mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-09-20 22:51:58 +00:00
Keep track of spans in format strings
This commit is contained in:
Jason Newcomb
parent
5b3e61d62f
commit
4450c21f51
1 changed files with 148 additions and 90 deletions
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@ -2,9 +2,8 @@ use std::borrow::Cow;
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use std::ops::Range;
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use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg, span_lint_and_then};
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use clippy_utils::source::snippet_with_applicability;
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use if_chain::if_chain;
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use rustc_ast::ast::{Expr, ExprKind, ImplKind, Item, ItemKind, LitKind, MacCall, StrLit, StrStyle};
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use clippy_utils::source::{snippet_opt, snippet_with_applicability};
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use rustc_ast::ast::{Expr, ExprKind, ImplKind, Item, ItemKind, LitKind, MacCall, Path, StrLit, StrStyle};
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use rustc_ast::token;
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use rustc_ast::tokenstream::TokenStream;
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use rustc_errors::Applicability;
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@ -12,8 +11,9 @@ use rustc_lexer::unescape::{self, EscapeError};
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use rustc_lint::{EarlyContext, EarlyLintPass};
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use rustc_parse::parser;
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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use rustc_span::symbol::kw;
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use rustc_span::{sym, BytePos, Span};
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use rustc_span::symbol::{kw, Symbol};
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use rustc_span::{sym, BytePos, Span, DUMMY_SP};
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use smallvec::SmallVec;
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declare_clippy_lint! {
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/// **What it does:** This lint warns when you use `println!("")` to
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@ -354,7 +354,117 @@ fn newline_span(fmtstr: &StrLit) -> Span {
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sp.with_lo(newline_sp_hi - newline_sp_len).with_hi(newline_sp_hi)
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}
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/// Stores a list of replacement spans for each argument, but only if all the replacements used an
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/// empty format string.
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#[derive(Default)]
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struct SimpleFormatArgs {
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unnamed: Vec<SmallVec<[Span; 1]>>,
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named: Vec<(Symbol, SmallVec<[Span; 1]>)>,
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}
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impl SimpleFormatArgs {
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fn get_unnamed(&self) -> impl Iterator<Item = &[Span]> {
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self.unnamed.iter().map(|x| match x.as_slice() {
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// Ignore the dummy span added from out of order format arguments.
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[DUMMY_SP] => &[],
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x => x,
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})
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}
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fn get_named(&self, n: &Path) -> &[Span] {
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self.named.iter().find(|x| *n == x.0).map_or(&[], |x| x.1.as_slice())
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}
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fn push(&mut self, arg: rustc_parse_format::Argument<'_>, span: Span) {
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use rustc_parse_format::{
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AlignUnknown, ArgumentImplicitlyIs, ArgumentIs, ArgumentNamed, CountImplied, FormatSpec,
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};
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const SIMPLE: FormatSpec<'_> = FormatSpec {
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fill: None,
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align: AlignUnknown,
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flags: 0,
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precision: CountImplied,
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precision_span: None,
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width: CountImplied,
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width_span: None,
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ty: "",
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ty_span: None,
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};
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match arg.position {
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ArgumentIs(n) | ArgumentImplicitlyIs(n) => {
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if self.unnamed.len() <= n {
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// Use a dummy span to mark all unseen arguments.
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self.unnamed.resize_with(n, || SmallVec::from([DUMMY_SP]));
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if arg.format == SIMPLE {
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self.unnamed.push(SmallVec::from([span]));
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} else {
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self.unnamed.push(SmallVec::new());
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}
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} else {
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let args = &mut self.unnamed[n];
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match (args.as_mut_slice(), arg.format == SIMPLE) {
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// A non-empty format string has been seen already.
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([], _) => (),
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// Replace the dummy span, if it exists.
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([dummy @ DUMMY_SP], true) => *dummy = span,
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([_, ..], true) => args.push(span),
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([_, ..], false) => *args = SmallVec::new(),
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}
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}
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},
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ArgumentNamed(n) => {
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if let Some(x) = self.named.iter_mut().find(|x| x.0 == n) {
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match x.1.as_slice() {
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// A non-empty format string has been seen already.
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[] => (),
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[_, ..] if arg.format == SIMPLE => x.1.push(span),
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[_, ..] => x.1 = SmallVec::new(),
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}
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} else if arg.format == SIMPLE {
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self.named.push((n, SmallVec::from([span])));
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} else {
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self.named.push((n, SmallVec::new()));
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}
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},
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};
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}
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}
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impl Write {
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/// Parses a format string into a collection of spans for each argument. This only keeps track
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/// of empty format arguments. Will also lint usages of debug format strings outside of debug
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/// impls.
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fn parse_fmt_string(&self, cx: &EarlyContext<'_>, str: &StrLit) -> Option<SimpleFormatArgs> {
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use rustc_parse_format::{ParseMode, Parser, Piece};
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let str_sym = str.symbol.as_str();
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let style = match str.style {
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StrStyle::Cooked => None,
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StrStyle::Raw(n) => Some(n as usize),
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};
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let mut parser = Parser::new(&str_sym, style, snippet_opt(cx, str.span), false, ParseMode::Format);
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let mut args = SimpleFormatArgs::default();
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while let Some(arg) = parser.next() {
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let arg = match arg {
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Piece::String(_) => continue,
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Piece::NextArgument(arg) => arg,
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};
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let span = parser.arg_places.last().map_or(DUMMY_SP, |&x| str.span.from_inner(x));
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if !self.in_debug_impl && arg.format.ty == "?" {
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// FIXME: modify rustc's fmt string parser to give us the current span
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span_lint(cx, USE_DEBUG, str.span, "use of `Debug`-based formatting");
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}
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args.push(arg, span);
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}
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parser.errors.is_empty().then(move || args)
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}
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/// Checks the arguments of `print[ln]!` and `write[ln]!` calls. It will return a tuple of two
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/// `Option`s. The first `Option` of the tuple is the macro's format string. It includes
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/// the contents of the string, whether it's a raw string, and the span of the literal in the
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@ -376,57 +486,31 @@ impl Write {
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/// ```
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#[allow(clippy::too_many_lines)]
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fn check_tts<'a>(&self, cx: &EarlyContext<'a>, tts: TokenStream, is_write: bool) -> (Option<StrLit>, Option<Expr>) {
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use rustc_parse_format::{
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AlignUnknown, ArgumentImplicitlyIs, ArgumentIs, ArgumentNamed, CountImplied, FormatSpec, ParseMode, Parser,
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Piece,
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};
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let mut parser = parser::Parser::new(&cx.sess.parse_sess, tts, false, None);
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let mut expr: Option<Expr> = None;
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if is_write {
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expr = match parser.parse_expr().map_err(|mut err| err.cancel()) {
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Ok(p) => Some(p.into_inner()),
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Err(_) => return (None, None),
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};
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// might be `writeln!(foo)`
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if parser.expect(&token::Comma).map_err(|mut err| err.cancel()).is_err() {
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return (None, expr);
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let expr = if is_write {
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match parser.parse_expr().map(|e| e.into_inner()).map_err(|mut e| e.cancel()) {
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// write!(e, ...)
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Ok(p) if parser.eat(&token::Comma) => Some(p),
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// write!(e) or error
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e => return (None, e.ok()),
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}
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}
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} else {
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None
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};
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let fmtstr = match parser.parse_str_lit() {
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Ok(fmtstr) => fmtstr,
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Err(_) => return (None, expr),
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};
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let tmp = fmtstr.symbol.as_str();
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let mut args = vec![];
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let mut fmt_parser = Parser::new(&tmp, None, None, false, ParseMode::Format);
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while let Some(piece) = fmt_parser.next() {
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if !fmt_parser.errors.is_empty() {
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return (None, expr);
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}
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if let Piece::NextArgument(arg) = piece {
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if !self.in_debug_impl && arg.format.ty == "?" {
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// FIXME: modify rustc's fmt string parser to give us the current span
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span_lint(cx, USE_DEBUG, parser.prev_token.span, "use of `Debug`-based formatting");
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}
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args.push(arg);
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}
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}
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let args = match self.parse_fmt_string(cx, &fmtstr) {
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Some(args) => args,
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None => return (Some(fmtstr), expr),
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};
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let lint = if is_write { WRITE_LITERAL } else { PRINT_LITERAL };
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let mut idx = 0;
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let mut unnamed_args = args.get_unnamed();
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loop {
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const SIMPLE: FormatSpec<'_> = FormatSpec {
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fill: None,
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align: AlignUnknown,
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flags: 0,
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precision: CountImplied,
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precision_span: None,
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width: CountImplied,
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width_span: None,
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ty: "",
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ty_span: None,
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};
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if !parser.eat(&token::Comma) {
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return (Some(fmtstr), expr);
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}
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@ -435,52 +519,26 @@ impl Write {
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} else {
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return (Some(fmtstr), None);
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};
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match &token_expr.kind {
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let (fmt_spans, span) = match &token_expr.kind {
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ExprKind::Lit(lit) if !matches!(lit.kind, LitKind::Int(..) | LitKind::Float(..)) => {
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let mut all_simple = true;
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let mut seen = false;
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for arg in &args {
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match arg.position {
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ArgumentImplicitlyIs(n) | ArgumentIs(n) => {
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if n == idx {
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all_simple &= arg.format == SIMPLE;
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seen = true;
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}
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},
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ArgumentNamed(_) => {},
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}
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}
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if all_simple && seen {
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span_lint(cx, lint, token_expr.span, "literal with an empty format string");
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}
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idx += 1;
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(unnamed_args.next().unwrap_or(&[]), token_expr.span)
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},
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ExprKind::Assign(lhs, rhs, _) => {
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if_chain! {
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if let ExprKind::Lit(ref lit) = rhs.kind;
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if !matches!(lit.kind, LitKind::Int(..) | LitKind::Float(..));
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if let ExprKind::Path(_, p) = &lhs.kind;
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then {
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let mut all_simple = true;
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let mut seen = false;
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for arg in &args {
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match arg.position {
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ArgumentImplicitlyIs(_) | ArgumentIs(_) => {},
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ArgumentNamed(name) => {
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if *p == name {
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seen = true;
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all_simple &= arg.format == SIMPLE;
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}
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},
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}
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}
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if all_simple && seen {
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span_lint(cx, lint, rhs.span, "literal with an empty format string");
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}
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}
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}
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ExprKind::Assign(lhs, rhs, _) => match (&lhs.kind, &rhs.kind) {
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(ExprKind::Path(_, p), ExprKind::Lit(lit))
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if !matches!(lit.kind, LitKind::Int(..) | LitKind::Float(..)) =>
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{
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(args.get_named(p), rhs.span)
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},
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_ => continue,
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},
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_ => idx += 1,
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_ => {
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unnamed_args.next();
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continue;
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},
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};
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if !fmt_spans.is_empty() {
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span_lint(cx, lint, span, "literal with an empty format string");
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}
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}
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}
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