[BUG] Cannot shadow variables which are already declared readonly

[karpfediem]

Describe the bug
The generated printf function tries create a local variable by the name "args". If this variable name was previously declared as readonly, bash exits with the error:

$ amber run name-collision.ab 
environment: line 9: args: readonly variable
environment: line 9: local: args: readonly variable
environment: line 10: args: readonly variable

amber 0.4.0-alpha
rev: d3ceda3

To Reproduce
File: name-collision.ab

import { echo_info } from "std/env"

main(args) {
echo_info("hi")
}

$ amber run name-collision.ab 
environment: line 9: args: readonly variable
environment: line 9: local: args: readonly variable
environment: line 10: args: readonly variable

Expected behavior
The scripts should not crash and be able to assign local variables.
We might need to use a prefix or generate variable names a user likely won't use in their own code. (Which would unfortunately make code more unreadable).

Additional context
Some discussions can be found here
https://lists.gnu.org/archive/html/bug-bash/2011-02/msg00105.html
and here
https://lists.gnu.org/archive/html/bug-bash/2019-03/msg00150.html

In the name-collision.ab example given in this issue, the variable args is already assigned as global read-only variable:

#!/usr/bin/env bash
# Written in [Amber](https://amber-lang.com/)
# version: 0.4.0-alpha
# date: 2025-01-15 17:04:11


printf__99_v0() {
    local format=$1
    local args=("${!2}")
     args=("${format}" "${args[@]}") ;
    __AS=$?
     printf "${args[@]}" ;
    __AS=$?
}
echo_info__106_v0() {
    local message=$1
    __AMBER_ARRAY_0=("${message}");
    printf__99_v0 "\x1b[1;3;97;44m%s\x1b[0m
" __AMBER_ARRAY_0[@];
    __AF_printf99_v0__147_5="$__AF_printf99_v0";
    echo "$__AF_printf99_v0__147_5" > /dev/null 2>&1
}
declare -r args=("$0" "$@")
    echo_info__106_v0 "hi";
    __AF_echo_info106_v0__4_1="$__AF_echo_info106_v0";
    echo "$__AF_echo_info106_v0__4_1" > /dev/null 2>&1

Relevant Parts:

declare -r args=("$0" "$@")

and later a reassignment even if shadowed is rejected:

    local args=("${!2}")

[Mte90]

So we need to improve this function code https://github.com/amber-lang/amber/blob/main/src/std/env.ab#L110

Maybe we can use a variable name less common like __args?

[hdwalters]

So we need to improve this function code https://github.com/amber-lang/amber/blob/main/src/std/env.ab#L110

Maybe we can use a variable name less common like __args?

That would only fix the problem in this instance. I think a better solution would be to name-mangle local as well as global variables, by using local __0_args instead of local args.

[hdwalters]

Specifically, we would need to change https://github.com/amber-lang/amber/blob/main/src/modules/variable/init.rs#L72, and other lines like it. This is one reason I've been wanting to centralise all Bash variable name generation, so we don't have to go searching for all instances... but that may be a larger task than is called for at this point.

[hdwalters]

Even better would be to just always assign a global ID. I'm trying a fix.

[hdwalters]

However, since this affects the translation layer, it would be sensible to wait until @Ph0enixKM has merged his forthcoming PR.