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
View file

@ -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(

12
src/test/ui/panic-brace.rs
View file

@ -1,10 +1,18 @@
// build-pass (FIXME(62277): should be check-pass)
const C: &str = "abc {}";
static S: &str = "{bla}";
#[allow(unreachable_code)]
fn main() {
panic!("here's a brace: {"); //~ WARN panic message contains a brace
std::panic!("another one: }"); //~ WARN panic message contains a brace
core::panic!("Hello {}"); //~ WARN panic message contains an unused formatting placeholder
assert!(false, "{:03x} {test} bla"); //~ WARN panic message contains unused formatting placeholders
debug_assert!(false, "{{}} bla"); //~ WARN panic message contains a brace
assert!(false, "{:03x} {test} bla");
//~^ WARN panic message contains unused formatting placeholders
debug_assert!(false, "{{}} bla"); //~ WARN panic message contains braces
panic!(C); // No warning (yet)
panic!(S); // No warning (yet)
panic!(concat!("{", "}")); //~ WARN panic message contains an unused formatting placeholder
panic!(concat!("{", "{")); //~ WARN panic message contains braces
}

48
src/test/ui/panic-brace.stderr
View file

@ -1,8 +1,8 @@
warning: panic message contains a brace
--> $DIR/panic-brace.rs:5:5
--> $DIR/panic-brace.rs:8:29
|
LL | panic!("here's a brace: {");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^
|
= note: `#[warn(panic_fmt)]` on by default
= note: this message is not used as a format string, but will be in a future Rust version
@ -12,10 +12,10 @@ LL | panic!("{}", "here's a brace: {");
| ^^^^^
warning: panic message contains a brace
--> $DIR/panic-brace.rs:6:5
--> $DIR/panic-brace.rs:9:31
|
LL | std::panic!("another one: }");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^
|
= note: this message is not used as a format string, but will be in a future Rust version
help: add a "{}" format string to use the message literally
@ -24,7 +24,7 @@ LL | std::panic!("{}", "another one: }");
| ^^^^^
warning: panic message contains an unused formatting placeholder
--> $DIR/panic-brace.rs:7:25
--> $DIR/panic-brace.rs:10:25
|
LL | core::panic!("Hello {}");
| ^^
@ -40,7 +40,7 @@ LL | core::panic!("{}", "Hello {}");
| ^^^^^
warning: panic message contains unused formatting placeholders
--> $DIR/panic-brace.rs:8:21
--> $DIR/panic-brace.rs:11:21
|
LL | assert!(false, "{:03x} {test} bla");
| ^^^^^^ ^^^^^^
@ -55,11 +55,11 @@ help: or add a "{}" format string to use the message literally
LL | assert!(false, "{}", "{:03x} {test} bla");
| ^^^^^
warning: panic message contains a brace
--> $DIR/panic-brace.rs:9:5
warning: panic message contains braces
--> $DIR/panic-brace.rs:13:27
|
LL | debug_assert!(false, "{{}} bla");
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| ^^^^
|
= note: this message is not used as a format string, but will be in a future Rust version
help: add a "{}" format string to use the message literally
@ -67,5 +67,33 @@ help: add a "{}" format string to use the message literally
LL | debug_assert!(false, "{}", "{{}} bla");
| ^^^^^
warning: 5 warnings emitted
warning: panic message contains an unused formatting placeholder
--> $DIR/panic-brace.rs:16:12
|
LL | panic!(concat!("{", "}"));
| ^^^^^^^^^^^^^^^^^
|
= note: this message is not used as a format string when given without arguments, but will be in a future Rust version
help: add the missing argument(s)
|
LL | panic!(concat!("{", "}"), ...);
| ^^^^^
help: or add a "{}" format string to use the message literally
|
LL | panic!("{}", concat!("{", "}"));
| ^^^^^
warning: panic message contains braces
--> $DIR/panic-brace.rs:17:5
|
LL | panic!(concat!("{", "{"));
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
|
= note: this message is not used as a format string, but will be in a future Rust version
help: add a "{}" format string to use the message literally
|
LL | panic!("{}", concat!("{", "{"));
| ^^^^^
warning: 7 warnings emitted