Nim/t24664.nim at araq-std-diff - Nim - Kyren's Code

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ringabout 1f07fdd2dc fixes #24664 ; always sets the \0 terminator in appendString (#24703 )

fixes #24664

```nim
proc main() = 
    for i in 0..1:
        var s = "12345"
        s.add s
        echo s

main()
```
In the given example, `add` contains two steps: `prepareAdd` and
`appendString`. In the first step, a new buffer is created in order to
store the final doubled string. But it doesn't copy the null terminator,
neither zeromem the left unused spaces. It causes a problem because
`appendString` will copy itself which doesn't end with `\0` properly so
contaminated memory is copied instead.

```
var s = 12345\0

prepareAdd:

var s = 12345xxxxx\0

appendString:

var s = 1234512345x
```

2025-02-19 23:01:56 +01:00

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 discard """
   output: '''
 TestString123TestString123
 TestString123TestString123
 '''
 """
 proc foostring() = # bug #24664
   for i in 0..1:
     var s = "TestString123"
     s.add s
     echo s
 foostring()