bjoernager/rust
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Detect missing if blocks

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When unnecessarily using a fat arrow after an if condition, suggest the
removal of it.

When finding an if statement with no block, point at the `if` keyword to
provide more context.
This commit is contained in:
Esteban Küber 2018-02-18 16:59:33 -08:00
parent 0c9afa87ba
commit ba7039cfd6
5 changed files with 60 additions and 10 deletions
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35
src/libsyntax/parse/parser.rs
View file

@ -652,9 +652,11 @@ impl<'a> Parser<'a> {
} else {
let token_str = Parser::token_to_string(t);
let this_token_str = self.this_token_to_string();
Err(self.fatal(&format!("expected `{}`, found `{}`",
token_str,
this_token_str)))
let mut err = self.fatal(&format!("expected `{}`, found `{}`",
token_str,
this_token_str));
err.span_label(self.span, format!("expected `{}`", token_str));
Err(err)
}
} else {
self.expect_one_of(unsafe { slice::from_raw_parts(t, 1) }, &[])
@ -1172,7 +1174,7 @@ impl<'a> Parser<'a> {
sep: SeqSep,
f: F)
-> PResult<'a, Vec<T>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
self.expect(bra)?;
let result = self.parse_seq_to_before_end(ket, sep, f)?;
@ -1190,7 +1192,7 @@ impl<'a> Parser<'a> {
sep: SeqSep,
f: F)
-> PResult<'a, Spanned<Vec<T>>> where
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
{
let lo = self.span;
self.expect(bra)?;
@ -3212,7 +3214,23 @@ impl<'a> Parser<'a> {
err.span_label(sp, "expected if condition here");
return Err(err)
}
let thn = self.parse_block()?;
let not_block = self.token != token::OpenDelim(token::Brace);
let fat_arrow_sp = if self.token == token::FatArrow {
Some(self.span)
} else {
None
};
let thn = self.parse_block().map_err(|mut err| {
if let Some(sp) = fat_arrow_sp {
// if cond => expr
err.span_suggestion(sp,
"only necessary in match arms, not before if blocks",
"".to_string());
} else if not_block {
err.span_label(lo, "this `if` statement has a condition, but no block");
}
err
})?;
let mut els: Option<P<Expr>> = None;
let mut hi = thn.span;
if self.eat_keyword(keywords::Else) {
@ -3629,8 +3647,9 @@ impl<'a> Parser<'a> {
self.bump();
if self.token != token::CloseDelim(token::Brace) {
let token_str = self.this_token_to_string();
return Err(self.fatal(&format!("expected `{}`, found `{}`", "}",
token_str)))
let mut err = self.fatal(&format!("expected `{}`, found `{}`", "}", token_str));
err.span_label(self.span, "expected `}`");
return Err(err);
}
etc = true;
break;