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Avoid ICE in macro's diagnostics #68633

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Merged
merged 2 commits into from
Feb 1, 2020
Merged

Avoid ICE in macro's diagnostics #68633

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Avoid ICE in macro's diagnostics
JohnTitor Jan 29, 2020
b1c91ee
Change Applicability to `HasPlaceholders`
JohnTitor Jan 30, 2020
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40 changes: 23 additions & 17 deletions src/librustc_parse/parser/item.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -1638,26 +1638,32 @@ impl<'a> Parser<'a> {
.span_to_snippet(self.prev_span)
.map(|s| s.ends_with(")") || s.ends_with("]"))
.unwrap_or(false);
let right_brace_span = if has_close_delim {
// it's safe to peel off one character only when it has the close delim
self.prev_span.with_lo(self.prev_span.hi() - BytePos(1))
} else {
self.prev_span.shrink_to_hi()
};

self.struct_span_err(
let mut err = self.struct_span_err(
self.prev_span,
"macros that expand to items must be delimited with braces or followed by a semicolon",
)
.multipart_suggestion(
"change the delimiters to curly braces",
vec![
(self.prev_span.with_hi(self.prev_span.lo() + BytePos(1)), "{".to_string()),
(right_brace_span, '}'.to_string()),
],
Applicability::MaybeIncorrect,
)
.span_suggestion(
);

// To avoid ICE, we shouldn't emit actual suggestions when it hasn't closing delims
if has_close_delim {
err.multipart_suggestion(
"change the delimiters to curly braces",
vec![
(self.prev_span.with_hi(self.prev_span.lo() + BytePos(1)), '{'.to_string()),
(self.prev_span.with_lo(self.prev_span.hi() - BytePos(1)), '}'.to_string()),
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Feels like there's a missing Span method here (self.prev_span.shift_left(...))

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I couldn't find the shift_left method: https://doc.rust-lang.org/nightly/nightly-rustc/rustc_span/struct.Span.html
Am I still missing something?

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I'm saying that we could add a higher level operation to avoid dealing with primitives like this. :)

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Ah, so we can add this tweak as a pub method of Span, right?

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Yeah that would be the idea, if we think it's a good one. cc also @petrochenkov

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@JohnTitor JohnTitor Jan 30, 2020 •
edited
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I feel it'd be nice that we'll do it as follow-up work, how about?

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Works for me.

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SourceMap::next_point let's you advance 1 char at a time (and is now unicode aware). We don't have a method to move left. It is in SourceMap instead of Span because you need to look at the underlying code for the span to be validated as not falling in the middle of a character.

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Also, this might work better with shrink_to_hi and shrink_to_lo instead of with_*.

],
Applicability::MaybeIncorrect,
);
} else {
err.span_suggestion(
self.prev_span,
"change the delimiters to curly braces",
" { /* items */ }".to_string(),
Applicability::HasPlaceholders,
);
}

err.span_suggestion(
self.prev_span.shrink_to_hi(),
"add a semicolon",
';'.to_string(),
Expand Down
5 changes: 2 additions & 3 deletions src/test/ui/parser/issue-62524.stderr
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Original file line number Diff line number Diff line change
Expand Up @@ -16,9 +16,8 @@ LL | | Ϥ,
|
help: change the delimiters to curly braces
|
LL | y!{
LL | Ϥ}
|
LL | y! { /* items */ }
| ^^^^^^^^^^^^^^^
help: add a semicolon
|
LL | Ϥ,;
Expand Down
Binary file added src/test/ui/parser/issue-68629.rs
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Binary file added src/test/ui/parser/issue-68629.stderr
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4 changes: 2 additions & 2 deletions src/test/ui/parser/mbe_missing_right_paren.stderr
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Expand Up @@ -14,8 +14,8 @@ LL | macro_rules! abc(ؼ
|
help: change the delimiters to curly braces
|
LL | macro_rules! abc{ؼ}
| ^ ^
LL | macro_rules! abc { /* items */ }
| ^^^^^^^^^^^^^^^
help: add a semicolon
|
LL | macro_rules! abc(ؼ;
Expand Down