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#3016 Add feedback and implement test for fixed hardcoded suggestion

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This commit is contained in:
Lachezar Lechev 2018-08-20 15:33:43 +02:00
parent 3015987f27
commit c292b80783
3 changed files with 26 additions and 17 deletions
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26
clippy_lints/src/write.rs
View File

@ -3,6 +3,7 @@ use rustc::{declare_lint, lint_array};
use syntax::ast::*;
use syntax::tokenstream::{ThinTokenStream, TokenStream};
use syntax::parse::{token, parser};
use std::borrow::Cow;
use crate::utils::{span_lint, span_lint_and_sugg, snippet};
/// **What it does:** This lint warns when you use `println!("")` to
@ -212,7 +213,7 @@ impl EarlyLintPass for Pass {
let check_tts = check_tts(cx, &mac.node.tts, true);
if let Some(fmtstr) = check_tts.0 {
if fmtstr == "" {
let suggestion = check_tts.1.map_or("v", |expr| snippet(cx, expr.span, "v").into_owned().as_str());
let suggestion = check_tts.1.map_or(Cow::Borrowed("v"), |expr| snippet(cx, expr.span, "v"));
span_lint_and_sugg(
cx,
@ -220,7 +221,7 @@ impl EarlyLintPass for Pass {
mac.span,
format!("using writeln!({}, \"\")", suggestion).as_str(),
"replace it with",
format!("writeln!({})", "v"),
format!("writeln!({})", suggestion),
);
}
}
@ -239,20 +240,19 @@ fn check_tts<'a>(cx: &EarlyContext<'a>, tts: &ThinTokenStream, is_write: bool) -
);
let mut expr: Option<Expr> = None;
if is_write {
// skip the initial write target
expr = match parser.parse_expr().map_err(|mut err| err.cancel()).ok() {
Some(p) => Some(p.and_then(|expr| expr)),
None => return (None, None),
expr = match parser.parse_expr().map_err(|mut err| err.cancel()) {
Ok(p) => Some(p.into_inner()),
Err(_) => return (None, None),
};
// might be `writeln!(foo)`
if let None = parser.expect(&token::Comma).map_err(|mut err| err.cancel()).ok() {
if parser.expect(&token::Comma).map_err(|mut err| err.cancel()).is_err() {
return (None, expr);
}
}
let fmtstr = match parser.parse_str().map_err(|mut err| err.cancel()).ok() {
Some(token) => token.0.to_string(),
None => return (None, expr),
let fmtstr = match parser.parse_str().map_err(|mut err| err.cancel()) {
Ok(token) => token.0.to_string(),
Err(_) => return (None, expr),
};
use fmt_macros::*;
let tmp = fmtstr.clone();
@ -281,9 +281,9 @@ fn check_tts<'a>(cx: &EarlyContext<'a>, tts: &ThinTokenStream, is_write: bool) -
assert!(parser.eat(&token::Eof));
return (Some(fmtstr), expr);
}
let token_expr = match parser.parse_expr().map_err(|mut err| err.cancel()).ok() {
Some(expr) => expr,
None => return (Some(fmtstr), None),
let token_expr = match parser.parse_expr().map_err(|mut err| err.cancel()) {
Ok(expr) => expr,
Err(_) => return (Some(fmtstr), None),
};
const SIMPLE: FormatSpec<'_> = FormatSpec {
fill: None,

5
tests/ui/writeln_empty_string.rs
View File

@ -5,9 +5,12 @@ use std::io::Write;
fn main() {
let mut v = Vec::new();
// This should fail
// These should fail
writeln!(&mut v, "");
let mut suggestion = Vec::new();
writeln!(&mut suggestion, "");
// These should be fine
writeln!(&mut v);
writeln!(&mut v, " ");

12
tests/ui/writeln_empty_string.stderr
View File

@ -1,10 +1,16 @@
error: using `writeln!(v, "")`
error: using writeln!(&mut v, "")
--> $DIR/writeln_empty_string.rs:9:5
|
9 | writeln!(&mut v, "");
| ^^^^^^^^^^^^^^^^^^^^ help: replace it with: `writeln!(v)`
| ^^^^^^^^^^^^^^^^^^^^ help: replace it with: `writeln!(&mut v)`
|
= note: `-D writeln-empty-string` implied by `-D warnings`
error: aborting due to previous error
error: using writeln!(&mut suggestion, "")
--> $DIR/writeln_empty_string.rs:12:5
|
12 | writeln!(&mut suggestion, "");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: replace it with: `writeln!(&mut suggestion)`
error: aborting due to 2 previous errors