bjoernager/rust
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Improve panic_fmt error messages for invalid format strings too.

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This commit is contained in:
Mara Bos 2020-10-20 22:59:53 +02:00
parent 6b44662669
commit 190c3ad64e
3 changed files with 66 additions and 16 deletions
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22
compiler/rustc_lint/src/panic_fmt.rs
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@ -4,7 +4,7 @@ use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_middle::ty;
use rustc_parse_format::{ParseMode, Parser, Piece};
use rustc_span::sym;
use rustc_span::{sym, InnerSpan};
declare_lint! {
/// The `panic_fmt` lint detects `panic!("..")` with `{` or `}` in the string literal.
@ -71,7 +71,7 @@ fn check_panic<'tcx>(cx: &LateContext<'tcx>, f: &'tcx hir::Expr<'tcx>, arg: &'tc
};
let mut fmt_parser =
Parser::new(fmt.as_ref(), style, snippet, false, ParseMode::Format);
Parser::new(fmt.as_ref(), style, snippet.clone(), false, ParseMode::Format);
let n_arguments =
(&mut fmt_parser).filter(|a| matches!(a, Piece::NextArgument(_))).count();
@ -115,8 +115,22 @@ fn check_panic<'tcx>(cx: &LateContext<'tcx>, f: &'tcx hir::Expr<'tcx>, arg: &'tc
l.emit();
});
} else {
cx.struct_span_lint(PANIC_FMT, expn.call_site, |lint| {
let mut l = lint.build("panic message contains a brace");
let brace_spans: Option<Vec<_>> = snippet
.filter(|s| s.starts_with('"') || s.starts_with("r#"))
.map(|s| {
s.char_indices()
.filter(|&(_, c)| c == '{' || c == '}')
.map(|(i, _)| {
fmt_span.from_inner(InnerSpan { start: i, end: i + 1 })
})
.collect()
});
let msg = match &brace_spans {
Some(v) if v.len() == 1 => "panic message contains a brace",
_ => "panic message contains braces",
};
cx.struct_span_lint(PANIC_FMT, brace_spans.unwrap_or(vec![expn.call_site]), |lint| {
let mut l = lint.build(msg);
l.note("this message is not used as a format string, but will be in a future Rust version");
if expn.call_site.contains(arg.span) {
l.span_suggestion(