bjoernager/rust
bjoernager/rust
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Nicer error message if the user attempts to do let...else if

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This commit is contained in:
est31 2021-10-17 07:02:52 +02:00
parent c1026539bd
commit 856541963c
3 changed files with 44 additions and 5 deletions
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21
compiler/rustc_parse/src/parser/stmt.rs
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@ -16,7 +16,7 @@ use rustc_ast::{
};
use rustc_ast::{Block, BlockCheckMode, Expr, ExprKind, Local, Stmt};
use rustc_ast::{StmtKind, DUMMY_NODE_ID};
use rustc_errors::{Applicability, PResult};
use rustc_errors::{Applicability, DiagnosticBuilder, PResult};
use rustc_span::source_map::{BytePos, Span};
use rustc_span::symbol::{kw, sym};
@ -300,6 +300,12 @@ impl<'a> Parser<'a> {
None => LocalKind::Decl,
Some(init) => {
if self.eat_keyword(kw::Else) {
if self.token.is_keyword(kw::If) {
// `let...else if`. Emit the same error that `parse_block()` would,
// but explicitly point out that this pattern is not allowed.
let msg = "conditional `else if` is not supported for `let...else`";
return Err(self.error_block_no_opening_brace_msg(msg));
}
let els = self.parse_block()?;
self.check_let_else_init_bool_expr(&init);
self.check_let_else_init_trailing_brace(&init);
@ -392,10 +398,9 @@ impl<'a> Parser<'a> {
Ok(block)
}
fn error_block_no_opening_brace<T>(&mut self) -> PResult<'a, T> {
fn error_block_no_opening_brace_msg(&mut self, msg: &str) -> DiagnosticBuilder<'a> {
let sp = self.token.span;
let tok = super::token_descr(&self.token);
let mut e = self.struct_span_err(sp, &format!("expected `{{`, found {}", tok));
let mut e = self.struct_span_err(sp, msg);
let do_not_suggest_help = self.token.is_keyword(kw::In) || self.token == token::Colon;
// Check to see if the user has written something like
@ -435,7 +440,13 @@ impl<'a> Parser<'a> {
_ => {}
}
e.span_label(sp, "expected `{`");
Err(e)
e
}
fn error_block_no_opening_brace<T>(&mut self) -> PResult<'a, T> {
let tok = super::token_descr(&self.token);
let msg = format!("expected `{{`, found {}", tok);
Err(self.error_block_no_opening_brace_msg(&msg))
}
/// Parses a block. Inner attributes are allowed.