } else { String::new() },
  text
  ),
  match style {
@@ -1541,7 +1542,9 @@ impl HumanEmitter {
  },
  );
  line += 1;
+ pad = true;
  }
+ pad = false;
  // We add lines above, but if the last line has no explicit newline (which would
  // yield an empty line), then we revert one line up to continue with the next
  // styled text chunk on the same line as the last one from the prior one. Otherwise

compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

@@ -1,3 +1,4 @@
+// ignore-tidy-filelength
 use core::ops::ControlFlow;
 use std::borrow::Cow;
 use std::path::PathBuf;
@@ -1906,13 +1907,13 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
  // ignore `do_not_recommend` items
  .filter(|def_id| !self.tcx.do_not_recommend_impl(*def_id))
  // Ignore automatically derived impls and `!Trait` impls.
- .map(|def_id| self.tcx.impl_trait_header(def_id))
- .filter_map(|header| {
- (header.polarity != ty::ImplPolarity::Negative
+ .map(|def_id| (self.tcx.impl_trait_header(def_id), def_id))
+ .filter_map(|(header, def_id)| {
+ (header.polarity == ty::ImplPolarity::Positive
  || self.tcx.is_automatically_derived(def_id))
- .then(|| header.trait_ref.instantiate_identity())
+ .then(|| (header.trait_ref.instantiate_identity(), def_id))
  })
- .filter(|trait_ref| {
+ .filter(|(trait_ref, _)| {
  let self_ty = trait_ref.self_ty();
  // Avoid mentioning type parameters.
  if let ty::Param(_) = self_ty.kind() {
@@ -1944,7 +1945,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
  })
  .collect();
 
- impl_candidates.sort_by_key(|tr| tr.to_string());
+ impl_candidates.sort_by_key(|(tr, _)| tr.to_string());
  impl_candidates.dedup();
  impl_candidates
  };
@@ -1972,7 +1973,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
  let candidates = if impl_candidates.is_empty() {
  alternative_candidates(trait_def_id)
  } else {
- impl_candidates.into_iter().map(|cand| cand.trait_ref).collect()
+ impl_candidates.into_iter().map(|cand| (cand.trait_ref, cand.impl_def_id)).collect()
  };
  let mut span: MultiSpan = self.tcx.def_span(trait_def_id).into();
  span.push_span_label(self.tcx.def_span(trait_def_id), "this is the required trait");
@@ -2004,7 +2005,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
  self.tcx.def_span(found_type),
  "this type doesn't implement the required trait",
  );
- for trait_ref in candidates {
+ for (trait_ref, _) in candidates {
  if let ty::Adt(def, _) = trait_ref.self_ty().peel_refs().kind()
  && let candidate_def_id = def.did()
  && let Some(name) = self.tcx.opt_item_name(candidate_def_id)
@@ -2191,7 +2192,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
  msg.extend(types.1.0);
  msg.push(StringPart::normal("`"));
  }
- err.highlighted_help(msg);
+ err.highlighted_span_help(self.tcx.def_span(single.impl_def_id), msg);
 
  if let [TypeError::Sorts(exp_found)] = &terrs[..] {
  let exp_found = self.resolve_vars_if_possible(*exp_found);
@@ -2217,12 +2218,12 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
  }
 
  let other = if other { "other " } else { "" };
- let report = |mut candidates: Vec<TraitRef<'tcx>>, err: &mut Diag<'_>| {
- candidates.retain(|tr| !tr.references_error());
+ let report = |mut candidates: Vec<(TraitRef<'tcx>, DefId)>, err: &mut Diag<'_>| {
+ candidates.retain(|(tr, _)| !tr.references_error());
  if candidates.is_empty() {
  return false;
  }
- if let &[cand] = &candidates[..] {
+ if let &[(cand, def_id)] = &candidates[..] {
  if self.tcx.is_diagnostic_item(sym::FromResidual, cand.def_id)
  && !self.tcx.features().enabled(sym::try_trait_v2)
  {
@@ -2238,56 +2239,87 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
  };
  let trait_ = self.tcx.short_string(cand.print_trait_sugared(), err.long_ty_path());
  let self_ty = self.tcx.short_string(cand.self_ty(), err.long_ty_path());
- err.highlighted_help(vec![
- StringPart::normal(format!("the trait `{trait_}` ",)),
- StringPart::highlighted("is"),
- StringPart::normal(desc),
- StringPart::highlighted(self_ty),
- StringPart::normal("`"),
- StringPart::normal(mention_castable),
- ]);
+ err.highlighted_span_help(
+ self.tcx.def_span(def_id),
+ vec![
+ StringPart::normal(format!("the trait `{trait_}` ",)),
+ StringPart::highlighted("is"),
+ StringPart::normal(desc),
+ StringPart::highlighted(self_ty),
+ StringPart::normal("`"),
+ StringPart::normal(mention_castable),
+ ],
+ );
  return true;
  }
- let trait_ref = TraitRef::identity(self.tcx, candidates[0].def_id);
+ let trait_ref = TraitRef::identity(self.tcx, candidates[0].0.def_id);
  // Check if the trait is the same in all cases. If so, we'll only show the type.
  let mut traits: Vec<_> =
- candidates.iter().map(|c| c.print_only_trait_path().to_string()).collect();
+ candidates.iter().map(|(c, _)| c.print_only_trait_path().to_string()).collect();
  traits.sort();
  traits.dedup();
  // FIXME: this could use a better heuristic, like just checking
  // that args[1..] is the same.
  let all_traits_equal = traits.len() == 1;
 
- let candidates: Vec<String> = candidates
- .into_iter()
- .map(|c| {
- if all_traits_equal {
- format!("\n {}", self.tcx.short_string(c.self_ty(), err.long_ty_path()))
- } else {
- format!(
- "\n `{}` implements `{}`",
- self.tcx.short_string(c.self_ty(), err.long_ty_path()),
- self.tcx.short_string(c.print_only_trait_path(), err.long_ty_path()),
- )
- }
- })
- .collect();
-
  let end = if candidates.len() <= 9 || self.tcx.sess.opts.verbose {
  candidates.len()
  } else {
  8
  };
- err.help(format!(
- "the following {other}types implement trait `{}`:{}{}",
- trait_ref.print_trait_sugared(),
- candidates[..end].join(""),
- if candidates.len() > 9 && !self.tcx.sess.opts.verbose {
- format!("\nand {} others", candidates.len() - 8)
- } else {
- String::new()
+ if candidates.len() < 5 {
+ let spans: Vec<_> =
+ candidates.iter().map(|(_, def_id)| self.tcx.def_span(def_id)).collect();
+ let mut span: MultiSpan = spans.into();
+ for (c, def_id) in &candidates {
+ let msg = if all_traits_equal {
+ format!("`{}`", self.tcx.short_string(c.self_ty(), err.long_ty_path()))
+ } else {
+ format!(
+ "`{}` implements `{}`",
+ self.tcx.short_string(c.self_ty(), err.long_ty_path()),
+ self.tcx.short_string(c.print_only_trait_path(), err.long_ty_path()),
+ )
+ };
+ span.push_span_label(self.tcx.def_span(def_id), msg);
  }
- ));
+ err.span_help(
+ span,
+ format!(
+ "the following {other}types implement trait `{}`",
+ trait_ref.print_trait_sugared(),
+ ),
+ );
+ } else {
+ let candidate_names: Vec<String> = candidates
+ .iter()
+ .map(|(c, _)| {
+ if all_traits_equal {
+ format!(
+ "\n {}",
+ self.tcx.short_string(c.self_ty(), err.long_ty_path())
+ )
+ } else {
+ format!(
+ "\n `{}` implements `{}`",
+ self.tcx.short_string(c.self_ty(), err.long_ty_path()),
+ self.tcx
+ .short_string(c.print_only_trait_path(), err.long_ty_path()),
+ )
+ }
+ })
+ .collect();
+ err.help(format!(
+ "the following {other}types implement trait `{}`:{}{}",
+ trait_ref.print_trait_sugared(),
+ candidate_names[..end].join(""),
+ if candidates.len() > 9 && !self.tcx.sess.opts.verbose {
+ format!("\nand {} others", candidates.len() - 8)
+ } else {
+ String::new()
+ }
+ ));
+ }
  true
  };
 
@@ -2349,7 +2381,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
  (cand.similarity, len, cand.trait_ref.to_string())
  });
  let mut impl_candidates: Vec<_> =
- impl_candidates.into_iter().map(|cand| cand.trait_ref).collect();
+ impl_candidates.into_iter().map(|cand| (cand.trait_ref, cand.impl_def_id)).collect();
  impl_candidates.dedup();
 
  report(impl_candidates, err)

tests/ui-fulldeps/rustc-dev-remap.only-remap.stderr

@@ -9,9 +9,13 @@ help: the trait `VisitorResult` is not implemented for `NotAValidResultType`
  |
 LL | struct NotAValidResultType;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^
- = help: the following other types implement trait `VisitorResult`:
- ()
- ControlFlow<T>
+help: the following other types implement trait `VisitorResult`
+ --> /rustc-dev/xyz/compiler/rustc_ast_ir/src/visit.rs:LL:COL
+ |
+ = note: `()`
+ ::: /rustc-dev/xyz/compiler/rustc_ast_ir/src/visit.rs:LL:COL
+ |
+ = note: `ControlFlow<T>`
 note: required by a bound in `rustc_ast::visit::Visitor::Result`
  --> /rustc-dev/xyz/compiler/rustc_ast/src/visit.rs:LL:COL
  = note: this error originates in the macro `common_visitor_and_walkers` (in Nightly builds, run with -Z macro-backtrace for more info)

tests/ui-fulldeps/rustc-dev-remap.remap-unremap.stderr

@@ -9,9 +9,14 @@ help: the trait `VisitorResult` is not implemented for `NotAValidResultType`
  |
 LL | struct NotAValidResultType;
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^
- = help: the following other types implement trait `VisitorResult`:
- ()
- ControlFlow<T>
+help: the following other types implement trait `VisitorResult`
+ --> $COMPILER_DIR_REAL/rustc_ast_ir/src/visit.rs:LL:COL
+ |
+LL | impl VisitorResult for () {
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^ `()`
+...
+LL | impl<T> VisitorResult for ControlFlow<T> {
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `ControlFlow<T>`
 note: required by a bound in `rustc_ast::visit::Visitor::Result`
  --> $COMPILER_DIR_REAL/rustc_ast/src/visit.rs:LL:COL
  |

tests/ui/allocator/not-an-allocator.rs

@@ -1,3 +1,6 @@
+//@ revisions: u w
+//@[u] only-unix
+//@[w] only-windows
 #[global_allocator]
 static A: usize = 0;
 //~^ ERROR E0277

tests/ui/allocator/not-an-allocator.stderr renamed to tests/ui/allocator/not-an-allocator.u.stderr

@@ -1,44 +1,48 @@
 error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
- --> $DIR/not-an-allocator.rs:2:11
+ --> $DIR/not-an-allocator.rs:5:11
  |
 LL | #[global_allocator]
  | ------------------- in this attribute macro expansion
 LL | static A: usize = 0;
  | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize`
  |
- = help: the trait `GlobalAlloc` is implemented for `System`
+help: the trait `GlobalAlloc` is implemented for `System`
+ --> $SRC_DIR/std/src/sys/alloc/unix.rs:LL:COL
 
 error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
- --> $DIR/not-an-allocator.rs:2:11
+ --> $DIR/not-an-allocator.rs:5:11
  |
 LL | #[global_allocator]
  | ------------------- in this attribute macro expansion
 LL | static A: usize = 0;
  | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize`
  |
- = help: the trait `GlobalAlloc` is implemented for `System`
+help: the trait `GlobalAlloc` is implemented for `System`
+ --> $SRC_DIR/std/src/sys/alloc/unix.rs:LL:COL
  = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
- --> $DIR/not-an-allocator.rs:2:11
+ --> $DIR/not-an-allocator.rs:5:11
  |
 LL | #[global_allocator]
  | ------------------- in this attribute macro expansion
 LL | static A: usize = 0;
  | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize`
  |
- = help: the trait `GlobalAlloc` is implemented for `System`
+help: the trait `GlobalAlloc` is implemented for `System`
+ --> $SRC_DIR/std/src/sys/alloc/unix.rs:LL:COL
  = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
- --> $DIR/not-an-allocator.rs:2:11
+ --> $DIR/not-an-allocator.rs:5:11
  |
 LL | #[global_allocator]
  | ------------------- in this attribute macro expansion
 LL | static A: usize = 0;
  | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize`
  |
- = help: the trait `GlobalAlloc` is implemented for `System`
+help: the trait `GlobalAlloc` is implemented for `System`
+ --> $SRC_DIR/std/src/sys/alloc/unix.rs:LL:COL
  = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
 
 error: aborting due to 4 previous errors

tests/ui/allocator/not-an-allocator.w.stderr

@@ -0,0 +1,50 @@
+error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
+ --> $DIR/not-an-allocator.rs:5:11
+ |
+LL | #[global_allocator]
+ | ------------------- in this attribute macro expansion
+LL | static A: usize = 0;
+ | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize`
+ |
+help: the trait `GlobalAlloc` is implemented for `System`
+ --> $SRC_DIR/std/src/sys/alloc/windows.rs:LL:COL
+
+error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
+ --> $DIR/not-an-allocator.rs:5:11
+ |
+LL | #[global_allocator]
+ | ------------------- in this attribute macro expansion
+LL | static A: usize = 0;
+ | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize`
+ |
+help: the trait `GlobalAlloc` is implemented for `System`
+ --> $SRC_DIR/std/src/sys/alloc/windows.rs:LL:COL
+ = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
+ --> $DIR/not-an-allocator.rs:5:11
+ |
+LL | #[global_allocator]
+ | ------------------- in this attribute macro expansion
+LL | static A: usize = 0;
+ | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize`
+ |
+help: the trait `GlobalAlloc` is implemented for `System`
+ --> $SRC_DIR/std/src/sys/alloc/windows.rs:LL:COL
+ = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error[E0277]: the trait bound `usize: GlobalAlloc` is not satisfied
+ --> $DIR/not-an-allocator.rs:5:11
+ |
+LL | #[global_allocator]
+ | ------------------- in this attribute macro expansion
+LL | static A: usize = 0;
+ | ^^^^^ the trait `GlobalAlloc` is not implemented for `usize`
+ |
+help: the trait `GlobalAlloc` is implemented for `System`
+ --> $SRC_DIR/std/src/sys/alloc/windows.rs:LL:COL
+ = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
+
+error: aborting due to 4 previous errors
+
+For more information about this error, try `rustc --explain E0277`.