nargo crashes generating ACIR if SSA IDs are normalised

[aakoshh]

Aim

I was investigating #6520 and tried commenting out the printing of the SSA pass but leaving the call to ssa.normalize_ids(); in. Then I tried to compile fold_2_to_17 and saw the application crash in a different way, this time during ACIR gen.

Expected Behavior

With the printing commented out I expected the program to compile.

Bug

~/Work/aztec/noir/test_programs/execution_success/fold_2_to_17
❯ RUST_BACKTRACE=1 cargo run -q -p nargo_cli --  --program-dir . compile --show-ssa
warning: unused variable: `msg`
   --> compiler/noirc_evaluator/src/ssa.rs:441:24
    |
441 |     fn print(mut self, msg: &str) -> Self {
    |                        ^^^ help: if this is intentional, prefix it with an underscore: `_msg`
    |
    = note: `#[warn(unused_variables)]` on by default

The application panicked (crashed).
Message:  internal error: entered unreachable code: Expected an associated final index for call to acir function f1 with args [Id(0)]
Location: compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs:805

This is a bug. We may have already fixed this in newer versions of Nargo so try searching for similar issues at https://github.com/noir-lang/noir/issues/.
If there isn't an open issue for this bug, consider opening one at https://github.com/noir-lang/noir/issues/new?labels=bug&template=bug_report.yml

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                                ⋮ 13 frames hidden ⋮                              
  14: noirc_evaluator::ssa::acir_gen::Context::convert_ssa_call::hfd35c09554e8433a
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs:805
  15: noirc_evaluator::ssa::acir_gen::Context::convert_ssa_instruction::h4b2f3c2b8a885846
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs:717
  16: noirc_evaluator::ssa::acir_gen::Context::convert_acir_main::hef8c2c04c27b0b71
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs:436
  17: noirc_evaluator::ssa::acir_gen::Context::convert_ssa_function::hd80ddd3b0a145ae1
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs:392
  18: noirc_evaluator::ssa::acir_gen::<impl noirc_evaluator::ssa::ssa_gen::program::Ssa>::into_acir::h09067afd42cb908a
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_evaluator/src/ssa/acir_gen/mod.rs:303
  19: noirc_evaluator::ssa::optimize_into_acir::{{closure}}::h88300a1e6ec66447
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_evaluator/src/ssa.rs:148
  20: noirc_evaluator::ssa::time::hceddfb481aadb799
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_evaluator/src/ssa.rs:156
  21: noirc_evaluator::ssa::optimize_into_acir::h24c31af36eb31fe9
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_evaluator/src/ssa.rs:147
  22: noirc_evaluator::ssa::create_program::h64f2e22eabd71bdd
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_evaluator/src/ssa.rs:230
  23: noirc_driver::compile_no_check::ha6d81709b83a6d4f
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_driver/src/lib.rs:595
  24: noirc_driver::compile_main::h0ce627c503b459a8
      at /Users/aakoshh/Work/aztec/noir/compiler/noirc_driver/src/lib.rs:342
  25: nargo::ops::compile::compile_program_with_debug_instrumenter::hbf9b46a47d3e0908
      at /Users/aakoshh/Work/aztec/noir/tooling/nargo/src/ops/compile.rs:92
  26: nargo::ops::compile::compile_program::h8dd2615617770064
      at /Users/aakoshh/Work/aztec/noir/tooling/nargo/src/ops/compile.rs:67
  27: nargo::cli::compile_cmd::compile_programs::{{closure}}::h315d5e3fb51b7747
      at /Users/aakoshh/Work/aztec/noir/tooling/nargo_cli/src/cli/compile_cmd.rs:183
...                

To Reproduce

1. cd test_programs/execution_success/fold_2_to_17
2. Comment out println!("{msg}\n{}", self.ssa); in SsaBuilder::print.
3. cargo run -q -p nargo_cli -- --program-dir . compile --show-ssa

Workaround

None

Workaround Description

No response

Additional Context

No response

Project Impact

None

Blocker Context

No response

Nargo Version

nargo version = 0.38.0 noirc version = 0.38.0+efd763cb77b3709948ef54ae534cbc3f1a8de0e9 (git version hash: a42c643, is dirty: true)

NoirJS Version

No response

Proving Backend Tooling & Version

No response

Would you like to submit a PR for this Issue?

None

Support Needs

No response