From 39bff4bf9c998ba77d12b36b26c604340638fa73 Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Wed, 6 Apr 2022 21:27:46 -0700
Subject: [PATCH] don't report int/float ambiguity when we have previous errors
---
.../src/traits/error_reporting/mod.rs | 22 +++++++++++--
.../ui/traits/no-fallback-multiple-impls.rs | 16 ++++++++++
.../traits/no-fallback-multiple-impls.stderr | 9 ++++++
src/test/ui/traits/test-2.rs | 4 +--
src/test/ui/traits/test-2.stderr | 32 ++-----------------
5 files changed, 48 insertions(+), 35 deletions(-)
create mode 100644 src/test/ui/traits/no-fallback-multiple-impls.rs
create mode 100644 src/test/ui/traits/no-fallback-multiple-impls.stderr
diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
index 9998c5bb087e1..ac98dd5801e40 100644
--- a/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs
@@ -36,6 +36,7 @@ use rustc_span::symbol::{kw, sym};
use rustc_span::{ExpnKind, Span, DUMMY_SP};
use std::fmt;
use std::iter;
+use std::ops::ControlFlow;
use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
use crate::traits::query::normalize::AtExt as _;
@@ -2226,9 +2227,10 @@ impl<'a, 'tcx> InferCtxtPrivExt<'a, 'tcx> for InferCtxt<'a, 'tcx> {
post.dedup();
if self.is_tainted_by_errors()
- && crate_names.len() == 1
- && ["`core`", "`alloc`", "`std`"].contains(&crate_names[0].as_str())
- && spans.len() == 0
+ && (crate_names.len() == 1
+ && spans.len() == 0
+ && ["`core`", "`alloc`", "`std`"].contains(&crate_names[0].as_str())
+ || predicate.visit_with(&mut HasNumericInferVisitor).is_break())
{
// Avoid complaining about other inference issues for expressions like
// `42 >> 1`, where the types are still `{integer}`, but we want to
@@ -2666,3 +2668,17 @@ impl ArgKind {
}
}
}
+
+struct HasNumericInferVisitor;
+
+impl<'tcx> ty::TypeVisitor<'tcx> for HasNumericInferVisitor {
+ type BreakTy = ();
+
+ fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
+ if matches!(ty.kind(), ty::Infer(ty::FloatVar(_) | ty::IntVar(_))) {
+ ControlFlow::Break(())
+ } else {
+ ControlFlow::CONTINUE
+ }
+ }
+}
diff --git a/src/test/ui/traits/no-fallback-multiple-impls.rs b/src/test/ui/traits/no-fallback-multiple-impls.rs
new file mode 100644
index 0000000000000..7ed3796f08b76
--- /dev/null
+++ b/src/test/ui/traits/no-fallback-multiple-impls.rs
@@ -0,0 +1,16 @@
+trait Fallback {
+ fn foo(&self) {}
+}
+
+impl Fallback for i32 {}
+
+impl Fallback for u64 {}
+
+impl Fallback for usize {}
+
+fn main() {
+ missing();
+ //~^ ERROR cannot find function `missing` in this scope
+ 0.foo();
+ // But then we shouldn't report an inference ambiguity here...
+}
diff --git a/src/test/ui/traits/no-fallback-multiple-impls.stderr b/src/test/ui/traits/no-fallback-multiple-impls.stderr
new file mode 100644
index 0000000000000..61c9e5aaabdb4
--- /dev/null
+++ b/src/test/ui/traits/no-fallback-multiple-impls.stderr
@@ -0,0 +1,9 @@
+error[E0425]: cannot find function `missing` in this scope
+ --> $DIR/no-fallback-multiple-impls.rs:12:5
+ |
+LL | missing();
+ | ^^^^^^^ not found in this scope
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0425`.
diff --git a/src/test/ui/traits/test-2.rs b/src/test/ui/traits/test-2.rs
index d062de25ac8c1..342928e882a55 100644
--- a/src/test/ui/traits/test-2.rs
+++ b/src/test/ui/traits/test-2.rs
@@ -6,9 +6,9 @@ impl bar for i32 { fn dup(&self) -> i32 { *self } fn blah<X>(&self) {} }
impl bar for u32 { fn dup(&self) -> u32 { *self } fn blah<X>(&self) {} }
fn main() {
- 10.dup::<i32>(); //~ ERROR type annotations needed
+ 10.dup::<i32>();
//~^ ERROR this associated function takes 0 generic arguments but 1
- 10.blah::<i32, i32>(); //~ ERROR type annotations needed
+ 10.blah::<i32, i32>();
//~^ ERROR this associated function takes 1 generic argument but 2
(Box::new(10) as Box<dyn bar>).dup();
//~^ ERROR E0038
diff --git a/src/test/ui/traits/test-2.stderr b/src/test/ui/traits/test-2.stderr
index 5eec012458450..77ea4e4e974eb 100644
--- a/src/test/ui/traits/test-2.stderr
+++ b/src/test/ui/traits/test-2.stderr
@@ -79,35 +79,7 @@ LL | trait bar { fn dup(&self) -> Self; fn blah<X>(&self); }
= note: required because of the requirements on the impl of `CoerceUnsized<Box<dyn bar>>` for `Box<{integer}>`
= note: required by cast to type `Box<dyn bar>`
-error[E0283]: type annotations needed
- --> $DIR/test-2.rs:9:8
- |
-LL | 10.dup::<i32>();
- | ^^^ cannot infer type for type `{integer}`
- |
-note: multiple `impl`s satisfying `{integer}: bar` found
- --> $DIR/test-2.rs:5:1
- |
-LL | impl bar for i32 { fn dup(&self) -> i32 { *self } fn blah<X>(&self) {} }
- | ^^^^^^^^^^^^^^^^
-LL | impl bar for u32 { fn dup(&self) -> u32 { *self } fn blah<X>(&self) {} }
- | ^^^^^^^^^^^^^^^^
-
-error[E0283]: type annotations needed
- --> $DIR/test-2.rs:11:8
- |
-LL | 10.blah::<i32, i32>();
- | ^^^^ cannot infer type for type `{integer}`
- |
-note: multiple `impl`s satisfying `{integer}: bar` found
- --> $DIR/test-2.rs:5:1
- |
-LL | impl bar for i32 { fn dup(&self) -> i32 { *self } fn blah<X>(&self) {} }
- | ^^^^^^^^^^^^^^^^
-LL | impl bar for u32 { fn dup(&self) -> u32 { *self } fn blah<X>(&self) {} }
- | ^^^^^^^^^^^^^^^^
-
-error: aborting due to 7 previous errors
+error: aborting due to 5 previous errors
-Some errors have detailed explanations: E0038, E0107, E0283.
+Some errors have detailed explanations: E0038, E0107.
For more information about an error, try `rustc --explain E0038`.