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Improve incomplete unicode escape reporting

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This improves diagnostic messages when \u escape is used incorrectly and { is
missing. Instead of saying “unknown character escape: u”, it will now report
that unicode escape sequence is incomplete and suggest what the correct syntax
is.
This commit is contained in:
Simonas Kazlauskas
2015-07-10 21:37:21 +03:00
parent fd8e175c4e
commit 0bd5dd6449
2 changed files with 20 additions and 6 deletions
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24
src/libsyntax/parse/lexer/mod.rs
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@@ -172,6 +172,11 @@ impl<'a> StringReader<'a> {
self.span_diagnostic.span_err(sp, m)
}
/// Suggest some help with a given span.
pub fn help_span(&self, sp: Span, m: &str) {
self.span_diagnostic.span_help(sp, m)
}
/// Report a fatal error spanning [`from_pos`, `to_pos`).
fn fatal_span_(&self, from_pos: BytePos, to_pos: BytePos, m: &str) -> ! {
self.fatal_span(codemap::mk_sp(from_pos, to_pos), m)
@@ -182,6 +187,11 @@ impl<'a> StringReader<'a> {
self.err_span(codemap::mk_sp(from_pos, to_pos), m)
}
/// Suggest some help spanning [`from_pos`, `to_pos`).
fn help_span_(&self, from_pos: BytePos, to_pos: BytePos, m: &str) {
self.help_span(codemap::mk_sp(from_pos, to_pos), m)
}
/// Report a lexical error spanning [`from_pos`, `to_pos`), appending an
/// escaped character to the error message
fn fatal_span_char(&self, from_pos: BytePos, to_pos: BytePos, m: &str, c: char) -> ! {
@@ -742,6 +752,13 @@ impl<'a> StringReader<'a> {
valid
}
}
'u' if !ascii_only => {
self.err_span_(escaped_pos, self.last_pos,
"incomplete unicode escape sequence");
self.help_span_(escaped_pos, self.last_pos,
"format of unicode escape sequences is `\\u{…}`");
false
}
'\n' if delim == '"' => {
self.consume_whitespace();
true
@@ -757,16 +774,13 @@ impl<'a> StringReader<'a> {
if ascii_only { "unknown byte escape" }
else { "unknown character escape" },
c);
let sp = codemap::mk_sp(escaped_pos, last_pos);
if e == '\r' {
self.span_diagnostic.span_help(
sp,
self.help_span_(escaped_pos, last_pos,
"this is an isolated carriage return; consider checking \
your editor and version control settings")
}
if (e == '{' || e == '}') && !ascii_only {
self.span_diagnostic.span_help(
sp,
self.help_span_(escaped_pos, last_pos,
"if used in a formatting string, \
curly braces are escaped with `{{` and `}}`")
}