Out-of-bounds in strformat

[christoph-ehm]

The ampersand macro allows for an out-of-bounds-access of f at two places. This happens, when a single brace is not closed properly. With high probability, this is not noticed but there is little probability that no error message occurs.

Nim/lib/pure/strformat.nim

Line 307 in 5845716

if f[i] == ':':

I'm a very new learner of Nim so that I don't know the software quality standards for Nim's library code but I think the readability of this macro (and the other big thing in the file) is not good. The unfortunate combination of missing parentheses with 2-space indentation makes it hard for me to see the end of big blocks. It's low-level spaghetti code but could have historical reasons. Better variable names and outlining procedures could improve the readability.

[juancarlospaco]

2-space indentation makes it hard for me

😕

[abisxir]

I still face this issue in version 2.2.0:
Works:
let key = "LIGHTS[" & $(lightCount) & "].TYPE"
Fails:
let key = fmt"LIGHTS[{lightCount}].TYPE" # Same for &"LIGHTS[{lightCount}].TYPE"

[narimiran]

Please, show a full self-contained example of the code that fails, and what would be the expected behavior.
(You can follow all the things you have to fill out when you open a new bug report)