[WIP] Ergonomic ref counting #134797

spastorino · 2024-12-26T19:08:15Z

Opening this now so @nikomatsakis can start taking a look at it. Going to write a proper description when the PR is done.

For this first version I'd need to:

review the handling of spans in Expr::Use which right now is not 100% ok
document things a little bit better
add a lot of tests

For following versions we need to implement optimizations, copy optimization post monomorphization and last use optimization.

This is an experimental version of ergonomic ref counting

RFC: rust-lang/rfcs#3680
Tracking issue: #132290
Project goal: rust-lang/rust-project-goals#107

r? @nikomatsakis

compiler/rustc_ast_lowering/src/expr.rs

nikomatsakis

Very close! First round of feedback.

nikomatsakis · 2024-12-27T17:16:35Z

compiler/rustc_ast_lowering/src/expr.rs

+    /// Desugar `<expr>.use` into:
+    /// ```ignore (pseudo-rust)
+    /// <expr>.clone()
+    /// ```


This comment is out of date

nikomatsakis · 2024-12-27T17:16:59Z

compiler/rustc_ast_lowering/src/expr.rs

+    /// ```
+    fn lower_expr_use(&mut self, use_kw_span: Span, expr: &Expr) -> hir::ExprKind<'hir> {
+        let expr = self.lower_expr(expr);
+        let span = self.mark_span_with_reason(DesugaringKind::Use, use_kw_span, None);


I don't think we want this DesugaringKind anymore

I was taking a quick look at this, this is used for diagnostic purposes, see for instance https://github.com/spastorino/rust/blob/b82e779259706ceb63fbd38fa5c9d8b9b632149a/compiler/rustc_borrowck/src/diagnostics/mod.rs#L1200-L1207
Do you meant to say that .use doesn't move so this error is not important. Also my code doesn't completely handles the DesugaringKind, so or I should remove if this error shouldn't happen or I should do the actual handling of it :).

nikomatsakis · 2024-12-27T17:18:59Z

compiler/rustc_mir_build/src/builder/expr/into.rs

+                let place = unpack!(block = this.as_place(block, expr));
+                let ty = place.ty(&this.local_decls, this.tcx).ty;
+
+                let success = this.cfg.start_new_block();


I know this is going to change in future commits, but it needs a comment. Just something like

// Convert `expr.use` to a call like `Clone::clone(&expr)`

would go a long way

nikomatsakis · 2024-12-27T17:21:35Z

compiler/rustc_parse/src/parser/expr.rs

@@ -1331,6 +1332,12 @@ impl<'a> Parser<'a> {
            return Ok(self.mk_await_expr(self_arg, lo));
        }

+        if self.eat_keyword(exp!(Use)) {
+            let use_span = self.prev_token.span;
+            self.psess.gated_spans.gate(sym::ergonomic_clones, use_span);


Is it normal to gate in the parser like this?

Looks like it is, I am not sure what's most common

From what I've seen in code it is and this is what @compiler-errors what asking me to do in a previous review. Can you confirm Michael?.

Not only is it "normal", it's literally imperative to gate in the parser to make sure that we don't accidentally stabilize the syntax in cfg'd code. Please make sure that there is a test that validates that this still gives an error when the code has #[cfg(any())].

nikomatsakis · 2024-12-27T17:22:27Z

compiler/rustc_span/src/hygiene.rs

@@ -1175,6 +1176,7 @@ impl DesugaringKind {
            DesugaringKind::CondTemporary => "`if` or `while` condition",
            DesugaringKind::Async => "`async` block or function",
            DesugaringKind::Await => "`await` expression",
+            DesugaringKind::Use => "`use` expression",


I don't think we need this

nikomatsakis · 2024-12-27T17:25:35Z

compiler/rustc_hir_typeck/src/upvar.rs

@@ -1685,10 +1687,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
            //
            // If the data will be moved out of this place, then the place will be truncated
            // at the first Deref in `adjust_for_move_closure` and then moved into the closure.


maybe you can extend this comment with the example I wrote in Zulip? I think it would help future readers.

nikomatsakis · 2024-12-27T17:29:43Z

compiler/rustc_hir_typeck/src/expr_use_visitor.rs

@@ -367,6 +367,10 @@ impl<'tcx, Cx: TypeInformationCtxt<'tcx>, D: Delegate<'tcx>> ExprUseVisitor<'tcx
                self.consume_exprs(args)?;
            }

+            hir::ExprKind::Use(expr, _) => {
+                self.consume_expr(expr)?;


Hmm-- I just realized, this is.... not necessarily correct. Not necessarily wrong either. This says that expr will be moved, but the true behavior is that expr will be moved unless it implements UseCloned. So this should be adjusted later on to take that into account.

Should we do something like consume_copy_or_borrow? if UseCloned borrow, if copy Copy and move otherwise.

nikomatsakis · 2024-12-27T17:32:31Z

compiler/rustc_hir_typeck/src/upvar.rs

@@ -2339,8 +2357,10 @@ fn determine_capture_info(
        }
    } else {
        // We select the CaptureKind which ranks higher based the following priority order:
-        // ByValue > MutBorrow > UniqueImmBorrow > ImmBorrow
+        // ByUse > ByValue > MutBorrow > UniqueImmBorrow > ImmBorrow


Hmm, the ordering of ByUse and ByValue seems unclear to me, but I also expect that you never see them together? Maybe we should say (ty::UpvarCapture::ByUse, ty::UpvarCapture::ByMove) => bug! (and vice versa) instead. -- I'd probably change the code here to not use _ but explicitly say (ByValue, ByRef(_)) => lhs, etc.

nikomatsakis · 2024-12-27T17:33:17Z

compiler/rustc_mir_build/src/builder/expr/into.rs

+                        Rvalue::Use(Operand::Copy(place)),
+                    );
+                    block.unit()
+                } else if this.infcx.type_is_use_cloned_modulo_regions(this.param_env, ty) {


this same logic needs to go into the ExprUseVisitor-- note that consume_expr I think already tests whether the expression is "copy" or not, so that is covered

nikomatsakis · 2024-12-27T17:33:42Z

library/core/src/clone.rs

+#[cfg_attr(not(bootstrap), lang = "use_cloned")]
+#[rustc_diagnostic_item = "UseCloned"]
+#[rustc_trivial_field_reads]
+pub trait UseCloned: Clone {}


should be "marker"

spastorino · 2024-12-27T21:36:35Z

I've pushed some tests and I've found some parsing errors, a diagnostic ICE and another issue that needs handling during borrowck. CI is going to be red but is fine as this is not yet done.

rust-log-analyzer · 2024-12-27T21:57:44Z

The job x86_64-gnu-llvm-18 failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

#22 exporting to docker image format
#22 sending tarball 27.9s done
#22 DONE 34.3s
##[endgroup]
Setting extra environment values for docker:  --env ENABLE_GCC_CODEGEN=1 --env GCC_EXEC_PREFIX=/usr/lib/gcc/
[CI_JOB_NAME=x86_64-gnu-llvm-18]
debug: `DISABLE_CI_RUSTC_IF_INCOMPATIBLE` configured.
---
sccache: Starting the server...
##[group]Configure the build
configure: processing command line
configure: 
configure: build.configure-args := ['--build=x86_64-unknown-linux-gnu', '--llvm-root=/usr/lib/llvm-18', '--enable-llvm-link-shared', '--set', 'rust.randomize-layout=true', '--set', 'rust.thin-lto-import-instr-limit=10', '--enable-verbose-configure', '--enable-sccache', '--disable-manage-submodules', '--enable-locked-deps', '--enable-cargo-native-static', '--set', 'rust.codegen-units-std=1', '--set', 'dist.compression-profile=balanced', '--dist-compression-formats=xz', '--set', 'rust.lld=false', '--disable-dist-src', '--release-channel=nightly', '--enable-debug-assertions', '--enable-overflow-checks', '--enable-llvm-assertions', '--set', 'rust.verify-llvm-ir', '--set', 'rust.codegen-backends=llvm,cranelift,gcc', '--set', 'llvm.static-libstdcpp', '--enable-new-symbol-mangling']
configure: target.x86_64-unknown-linux-gnu.llvm-config := /usr/lib/llvm-18/bin/llvm-config
configure: llvm.link-shared     := True
configure: rust.randomize-layout := True
configure: rust.thin-lto-import-instr-limit := 10
---
---- [ui] tests/ui/ergonomic-clones/closure/nested.rs stdout ----

error: test compilation failed although it shouldn't!
status: exit status: 1
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/ergonomic-clones/closure/nested.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2" "--target=x86_64-unknown-linux-gnu" "--check-cfg" "cfg(FALSE)" "-O" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/ergonomic-clones/closure/nested/a" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers"
--- stderr -------------------------------
error: expected identifier, found `||`
##[error]  --> /checkout/tests/ui/ergonomic-clones/closure/nested.rs:20:7
   |
   |
LL |   use || { use || { use || { Foo } } };

error: aborting due to 1 previous error
------------------------------------------



---- [ui] tests/ui/ergonomic-clones/closure/expect-region.rs stdout ----

error: Error: expected failure status (Some(1)) but received status Some(101).
status: exit status: 101
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/ergonomic-clones/closure/expect-region.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2" "--target=x86_64-unknown-linux-gnu" "--check-cfg" "cfg(FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/ergonomic-clones/closure/expect-region" "-A" "unused" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers"
--- stderr -------------------------------
error: lifetime may not live long enough
##[error]  --> /checkout/tests/ui/ergonomic-clones/closure/expect-region.rs:18:34
   |
   |
LL | fn expect_bound_supply_named<'x>() {
   |                              -- lifetime `'x` defined here
...
LL |     closure_expecting_bound(use |x: &'x u32| {
   |                                  ^  - let's call the lifetime of this reference `'1`
   |                                  |
   |                                  requires that `'1` must outlive `'x`
##[error]error: internal compiler error: compiler/rustc_borrowck/src/lib.rs:1408:29: closures should only capture user variables or references to user variables

thread 'rustc' panicked at compiler/rustc_borrowck/src/lib.rs:1408:29:
Box<dyn Any>
Box<dyn Any>
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: <rustc_errors::diagnostic::BugAbort as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
   3: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
   4: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   5: rustc_middle::util::bug::bug_fmt
   5: rustc_middle::util::bug::bug_fmt
   6: <rustc_borrowck::MirBorrowckCtxt as rustc_mir_dataflow::framework::visitor::ResultsVisitor<rustc_borrowck::dataflow::Borrowck>>::visit_after_early_statement_effect
   7: <rustc_mir_dataflow::framework::direction::Forward as rustc_mir_dataflow::framework::direction::Direction>::visit_results_in_block::<rustc_borrowck::dataflow::Borrowck, rustc_borrowck::MirBorrowckCtxt>
   8: rustc_mir_dataflow::framework::visitor::visit_results::<rustc_borrowck::dataflow::Borrowck, core::iter::adapters::map::Map<core::iter::adapters::map::Map<core::slice::iter::Iter<rustc_middle::mir::BasicBlock>, rustc_middle::mir::traversal::reverse_postorder::{closure#0}>, rustc_borrowck::do_mir_borrowck::{closure#2}>, rustc_borrowck::MirBorrowckCtxt>
   9: rustc_borrowck::do_mir_borrowck
  10: rustc_borrowck::mir_borrowck
      [... omitted 2 frames ...]
  11: <rustc_middle::hir::map::Map>::par_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
  12: <rustc_session::session::Session>::time::<(), rustc_interface::passes::run_required_analyses::{closure#2}>
  13: rustc_interface::passes::analysis
      [... omitted 2 frames ...]
  14: <rustc_middle::ty::context::TyCtxt>::create_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}>
  15: <rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  16: <alloc::boxed::Box<dyn for<'a> core::ops::function::FnOnce<(&'a rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, &'a std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt<'a>>, &'a rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena<'a>>, &'a rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena<'a>>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}), Output = core::option::Option<rustc_interface::queries::Linker>>> as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once
  18: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}, ()>
  19: rustc_span::create_session_globals_then::<(), rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.


note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: please make sure that you have updated to the latest nightly

note: rustc 1.85.0-nightly (ac95a9834 2024-12-27) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z threads=1 -Z simulate-remapped-rust-src-base=/rustc/FAKE_PREFIX -Z translate-remapped-path-to-local-path=no -Z ignore-directory-in-diagnostics-source-blocks=/cargo -Z ignore-directory-in-diagnostics-source-blocks=/checkout/vendor -C codegen-units=1 -Z ui-testing -Z deduplicate-diagnostics=no -Z write-long-types-to-disk=no -C strip=debuginfo -C prefer-dynamic -C rpath -C debuginfo=0
query stack during panic:
query stack during panic:
#0 [mir_borrowck] borrow-checking `expect_bound_supply_named`
end of query stack
error: aborting due to 2 previous errors
------------------------------------------



---- [ui] tests/ui/ergonomic-clones/closure/mutation.rs stdout ----

error: Error: expected failure status (Some(1)) but received status Some(101).
status: exit status: 101
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/ergonomic-clones/closure/mutation.rs" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2" "--target=x86_64-unknown-linux-gnu" "--check-cfg" "cfg(FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/ergonomic-clones/closure/mutation" "-A" "unused" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers"
--- stderr -------------------------------
##[error]error: internal compiler error: compiler/rustc_borrowck/src/lib.rs:1408:29: closures should only capture user variables or references to user variables

thread 'rustc' panicked at compiler/rustc_borrowck/src/lib.rs:1408:29:
thread 'rustc' panicked at compiler/rustc_borrowck/src/lib.rs:1408:29:
Box<dyn Any>
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: <rustc_errors::diagnostic::BugAbort as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
   3: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
   4: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   5: rustc_middle::util::bug::bug_fmt
   5: rustc_middle::util::bug::bug_fmt
   6: <rustc_borrowck::MirBorrowckCtxt as rustc_mir_dataflow::framework::visitor::ResultsVisitor<rustc_borrowck::dataflow::Borrowck>>::visit_after_early_statement_effect
   7: <rustc_mir_dataflow::framework::direction::Forward as rustc_mir_dataflow::framework::direction::Direction>::visit_results_in_block::<rustc_borrowck::dataflow::Borrowck, rustc_borrowck::MirBorrowckCtxt>
   8: rustc_mir_dataflow::framework::visitor::visit_results::<rustc_borrowck::dataflow::Borrowck, core::iter::adapters::map::Map<core::iter::adapters::map::Map<core::slice::iter::Iter<rustc_middle::mir::BasicBlock>, rustc_middle::mir::traversal::reverse_postorder::{closure#0}>, rustc_borrowck::do_mir_borrowck::{closure#2}>, rustc_borrowck::MirBorrowckCtxt>
   9: rustc_borrowck::do_mir_borrowck
  10: rustc_borrowck::mir_borrowck
      [... omitted 2 frames ...]
  11: <rustc_middle::hir::map::Map>::par_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
  12: <rustc_session::session::Session>::time::<(), rustc_interface::passes::run_required_analyses::{closure#2}>
  13: rustc_interface::passes::analysis
      [... omitted 2 frames ...]
  14: <rustc_middle::ty::context::TyCtxt>::create_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}>
  15: <rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  16: <alloc::boxed::Box<dyn for<'a> core::ops::function::FnOnce<(&'a rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, &'a std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt<'a>>, &'a rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena<'a>>, &'a rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena<'a>>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}), Output = core::option::Option<rustc_interface::queries::Linker>>> as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once
  18: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}, ()>
  19: rustc_span::create_session_globals_then::<(), rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.


note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: please make sure that you have updated to the latest nightly

note: rustc 1.85.0-nightly (ac95a9834 2024-12-27) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z threads=1 -Z simulate-remapped-rust-src-base=/rustc/FAKE_PREFIX -Z translate-remapped-path-to-local-path=no -Z ignore-directory-in-diagnostics-source-blocks=/cargo -Z ignore-directory-in-diagnostics-source-blocks=/checkout/vendor -C codegen-units=1 -Z ui-testing -Z deduplicate-diagnostics=no -Z write-long-types-to-disk=no -C strip=debuginfo -C prefer-dynamic -C rpath -C debuginfo=0
query stack during panic:
query stack during panic:
#0 [mir_borrowck] borrow-checking `main`
end of query stack
error: aborting due to 1 previous error
------------------------------------------



---- [ui] tests/ui/ergonomic-clones/closure/immutable-outer-variable.rs stdout ----

error: failed to compile fixed code
status: exit status: 101
command: env -u RUSTC_LOG_COLOR RUSTC_ICE="0" RUST_BACKTRACE="short" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/tests/ui/ergonomic-clones/closure/immutable-outer-variable.fixed" "-Zthreads=1" "-Zsimulate-remapped-rust-src-base=/rustc/FAKE_PREFIX" "-Ztranslate-remapped-path-to-local-path=no" "-Z" "ignore-directory-in-diagnostics-source-blocks=/cargo" "-Z" "ignore-directory-in-diagnostics-source-blocks=/checkout/vendor" "--sysroot" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2" "--target=x86_64-unknown-linux-gnu" "--check-cfg" "cfg(FALSE)" "--error-format" "json" "--json" "future-incompat" "-Ccodegen-units=1" "-Zui-testing" "-Zdeduplicate-diagnostics=no" "-Zwrite-long-types-to-disk=no" "-Cstrip=debuginfo" "--emit" "metadata" "-C" "prefer-dynamic" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/ergonomic-clones/closure/immutable-outer-variable/a" "-A" "internal_features" "-Crpath" "-Cdebuginfo=0" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers"
--- stderr -------------------------------
##[error]error: internal compiler error: compiler/rustc_borrowck/src/lib.rs:1408:29: closures should only capture user variables or references to user variables

thread 'rustc' panicked at compiler/rustc_borrowck/src/lib.rs:1408:29:
thread 'rustc' panicked at compiler/rustc_borrowck/src/lib.rs:1408:29:
Box<dyn Any>
stack backtrace:
   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
   1: <rustc_errors::diagnostic::BugAbort as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
   3: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}
   4: rustc_middle::ty::context::tls::with_context_opt::<rustc_middle::ty::context::tls::with_opt<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>::{closure#0}, !>
   5: rustc_middle::util::bug::bug_fmt
   5: rustc_middle::util::bug::bug_fmt
   6: <rustc_borrowck::MirBorrowckCtxt as rustc_mir_dataflow::framework::visitor::ResultsVisitor<rustc_borrowck::dataflow::Borrowck>>::visit_after_early_statement_effect
   7: <rustc_mir_dataflow::framework::direction::Forward as rustc_mir_dataflow::framework::direction::Direction>::visit_results_in_block::<rustc_borrowck::dataflow::Borrowck, rustc_borrowck::MirBorrowckCtxt>
   8: rustc_mir_dataflow::framework::visitor::visit_results::<rustc_borrowck::dataflow::Borrowck, core::iter::adapters::map::Map<core::iter::adapters::map::Map<core::slice::iter::Iter<rustc_middle::mir::BasicBlock>, rustc_middle::mir::traversal::reverse_postorder::{closure#0}>, rustc_borrowck::do_mir_borrowck::{closure#2}>, rustc_borrowck::MirBorrowckCtxt>
   9: rustc_borrowck::do_mir_borrowck
  10: rustc_borrowck::mir_borrowck
      [... omitted 2 frames ...]
  11: <rustc_middle::hir::map::Map>::par_body_owners::<rustc_interface::passes::run_required_analyses::{closure#2}::{closure#0}>::{closure#0}
  12: <rustc_session::session::Session>::time::<(), rustc_interface::passes::run_required_analyses::{closure#2}>
  13: rustc_interface::passes::analysis
      [... omitted 2 frames ...]
  14: <rustc_middle::ty::context::TyCtxt>::create_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}>
  15: <rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0}
  16: <alloc::boxed::Box<dyn for<'a> core::ops::function::FnOnce<(&'a rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, &'a std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt<'a>>, &'a rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena<'a>>, &'a rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena<'a>>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}), Output = core::option::Option<rustc_interface::queries::Linker>>> as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once
  18: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}, ()>
  19: rustc_span::create_session_globals_then::<(), rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}>
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.


note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: please make sure that you have updated to the latest nightly

note: rustc 1.85.0-nightly (ac95a9834 2024-12-27) running on x86_64-unknown-linux-gnu

note: compiler flags: -Z threads=1 -Z simulate-remapped-rust-src-base=/rustc/FAKE_PREFIX -Z translate-remapped-path-to-local-path=no -Z ignore-directory-in-diagnostics-source-blocks=/cargo -Z ignore-directory-in-diagnostics-source-blocks=/checkout/vendor -C codegen-units=1 -Z ui-testing -Z deduplicate-diagnostics=no -Z write-long-types-to-disk=no -C strip=debuginfo -C prefer-dynamic -C rpath -C debuginfo=0
query stack during panic:
query stack during panic:
#0 [mir_borrowck] borrow-checking `main`
end of query stack
error: aborting due to 1 previous error
------------------------------------------

rustbot assigned nikomatsakis Dec 26, 2024

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Dec 26, 2024

Add ergonomic_clones feature flag

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compiler/rustc_ast_lowering/src/expr.rs Outdated Show resolved Hide resolved

spastorino force-pushed the ergonomic-ref-counting-1 branch from e4e8ad3 to b003b20 Compare December 26, 2024 19:43

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spastorino force-pushed the ergonomic-ref-counting-1 branch from b003b20 to 94d4dde Compare December 26, 2024 20:47

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spastorino added 3 commits December 27, 2024 00:55

Implement .use keyword as an alias of clone

9fd5694

Use closure parse code

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Generate the right MIR for by use closures

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spastorino force-pushed the ergonomic-ref-counting-1 branch from 42e6956 to 0aaedb8 Compare December 27, 2024 03:55

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spastorino force-pushed the ergonomic-ref-counting-1 branch from f9a2abe to 0c29a0b Compare December 27, 2024 13:14

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spastorino added 3 commits December 27, 2024 11:35

Add UseCloned trait related code

095b4b1

Fix clippy

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Fix rustfmt

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spastorino force-pushed the ergonomic-ref-counting-1 branch from 0c29a0b to b82e779 Compare December 27, 2024 14:35

Separate closures, async and dotuse tests in directories

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rustbot added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Dec 27, 2024

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[WIP] Ergonomic ref counting #134797

[WIP] Ergonomic ref counting #134797

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rust-log-analyzer commented Dec 27, 2024

[WIP] Ergonomic ref counting #134797

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[WIP] Ergonomic ref counting #134797

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spastorino commented Dec 27, 2024

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spastorino commented Dec 26, 2024 •

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