explicit tail call tests with indexing, idirect operands in LLVM

tnuha · tnuha · commit 06db3a56edd6 · 2025-07-29T14:02:25.000-06:00
diff --git a/tests/ui/explicit-tail-calls/drop-order.rs b/tests/ui/explicit-tail-calls/drop-order.rs
@@ -1,5 +1,3 @@
-// FIXME(explicit_tail_calls): enable this test once rustc_codegen_ssa supports tail calls
-//@ ignore-test: tail calls are not implemented in rustc_codegen_ssa yet, so this causes 🧊
 //@ run-pass
 #![expect(incomplete_features)]
 #![feature(explicit_tail_calls)]
diff --git a/tests/ui/explicit-tail-calls/indexer.rs b/tests/ui/explicit-tail-calls/indexer.rs
@@ -0,0 +1,21 @@
+// Indexing taken from
+// https://github.com/phi-go/rfcs/blob/guaranteed-tco/text%2F0000-explicit-tail-calls.md#tail-call-elimination
+// should probably come back to after some decision on verbiage
+#![expect(incomplete_features)]
+#![feature(explicit_tail_calls)]
+
+fn f0(_: usize) {}
+fn f1(_: usize) {}
+fn f2(_: usize) {}
+
+fn indexer(idx: usize) {
+    let v: [&dyn Fn(usize); 3] = [&f0, &f1, &f2];
+    become v[idx](idx) //~ error: mismatched function ABIs
+    //~^ error: mismatched signatures
+}
+
+fn main() {
+    for idx in 0..3 {
+        indexer(idx);
+    }
+}
diff --git a/tests/ui/explicit-tail-calls/indexer.stderr b/tests/ui/explicit-tail-calls/indexer.stderr
@@ -0,0 +1,21 @@
+error: mismatched function ABIs
+  --> $DIR/indexer.rs:13:5
+   |
+LL |     become v[idx](idx)
+   |     ^^^^^^^^^^^^^^^^^^
+   |
+   = note: `become` requires caller and callee to have the same ABI
+   = note: caller ABI is `"Rust"`, while callee ABI is `"rust-call"`
+
+error: mismatched signatures
+  --> $DIR/indexer.rs:13:5
+   |
+LL |     become v[idx](idx)
+   |     ^^^^^^^^^^^^^^^^^^
+   |
+   = note: `become` requires caller and callee to have matching signatures
+   = note: caller signature: `fn(usize)`
+   = note: callee signature: `extern "rust-call" fn(&dyn Fn(usize), (usize,))`
+
+error: aborting due to 2 previous errors
+
diff --git a/tests/ui/explicit-tail-calls/recursion-etc-u64wrapper.rs b/tests/ui/explicit-tail-calls/recursion-etc-u64wrapper.rs
@@ -0,0 +1,44 @@
+//@build-fail
+//@known-bug: #144293
+//@ failure-status: 101
+// Same as recursion-etc but eggs LLVM emission into giving indirect arguments.
+#![expect(incomplete_features)]
+#![feature(explicit_tail_calls)]
+
+use std::hint::black_box;
+
+struct U64Wrapper {
+    pub x: u64,
+    pub arbitrary: String,
+}
+
+fn count(curr: U64Wrapper, top: U64Wrapper) -> U64Wrapper {
+    if black_box(curr.x) >= top.x {
+        curr
+    } else {
+        become count(
+            U64Wrapper {
+                x: curr.x + 1,
+                arbitrary: curr.arbitrary,
+            },
+            top,
+        )
+    }
+}
+
+fn main() {
+    println!(
+        "{}",
+        count(
+            U64Wrapper {
+                x: 0,
+                arbitrary: "hello!".into()
+            },
+            black_box(U64Wrapper {
+                x: 1000000,
+                arbitrary: "goodbye!".into()
+            })
+        )
+        .x
+    );
+}
diff --git a/tests/ui/explicit-tail-calls/recursion-etc-u64wrapper.stderr b/tests/ui/explicit-tail-calls/recursion-etc-u64wrapper.stderr
@@ -0,0 +1,135 @@
+error: internal compiler error: $COMPILER_DIR_REAL/rustc_codegen_ssa/src/mir/block.rs:1059:17: arguments using PassMode::Indirect are currently not supported for tail calls
+  --> $DIR/recursion-etc-u64wrapper.rs:19:16
+   |
+LL |           become count(
+   |  ________________^
+LL | |             U64Wrapper {
+LL | |                 x: curr.x + 1,
+LL | |                 arbitrary: curr.arbitrary,
+LL | |             },
+LL | |             top,
+LL | |         )
+   | |_________^
+
+
+thread 'rustc' panicked at $COMPILER_DIR_REAL/rustc_codegen_ssa/src/mir/block.rs:1059:17:
+Box<dyn Any>
+stack backtrace:
+   0: std::panicking::begin_panic::<rustc_errors::ExplicitBug>
+             at /rustc/390a0ab5dc4a895235a551e502c3893c3337731d/library/std/src/panicking.rs:769:5
+   1: std::panic::panic_any::<rustc_errors::ExplicitBug>
+             at /rustc/390a0ab5dc4a895235a551e502c3893c3337731d/library/std/src/panic.rs:260:5
+   2: <rustc_errors::diagnostic::BugAbort as rustc_errors::diagnostic::EmissionGuarantee>::emit_producing_guarantee
+             at ./compiler/rustc_errors/src/diagnostic.rs:83:9
+   3: <rustc_errors::diagnostic::Diag<rustc_errors::diagnostic::BugAbort>>::emit
+             at ./compiler/rustc_errors/src/diagnostic.rs:1416:9
+   4: <rustc_errors::DiagCtxtHandle>::span_bug::<rustc_span::span_encoding::Span, alloc::string::String>
+             at ./compiler/rustc_errors/src/lib.rs:1234:48
+   5: {closure#0}<rustc_span::span_encoding::Span>
+             at ./compiler/rustc_middle/src/util/bug.rs:38:54
+   6: {closure#0}<rustc_middle::util::bug::opt_span_bug_fmt::{closure_env#0}<rustc_span::span_encoding::Span>, !>
+             at ./compiler/rustc_middle/src/ty/context/tls.rs:136:23
+   7: with_context_opt<rustc_middle::ty::context::tls::with_opt::{closure_env#0}<rustc_middle::util::bug::opt_span_bug_fmt::{closure_env#0}<rustc_span::span_encoding::Span>, !>, !>
+             at ./compiler/rustc_middle/src/ty/context/tls.rs:79:18
+   8: rustc_middle::ty::context::tls::with_opt::<rustc_middle::util::bug::opt_span_bug_fmt<rustc_span::span_encoding::Span>::{closure#0}, !>
+             at ./compiler/rustc_middle/src/ty/context/tls.rs:134:5
+   9: rustc_middle::util::bug::opt_span_bug_fmt::<rustc_span::span_encoding::Span>
+             at ./compiler/rustc_middle/src/util/bug.rs:33:5
+  10: rustc_middle::util::bug::span_bug_fmt::<rustc_span::span_encoding::Span>
+             at ./compiler/rustc_middle/src/util/bug.rs:24:5
+  11: codegen_call_terminator<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+  12: codegen_terminator<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+  13: codegen_block<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+             at ./compiler/rustc_codegen_ssa/src/mir/block.rs:1299:37
+  14: codegen_mir<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+             at ./compiler/rustc_codegen_ssa/src/mir/mod.rs:310:12
+  15: codegen_instance<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+             at ./compiler/rustc_codegen_ssa/src/base.rs:394:5
+  16: define<rustc_codegen_llvm::builder::GenericBuilder<rustc_codegen_llvm::context::FullCx>>
+             at ./compiler/rustc_codegen_ssa/src/mono_item.rs:48:21
+  17: module_codegen
+             at ./compiler/rustc_codegen_llvm/src/base.rs:99:27
+  18: with_task<rustc_middle::dep_graph::DepsType, rustc_middle::ty::context::TyCtxt, rustc_span::symbol::Symbol, rustc_codegen_ssa::ModuleCodegen<rustc_codegen_llvm::ModuleLlvm>>
+             at ./compiler/rustc_query_system/src/dep_graph/graph.rs:274:22
+  19: compile_codegen_unit
+             at ./compiler/rustc_codegen_llvm/src/base.rs:63:37
+  20: <rustc_codegen_llvm::LlvmCodegenBackend as rustc_codegen_ssa::traits::backend::ExtraBackendMethods>::compile_codegen_unit
+             at ./compiler/rustc_codegen_llvm/src/lib.rs:128:9
+  21: codegen_crate<rustc_codegen_llvm::LlvmCodegenBackend>
+             at ./compiler/rustc_codegen_ssa/src/base.rs:794:42
+  22: codegen_crate
+             at ./compiler/rustc_codegen_llvm/src/lib.rs:344:18
+  23: {closure#0}
+             at ./compiler/rustc_interface/src/passes.rs:1219:74
+  24: run<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
+             at ./compiler/rustc_data_structures/src/profiling.rs:839:9
+  25: time<alloc::boxed::Box<dyn core::any::Any, alloc::alloc::Global>, rustc_interface::passes::start_codegen::{closure_env#0}>
+             at ./compiler/rustc_session/src/utils.rs:16:50
+  26: start_codegen
+             at ./compiler/rustc_interface/src/passes.rs:1219:28
+  27: codegen_and_build_linker
+             at ./compiler/rustc_interface/src/queries.rs:32:43
+  28: {closure#2}
+             at ./compiler/rustc_driver_impl/src/lib.rs:386:18
+  29: {closure#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
+             at ./compiler/rustc_interface/src/passes.rs:1002:27
+  30: {closure#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
+             at ./compiler/rustc_middle/src/ty/context.rs:1528:37
+  31: {closure#0}<rustc_middle::ty::context::{impl#21}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
+             at ./compiler/rustc_middle/src/ty/context/tls.rs:60:9
+  32: try_with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#21}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
+             at /rustc/390a0ab5dc4a895235a551e502c3893c3337731d/library/std/src/thread/local.rs:315:12
+  33: with<core::cell::Cell<*const ()>, rustc_middle::ty::context::tls::enter_context::{closure_env#0}<rustc_middle::ty::context::{impl#21}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
+             at /rustc/390a0ab5dc4a895235a551e502c3893c3337731d/library/std/src/thread/local.rs:279:20
+  34: enter_context<rustc_middle::ty::context::{impl#21}::enter::{closure_env#1}<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>, core::option::Option<rustc_interface::queries::Linker>>
+             at ./compiler/rustc_middle/src/ty/context/tls.rs:57:9
+  35: enter<rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, core::option::Option<rustc_interface::queries::Linker>>
+             at ./compiler/rustc_middle/src/ty/context.rs:1528:9
+  36: create_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt::{closure#2}::{closure_env#0}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>>
+             at ./compiler/rustc_middle/src/ty/context.rs:1733:13
+  37: {closure#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
+             at ./compiler/rustc_interface/src/passes.rs:969:9
+  38: call_once<rustc_interface::passes::create_and_enter_global_ctxt::{closure_env#2}<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>, (&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &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_env#2})>
+             at /rustc/390a0ab5dc4a895235a551e502c3893c3337731d/library/core/src/ops/function.rs:250:5
+  39: call_once<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &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_env#2}), dyn core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy, alloc::alloc::Global>, &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_env#2}), Output=core::option::Option<rustc_interface::queries::Linker>>, alloc::alloc::Global>
+             at /rustc/390a0ab5dc4a895235a551e502c3893c3337731d/library/alloc/src/boxed.rs:1966:9
+  40: create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure_env#2}>
+             at ./compiler/rustc_interface/src/passes.rs:1010:5
+  41: {closure#0}
+             at ./compiler/rustc_driver_impl/src/lib.rs:343:22
+  42: {closure#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
+             at ./compiler/rustc_interface/src/interface.rs:525:80
+  43: call_once<(), rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>
+             at /rustc/390a0ab5dc4a895235a551e502c3893c3337731d/library/core/src/panic/unwind_safe.rs:272:9
+  44: do_call<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
+             at /rustc/390a0ab5dc4a895235a551e502c3893c3337731d/library/std/src/panicking.rs:589:40
+  45: catch_unwind<(), core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>>
+             at /rustc/390a0ab5dc4a895235a551e502c3893c3337731d/library/std/src/panicking.rs:552:19
+  46: catch_unwind<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler::{closure#1}::{closure_env#0}<(), rustc_driver_impl::run_compiler::{closure_env#0}>>, ()>
+             at /rustc/390a0ab5dc4a895235a551e502c3893c3337731d/library/std/src/panic.rs:359:14
+  47: {closure#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>
+             at ./compiler/rustc_interface/src/interface.rs:525:23
+  48: {closure#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>
+             at ./compiler/rustc_interface/src/util.rs:199:17
+  49: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
+             at ./compiler/rustc_interface/src/util.rs:153:24
+  50: set<rustc_span::SessionGlobals, rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>, ()>
+             at /home/ash/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/scoped-tls-1.0.1/src/lib.rs:137:9
+  51: create_session_globals_then<(), rustc_interface::util::run_in_thread_with_globals::{closure#0}::{closure#0}::{closure_env#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>>
+             at ./compiler/rustc_span/src/lib.rs:145:21
+  52: {closure#0}<rustc_interface::util::run_in_thread_pool_with_globals::{closure_env#0}<rustc_interface::interface::run_compiler::{closure_env#1}<(), rustc_driver_impl::run_compiler::{closure_env#0}>, ()>, ()>
+             at ./compiler/rustc_interface/src/util.rs:149:17
+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 1.90.0-dev 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=/home/ash/.cargo -Z ignore-directory-in-diagnostics-source-blocks=/home/ash/Projects/foss/rust/working/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:
+end of query stack
+error: aborting due to 1 previous error
+

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,3 @@`
`1`		`-// FIXME(explicit_tail_calls): enable this test once rustc_codegen_ssa supports tail calls`
`2`		`-//@ ignore-test: tail calls are not implemented in rustc_codegen_ssa yet, so this causes 🧊`
`3`	`1`	`//@ run-pass`
`4`	`2`	`#![expect(incomplete_features)]`
`5`	`3`	`#![feature(explicit_tail_calls)]`