From 58765d61ee1762ce0dd9565074000cb9c1267a02 Mon Sep 17 00:00:00 2001 From: Yuki Okushi Date: Fri, 18 Jun 2021 10:22:23 +0900 Subject: [PATCH 1/2] Emit clearer diagnostics for parens around `for` loop heads --- compiler/rustc_parse/src/parser/diagnostics.rs | 5 +++-- src/test/ui/parser/recover-for-loop-parens-around-head.rs | 2 +- .../ui/parser/recover-for-loop-parens-around-head.stderr | 7 +++---- 3 files changed, 7 insertions(+), 7 deletions(-) diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs index 4fccfc287fd..ab7478c7e5f 100644 --- a/compiler/rustc_parse/src/parser/diagnostics.rs +++ b/compiler/rustc_parse/src/parser/diagnostics.rs @@ -1346,8 +1346,9 @@ impl<'a> Parser<'a> { .span_to_snippet(pat.span.trim_start(begin_par_sp).unwrap()) .unwrap_or_else(|_| pprust::pat_to_string(&pat)); - self.struct_span_err(self.prev_token.span, "unexpected closing `)`") - .span_label(begin_par_sp, "opening `(`") + let sp = MultiSpan::from_spans(vec![begin_par_sp, self.prev_token.span]); + + self.struct_span_err(sp, "unexpected parenthesis surrounding `for` loop head") .span_suggestion( begin_par_sp.to(self.prev_token.span), "remove parenthesis in `for` loop", diff --git a/src/test/ui/parser/recover-for-loop-parens-around-head.rs b/src/test/ui/parser/recover-for-loop-parens-around-head.rs index 779e1646344..8080dbc332a 100644 --- a/src/test/ui/parser/recover-for-loop-parens-around-head.rs +++ b/src/test/ui/parser/recover-for-loop-parens-around-head.rs @@ -9,7 +9,7 @@ fn main() { for ( elem in vec ) { //~^ ERROR expected one of `)`, `,`, `@`, or `|`, found keyword `in` - //~| ERROR unexpected closing `)` + //~| ERROR unexpected parenthesis surrounding `for` loop head const RECOVERY_WITNESS: () = 0; //~ ERROR mismatched types } } diff --git a/src/test/ui/parser/recover-for-loop-parens-around-head.stderr b/src/test/ui/parser/recover-for-loop-parens-around-head.stderr index e97cf544ac2..98f6b5b884b 100644 --- a/src/test/ui/parser/recover-for-loop-parens-around-head.stderr +++ b/src/test/ui/parser/recover-for-loop-parens-around-head.stderr @@ -4,13 +4,12 @@ error: expected one of `)`, `,`, `@`, or `|`, found keyword `in` LL | for ( elem in vec ) { | ^^ expected one of `)`, `,`, `@`, or `|` -error: unexpected closing `)` - --> $DIR/recover-for-loop-parens-around-head.rs:10:23 +error: unexpected parenthesis surrounding `for` loop head + --> $DIR/recover-for-loop-parens-around-head.rs:10:9 | LL | for ( elem in vec ) { - | --------------^ + | ^-------------^ | | - | opening `(` | help: remove parenthesis in `for` loop: `elem in vec` error[E0308]: mismatched types From e9bf73cb2b025e188787683f1423177a9102d260 Mon Sep 17 00:00:00 2001 From: Yuki Okushi Date: Fri, 17 Sep 2021 13:39:26 +0900 Subject: [PATCH 2/2] Use `multipart_suggestion` --- .../rustc_parse/src/parser/diagnostics.rs | 32 ++++++++----------- compiler/rustc_parse/src/parser/expr.rs | 2 +- ...recover-for-loop-parens-around-head.stderr | 10 ++++-- 3 files changed, 21 insertions(+), 23 deletions(-) diff --git a/compiler/rustc_parse/src/parser/diagnostics.rs b/compiler/rustc_parse/src/parser/diagnostics.rs index ab7478c7e5f..88b5f89f680 100644 --- a/compiler/rustc_parse/src/parser/diagnostics.rs +++ b/compiler/rustc_parse/src/parser/diagnostics.rs @@ -1334,31 +1334,25 @@ impl<'a> Parser<'a> { pub(super) fn recover_parens_around_for_head( &mut self, pat: P, - expr: &Expr, begin_paren: Option, ) -> P { match (&self.token.kind, begin_paren) { (token::CloseDelim(token::Paren), Some(begin_par_sp)) => { self.bump(); - let pat_str = self - // Remove the `(` from the span of the pattern: - .span_to_snippet(pat.span.trim_start(begin_par_sp).unwrap()) - .unwrap_or_else(|_| pprust::pat_to_string(&pat)); - - let sp = MultiSpan::from_spans(vec![begin_par_sp, self.prev_token.span]); - - self.struct_span_err(sp, "unexpected parenthesis surrounding `for` loop head") - .span_suggestion( - begin_par_sp.to(self.prev_token.span), - "remove parenthesis in `for` loop", - format!("{} in {}", pat_str, pprust::expr_to_string(&expr)), - // With e.g. `for (x) in y)` this would replace `(x) in y)` - // with `x) in y)` which is syntactically invalid. - // However, this is prevented before we get here. - Applicability::MachineApplicable, - ) - .emit(); + self.struct_span_err( + MultiSpan::from_spans(vec![begin_par_sp, self.prev_token.span]), + "unexpected parenthesis surrounding `for` loop head", + ) + .multipart_suggestion( + "remove parenthesis in `for` loop", + vec![(begin_par_sp, String::new()), (self.prev_token.span, String::new())], + // With e.g. `for (x) in y)` this would replace `(x) in y)` + // with `x) in y)` which is syntactically invalid. + // However, this is prevented before we get here. + Applicability::MachineApplicable, + ) + .emit(); // Unwrap `(pat)` into `pat` to avoid the `unused_parens` lint. pat.and_then(|pat| match pat.kind { diff --git a/compiler/rustc_parse/src/parser/expr.rs b/compiler/rustc_parse/src/parser/expr.rs index 737f1d9cbb1..d8f9fc9179e 100644 --- a/compiler/rustc_parse/src/parser/expr.rs +++ b/compiler/rustc_parse/src/parser/expr.rs @@ -2042,7 +2042,7 @@ impl<'a> Parser<'a> { self.check_for_for_in_in_typo(self.prev_token.span); let expr = self.parse_expr_res(Restrictions::NO_STRUCT_LITERAL, None)?; - let pat = self.recover_parens_around_for_head(pat, &expr, begin_paren); + let pat = self.recover_parens_around_for_head(pat, begin_paren); let (iattrs, loop_block) = self.parse_inner_attrs_and_block()?; attrs.extend(iattrs); diff --git a/src/test/ui/parser/recover-for-loop-parens-around-head.stderr b/src/test/ui/parser/recover-for-loop-parens-around-head.stderr index 98f6b5b884b..21991348327 100644 --- a/src/test/ui/parser/recover-for-loop-parens-around-head.stderr +++ b/src/test/ui/parser/recover-for-loop-parens-around-head.stderr @@ -8,9 +8,13 @@ error: unexpected parenthesis surrounding `for` loop head --> $DIR/recover-for-loop-parens-around-head.rs:10:9 | LL | for ( elem in vec ) { - | ^-------------^ - | | - | help: remove parenthesis in `for` loop: `elem in vec` + | ^ ^ + | +help: remove parenthesis in `for` loop + | +LL - for ( elem in vec ) { +LL + for elem in vec { + | error[E0308]: mismatched types --> $DIR/recover-for-loop-parens-around-head.rs:13:38