Overzealous `uninlined_format_args`

[sebschmi]

Description

Consider this snippet from a match statement:

Self::TemplateSwitchExit {
    entrance_reference_index,
    entrance_query_index,
    template_switch_primary,
    template_switch_secondary,
    primary_index,
    anti_primary_gap,
} => write!(
    f,
    "TemplateSwitchExit({}R, {}Q, {}P, {}G, {}, {})",
    entrance_reference_index,
    entrance_query_index,
    primary_index,
    anti_primary_gap,
    template_switch_primary,
    template_switch_secondary
),

Clippy wants me to put all format args into the string, but that would make the string incredibly long. cargo fmt would not break up the string into multiple lines either.

I think the code is easier to read like this. Clippy should not suggest inlining format args if the resulting string gets too long.

Version

rustc 1.88.0-nightly (df35ff6c3 2025-04-23)
binary: rustc
commit-hash: df35ff6c354f1f1fbf430b84e7dea37dfe997f34
commit-date: 2025-04-23
host: x86_64-unknown-linux-gnu
release: 1.88.0-nightly
LLVM version: 20.1.2

Additional Labels

No response

[Jarcho]

You can manually split the string across lines. e.g.

"TemplateSwitchExit(\
    {entrance_reference_index}R, \
    {entrance_query_index}Q, \
    {primary_index}P, \
    {anti_primary_gap}G, \
    {template_switch_primary}, \
    {template_switch_secondary})",

I wouldn't say it's any better this way, but it's an option.

[sebschmi]

Thanks for the response. That is true. However, I think that multiline strings in Rust are a bit too magic, because they implicitly strip whitespace after escaped newlines. So I try to avoid them.

Hence, if uninlined_format_args becomes enabled by default, I would propose to restrict it to cases where the resulting string would not create an overly long line.