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Don't fail for raw string ending in \n

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Pass tests for #3778, {print,write}_with_newline false positive

This change guards the lint from checking newlines with a sort of complicated
check to see if it's a raw string. Raw strings shouldn't be newline-checked,
since r"\n" is literally \-n, not a newline. I think it's ok not to check for
_literal_ newlines at the end of raw strings, but maybe that's debatable.

I... don't think this code is that great. I wanted to write the check after
`check_tts`, but that was too late -- raw string type info is lost (or I
couldn't find it). Putting it inside `check_tts` feels heavy-duty and the check
itself feels like a brittle reach possibly into places it shouldn't.

Maybe someone can fix this up :)
This commit is contained in:
phil 2019-02-18 00:53:30 -05:00
parent cf5d4a1b45
commit 3fa3bd8e94
1 changed files with 31 additions and 15 deletions
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46
clippy_lints/src/write.rs
View File

@ -5,7 +5,7 @@ use rustc_errors::Applicability;
use std::borrow::Cow;
use syntax::ast::*;
use syntax::parse::{parser, token};
use syntax::tokenstream::TokenStream;
use syntax::tokenstream::{TokenStream, TokenTree};
/// **What it does:** This lint warns when you use `println!("")` to
/// print a newline.
@ -200,8 +200,8 @@ impl EarlyLintPass for Pass {
}
} else if mac.node.path == "print" {
span_lint(cx, PRINT_STDOUT, mac.span, "use of `print!`");
if let Some(fmtstr) = check_tts(cx, &mac.node.tts, false).0 {
if check_newlines(&fmtstr) {
if let (Some(fmtstr), _, is_raw) = check_tts(cx, &mac.node.tts, false) {
if !is_raw && check_newlines(&fmtstr) {
span_lint(
cx,
PRINT_WITH_NEWLINE,
@ -212,8 +212,8 @@ impl EarlyLintPass for Pass {
}
}
} else if mac.node.path == "write" {
if let Some(fmtstr) = check_tts(cx, &mac.node.tts, true).0 {
if check_newlines(&fmtstr) {
if let (Some(fmtstr), _, is_raw) = check_tts(cx, &mac.node.tts, true) {
if !is_raw && check_newlines(&fmtstr) {
span_lint(
cx,
WRITE_WITH_NEWLINE,
@ -252,8 +252,9 @@ impl EarlyLintPass for Pass {
}
/// Checks the arguments of `print[ln]!` and `write[ln]!` calls. It will return a tuple of two
/// options. The first part of the tuple is `format_str` of the macros. The second part of the tuple
/// is in the `write[ln]!` case the expression the `format_str` should be written to.
/// options and a bool. The first part of the tuple is `format_str` of the macros. The second part
/// of the tuple is in the `write[ln]!` case the expression the `format_str` should be written to.
/// The final part is a boolean flag indicating if the string is a raw string.
///
/// Example:
///
@ -263,34 +264,49 @@ impl EarlyLintPass for Pass {
/// ```
/// will return
/// ```rust,ignore
/// (Some("string to write: {}"), Some(buf))
/// (Some("string to write: {}"), Some(buf), false)
/// ```
fn check_tts<'a>(cx: &EarlyContext<'a>, tts: &TokenStream, is_write: bool) -> (Option<String>, Option<Expr>) {
fn check_tts<'a>(cx: &EarlyContext<'a>, tts: &TokenStream, is_write: bool) -> (Option<String>, Option<Expr>, bool) {
use fmt_macros::*;
let tts = tts.clone();
let mut is_raw = false;
if let TokenStream(Some(tokens)) = &tts {
for token in tokens.iter() {
if let (TokenTree::Token(_, token::Token::Literal(lit, _)), _) = token {
match lit {
token::Lit::Str_(_) => break,
token::Lit::StrRaw(_, _) => {
is_raw = true;
break;
},
_ => {},
}
}
}
}
let mut parser = parser::Parser::new(&cx.sess.parse_sess, tts, None, false, false);
let mut expr: Option<Expr> = None;
if is_write {
expr = match parser.parse_expr().map_err(|mut err| err.cancel()) {
Ok(p) => Some(p.into_inner()),
Err(_) => return (None, None),
Err(_) => return (None, None, is_raw),
};
// might be `writeln!(foo)`
if parser.expect(&token::Comma).map_err(|mut err| err.cancel()).is_err() {
return (None, expr);
return (None, expr, is_raw);
}
}
let fmtstr = match parser.parse_str().map_err(|mut err| err.cancel()) {
Ok(token) => token.0.to_string(),
Err(_) => return (None, expr),
Err(_) => return (None, expr, is_raw),
};
let tmp = fmtstr.clone();
let mut args = vec![];
let mut fmt_parser = Parser::new(&tmp, None, Vec::new(), false);
while let Some(piece) = fmt_parser.next() {
if !fmt_parser.errors.is_empty() {
return (None, expr);
return (None, expr, is_raw);
}
if let Piece::NextArgument(arg) = piece {
if arg.format.ty == "?" {
@ -312,11 +328,11 @@ fn check_tts<'a>(cx: &EarlyContext<'a>, tts: &TokenStream, is_write: bool) -> (O
ty: "",
};
if !parser.eat(&token::Comma) {
return (Some(fmtstr), expr);
return (Some(fmtstr), expr, is_raw);
}
let token_expr = match parser.parse_expr().map_err(|mut err| err.cancel()) {
Ok(expr) => expr,
Err(_) => return (Some(fmtstr), None),
Err(_) => return (Some(fmtstr), None, is_raw),
};
match &token_expr.node {
ExprKind::Lit(_) => {