From 3c974adb4c4c6de497a36dec362af6c0928c7367 Mon Sep 17 00:00:00 2001 From: Aaron Hill Date: Sun, 3 Oct 2021 15:25:26 -0500 Subject: [PATCH] Note specific regions involved in 'borrowed data escapes' error Fixes #67007 Currently, a 'borrowed data escapes' error does not mention the specific lifetime involved (except indirectly through a suggestion about adding a lifetime bound). We now explain the specific lifetime relationship that failed to hold, which improves otherwise vague error messages. --- .../src/diagnostics/region_errors.rs | 21 +++++++++++ .../async-await/issues/issue-62097.nll.stderr | 10 ++++-- .../dyn-trait.nll.stderr | 9 +++-- src/test/ui/issues/issue-16683.nll.stderr | 13 +++++-- src/test/ui/issues/issue-17758.nll.stderr | 13 +++++-- ...etime-bound-will-change-warning.nll.stderr | 18 +++++++--- ...oximated-shorter-to-static-no-bound.stderr | 9 +++-- ...mated-shorter-to-static-wrong-bound.stderr | 9 +++-- src/test/ui/nll/issue-67007-escaping-data.rs | 26 ++++++++++++++ .../ui/nll/issue-67007-escaping-data.stderr | 21 +++++++++++ .../ui/nll/outlives-suggestion-simple.stderr | 9 ++++- .../user-annotations/closure-substs.stderr | 9 +++-- .../object-lifetime-default-mybox.nll.stderr | 9 +++-- src/test/ui/regions/issue-78262.nll.stderr | 7 ++-- .../ui/regions/issue-78262.polonius.stderr | 7 ++-- ...nvariant-static-error-reporting.nll.stderr | 9 +++-- ...hod-type-parameters-trait-bound.nll.stderr | 13 ++++--- ...rait-with-implicit-static-bound.nll.stderr | 36 ++++++++++++++----- 18 files changed, 209 insertions(+), 39 deletions(-) create mode 100644 src/test/ui/nll/issue-67007-escaping-data.rs create mode 100644 src/test/ui/nll/issue-67007-escaping-data.stderr diff --git a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs index d05cfebc5f02e..11cdbe84accb7 100644 --- a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs @@ -498,6 +498,27 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { diag.span_label(*span, format!("`{}` escapes the {} body here", fr_name, escapes_from)); } + // Only show an extra note if we can find an 'error region' for both of the region + // variables. This avoids showing a noisy note that just mentions 'synthetic' regions + // that don't help the user understand the error. + if self.to_error_region(errci.fr).is_some() + && self.to_error_region(errci.outlived_fr).is_some() + { + let fr_region_name = self.give_region_a_name(errci.fr).unwrap(); + fr_region_name.highlight_region_name(&mut diag); + let outlived_fr_region_name = self.give_region_a_name(errci.outlived_fr).unwrap(); + outlived_fr_region_name.highlight_region_name(&mut diag); + + diag.span_label( + *span, + format!( + "{}requires that `{}` must outlive `{}`", + category.description(), + fr_region_name, + outlived_fr_region_name, + ), + ); + } diag } diff --git a/src/test/ui/async-await/issues/issue-62097.nll.stderr b/src/test/ui/async-await/issues/issue-62097.nll.stderr index e71bcf5822808..786f621326049 100644 --- a/src/test/ui/async-await/issues/issue-62097.nll.stderr +++ b/src/test/ui/async-await/issues/issue-62097.nll.stderr @@ -20,9 +20,15 @@ error[E0521]: borrowed data escapes outside of associated function --> $DIR/issue-62097.rs:13:9 | LL | pub async fn run_dummy_fn(&self) { - | ----- `self` is a reference that is only valid in the associated function body + | ----- + | | + | `self` is a reference that is only valid in the associated function body + | let's call the lifetime of this reference `'1` LL | foo(|| self.bar()).await; - | ^^^^^^^^^^^^^^^^^^ `self` escapes the associated function body here + | ^^^^^^^^^^^^^^^^^^ + | | + | `self` escapes the associated function body here + | argument requires that `'1` must outlive `'static` error: aborting due to 2 previous errors diff --git a/src/test/ui/impl-header-lifetime-elision/dyn-trait.nll.stderr b/src/test/ui/impl-header-lifetime-elision/dyn-trait.nll.stderr index e49bd9da754d6..88c260b18cbb0 100644 --- a/src/test/ui/impl-header-lifetime-elision/dyn-trait.nll.stderr +++ b/src/test/ui/impl-header-lifetime-elision/dyn-trait.nll.stderr @@ -2,9 +2,14 @@ error[E0521]: borrowed data escapes outside of function --> $DIR/dyn-trait.rs:20:5 | LL | fn with_dyn_debug_static<'a>(x: Box) { - | - `x` is a reference that is only valid in the function body + | -- - `x` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | static_val(x); - | ^^^^^^^^^^^^^ `x` escapes the function body here + | ^^^^^^^^^^^^^ + | | + | `x` escapes the function body here + | argument requires that `'a` must outlive `'static` error: aborting due to previous error diff --git a/src/test/ui/issues/issue-16683.nll.stderr b/src/test/ui/issues/issue-16683.nll.stderr index 51d86eaf9e60c..0e8f520353fba 100644 --- a/src/test/ui/issues/issue-16683.nll.stderr +++ b/src/test/ui/issues/issue-16683.nll.stderr @@ -1,10 +1,19 @@ error[E0521]: borrowed data escapes outside of associated function --> $DIR/issue-16683.rs:4:9 | +LL | trait T<'a> { + | -- lifetime `'a` defined here +LL | fn a(&'a self) -> &'a bool; LL | fn b(&self) { - | ----- `self` is a reference that is only valid in the associated function body + | ----- + | | + | `self` is a reference that is only valid in the associated function body + | let's call the lifetime of this reference `'1` LL | self.a(); - | ^^^^^^^^ `self` escapes the associated function body here + | ^^^^^^^^ + | | + | `self` escapes the associated function body here + | argument requires that `'1` must outlive `'a` error: aborting due to previous error diff --git a/src/test/ui/issues/issue-17758.nll.stderr b/src/test/ui/issues/issue-17758.nll.stderr index 075c141ed7af6..b929fdbf3687a 100644 --- a/src/test/ui/issues/issue-17758.nll.stderr +++ b/src/test/ui/issues/issue-17758.nll.stderr @@ -1,10 +1,19 @@ error[E0521]: borrowed data escapes outside of associated function --> $DIR/issue-17758.rs:7:9 | +LL | trait Foo<'a> { + | -- lifetime `'a` defined here +LL | fn foo(&'a self); LL | fn bar(&self) { - | ----- `self` is a reference that is only valid in the associated function body + | ----- + | | + | `self` is a reference that is only valid in the associated function body + | let's call the lifetime of this reference `'1` LL | self.foo(); - | ^^^^^^^^^^ `self` escapes the associated function body here + | ^^^^^^^^^^ + | | + | `self` escapes the associated function body here + | argument requires that `'1` must outlive `'a` error: aborting due to previous error diff --git a/src/test/ui/lifetimes/lifetime-bound-will-change-warning.nll.stderr b/src/test/ui/lifetimes/lifetime-bound-will-change-warning.nll.stderr index 050d5fcf05ef4..6f3f84096e400 100644 --- a/src/test/ui/lifetimes/lifetime-bound-will-change-warning.nll.stderr +++ b/src/test/ui/lifetimes/lifetime-bound-will-change-warning.nll.stderr @@ -2,19 +2,29 @@ error[E0521]: borrowed data escapes outside of function --> $DIR/lifetime-bound-will-change-warning.rs:34:5 | LL | fn test2<'a>(x: &'a Box) { - | - `x` is a reference that is only valid in the function body + | -- - `x` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | // but ref_obj will not, so warn. LL | ref_obj(x) - | ^^^^^^^^^^ `x` escapes the function body here + | ^^^^^^^^^^ + | | + | `x` escapes the function body here + | argument requires that `'a` must outlive `'static` error[E0521]: borrowed data escapes outside of function --> $DIR/lifetime-bound-will-change-warning.rs:39:5 | LL | fn test2cc<'a>(x: &'a Box) { - | - `x` is a reference that is only valid in the function body + | -- - `x` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | // same as test2, but cross crate LL | lib::ref_obj(x) - | ^^^^^^^^^^^^^^^ `x` escapes the function body here + | ^^^^^^^^^^^^^^^ + | | + | `x` escapes the function body here + | argument requires that `'a` must outlive `'static` error: aborting due to 2 previous errors diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr index d17a40a95c1b8..d77793291c5c5 100644 --- a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr +++ b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-no-bound.stderr @@ -38,14 +38,19 @@ error[E0521]: borrowed data escapes outside of function --> $DIR/propagate-approximated-shorter-to-static-no-bound.rs:32:5 | LL | fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) { - | ------ `cell_a` is a reference that is only valid in the function body + | -- ------ `cell_a` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | / establish_relationships(&cell_a, &cell_b, |_outlives, x, y| { LL | | LL | | LL | | // Only works if 'x: 'y: LL | | demand_y(x, y, x.get()) LL | | }); - | |______^ `cell_a` escapes the function body here + | | ^ + | | | + | |______`cell_a` escapes the function body here + | argument requires that `'a` must outlive `'static` error: aborting due to previous error diff --git a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr index 06c46ec8259a0..cc67270ad20c1 100644 --- a/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr +++ b/src/test/ui/nll/closure-requirements/propagate-approximated-shorter-to-static-wrong-bound.stderr @@ -38,14 +38,19 @@ error[E0521]: borrowed data escapes outside of function --> $DIR/propagate-approximated-shorter-to-static-wrong-bound.rs:35:5 | LL | fn supply<'a, 'b>(cell_a: Cell<&'a u32>, cell_b: Cell<&'b u32>) { - | ------ `cell_a` is a reference that is only valid in the function body + | -- ------ `cell_a` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | / establish_relationships(&cell_a, &cell_b, |_outlives1, _outlives2, x, y| { LL | | LL | | LL | | // Only works if 'x: 'y: LL | | demand_y(x, y, x.get()) LL | | }); - | |______^ `cell_a` escapes the function body here + | | ^ + | | | + | |______`cell_a` escapes the function body here + | argument requires that `'a` must outlive `'static` error: aborting due to previous error diff --git a/src/test/ui/nll/issue-67007-escaping-data.rs b/src/test/ui/nll/issue-67007-escaping-data.rs new file mode 100644 index 0000000000000..8c21737e05fe8 --- /dev/null +++ b/src/test/ui/nll/issue-67007-escaping-data.rs @@ -0,0 +1,26 @@ +// Regression test for issue #67007 +// Ensures that we show information about the specific regions involved + +#![feature(nll)] + +// Covariant over 'a, invariant over 'tcx +struct FnCtxt<'a, 'tcx: 'a>(&'a (), *mut &'tcx ()); + +impl<'a, 'tcx> FnCtxt<'a, 'tcx> { + fn use_it(&self, _: &'tcx ()) {} +} + +struct Consumer<'tcx>(&'tcx ()); + +impl<'tcx> Consumer<'tcx> { + fn bad_method<'a>(&self, fcx: &FnCtxt<'a, 'tcx>) { + let other = self.use_fcx(fcx); //~ ERROR borrowed data + fcx.use_it(other); + } + + fn use_fcx<'a>(&self, _: &FnCtxt<'a, 'tcx>) -> &'a () { + &() + } +} + +fn main() {} diff --git a/src/test/ui/nll/issue-67007-escaping-data.stderr b/src/test/ui/nll/issue-67007-escaping-data.stderr new file mode 100644 index 0000000000000..2834d6fb0d214 --- /dev/null +++ b/src/test/ui/nll/issue-67007-escaping-data.stderr @@ -0,0 +1,21 @@ +error[E0521]: borrowed data escapes outside of associated function + --> $DIR/issue-67007-escaping-data.rs:17:21 + | +LL | impl<'tcx> Consumer<'tcx> { + | ---- lifetime `'tcx` defined here +LL | fn bad_method<'a>(&self, fcx: &FnCtxt<'a, 'tcx>) { + | -- ----- --- `fcx` is a reference that is only valid in the associated function body + | | | + | | `self` declared here, outside of the associated function body + | lifetime `'a` defined here +LL | let other = self.use_fcx(fcx); + | ^^^^^^^^^^^^^^^^^ + | | + | `fcx` escapes the associated function body here + | argument requires that `'a` must outlive `'tcx` + | + = help: consider adding the following bound: `'a: 'tcx` + +error: aborting due to previous error + +For more information about this error, try `rustc --explain E0521`. diff --git a/src/test/ui/nll/outlives-suggestion-simple.stderr b/src/test/ui/nll/outlives-suggestion-simple.stderr index fa85ce2799083..3b2017d2d03a1 100644 --- a/src/test/ui/nll/outlives-suggestion-simple.stderr +++ b/src/test/ui/nll/outlives-suggestion-simple.stderr @@ -92,13 +92,20 @@ LL | self.x error[E0521]: borrowed data escapes outside of associated function --> $DIR/outlives-suggestion-simple.rs:73:9 | +LL | impl<'a> Foo2<'a> { + | -- lifetime `'a` defined here +LL | // should not produce outlives suggestions to name 'self LL | fn get_bar(&self) -> Bar2 { | ----- | | | `self` declared here, outside of the associated function body | `self` is a reference that is only valid in the associated function body + | let's call the lifetime of this reference `'1` LL | Bar2::new(&self) - | ^^^^^^^^^^^^^^^^ `self` escapes the associated function body here + | ^^^^^^^^^^^^^^^^ + | | + | `self` escapes the associated function body here + | argument requires that `'1` must outlive `'a` error: aborting due to 9 previous errors diff --git a/src/test/ui/nll/user-annotations/closure-substs.stderr b/src/test/ui/nll/user-annotations/closure-substs.stderr index 55bb3a6090c01..20002e4591d1a 100644 --- a/src/test/ui/nll/user-annotations/closure-substs.stderr +++ b/src/test/ui/nll/user-annotations/closure-substs.stderr @@ -28,9 +28,14 @@ error[E0521]: borrowed data escapes outside of closure --> $DIR/closure-substs.rs:29:9 | LL | |x: &i32, b: fn(&'static i32)| { - | - `x` is a reference that is only valid in the closure body + | - - let's call the lifetime of this reference `'1` + | | + | `x` is a reference that is only valid in the closure body LL | b(x); - | ^^^^ `x` escapes the closure body here + | ^^^^ + | | + | `x` escapes the closure body here + | argument requires that `'1` must outlive `'static` error: aborting due to 4 previous errors diff --git a/src/test/ui/object-lifetime/object-lifetime-default-mybox.nll.stderr b/src/test/ui/object-lifetime/object-lifetime-default-mybox.nll.stderr index 6ce1b2eed85d2..af20c5e5fc0da 100644 --- a/src/test/ui/object-lifetime/object-lifetime-default-mybox.nll.stderr +++ b/src/test/ui/object-lifetime/object-lifetime-default-mybox.nll.stderr @@ -15,9 +15,14 @@ error[E0521]: borrowed data escapes outside of function --> $DIR/object-lifetime-default-mybox.rs:31:5 | LL | fn load2<'a>(ss: &MyBox) -> MyBox { - | -- `ss` is a reference that is only valid in the function body + | -- -- `ss` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | load0(ss) - | ^^^^^^^^^ `ss` escapes the function body here + | ^^^^^^^^^ + | | + | `ss` escapes the function body here + | argument requires that `'a` must outlive `'static` error: aborting due to 2 previous errors diff --git a/src/test/ui/regions/issue-78262.nll.stderr b/src/test/ui/regions/issue-78262.nll.stderr index a35d6fd9bf885..721dafac0be76 100644 --- a/src/test/ui/regions/issue-78262.nll.stderr +++ b/src/test/ui/regions/issue-78262.nll.stderr @@ -2,8 +2,11 @@ error[E0521]: borrowed data escapes outside of closure --> $DIR/issue-78262.rs:14:26 | LL | let f = |x: &dyn TT| x.func(); - | - ^^^^^^^^ `x` escapes the closure body here - | | + | - - ^^^^^^^^ + | | | | + | | | `x` escapes the closure body here + | | | argument requires that `'1` must outlive `'static` + | | let's call the lifetime of this reference `'1` | `x` is a reference that is only valid in the closure body error: aborting due to previous error diff --git a/src/test/ui/regions/issue-78262.polonius.stderr b/src/test/ui/regions/issue-78262.polonius.stderr index a35d6fd9bf885..721dafac0be76 100644 --- a/src/test/ui/regions/issue-78262.polonius.stderr +++ b/src/test/ui/regions/issue-78262.polonius.stderr @@ -2,8 +2,11 @@ error[E0521]: borrowed data escapes outside of closure --> $DIR/issue-78262.rs:14:26 | LL | let f = |x: &dyn TT| x.func(); - | - ^^^^^^^^ `x` escapes the closure body here - | | + | - - ^^^^^^^^ + | | | | + | | | `x` escapes the closure body here + | | | argument requires that `'1` must outlive `'static` + | | let's call the lifetime of this reference `'1` | `x` is a reference that is only valid in the closure body error: aborting due to previous error diff --git a/src/test/ui/regions/region-invariant-static-error-reporting.nll.stderr b/src/test/ui/regions/region-invariant-static-error-reporting.nll.stderr index 7221759dbd450..e220cbf555956 100644 --- a/src/test/ui/regions/region-invariant-static-error-reporting.nll.stderr +++ b/src/test/ui/regions/region-invariant-static-error-reporting.nll.stderr @@ -2,10 +2,15 @@ error[E0521]: borrowed data escapes outside of function --> $DIR/region-invariant-static-error-reporting.rs:15:9 | LL | fn unify<'a>(x: Option>, f: fn(Invariant<'a>)) { - | - `x` is a reference that is only valid in the function body + | -- - `x` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | let bad = if x.is_some() { LL | x.unwrap() - | ^^^^^^^^^^ `x` escapes the function body here + | ^^^^^^^^^^ + | | + | `x` escapes the function body here + | argument requires that `'a` must outlive `'static` error: aborting due to previous error diff --git a/src/test/ui/regions/regions-bounded-method-type-parameters-trait-bound.nll.stderr b/src/test/ui/regions/regions-bounded-method-type-parameters-trait-bound.nll.stderr index ed7b17c207c30..83d6e13dc0a68 100644 --- a/src/test/ui/regions/regions-bounded-method-type-parameters-trait-bound.nll.stderr +++ b/src/test/ui/regions/regions-bounded-method-type-parameters-trait-bound.nll.stderr @@ -2,12 +2,17 @@ error[E0521]: borrowed data escapes outside of function --> $DIR/regions-bounded-method-type-parameters-trait-bound.rs:20:5 | LL | fn caller2<'a,'b,F:Foo<'a>>(a: Inv<'a>, b: Inv<'b>, f: F) { - | - - `b` is a reference that is only valid in the function body - | | - | `a` declared here, outside of the function body + | -- -- - - `b` is a reference that is only valid in the function body + | | | | + | | | `a` declared here, outside of the function body + | | lifetime `'b` defined here + | lifetime `'a` defined here LL | // Here the value provided for 'y is 'b, and hence 'b:'a does not hold. LL | f.method(b); - | ^^^^^^^^^^^ `b` escapes the function body here + | ^^^^^^^^^^^ + | | + | `b` escapes the function body here + | argument requires that `'b` must outlive `'a` | = help: consider adding the following bound: `'b: 'a` diff --git a/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound.nll.stderr b/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound.nll.stderr index 32a2de1e84d8f..a1ef32c5445b5 100644 --- a/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound.nll.stderr +++ b/src/test/ui/suggestions/impl-on-dyn-trait-with-implicit-static-bound.nll.stderr @@ -2,33 +2,53 @@ error[E0521]: borrowed data escapes outside of function --> $DIR/impl-on-dyn-trait-with-implicit-static-bound.rs:20:9 | LL | fn use_it<'a, T>(val: &'a dyn ObjectTrait) -> impl OtherTrait<'a> + 'a { - | --- `val` is a reference that is only valid in the function body + | -- --- `val` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | val.use_self::() - | ^^^^^^^^^^^^^^^^^^^ `val` escapes the function body here + | ^^^^^^^^^^^^^^^^^^^ + | | + | `val` escapes the function body here + | argument requires that `'a` must outlive `'static` error[E0521]: borrowed data escapes outside of function --> $DIR/impl-on-dyn-trait-with-implicit-static-bound.rs:69:9 | LL | fn use_it<'a>(val: &'a dyn ObjectTrait) -> impl OtherTrait<'a> + 'a { - | --- `val` is a reference that is only valid in the function body + | -- --- `val` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | val.use_self() - | ^^^^^^^^^^^^^^ `val` escapes the function body here + | ^^^^^^^^^^^^^^ + | | + | `val` escapes the function body here + | argument requires that `'a` must outlive `'static` error[E0521]: borrowed data escapes outside of function --> $DIR/impl-on-dyn-trait-with-implicit-static-bound.rs:88:9 | LL | fn use_it<'a>(val: &'a dyn ObjectTrait) -> impl OtherTrait<'a> { - | --- `val` is a reference that is only valid in the function body + | -- --- `val` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | val.use_self() - | ^^^^^^^^^^^^^^ `val` escapes the function body here + | ^^^^^^^^^^^^^^ + | | + | `val` escapes the function body here + | argument requires that `'a` must outlive `'static` error[E0521]: borrowed data escapes outside of function --> $DIR/impl-on-dyn-trait-with-implicit-static-bound.rs:108:9 | LL | fn use_it<'a>(val: &'a dyn ObjectTrait) -> impl OtherTrait<'a> + 'a { - | --- `val` is a reference that is only valid in the function body + | -- --- `val` is a reference that is only valid in the function body + | | + | lifetime `'a` defined here LL | MyTrait::use_self(val) - | ^^^^^^^^^^^^^^^^^^^^^^ `val` escapes the function body here + | ^^^^^^^^^^^^^^^^^^^^^^ + | | + | `val` escapes the function body here + | argument requires that `'a` must outlive `'static` error: aborting due to 4 previous errors