From 800f1f351399a4923636c77b7a34a66ee0b09d8b Mon Sep 17 00:00:00 2001 From: Michael Goulet Date: Wed, 25 Jan 2023 19:18:01 +0000 Subject: [PATCH 1/2] Liberate late-bound regions correctly --- .../src/traits/error_reporting/suggestions.rs | 4 +-- .../late-bound-in-borrow-closure-sugg.rs | 28 +++++++++++++++++++ .../late-bound-in-borrow-closure-sugg.stderr | 26 +++++++++++++++++ 3 files changed, 56 insertions(+), 2 deletions(-) create mode 100644 tests/ui/suggestions/late-bound-in-borrow-closure-sugg.rs create mode 100644 tests/ui/suggestions/late-bound-in-borrow-closure-sugg.stderr diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs index 39e50b2accf17..3028242781cb0 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs @@ -3758,13 +3758,13 @@ fn hint_missing_borrow<'tcx>( err: &mut Diagnostic, ) { let found_args = match found.kind() { - ty::FnPtr(f) => f.inputs().skip_binder().iter(), + ty::FnPtr(f) => infcx.replace_bound_vars_with_placeholders(*f).inputs().iter(), kind => { span_bug!(span, "found was converted to a FnPtr above but is now {:?}", kind) } }; let expected_args = match expected.kind() { - ty::FnPtr(f) => f.inputs().skip_binder().iter(), + ty::FnPtr(f) => infcx.replace_bound_vars_with_placeholders(*f).inputs().iter(), kind => { span_bug!(span, "expected was converted to a FnPtr above but is now {:?}", kind) } diff --git a/tests/ui/suggestions/late-bound-in-borrow-closure-sugg.rs b/tests/ui/suggestions/late-bound-in-borrow-closure-sugg.rs new file mode 100644 index 0000000000000..3bf6b7bb9b19e --- /dev/null +++ b/tests/ui/suggestions/late-bound-in-borrow-closure-sugg.rs @@ -0,0 +1,28 @@ +use std::cell::RefCell; +use std::collections::HashMap; +use std::rc::Rc; + +pub struct Trader<'a> { + closure: Box, +} + +impl<'a> Trader<'a> { + pub fn new() -> Self { + Trader { + closure: Box::new(|_| {}), + } + } + pub fn set_closure(&mut self, function: impl Fn(&mut Trader) + 'a) { + //foo + } +} + +fn main() { + let closure = |trader : Trader| { + println!("Woooosh!"); + }; + + let mut trader = Trader::new(); + trader.set_closure(closure); + //~^ ERROR type mismatch in closure arguments +} diff --git a/tests/ui/suggestions/late-bound-in-borrow-closure-sugg.stderr b/tests/ui/suggestions/late-bound-in-borrow-closure-sugg.stderr new file mode 100644 index 0000000000000..4fb5c65235cbb --- /dev/null +++ b/tests/ui/suggestions/late-bound-in-borrow-closure-sugg.stderr @@ -0,0 +1,26 @@ +error[E0631]: type mismatch in closure arguments + --> $DIR/late-bound-in-borrow-closure-sugg.rs:26:24 + | +LL | let closure = |trader : Trader| { + | ----------------- found signature defined here +... +LL | trader.set_closure(closure); + | ----------- ^^^^^^^ expected due to this + | | + | required by a bound introduced by this call + | + = note: expected closure signature `for<'a, 'b> fn(&'a mut Trader<'b>) -> _` + found closure signature `for<'a> fn(Trader<'a>) -> _` +note: required by a bound in `Trader::<'a>::set_closure` + --> $DIR/late-bound-in-borrow-closure-sugg.rs:15:50 + | +LL | pub fn set_closure(&mut self, function: impl Fn(&mut Trader) + 'a) { + | ^^^^^^^^^^^^^^^ required by this bound in `Trader::<'a>::set_closure` +help: consider borrowing the argument + | +LL | let closure = |trader : &Trader| { + | + + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0631`. From b83ab0ce965356308921acabe8a40fe88bcdd8c7 Mon Sep 17 00:00:00 2001 From: Michael Goulet Date: Wed, 25 Jan 2023 19:17:46 +0000 Subject: [PATCH 2/2] Suggest mutable borrows correctly --- .../src/traits/error_reporting/suggestions.rs | 26 +++++++++++++------ .../late-bound-in-borrow-closure-sugg.stderr | 4 +-- 2 files changed, 20 insertions(+), 10 deletions(-) diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs index 3028242781cb0..64f19aa009700 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs @@ -3775,12 +3775,12 @@ fn hint_missing_borrow<'tcx>( let args = fn_decl.inputs.iter().map(|ty| ty); - fn get_deref_type_and_refs(mut ty: Ty<'_>) -> (Ty<'_>, usize) { - let mut refs = 0; + fn get_deref_type_and_refs(mut ty: Ty<'_>) -> (Ty<'_>, Vec) { + let mut refs = vec![]; - while let ty::Ref(_, new_ty, _) = ty.kind() { + while let ty::Ref(_, new_ty, mutbl) = ty.kind() { ty = *new_ty; - refs += 1; + refs.push(*mutbl); } (ty, refs) @@ -3794,11 +3794,21 @@ fn hint_missing_borrow<'tcx>( let (expected_ty, expected_refs) = get_deref_type_and_refs(*expected_arg); if infcx.can_eq(param_env, found_ty, expected_ty).is_ok() { - if found_refs < expected_refs { - to_borrow.push((arg.span.shrink_to_lo(), "&".repeat(expected_refs - found_refs))); - } else if found_refs > expected_refs { + // FIXME: This could handle more exotic cases like mutability mismatches too! + if found_refs.len() < expected_refs.len() + && found_refs[..] == expected_refs[expected_refs.len() - found_refs.len()..] + { + to_borrow.push(( + arg.span.shrink_to_lo(), + expected_refs[..expected_refs.len() - found_refs.len()] + .iter() + .map(|mutbl| format!("&{}", mutbl.prefix_str())) + .collect::>() + .join(""), + )); + } else if found_refs.len() > expected_refs.len() { let mut span = arg.span.shrink_to_lo(); - let mut left = found_refs - expected_refs; + let mut left = found_refs.len() - expected_refs.len(); let mut ty = arg; while let hir::TyKind::Ref(_, mut_ty) = &ty.kind && left > 0 { span = span.with_hi(mut_ty.ty.span.lo()); diff --git a/tests/ui/suggestions/late-bound-in-borrow-closure-sugg.stderr b/tests/ui/suggestions/late-bound-in-borrow-closure-sugg.stderr index 4fb5c65235cbb..6820af1fd45c3 100644 --- a/tests/ui/suggestions/late-bound-in-borrow-closure-sugg.stderr +++ b/tests/ui/suggestions/late-bound-in-borrow-closure-sugg.stderr @@ -18,8 +18,8 @@ LL | pub fn set_closure(&mut self, function: impl Fn(&mut Trader) + 'a) { | ^^^^^^^^^^^^^^^ required by this bound in `Trader::<'a>::set_closure` help: consider borrowing the argument | -LL | let closure = |trader : &Trader| { - | + +LL | let closure = |trader : &mut Trader| { + | ++++ error: aborting due to previous error