[Bug] `juliac.jl --trim` removes essential standard I/O functions in 1.12-beta3, causing compilation failure

[draftman9]

• Julia Version: 1.12.0-beta3+0.x64.linux.gnu (installed by juliaup)
• OS/Architecture: Linux x86_64, Ubuntu 22.04

Description

When attempting to compile a simple Julia script that uses basic standard input (readline) and output (println) into a standalone executable using juliac.jl --experimental --trim in Julia 1.12.0-beta3, the compilation fails with "Verifier error: unresolved call" messages.

Compiling without --trim succeeds, but the resulting executable fails at runtime with an ArgumentError related to the TTY not being initialized.

Steps to Reproduce

Save the following code as TestInput.jl:

```julia
module TestInput

using Printf

Base.@ccallable function main()::Cint
    println("Input an integer: ")
    num = readline(Base.stdin)
    println("The number is: ", parse(Int, num))
    return 0
end

end
```

With --trim

Attempt to compile the code using juliac.jl with the --trim flag:

julia +1.12.0-beta3 /path/juliaup/julia-1.12.0-beta3+0.x64.linux.gnu/share/julia/juliac.jl --output-exe TestInput-trimmed --experimental --trim TestInput.jl

Replace /path/ with the actual path to your Julia installation

The compilation fails and the full output is provided below:

Verifier error #1: unresolved call from statement TestInput.readline(Base.getglobal(TestInput.Base, :stdin)::IO)::String
Stacktrace:
 [1] main()
   @ TestInput /media/Big/test/compile-trim-beta3/TestInput.jl:7

Verifier error #2: unresolved call from statement Base.print(Base.stdout::IO, x1::String, x2::Int64, "\n")::Nothing
Stacktrace:
 [1] println(x1::String, x2::Int64)
   @ Base coreio.jl:6
 [2] main()
   @ TestInput /media/Big/test/compile-trim-beta3/TestInput.jl:8

Verifier error #3: unresolved call from statement Base.print(Base.stdout::IO, x::Any, "\n")::Nothing
Stacktrace:
 [1] println(x::String)
   @ Base coreio.jl:5
 [2] main()
   @ TestInput /media/Big/test/compile-trim-beta3/TestInput.jl:6

Verifier error #4: unresolved call from statement TestInput.readline(Base.getglobal(TestInput.Base, :stdin)::IO)::String
Stacktrace:
 [1] main()
   @ TestInput /media/Big/test/compile-trim-beta3/TestInput.jl:7

Verifier error #5: unresolved call from statement Base.print(Base.stdout::IO, x1::String, x2::Int64, "\n")::Nothing
Stacktrace:
 [1] println(x1::String, x2::Int64)
   @ Base coreio.jl:6
 [2] main()
   @ TestInput /media/Big/test/compile-trim-beta3/TestInput.jl:8

Verifier error #6: unresolved call from statement Base.print(Base.stdout::IO, x::Any, "\n")::Nothing
Stacktrace:
 [1] println(x::String)
   @ Base coreio.jl:5
 [2] main()
   @ TestInput /media/Big/test/compile-trim-beta3/TestInput.jl:6

Trim verify finished with 6 errors, 0 warnings.

Failed to compile TestInput.jl

Without --trim

For context, compiling without --trim succeeds:

julia +1.12.0-beta3 /path/juliaup/julia-1.12.0-beta3+0.x64.linux.gnu/share/julia/juliac.jl --output-exe TestInput --experimental TestInput.jl

However the resulting executable fails at runtime (run by execute ./TestInput) and the full output is provided below:

Input an integer: 
fatal: error thrown and no exception handler available.
ArgumentError(msg="TTY(RawFD(-1) invalid status, 0 bytes waiting) is not initialized")
isopen at ./stream.jl:381 [inlined]
#copyuntil#650 at ./stream.jl:1035
copyuntil at ./stream.jl:1029 [inlined]
#copyline#395 at ./iobuffer.jl:942
copyline at ./iobuffer.jl:918 [inlined]
#readline#355 at ./io.jl:619
readline at ./io.jl:619
unknown function (ip: 0x7f2f300f52b7) at (unknown file)
main at /media/Big/test/compile-trim-beta3/TestInput.jl:7
main at ./TestInput (unknown line)
unknown function (ip: 0x7f2f3fe29d8f) at /lib/x86_64-linux-gnu/libc.so.6
__libc_start_main at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
_start at ./TestInput (unknown line)

[JeffBezanson]

This is a known issue, due to the stdout and stdin variables being dynamically typed, as they can be redirected to different kinds of streams. The workaround is to use Core.stdout instead. We need documentation that lists items like this; generally applications will need a couple changes to be trimmable. The case without --trim is a bug we can fix.

[draftman9]

Following the helpful advice, I've modified the source code to explicitly use Core.stdin and Core.stdout.

The modified TestInput2.jl code is now:

module TestInput

using Printf

Base.@ccallable function main()::Cint
    println(Core.stdout, "Input an integer: ") # Explicitly use Core.stdout
    num = readline(Core.stdin) # Use Core.stdin
    println(Core.stdout, "The number is: ", parse(Int, num)) # Explicitly use Core.stdout
    return 0
end

end

With --trim

Then compile with --trim by

julia +1.12.0-beta3 /path/juliaup/julia-1.12.0-beta3+0.x64.linux.gnu/share/julia/juliac.jl --output-exe TestInput2-trimmed --experimental --trim TestInput2.jl

However it threw errors:

Verifier error #1: unresolved call from statement TestInput.readline(Base.getglobal(TestInput.Core, :stdin)::Any)::String
Stacktrace:
 [1] main()
   @ TestInput /media/Big/test/compile-trim-beta3/Input/TestInput2.jl:7

Verifier error #2: unresolved call from statement TestInput.readline(Base.getglobal(TestInput.Core, :stdin)::Any)::String
Stacktrace:
 [1] main()
   @ TestInput /media/Big/test/compile-trim-beta3/Input/TestInput2.jl:7

Trim verify finished with 2 errors, 0 warnings.

Failed to compile TestInput2.jl

Without --trim

Then compile without --trim by

julia +1.12.0-beta3 /path/juliaup/julia-1.12.0-beta3+0.x64.linux.gnu/share/julia/juliac.jl --output-exe TestInput2 --experimental TestInput2.jl

Here is the exact output from running the compiled executable (./TestInput2 in this case):

Input an integer: 
fatal: error thrown and no exception handler available.
UndefVarError(var=:stdin, world=0x000000000000968b, scope=Core)
ijl_undefined_var_error at /cache/build/tester-amdci5-10/julialang/julia-release-1-dot-12/src/rtutils.c:154
getproperty at ./Base_compiler.jl:47 [inlined]
main at /media/Big/test/compile-trim-beta3/Input/TestInput2.jl:7
main at ./TestInput2 (unknown line)
unknown function (ip: 0x7f97b7629d8f) at /lib/x86_64-linux-gnu/libc.so.6
__libc_start_main at /lib/x86_64-linux-gnu/libc.so.6 (unknown line)
_start at ./TestInput2 (unknown line)

Happy to provide any further debugging information or test cases.

[JeffBezanson]

The problem there is that Core.stdin does not exist 😆 I guess we should add it.

[KristofferC]

Ref #55482