From 98ed5548d7e604470ab9a97ffed4d9c12e424d83 Mon Sep 17 00:00:00 2001
From: Michael Howell <michael@notriddle.com>
Date: Thu, 30 Sep 2021 22:47:41 -0700
Subject: [PATCH] nice_region_error: Include lifetime placeholders in error
output
As you can see in src/test/ui/traits/self-without-lifetime-constraint.stderr
you can get very confusing type names if you don't have this.
Fixes #87763
---
.../trait_impl_difference.rs | 59 +++++++++++++++----
.../mismatched_trait_impl-2.stderr | 8 +--
.../mismatched_trait_impl.nll.stderr | 8 +--
.../mismatched_trait_impl.stderr | 8 +--
...ime-mismatch-between-trait-and-impl.stderr | 8 +--
.../issue-75361-mismatched-impl.stderr | 8 +--
.../param-without-lifetime-constraint.stderr | 8 +--
.../self-without-lifetime-constraint.stderr | 8 +--
8 files changed, 76 insertions(+), 39 deletions(-)
diff --git a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
index ea9d0eae17e..b9e7ee12bc8 100644
--- a/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
+++ b/compiler/rustc_infer/src/infer/error_reporting/nice_region_error/trait_impl_difference.rs
@@ -9,10 +9,13 @@ use rustc_hir as hir;
use rustc_hir::def::Res;
use rustc_hir::def_id::DefId;
use rustc_hir::intravisit::Visitor;
-use rustc_middle::ty::error::ExpectedFound;
-use rustc_middle::ty::{self, Ty, TyCtxt};
+use rustc_middle::ty::print::RegionHighlightMode;
+use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeVisitor};
+
use rustc_span::{MultiSpan, Span, Symbol};
+use std::ops::ControlFlow;
+
impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
/// Print the error message for lifetime errors when the `impl` doesn't conform to the `trait`.
pub(super) fn try_report_impl_not_conforming_to_trait(&self) -> Option<ErrorReported> {
@@ -69,6 +72,47 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
.tcx()
.sess
.struct_span_err(sp, "`impl` item signature doesn't match `trait` item signature");
+
+ // Mark all unnamed regions in the type with a number.
+ // This diagnostic is called in response to lifetime errors, so be informative.
+ struct HighlightBuilder<'tcx> {
+ highlight: RegionHighlightMode,
+ tcx: TyCtxt<'tcx>,
+ counter: usize,
+ }
+
+ impl HighlightBuilder<'tcx> {
+ fn build(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> RegionHighlightMode {
+ let mut builder =
+ HighlightBuilder { highlight: RegionHighlightMode::default(), counter: 1, tcx };
+ builder.visit_ty(ty);
+ builder.highlight
+ }
+ }
+
+ impl<'tcx> ty::fold::TypeVisitor<'tcx> for HighlightBuilder<'tcx> {
+ fn tcx_for_anon_const_substs(&self) -> Option<TyCtxt<'tcx>> {
+ Some(self.tcx)
+ }
+
+ fn visit_region(&mut self, r: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
+ if !r.has_name() && self.counter <= 3 {
+ self.highlight.highlighting_region(r, self.counter);
+ self.counter += 1;
+ }
+ r.super_visit_with(self)
+ }
+ }
+
+ let expected_highlight = HighlightBuilder::build(self.tcx(), expected);
+ let expected = self
+ .infcx
+ .extract_inference_diagnostics_data(expected.into(), Some(expected_highlight))
+ .name;
+ let found_highlight = HighlightBuilder::build(self.tcx(), found);
+ let found =
+ self.infcx.extract_inference_diagnostics_data(found.into(), Some(found_highlight)).name;
+
err.span_label(sp, &format!("found `{}`", found));
err.span_label(trait_sp, &format!("expected `{}`", expected));
@@ -96,15 +140,8 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
);
}
- if let Some((expected, found)) =
- self.infcx.expected_found_str_ty(ExpectedFound { expected, found })
- {
- // Highlighted the differences when showing the "expected/found" note.
- err.note_expected_found(&"", expected, &"", found);
- } else {
- // This fallback shouldn't be necessary, but let's keep it in just in case.
- err.note(&format!("expected `{}`\n found `{}`", expected, found));
- }
+ err.note(&format!("expected `{}`\n found `{}`", expected, found));
+
err.span_help(
type_param_span,
"the lifetime requirements from the `impl` do not correspond to the requirements in \
diff --git a/src/test/ui/in-band-lifetimes/mismatched_trait_impl-2.stderr b/src/test/ui/in-band-lifetimes/mismatched_trait_impl-2.stderr
index b15efd6c770..0546b6b51b2 100644
--- a/src/test/ui/in-band-lifetimes/mismatched_trait_impl-2.stderr
+++ b/src/test/ui/in-band-lifetimes/mismatched_trait_impl-2.stderr
@@ -2,15 +2,15 @@ error: `impl` item signature doesn't match `trait` item signature
--> $DIR/mismatched_trait_impl-2.rs:8:5
|
LL | fn deref(&self) -> &dyn Trait {
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&Struct) -> &dyn Trait`
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 Struct) -> &'1 (dyn Trait + '1)`
|
::: $SRC_DIR/core/src/ops/deref.rs:LL:COL
|
LL | fn deref(&self) -> &Self::Target;
- | --------------------------------- expected `fn(&Struct) -> &(dyn Trait + 'static)`
+ | --------------------------------- expected `fn(&'1 Struct) -> &'1 (dyn Trait + 'static)`
|
- = note: expected `fn(&Struct) -> &(dyn Trait + 'static)`
- found `fn(&Struct) -> &dyn Trait`
+ = note: expected `fn(&'1 Struct) -> &'1 (dyn Trait + 'static)`
+ found `fn(&'1 Struct) -> &'1 (dyn Trait + '1)`
= help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
= help: verify the lifetime relationships in the `trait` and `impl` between the `self` argument, the other inputs and its output
diff --git a/src/test/ui/in-band-lifetimes/mismatched_trait_impl.nll.stderr b/src/test/ui/in-band-lifetimes/mismatched_trait_impl.nll.stderr
index 149c2aeb958..c7a90c57add 100644
--- a/src/test/ui/in-band-lifetimes/mismatched_trait_impl.nll.stderr
+++ b/src/test/ui/in-band-lifetimes/mismatched_trait_impl.nll.stderr
@@ -2,13 +2,13 @@ error: `impl` item signature doesn't match `trait` item signature
--> $DIR/mismatched_trait_impl.rs:9:5
|
LL | fn foo(&self, x: &'a u32, y: &u32) -> &'a u32;
- | ---------------------------------------------- expected `fn(&i32, &'a u32, &u32) -> &'a u32`
+ | ---------------------------------------------- expected `fn(&'1 i32, &'a u32, &'2 u32) -> &'a u32`
...
LL | fn foo(&self, x: &u32, y: &'a u32) -> &'a u32 {
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&i32, &u32, &u32) -> &u32`
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 i32, &'2 u32, &'3 u32) -> &'3 u32`
|
- = note: expected `fn(&i32, &'a u32, &u32) -> &'a u32`
- found `fn(&i32, &u32, &u32) -> &u32`
+ = note: expected `fn(&'1 i32, &'a u32, &'2 u32) -> &'a u32`
+ found `fn(&'1 i32, &'2 u32, &'3 u32) -> &'3 u32`
= help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
= help: verify the lifetime relationships in the `trait` and `impl` between the `self` argument, the other inputs and its output
diff --git a/src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr b/src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr
index 9a0bd827850..84e5339122e 100644
--- a/src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr
+++ b/src/test/ui/in-band-lifetimes/mismatched_trait_impl.stderr
@@ -2,13 +2,13 @@ error: `impl` item signature doesn't match `trait` item signature
--> $DIR/mismatched_trait_impl.rs:9:5
|
LL | fn foo(&self, x: &'a u32, y: &u32) -> &'a u32;
- | ---------------------------------------------- expected `fn(&i32, &'a u32, &u32) -> &'a u32`
+ | ---------------------------------------------- expected `fn(&'1 i32, &'a u32, &'2 u32) -> &'a u32`
...
LL | fn foo(&self, x: &u32, y: &'a u32) -> &'a u32 {
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&i32, &u32, &u32) -> &u32`
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 i32, &'2 u32, &'3 u32) -> &'3 u32`
|
- = note: expected `fn(&i32, &'a u32, &u32) -> &'a u32`
- found `fn(&i32, &u32, &u32) -> &u32`
+ = note: expected `fn(&'1 i32, &'a u32, &'2 u32) -> &'a u32`
+ found `fn(&'1 i32, &'2 u32, &'3 u32) -> &'3 u32`
= help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
= help: verify the lifetime relationships in the `trait` and `impl` between the `self` argument, the other inputs and its output
diff --git a/src/test/ui/lifetimes/lifetime-mismatch-between-trait-and-impl.stderr b/src/test/ui/lifetimes/lifetime-mismatch-between-trait-and-impl.stderr
index 060e6954403..3040a8512ce 100644
--- a/src/test/ui/lifetimes/lifetime-mismatch-between-trait-and-impl.stderr
+++ b/src/test/ui/lifetimes/lifetime-mismatch-between-trait-and-impl.stderr
@@ -2,13 +2,13 @@ error: `impl` item signature doesn't match `trait` item signature
--> $DIR/lifetime-mismatch-between-trait-and-impl.rs:6:5
|
LL | fn foo<'a>(x: &i32, y: &'a i32) -> &'a i32;
- | ------------------------------------------- expected `fn(&i32, &'a i32) -> &'a i32`
+ | ------------------------------------------- expected `fn(&'1 i32, &'a i32) -> &'a i32`
...
LL | fn foo<'a>(x: &'a i32, y: &'a i32) -> &'a i32 {
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&i32, &i32) -> &i32`
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 i32, &'1 i32) -> &'1 i32`
|
- = note: expected `fn(&i32, &'a i32) -> &'a i32`
- found `fn(&i32, &i32) -> &i32`
+ = note: expected `fn(&'1 i32, &'a i32) -> &'a i32`
+ found `fn(&'1 i32, &'1 i32) -> &'1 i32`
= help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
= help: verify the lifetime relationships in the `trait` and `impl` between the `self` argument, the other inputs and its output
diff --git a/src/test/ui/mismatched_types/issue-75361-mismatched-impl.stderr b/src/test/ui/mismatched_types/issue-75361-mismatched-impl.stderr
index 9867addaf38..2a2c23c9421 100644
--- a/src/test/ui/mismatched_types/issue-75361-mismatched-impl.stderr
+++ b/src/test/ui/mismatched_types/issue-75361-mismatched-impl.stderr
@@ -2,13 +2,13 @@ error: `impl` item signature doesn't match `trait` item signature
--> $DIR/issue-75361-mismatched-impl.rs:18:3
|
LL | fn adjacent_edges(&self) -> Box<dyn MyTrait<Item = &Self::EdgeType>>;
- | --------------------------------------------------------------------- expected `fn(&T) -> Box<(dyn MyTrait<Item = &T> + 'static)>`
+ | --------------------------------------------------------------------- expected `fn(&'1 T) -> Box<(dyn MyTrait<Item = &'1 T> + 'static)>`
...
LL | fn adjacent_edges(&self) -> Box<dyn MyTrait<Item = &Self::EdgeType> + '_> {
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&T) -> Box<dyn MyTrait<Item = &T>>`
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 T) -> Box<(dyn MyTrait<Item = &'1 T> + '1)>`
|
- = note: expected `fn(&T) -> Box<(dyn MyTrait<Item = &T> + 'static)>`
- found `fn(&T) -> Box<dyn MyTrait<Item = &T>>`
+ = note: expected `fn(&'1 T) -> Box<(dyn MyTrait<Item = &'1 T> + 'static)>`
+ found `fn(&'1 T) -> Box<(dyn MyTrait<Item = &'1 T> + '1)>`
help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
--> $DIR/issue-75361-mismatched-impl.rs:12:55
|
diff --git a/src/test/ui/traits/param-without-lifetime-constraint.stderr b/src/test/ui/traits/param-without-lifetime-constraint.stderr
index 763fb5186cc..118b2cf3ecd 100644
--- a/src/test/ui/traits/param-without-lifetime-constraint.stderr
+++ b/src/test/ui/traits/param-without-lifetime-constraint.stderr
@@ -2,13 +2,13 @@ error: `impl` item signature doesn't match `trait` item signature
--> $DIR/param-without-lifetime-constraint.rs:14:5
|
LL | fn get_relation(&self) -> To;
- | ----------------------------- expected `fn(&Article) -> &ProofReader`
+ | ----------------------------- expected `fn(&'1 Article) -> &'2 ProofReader`
...
LL | fn get_relation(&self) -> &ProofReader {
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&Article) -> &ProofReader`
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(&'1 Article) -> &'1 ProofReader`
|
- = note: expected `fn(&Article) -> &ProofReader`
- found `fn(&Article) -> &ProofReader`
+ = note: expected `fn(&'1 Article) -> &'2 ProofReader`
+ found `fn(&'1 Article) -> &'1 ProofReader`
help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
--> $DIR/param-without-lifetime-constraint.rs:10:31
|
diff --git a/src/test/ui/traits/self-without-lifetime-constraint.stderr b/src/test/ui/traits/self-without-lifetime-constraint.stderr
index 73b5aec022c..85fada3b87c 100644
--- a/src/test/ui/traits/self-without-lifetime-constraint.stderr
+++ b/src/test/ui/traits/self-without-lifetime-constraint.stderr
@@ -2,13 +2,13 @@ error: `impl` item signature doesn't match `trait` item signature
--> $DIR/self-without-lifetime-constraint.rs:45:5
|
LL | fn column_result(value: ValueRef<'_>) -> FromSqlResult<Self, &Self>;
- | -------------------------------------------------------------------- expected `fn(ValueRef<'_>) -> Result<(&str, &&str), FromSqlError>`
+ | -------------------------------------------------------------------- expected `fn(ValueRef<'1>) -> Result<(&'2 str, &'1 &'2 str), FromSqlError>`
...
LL | fn column_result(value: ValueRef<'_>) -> FromSqlResult<&str, &&str> {
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(ValueRef<'_>) -> Result<(&str, &&str), FromSqlError>`
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ found `fn(ValueRef<'1>) -> Result<(&'1 str, &'1 &'1 str), FromSqlError>`
|
- = note: expected `fn(ValueRef<'_>) -> Result<(&str, &&str), _>`
- found `fn(ValueRef<'_>) -> Result<(&str, &&str), _>`
+ = note: expected `fn(ValueRef<'1>) -> Result<(&'2 str, &'1 &'2 str), FromSqlError>`
+ found `fn(ValueRef<'1>) -> Result<(&'1 str, &'1 &'1 str), FromSqlError>`
help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
--> $DIR/self-without-lifetime-constraint.rs:41:60
|