Hard-to-read ICEs when fluent translation uses non-existing variable

[RalfJung]

When I screw up the variable names in a messages.flt file, I am getting the following error:

thread 'rustc' panicked at compiler/rustc_errors/src/json.rs:412:56:
called `Result::unwrap()` on an `Err` value: Two { primary: One { id: "const_eval_pointer_out_of_bounds", args: FluentArgs([("alloc_size", Number(FluentNumber { value: 4.0, options: FluentNumberOptions { style: Decimal, currency: None, currency_display: Symbol, use_grouping: true, minimum_integer_digits: None, minimum_fraction_digits: None, maximum_fraction_digits: None, minimum_significant_digits: None, maximum_significant_digits: None } })), ("alloc_size_minus_ptr_offset", Number(FluentNumber { value: 4.0, options: FluentNumberOptions { style: Decimal, currency: None, currency_display: Symbol, use_grouping: true, minimum_integer_digits: None, minimum_fraction_digits: None, maximum_fraction_digits: None, minimum_significant_digits: None, maximum_significant_digits: None } })), ("bad_pointer_message", String("out-of-bounds `offset_from`")), ("error_kind", String("const")), ("inbounds_size_abs", Number(FluentNumber { value: 10.0, options: FluentNumberOptions { style: Decimal, currency: None, currency_display: Symbol, use_grouping: true, minimum_integer_digits: None, minimum_fraction_digits: None, maximum_fraction_digits: None, minimum_significant_digits: None, maximum_significant_digits: None } })), ("inbounds_size_is_neg", String("false")), ("instance", String("")), ("pointer", String("alloc30")), ("ptr_offset_is_neg", String("false"))]), kind: PrimaryBundleMissing }, fallback: One { id: "const_eval_pointer_out_of_bounds", args: FluentArgs([("alloc_size", Number(FluentNumber { value: 4.0, options: FluentNumberOptions { style: Decimal, currency: None, currency_display: Symbol, use_grouping: true, minimum_integer_digits: None, minimum_fraction_digits: None, maximum_fraction_digits: None, minimum_significant_digits: None, maximum_significant_digits: None } })), ("alloc_size_minus_ptr_offset", Number(FluentNumber { value: 4.0, options: FluentNumberOptions { style: Decimal, currency: None, currency_display: Symbol, use_grouping: true, minimum_integer_digits: None, minimum_fraction_digits: None, maximum_fraction_digits: None, minimum_significant_digits: None, maximum_significant_digits: None } })), ("bad_pointer_message", String("out-of-bounds `offset_from`")), ("error_kind", String("const")), ("inbounds_size_abs", Number(FluentNumber { value: 10.0, options: FluentNumberOptions { style: Decimal, currency: None, currency_display: Symbol, use_grouping: true, minimum_integer_digits: None, minimum_fraction_digits: None, maximum_fraction_digits: None, minimum_significant_digits: None, maximum_significant_digits: None } })), ("inbounds_size_is_neg", String("false")), ("instance", String("")), ("pointer", String("alloc30")), ("ptr_offset_is_neg", String("false"))]), kind: Fluent { errs: [ResolverError(Reference(Variable { id: "pointer_xx" }))] } } }

Needless to say, this is not exactly a pleasant debugging experience. Would be nice to get a clear message saying what went wrong. :)

In this case, the string const_eval_pointer_out_of_bounds referenced $pointer_xx which does not exist.

[veera-sivarajan]

@rustbot label -needs-triage +C-enhancement +T-compiler +A-translation +D-diagnostic-infra

[workingjubilee]

...Honestly I feel like this should not even ICE.

[chenyukang]

cc #101109
I think #101109 was partially solved.

[chenyukang]

...Honestly I feel like this should not even ICE.

as we discussed, seems we need static analysis in tidy.
#101109 (comment)

[RalfJung]

Also note that the code that caused the ICE for me doesn't even use diagnostic types, it passes arguments to fluent manually. Even the suggested static analysis would not catch that.