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Change < interpreted as generic arg start warning

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```
warning: `<` is interpreted as a start of generic arguments for `usize`, not a comparison
  --> $DIR/issue-22644.rs:16:33
   |
16 |     println!("{}", a as usize < b);
   |                               - ^ interpreted as generic argument
   |                               |
   |                               not interpreted as comparison
   |
help: if you want to compare the casted value then write:
   |     println!("{}", (a as usize) < b);
```
This commit is contained in:
Esteban Küber 2017-06-12 10:22:08 -07:00
parent 5fcfa08e98
commit 46a6af12aa
2 changed files with 39 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

56
src/libsyntax/parse/parser.rs
View File

@ -42,7 +42,7 @@
use {ast, attr};
use codemap::{self, CodeMap, Spanned, respan};
use syntax_pos::{self, Span, BytePos};
use errors::{self, DiagnosticBuilder, Level};
use errors::{self, DiagnosticBuilder};
use parse::{self, classify, token};
use parse::common::SeqSep;
use parse::lexer::TokenAndSpan;
@ -441,7 +441,14 @@ fn dummy_arg(span: Span) -> Arg {
Arg { ty: P(ty), pat: pat, id: ast::DUMMY_NODE_ID }
}
type RewindPoint = (token::Token, Span, Option<Span>, Span, TokenCursor, Vec<TokenType>);
struct RewindPoint {
token: token::Token,
span: Span,
meta_var_span: Option<Span>,
prev_span: Span,
token_cursor: TokenCursor,
expected_tokens: Vec<TokenType>,
}
impl<'a> Parser<'a> {
pub fn new(sess: &'a ParseSess,
@ -2835,11 +2842,13 @@ pub fn parse_assoc_expr_with(&mut self,
// Rewind to before attempting to parse the type with generics, to get
// arround #22644.
let rp_err = self.get_rewind_point();
let sp = rp_err.span.clone();
self.rewind(rp);
let lo = self.span;
let path = match self.parse_path_without_generics(PathStyle::Type) {
Ok(path) => {
// Successfully parsed the type leaving a `<` yet to parse
err.cancel();
let codemap = self.sess.codemap();
let suggestion_span = lhs_span.to(self.prev_span);
let suggestion = match codemap.span_to_snippet(suggestion_span) {
@ -2850,15 +2859,17 @@ pub fn parse_assoc_expr_with(&mut self,
Ok(lstring) => format!("`{}`", lstring),
_ => "a type".to_string(),
};
err.span_suggestion(suggestion_span,
let msg = format!("`<` is interpreted as a start of generic \
arguments for {}, not a comparison",
warn_message);
let mut warn = self.sess.span_diagnostic.struct_span_warn(sp, &msg);
warn.span_label(sp, "interpreted as generic argument");
warn.span_label(self.span, "not interpreted as comparison");
warn.span_suggestion(suggestion_span,
"if you want to compare the casted value \
then write:",
suggestion);
err.level = Level::Warning;
err.set_message(&format!("`<` is interpreted as a start of generic \
arguments for {}, not a comparison",
warn_message));
err.emit();
warn.emit();
path
}
Err(mut path_err) => {
@ -6255,23 +6266,22 @@ pub fn parse_str(&mut self) -> PResult<'a, (Symbol, StrStyle)> {
}
fn get_rewind_point(&mut self) -> RewindPoint {
(
self.token.clone(),
self.span,
self.meta_var_span,
self.prev_span,
self.token_cursor.clone(),
self.expected_tokens.clone(),
)
RewindPoint {
token: self.token.clone(),
span: self.span,
meta_var_span: self.meta_var_span,
prev_span: self.prev_span,
token_cursor: self.token_cursor.clone(),
expected_tokens: self.expected_tokens.clone(),
}
}
fn rewind(&mut self, rp: RewindPoint) {
let (token, span, meta_var_span, prev_span, token_cursor, expected_tokens,) = rp;
self.token = token;
self.span = span;
self.meta_var_span = meta_var_span;
self.prev_span = prev_span;
self.token_cursor = token_cursor;
self.expected_tokens = expected_tokens;
self.token = rp.token;
self.span = rp.span;
self.meta_var_span = rp.meta_var_span;
self.prev_span = rp.prev_span;
self.token_cursor = rp.token_cursor;
self.expected_tokens = rp.expected_tokens;
}
}

10
src/test/ui/issue-22644.stderr
View File

@ -2,7 +2,9 @@ warning: `<` is interpreted as a start of generic arguments for `usize`, not a c
--> $DIR/issue-22644.rs:16:33
|
16 | println!("{}", a as usize < b);
| ^ expected one of `!`, `(`, `+`, `,`, `::`, or `>` here
| - ^ interpreted as generic argument
| |
| not interpreted as comparison
|
help: if you want to compare the casted value then write:
| println!("{}", (a as usize) < b);
@ -11,9 +13,9 @@ warning: `<` is interpreted as a start of generic arguments for `usize`, not a c
--> $DIR/issue-22644.rs:17:33
|
17 | println!("{}", a as usize < 4);
| -^ unexpected token
| |
| expected one of `>`, identifier, lifetime, or type here
| - ^ interpreted as generic argument
| |
| not interpreted as comparison
|
help: if you want to compare the casted value then write:
| println!("{}", (a as usize) < 4);