bjoernager/rust
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improve diagnostics for unterminated nested block comment

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This commit is contained in:
rainy-me 2022-04-14 03:22:02 +09:00
parent 399dd8049d
commit 4a0f8d5175
3 changed files with 78 additions and 10 deletions
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63
compiler/rustc_parse/src/lexer/mod.rs
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@ -182,16 +182,7 @@ impl<'a> StringReader<'a> {
}
rustc_lexer::TokenKind::BlockComment { doc_style, terminated } => {
if !terminated {
let msg = match doc_style {
Some(_) => "unterminated block doc-comment",
None => "unterminated block comment",
};
let last_bpos = self.pos;
self.sess.span_diagnostic.span_fatal_with_code(
self.mk_sp(start, last_bpos),
msg,
error_code!(E0758),
);
self.report_unterminated_block_comment(start, doc_style);
}
// Skip non-doc comments
@ -553,6 +544,58 @@ impl<'a> StringReader<'a> {
err.emit()
}
fn report_unterminated_block_comment(&self, start: BytePos, doc_style: Option<DocStyle>) {
let msg = match doc_style {
Some(_) => "unterminated block doc-comment",
None => "unterminated block comment",
};
let last_bpos = self.pos;
let mut err = self.sess.span_diagnostic.struct_span_fatal_with_code(
self.mk_sp(start, last_bpos),
msg,
error_code!(E0758),
);
let mut nested_block_comment_open_idxs = vec![];
let mut last_nested_block_comment_idxs = None;
let mut content_chars = self.str_from(start).char_indices();
if let Some((_, mut last_char)) = content_chars.next() {
while let Some((idx, c)) = content_chars.next() {
match c {
'*' if last_char == '/' => {
nested_block_comment_open_idxs.push(idx);
}
'/' if last_char == '*' => {
last_nested_block_comment_idxs =
nested_block_comment_open_idxs.pop().map(|open_idx| (open_idx, idx));
}
_ => {}
};
last_char = c;
}
}
if let Some((nested_open_idx, nested_close_idx)) = last_nested_block_comment_idxs {
err.span_label(self.mk_sp(start, start + BytePos(2)), msg)
.span_label(
self.mk_sp(
start + BytePos(nested_open_idx as u32 - 1),
start + BytePos(nested_open_idx as u32 + 1),
),
"...as last nested comment starts here, maybe you want to close this instead?",
)
.span_label(
self.mk_sp(
start + BytePos(nested_close_idx as u32 - 1),
start + BytePos(nested_close_idx as u32 + 1),
),
"...and last nested comment terminates here",
);
}
err.emit();
}
// RFC 3101 introduced the idea of (reserved) prefixes. As of Rust 2021,
// using a (unknown) prefix is an error. In earlier editions, however, they
// only result in a (allowed by default) lint, and are treated as regular