From 46db4bab0b44294a6e41eb756587904f8bed6049 Mon Sep 17 00:00:00 2001 From: Aaron Hill <aa1ronham@gmail.com> Date: Tue, 23 Feb 2021 09:44:01 -0500 Subject: [PATCH] Skip emitting closure diagnostic when closure_kind_origins has no entry Fixes #82438 This map is not guarnateed to have an entry for a closure. --- .../diagnostics/mutability_errors.rs | 51 ++++++++++--------- .../closures/issue-82438-mut-without-upvar.rs | 28 ++++++++++ .../issue-82438-mut-without-upvar.stderr | 12 +++++ 3 files changed, 66 insertions(+), 25 deletions(-) create mode 100644 src/test/ui/closures/issue-82438-mut-without-upvar.rs create mode 100644 src/test/ui/closures/issue-82438-mut-without-upvar.stderr diff --git a/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs b/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs index 0400431a542ee..2f40a90fb5516 100644 --- a/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs +++ b/compiler/rustc_mir/src/borrow_check/diagnostics/mutability_errors.rs @@ -513,32 +513,33 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { let id = id.expect_local(); let tables = tcx.typeck(id); let hir_id = tcx.hir().local_def_id_to_hir_id(id); - let (span, place) = &tables.closure_kind_origins()[hir_id]; - let reason = if let PlaceBase::Upvar(upvar_id) = place.base { - let upvar = ty::place_to_string_for_capture(tcx, place); - match tables.upvar_capture(upvar_id) { - ty::UpvarCapture::ByRef(ty::UpvarBorrow { - kind: ty::BorrowKind::MutBorrow | ty::BorrowKind::UniqueImmBorrow, - .. - }) => { - format!("mutable borrow of `{}`", upvar) - } - ty::UpvarCapture::ByValue(_) => { - format!("possible mutation of `{}`", upvar) + if let Some((span, place)) = tables.closure_kind_origins().get(hir_id) { + let reason = if let PlaceBase::Upvar(upvar_id) = place.base { + let upvar = ty::place_to_string_for_capture(tcx, place); + match tables.upvar_capture(upvar_id) { + ty::UpvarCapture::ByRef(ty::UpvarBorrow { + kind: ty::BorrowKind::MutBorrow | ty::BorrowKind::UniqueImmBorrow, + .. + }) => { + format!("mutable borrow of `{}`", upvar) + } + ty::UpvarCapture::ByValue(_) => { + format!("possible mutation of `{}`", upvar) + } + val => bug!("upvar `{}` borrowed, but not mutably: {:?}", upvar, val), } - val => bug!("upvar `{}` borrowed, but not mutably: {:?}", upvar, val), - } - } else { - bug!("not an upvar") - }; - err.span_label( - *span, - format!( - "calling `{}` requires mutable binding due to {}", - self.describe_place(the_place_err).unwrap(), - reason - ), - ); + } else { + bug!("not an upvar") + }; + err.span_label( + *span, + format!( + "calling `{}` requires mutable binding due to {}", + self.describe_place(the_place_err).unwrap(), + reason + ), + ); + } } // Attempt to search similar mutable associated items for suggestion. diff --git a/src/test/ui/closures/issue-82438-mut-without-upvar.rs b/src/test/ui/closures/issue-82438-mut-without-upvar.rs new file mode 100644 index 0000000000000..5d88e1e77d450 --- /dev/null +++ b/src/test/ui/closures/issue-82438-mut-without-upvar.rs @@ -0,0 +1,28 @@ +use std::error::Error; +struct A { +} + +impl A { + pub fn new() -> A { + A { + } + } + + pub fn f<'a>( + &'a self, + team_name: &'a str, + c: &'a mut dyn FnMut(String, String, u64, u64) + ) -> Result<(), Box<dyn Error>> { + Ok(()) + } +} + + +fn main() { + let A = A::new(); + let participant_name = "A"; + + let c = |a, b, c, d| {}; + + A.f(participant_name, &mut c); //~ ERROR cannot borrow +} diff --git a/src/test/ui/closures/issue-82438-mut-without-upvar.stderr b/src/test/ui/closures/issue-82438-mut-without-upvar.stderr new file mode 100644 index 0000000000000..06e2b5d0c1bce --- /dev/null +++ b/src/test/ui/closures/issue-82438-mut-without-upvar.stderr @@ -0,0 +1,12 @@ +error[E0596]: cannot borrow `c` as mutable, as it is not declared as mutable + --> $DIR/issue-82438-mut-without-upvar.rs:27:27 + | +LL | let c = |a, b, c, d| {}; + | - help: consider changing this to be mutable: `mut c` +LL | +LL | A.f(participant_name, &mut c); + | ^^^^^^ cannot borrow as mutable + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0596`.