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Preserve raw strs for: format!(s) to s.to_string() lint
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Ie:
|     let s = format!(r#""hello""#);
|             ^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `r#""hello""#.to_string()`
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bofh69 committed Oct 9, 2020
1 parent fcf22d9 commit 7b7ddfa
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Showing 3 changed files with 15 additions and 4 deletions.
8 changes: 6 additions & 2 deletions clippy_lints/src/format.rs
Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
use crate::utils::paths;
use crate::utils::{
is_expn_of, is_type_diagnostic_item, last_path_segment, match_def_path, match_function_call, snippet,
is_expn_of, is_type_diagnostic_item, last_path_segment, match_def_path, match_function_call, snippet, snippet_opt,
span_lint_and_then,
};
use if_chain::if_chain;
Expand Down Expand Up @@ -132,7 +132,11 @@ fn on_new_v1<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<Strin
then {
// `format!("foo")` expansion contains `match () { () => [], }`
if tup.is_empty() {
return Some(format!("{:?}.to_string()", s.as_str()));
if let Some(s_src) = snippet_opt(cx, lit.span) {
// Simulate macro expansion, converting {{ and }} to { and }.
let s_expand = s_src.replace("{{", "{").replace("}}", "}");
return Some(format!("{}.to_string()", s_expand))
}
} else if s.as_str().is_empty() {
return on_argumentv1_new(cx, &tup[0], arms);
}
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3 changes: 2 additions & 1 deletion tests/ui/format.fixed
Original file line number Diff line number Diff line change
Expand Up @@ -13,7 +13,8 @@ fn main() {
"foo".to_string();
"{}".to_string();
"{} abc {}".to_string();
"foo {}\n\" bar".to_string();
r##"foo {}
" bar"##.to_string();

"foo".to_string();
format!("{:?}", "foo"); // Don't warn about `Debug`.
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8 changes: 7 additions & 1 deletion tests/ui/format.stderr
Original file line number Diff line number Diff line change
Expand Up @@ -25,7 +25,13 @@ LL | / format!(
LL | | r##"foo {{}}
LL | | " bar"##
LL | | );
| |______^ help: consider using `.to_string()`: `"foo {}/n/" bar".to_string();`
| |______^
|
help: consider using `.to_string()`
|
LL | r##"foo {}
LL | " bar"##.to_string();
|

error: useless use of `format!`
--> $DIR/format.rs:21:5
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