ICE: Tried to insert symbol which already existed

I tried this code:

/*!
 * Try to double-check that static fns have the right size (with or
 * without dummy env ptr, as appropriate) by iterating a size-2 array.
 * If the static size differs from the runtime size, the second element
 * should be read as a null or otherwise wrong pointer and crash.
 */

fn f() {}
static mut CLOSURES: &'static mut [fn()] = &mut [f as fn(), f as fn()];

#[kani::proof]
pub fn main() {
    unsafe {
        for closure in &mut *CLOSURES {
            (*closure)()
        }
    }
}

using the following command line invocation:

kani <file>

with Kani version: 0.22.0

I expected to see this happen: explanation

Instead, this happened: explanation

thread '<unnamed>' panicked at 'Tried to insert symbol which already existed
	: Symbol { name: "const_vec_of_fns.644c7146::const_vec_of_fns::alloc4_init::1::var_0", location: None, typ: StructTag("tag-const_vec_of_fns.644c7146::const_vec_of_fns::alloc4::struct"), value: None, base_name: Some("var_0"), pretty_name: None, module: None, mode: C, is_exported: false, is_input: false, is_macro: false, is_output: false, is_property: false, is_state_var: true, is_type: false, is_auxiliary: true, is_extern: false, is_file_local: false, is_lvalue: true, is_parameter: false, is_static_lifetime: false, is_thread_local: true, is_volatile: false, is_weak: false }
	', cprover_bindings/src/goto_program/symbol_table.rs:49:9
stack backtrace:
   0:     0x7fcffdd667da - std::backtrace_rs::backtrace::libunwind::trace::hc84915c67f6fb1e5
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/../../backtrace/src/backtrace/libunwind.rs:93:5
   1:     0x7fcffdd667da - std::backtrace_rs::backtrace::trace_unsynchronized::h74fef551999c3a2f
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7fcffdd667da - std::sys_common::backtrace::_print_fmt::h8acfd19c1a6f1d1d
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/sys_common/backtrace.rs:65:5
   3:     0x7fcffdd667da - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h9271b09f3576b7e0
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7fcffddc92ee - core::fmt::write::h27d0bbb767cff1d5
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/core/src/fmt/mod.rs:1208:17
   5:     0x7fcffdd56c65 - std::io::Write::write_fmt::hc409ea2bb818fbea
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/io/mod.rs:1682:15
   6:     0x7fcffdd665a5 - std::sys_common::backtrace::_print::hfa031a98cf1e4011
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/sys_common/backtrace.rs:47:5
   7:     0x7fcffdd665a5 - std::sys_common::backtrace::print::he69ac0980f15620d
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/sys_common/backtrace.rs:34:9
   8:     0x7fcffdd692ef - std::panicking::default_hook::{{closure}}::h014cf704a69dce2b
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/panicking.rs:267:22
   9:     0x7fcffdd6902b - std::panicking::default_hook::h380e71f8d8d49df7
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/panicking.rs:286:9
  10:     0x562c06baeb0d - kani_compiler::session::PANIC_HOOK::{{closure}}::{{closure}}::h10f33c4e395bf462
  11:     0x562c06b04f67 - kani_compiler::codegen_cprover_gotoc::utils::debug::DEFAULT_HOOK::{{closure}}::{{closure}}::hf568cc16e5ffa08a
  12:     0x7fcffdd69b2d - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::hcfa7e50330911a79
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/alloc/src/boxed.rs:2032:9
  13:     0x7fcffdd69b2d - std::panicking::rust_panic_with_hook::h483f1ef90c766581
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/panicking.rs:692:13
  14:     0x7fcffdd698a9 - std::panicking::begin_panic_handler::{{closure}}::hd4c7d9116c0ef489
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/panicking.rs:579:13
  15:     0x7fcffdd66c8c - std::sys_common::backtrace::__rust_end_short_backtrace::had27a083c7d7188b
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/sys_common/backtrace.rs:137:18
  16:     0x7fcffdd695b2 - rust_begin_unwind
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/panicking.rs:575:5
  17:     0x7fcffddc5cd3 - core::panicking::panic_fmt::hbacb72817da3b060
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/core/src/panicking.rs:64:14
  18:     0x562c06d1fd5c - cprover_bindings::goto_program::symbol_table::SymbolTable::insert::hf9e982da35288260
  19:     0x562c06aee61a - kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx::gen_stack_variable::hbaf5093eaa613a74
  20:     0x562c06ac112c - kani_compiler::codegen_cprover_gotoc::codegen::operand::<impl kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx>::codegen_alloc_in_memory::h64078d2ed514f166
  21:     0x562c06abec02 - kani_compiler::codegen_cprover_gotoc::codegen::operand::<impl kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx>::codegen_alloc_pointer::hbbb8bbc3b328ec9e
  22:     0x562c06ac1c16 - kani_compiler::codegen_cprover_gotoc::codegen::operand::<impl kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx>::codegen_allocation_data::h449038142e0de7e0
  23:     0x562c06ac0fe1 - kani_compiler::codegen_cprover_gotoc::codegen::operand::<impl kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx>::codegen_alloc_in_memory::h64078d2ed514f166
  24:     0x562c06ae0066 - kani_compiler::codegen_cprover_gotoc::codegen::static_var::<impl kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx>::codegen_static::h52db0ab987982228
  25:     0x562c06b08ebc - std::thread::local::LocalKey<T>::with::h39239975608b0fa2
  26:     0x562c06b962c9 - <kani_compiler::codegen_cprover_gotoc::compiler_interface::GotocCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate::heaa499391d53b3f6
  27:     0x7fd000286fa1 - <rustc_session[19dfb3d05ff8562d]::session::Session>::time::<alloc[58cfa59ca61fafa9]::boxed::Box<dyn core[6d94cc961ac87456]::any::Any>, rustc_interface[aec886e93b1add3f]::passes::start_codegen::{closure#0}>
  28:     0x7fd000286ac9 - rustc_interface[aec886e93b1add3f]::passes::start_codegen
  29:     0x7fd0002847a6 - <rustc_interface[aec886e93b1add3f]::passes::QueryContext>::enter::<<rustc_interface[aec886e93b1add3f]::queries::Queries>::ongoing_codegen::{closure#0}::{closure#0}, core[6d94cc961ac87456]::result::Result<alloc[58cfa59ca61fafa9]::boxed::Box<dyn core[6d94cc961ac87456]::any::Any>, rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>>
  30:     0x7fd000281a46 - <rustc_interface[aec886e93b1add3f]::queries::Queries>::ongoing_codegen
  31:     0x7fd000280f67 - <rustc_interface[aec886e93b1add3f]::interface::Compiler>::enter::<rustc_driver[94a2f0241de75afa]::run_compiler::{closure#1}::{closure#2}, core[6d94cc961ac87456]::result::Result<core[6d94cc961ac87456]::option::Option<rustc_interface[aec886e93b1add3f]::queries::Linker>, rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>>
  32:     0x7fd00027bf88 - rustc_span[ae2df7aa7c6c667b]::with_source_map::<core[6d94cc961ac87456]::result::Result<(), rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>, rustc_interface[aec886e93b1add3f]::interface::run_compiler<core[6d94cc961ac87456]::result::Result<(), rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>, rustc_driver[94a2f0241de75afa]::run_compiler::{closure#1}>::{closure#0}::{closure#0}>
  33:     0x7fd00027ba75 - <scoped_tls[db87656d258d017b]::ScopedKey<rustc_span[ae2df7aa7c6c667b]::SessionGlobals>>::set::<rustc_interface[aec886e93b1add3f]::interface::run_compiler<core[6d94cc961ac87456]::result::Result<(), rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>, rustc_driver[94a2f0241de75afa]::run_compiler::{closure#1}>::{closure#0}, core[6d94cc961ac87456]::result::Result<(), rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>>
  34:     0x7fd00027b062 - std[acd1f573e90225f]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[aec886e93b1add3f]::util::run_in_thread_pool_with_globals<rustc_interface[aec886e93b1add3f]::interface::run_compiler<core[6d94cc961ac87456]::result::Result<(), rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>, rustc_driver[94a2f0241de75afa]::run_compiler::{closure#1}>::{closure#0}, core[6d94cc961ac87456]::result::Result<(), rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[6d94cc961ac87456]::result::Result<(), rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>>
  35:     0x7fd0008ec49e - <<std[acd1f573e90225f]::thread::Builder>::spawn_unchecked_<rustc_interface[aec886e93b1add3f]::util::run_in_thread_pool_with_globals<rustc_interface[aec886e93b1add3f]::interface::run_compiler<core[6d94cc961ac87456]::result::Result<(), rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>, rustc_driver[94a2f0241de75afa]::run_compiler::{closure#1}>::{closure#0}, core[6d94cc961ac87456]::result::Result<(), rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[6d94cc961ac87456]::result::Result<(), rustc_errors[56887b15c7ec6fbf]::ErrorGuaranteed>>::{closure#1} as core[6d94cc961ac87456]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  36:     0x7fd001dda2d3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::he955d3e33f115328
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/alloc/src/boxed.rs:2000:9
  37:     0x7fd001dda2d3 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h32515d9eaa012a19
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/alloc/src/boxed.rs:2000:9
  38:     0x7fd001dda2d3 - std::sys::unix::thread::Thread::new::thread_start::h5af9cdd9a5a58d64
                               at /rustc/c6fcdb690609769a240fc8ab0de0ce68d5ea7dba/library/std/src/sys/unix/thread.rs:108:17
  39:     0x7fcffda1dbb5 - <unknown>
  40:     0x7fcffda9fd90 - <unknown>
  41:                0x0 - <unknown>

Kani unexpectedly panicked during compilation.
Please file an issue here: https://github.com/model-checking/kani/issues/new?labels=bug&template=bug_report.md

[Kani] current codegen item: codegen_static: DefId(0:4 ~ const_vec_of_fns[6b92]::CLOSURES)
[Kani] current codegen location: Loc { file: "/tmp/im/const-vec-of-fns.rs", function: None, start_line: 9, start_col: Some(1), end_line: 9, end_col: Some(41) }

Kani Rust Verifier 0.40.0 (standalone)
thread 'rustc' panicked at kani-compiler/src/codegen_cprover_gotoc/codegen/operand.rs:547:9:
assertion `left == right` failed: Expected constant allocation for `Some("a.7ac19d9bf548ce0e::a::alloc6")`, but got a mutable instead
  left: Mut
 right: Not
stack backtrace:
   0:     0x7f4521969cfc - std::backtrace_rs::backtrace::libunwind::trace::h974857262e179b17
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/../../backtrace/src/backtrace/libunwind.rs:104:5
   1:     0x7f4521969cfc - std::backtrace_rs::backtrace::trace_unsynchronized::h6adce2053c056ac9
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
   2:     0x7f4521969cfc - std::sys_common::backtrace::_print_fmt::hcf2018a5ad956761
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/sys_common/backtrace.rs:67:5
   3:     0x7f4521969cfc - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h3d39e48ce4d7e36f
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/sys_common/backtrace.rs:44:22
   4:     0x7f45219cbf50 - core::fmt::rt::Argument::fmt::hef0ae15422a7f61d
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/core/src/fmt/rt.rs:142:9
   5:     0x7f45219cbf50 - core::fmt::write::hf465a4ba34489409
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/core/src/fmt/mod.rs:1117:17
   6:     0x7f452195dc1f - std::io::Write::write_fmt::hf34ad5986fa99e89
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/io/mod.rs:1763:15
   7:     0x7f4521969ae4 - std::sys_common::backtrace::_print::h5aa7f1d99916c125
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/sys_common/backtrace.rs:47:5
   8:     0x7f4521969ae4 - std::sys_common::backtrace::print::h036d85b5c81889eb
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/sys_common/backtrace.rs:34:9
   9:     0x7f452196c777 - std::panicking::default_hook::{{closure}}::h9b311bcc8d2b2a40
  10:     0x7f452196c4df - std::panicking::default_hook::hd7a03fd029ce4ee2
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/panicking.rs:292:9
  11:     0x561925607c0d - kani_compiler::session::PANIC_HOOK::{{closure}}::{{closure}}::h270fbeb056d900dc
  12:     0x561925607703 - kani_compiler::codegen_cprover_gotoc::utils::debug::DEFAULT_HOOK::{{closure}}::{{closure}}::h410a2f5534eafaf7
  13:     0x7f452196ceb8 - <alloc::boxed::Box<F,A> as core::ops::function::Fn<Args>>::call::h079168172b9ee18d
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/alloc/src/boxed.rs:2021:9
  14:     0x7f452196ceb8 - std::panicking::rust_panic_with_hook::h9ec5267af19ebd61
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/panicking.rs:783:13
  15:     0x7f452196cc0e - std::panicking::begin_panic_handler::{{closure}}::hded4ae2a191a7bae
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/panicking.rs:657:13
  16:     0x7f452196a1c6 - std::sys_common::backtrace::__rust_end_short_backtrace::h3b03f6ccd27da73f
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/sys_common/backtrace.rs:170:18
  17:     0x7f452196c972 - rust_begin_unwind
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/panicking.rs:645:5
  18:     0x7f45219c8675 - core::panicking::panic_fmt::h290f6f1be63b094c
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/core/src/panicking.rs:72:14
  19:     0x7f45219c8cd1 - core::panicking::assert_failed_inner::h44691747029b7627
  20:     0x5619254ad97f - core::panicking::assert_failed::ha211627436eb9cbc
  21:     0x5619254f1f54 - kani_compiler::codegen_cprover_gotoc::codegen::operand::<impl kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx>::codegen_const_allocation::h432ea3e3f7c1a597
  22:     0x5619254f0d0f - kani_compiler::codegen_cprover_gotoc::codegen::operand::<impl kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx>::codegen_alloc_pointer::ha18c90c70db41e67
  23:     0x5619254f343e - kani_compiler::codegen_cprover_gotoc::codegen::operand::<impl kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx>::codegen_allocation_data::hb59fa9ade7d4bb1f
  24:     0x5619254f22ff - kani_compiler::codegen_cprover_gotoc::codegen::operand::<impl kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx>::codegen_alloc_in_memory::he849ad2b22bf09d0
  25:     0x561925526001 - kani_compiler::codegen_cprover_gotoc::utils::debug::<impl kani_compiler::codegen_cprover_gotoc::context::goto_ctx::GotocCtx>::call_with_panic_debug_info::h558cbe68fee5d6f7
  26:     0x56192555b1ec - kani_compiler::codegen_cprover_gotoc::compiler_interface::GotocCodegenBackend::codegen_items::hc367daaf74d3c1cb
  27:     0x56192555fcf5 - <kani_compiler::codegen_cprover_gotoc::compiler_interface::GotocCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate::h2ef5769ca04f3bc4
  28:     0x7f4526380fd9 - rustc_interface[90d65b0f51490bf6]::passes::start_codegen
  29:     0x7f4526380a96 - <rustc_interface[90d65b0f51490bf6]::queries::Queries>::ongoing_codegen
  30:     0x7f4526343693 - std[d7fc13cc5242579e]::sys_common::backtrace::__rust_begin_short_backtrace::<rustc_interface[90d65b0f51490bf6]::util::run_in_thread_with_globals<rustc_interface[90d65b0f51490bf6]::interface::run_compiler<core[53bdee0566a68c19]::result::Result<(), rustc_span[88faddf4715d2d43]::ErrorGuaranteed>, rustc_driver_impl[88c66c37425cba72]::run_compiler::{closure#1}>::{closure#0}, core[53bdee0566a68c19]::result::Result<(), rustc_span[88faddf4715d2d43]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[53bdee0566a68c19]::result::Result<(), rustc_span[88faddf4715d2d43]::ErrorGuaranteed>>
  31:     0x7f4526342909 - <<std[d7fc13cc5242579e]::thread::Builder>::spawn_unchecked_<rustc_interface[90d65b0f51490bf6]::util::run_in_thread_with_globals<rustc_interface[90d65b0f51490bf6]::interface::run_compiler<core[53bdee0566a68c19]::result::Result<(), rustc_span[88faddf4715d2d43]::ErrorGuaranteed>, rustc_driver_impl[88c66c37425cba72]::run_compiler::{closure#1}>::{closure#0}, core[53bdee0566a68c19]::result::Result<(), rustc_span[88faddf4715d2d43]::ErrorGuaranteed>>::{closure#0}::{closure#0}, core[53bdee0566a68c19]::result::Result<(), rustc_span[88faddf4715d2d43]::ErrorGuaranteed>>::{closure#1} as core[53bdee0566a68c19]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  32:     0x7f4521977c85 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::he310d06a8f297797
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/alloc/src/boxed.rs:2007:9
  33:     0x7f4521977c85 - <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once::h69350f715ad37c20
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/alloc/src/boxed.rs:2007:9
  34:     0x7f4521977c85 - std::sys::unix::thread::Thread::new::thread_start::h7310dea1d780d6a0
                               at /rustc/31bc7e2c47e82798a392c770611975a6883132c8/library/std/src/sys/unix/thread.rs:108:17
  35:     0x7f452161f9eb - <unknown>
  36:     0x7f45216a37cc - <unknown>
  37:                0x0 - <unknown>

Kani unexpectedly panicked during compilation.
Please file an issue here: https://github.com/model-checking/kani/issues/new?labels=bug&template=bug_report.md

[Kani] current codegen item: codegen_static: DefId(0:4 ~ a[7ac1]::CLOSURES)
[Kani] current codegen location: Loc { file: "/tmp/icemaker/a.rs", function: None, start_line: 2, start_col: Some(1), end_line: 2, end_col: Some(41) }
error: /home/matthias/.kani/kani-0.40.0/bin/kani-compiler exited with status exit status: 101

Triaged against main (de756c9, nightly-2026-09-23, Kani 0.68.0). kani code.rs → Complete - 1 successfully verified harnesses, 0 failures, 1 total. (the caller_location and rust_begin_unwind unsupported checks in the results are unreachable, hence the pass.)

Closing as no longer reproducible — please reopen if you can still hit it on main.

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ICE: `Tried to insert symbol which already existed` #2238

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ICE: Tried to insert symbol which already existed #2238

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matthiaskrgr commented on Nov 12, 2023

feliperodri commented on Sep 25, 2026

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ICE: `Tried to insert symbol which already existed` #2238