[BUG] Mojo crashes when attempting run str() during compilation.

[thatstoasty]

Bug description

Running str() within in an alias causes the compiler to crash. I think we should be able to convert Stringables to String during compilation unless I'm missing something. Thanks!

Steps to reproduce

• Include relevant code snippet or link to code that did not work as expected.
• If applicable, add screenshots to help explain the problem.
• If using the Playground, name the pre-existing notebook that failed and the steps that led to failure.
• Include anything else that might help us debug the issue.

Minimal example to reproduce the error:

fn main() -> None:
    alias s = str(1)

System information

- What OS did you do install Mojo on ? MacOS 14.4.1
- Provide version information for Mojo by pasting the output of `mojo -v` mojo 2024.5.2012 (fb60fe4f)
- Provide Modular CLI version by pasting the output of `modular -v` modular 0.7.1 (28ddab26)

[JoeLoser]

FYI @laszlokindrat as we were talking about this last week if I recall correctly.

[laszlokindrat]

@thatstoasty Thanks for opening the ticket! Can you please provide the error message or trace you are getting?

[thatstoasty]

@laszlokindrat Sure! Here's the trace

/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/_startup.mojo:136:4: error: function instantiation failed
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/_startup.mojo:136:4: note:   call expansion failed - no concrete specializations
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/_startup.mojo:67:4: note:     function instantiation failed
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/_startup.mojo:82:14: note:       call expansion failed - no concrete specializations
/Users/mikhailtavarez/Git/mojo/mist/test.mojo:1:4: note:         function instantiation failed
fn main() -> None:
   ^
/Users/mikhailtavarez/Git/mojo/mist/test.mojo:2:5: note:           failed to evaluate 'apply'
    alias s = str(1)
    ^
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/str.mojo:134:4: note:             failed to interpret function @stdlib::builtin::str::str[stdlib::builtin::str::Stringable]($0),T=[index, {"__str__" : (!kgen.pointer<index> borrow_in_mem, !kgen.pointer<struct<(struct<(pointer<none>, index, index) memoryOnly>) memoryOnly>> byref_result) -> !kgen.none = @"stdlib::builtin::int::Int::__str__(stdlib::builtin::int::Int)_thunk", "__del__" : (!kgen.pointer<index> owned_in_mem) -> !kgen.none = @"stdlib::builtin::int::Int::__del__(stdlib::builtin::int::Int)_thunk"}]
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/str.mojo:146:25: note:               failed to evaluate call
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/int.mojo:241:8: note:                 failed to interpret function @stdlib::builtin::int::Int::__str__(stdlib::builtin::int::Int)_thunk
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/int.mojo:241:8: note:                   error recurses 1 times:
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/int.mojo:241:8: note:                     failed to evaluate call
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/int.mojo:351:8: note:                       failed to interpret function @stdlib::builtin::int::Int::__str__(stdlib::builtin::int::Int)
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/int.mojo:358:38: note:                         failed to evaluate call
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/string.mojo:1108:8: note:                           failed to interpret function @stdlib::builtin::string::String::format_sequence[*stdlib::utils::_format::Formattable](*$0),Ts=[[index, {"format_to" : (!kgen.pointer<index> borrow_in_mem, !kgen.pointer<struct<((!kgen.pointer<none> borrow, !kgen.struct<(pointer<none>, index)> borrow) -> !kgen.none, pointer<none>) memoryOnly>> byref) -> !kgen.none = @"stdlib::builtin::int::Int::format_to(stdlib::builtin::int::Int,stdlib::utils::_format::Formatter&)_thunk", "__del__" : (!kgen.pointer<index> owned_in_mem) -> !kgen.none = @"stdlib::builtin::int::Int::__del__(stdlib::builtin::int::Int)_thunk"}]]
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/string.mojo:1130:29: note:                             failed to evaluate call
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/builtin_list.mojo:635:8: note:                               failed to interpret function @stdlib::builtin::builtin_list::VariadicPack::each[fn[$2]($0, /) capturing -> None](stdlib::builtin::builtin_list::VariadicPack[$0, $1, $2, $3]),elt_is_mutable=0,lifetime={  },element_trait=type,element_types=[[index, {"format_to" : (!kgen.pointer<index> borrow_in_mem, !kgen.pointer<struct<((!kgen.pointer<none> borrow, !kgen.struct<(pointer<none>, index)> borrow) -> !kgen.none, pointer<none>) memoryOnly>> byref) -> !kgen.none = @"stdlib::builtin::int::Int::format_to(stdlib::builtin::int::Int,stdlib::utils::_format::Formatter&)_thunk", "__del__" : (!kgen.pointer<index> owned_in_mem) -> !kgen.none = @"stdlib::builtin::int::Int::__del__(stdlib::builtin::int::Int)_thunk"}]],func=@"stdlib::builtin::string::String::format_sequence[*stdlib::utils::_format::Formattable](*$0)_write_arg[stdlib::utils::_format::Formattable]($0)"
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/builtin_list.mojo:649:41: note:                                 failed to evaluate call
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/utils/loop.mojo:30:4: note:                                   failed to interpret function @stdlib::utils::loop::unroll[fn[stdlib::builtin::int::Int]() capturing -> None,stdlib::builtin::int::Int](),func=@"stdlib::builtin::builtin_list::VariadicPack::each[fn[$2]($0, /) capturing -> None](stdlib::builtin::builtin_list::VariadicPack[$0, $1, $2, $3])_unrolled[stdlib::builtin::int::Int]()"<:type type, :variadic<type> [[index, {"format_to" : (!kgen.pointer<index> borrow_in_mem, !kgen.pointer<struct<((!kgen.pointer<none> borrow, !kgen.struct<(pointer<none>, index)> borrow) -> !kgen.none, pointer<none>) memoryOnly>> byref) -> !kgen.none = @"stdlib::builtin::int::Int::format_to(stdlib::builtin::int::Int,stdlib::utils::_format::Formatter&)_thunk", "__del__" : (!kgen.pointer<index> owned_in_mem) -> !kgen.none = @"stdlib::builtin::int::Int::__del__(stdlib::builtin::int::Int)_thunk"}]], :<type>(!kgen.pointer<*(0,0)> borrow_in_mem) capturing -> !kgen.none @"stdlib::builtin::string::String::format_sequence[*stdlib::utils::_format::Formattable](*$0)_write_arg[stdlib::utils::_format::Formattable]($0)", ?>,count=1
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/utils/loop.mojo:44:16: note:                                     failed to evaluate call
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/builtin_list.mojo:646:12: note:                                       failed to interpret function @stdlib::builtin::builtin_list::VariadicPack::each[fn[$2]($0, /) capturing -> None](stdlib::builtin::builtin_list::VariadicPack[$0, $1, $2, $3])_unrolled[stdlib::builtin::int::Int](),element_trait=type,element_types=[[index, {"format_to" : (!kgen.pointer<index> borrow_in_mem, !kgen.pointer<struct<((!kgen.pointer<none> borrow, !kgen.struct<(pointer<none>, index)> borrow) -> !kgen.none, pointer<none>) memoryOnly>> byref) -> !kgen.none = @"stdlib::builtin::int::Int::format_to(stdlib::builtin::int::Int,stdlib::utils::_format::Formatter&)_thunk", "__del__" : (!kgen.pointer<index> owned_in_mem) -> !kgen.none = @"stdlib::builtin::int::Int::__del__(stdlib::builtin::int::Int)_thunk"}]],func=@"stdlib::builtin::string::String::format_sequence[*stdlib::utils::_format::Formattable](*$0)_write_arg[stdlib::utils::_format::Formattable]($0)",i=0
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/builtin_list.mojo:647:17: note:                                         failed to evaluate call
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/string.mojo:1127:12: note:                                           failed to interpret function @stdlib::builtin::string::String::format_sequence[*stdlib::utils::_format::Formattable](*$0)_write_arg[stdlib::utils::_format::Formattable]($0),T=[index, {"format_to" : (!kgen.pointer<index> borrow_in_mem, !kgen.pointer<struct<((!kgen.pointer<none> borrow, !kgen.struct<(pointer<none>, index)> borrow) -> !kgen.none, pointer<none>) memoryOnly>> byref) -> !kgen.none = @"stdlib::builtin::int::Int::format_to(stdlib::builtin::int::Int,stdlib::utils::_format::Formatter&)_thunk", "__del__" : (!kgen.pointer<index> owned_in_mem) -> !kgen.none = @"stdlib::builtin::int::Int::__del__(stdlib::builtin::int::Int)_thunk"}]
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/string.mojo:1128:26: note:                                             failed to evaluate call
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/int.mojo:241:8: note:                                               failed to interpret function @stdlib::builtin::int::Int::format_to(stdlib::builtin::int::Int,stdlib::utils::_format::Formatter&)_thunk
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/int.mojo:241:8: note:                   remaining errors after:
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/int.mojo:241:8: note:                     failed to evaluate call
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/int.mojo:360:8: note:                       failed to interpret function @stdlib::builtin::int::Int::format_to(stdlib::builtin::int::Int,stdlib::utils::_format::Formatter&)
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/int.mojo:383:32: note:                         failed to evaluate call
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/io.mojo:136:4: note:                           failed to interpret function @stdlib::builtin::io::_snprintf[*stdlib::builtin::anytype::AnyType](stdlib::memory::unsafe_pointer::UnsafePointer[stdlib::builtin::simd::SIMD[{uint8}, {1}], {{0}}],stdlib::builtin::int::Int,stdlib::builtin::string_literal::StringLiteral,*$0),types=[[index, {"__del__" : (!kgen.pointer<index> owned_in_mem) -> !kgen.none = @"stdlib::builtin::_stubs::__MLIRType::__del__(stdlib::builtin::_stubs::__MLIRType[$0])_thunk"<:type index>}]]
/Users/ec2-user/actions-runner/_work/modular/modular/Kernels/mojo/stdlib/builtin/io.mojo:162:49: note:                             failed to fold operation kgen.pack.load(#kgen.pack<2000000136> : !kgen.pack<[pointer<index>]>)
mojo: error: failed to run the pass manager

[laszlokindrat]

@Mogball is this a potential issue with variadic packs in the compiler?

[zyx-billy]

After fixing the issue with packs, evaluation still fails due to a dependency on an external call to snprintf in stdlib for formatting ints. So unfortunately this is not something that can be supported at compile-time unless the implementation no longer depends on the external call. Thanks for filing the issue though, it helped plug a hole with interpreting packs.

[thatstoasty]

No problem, my use case will be covered once #1573 is resolved!