From f35d43cdf01f8405009ee6167ac2afe4e02ba51c Mon Sep 17 00:00:00 2001
From: Michael Goulet <michael@errs.io>
Date: Tue, 1 Feb 2022 21:44:44 -0800
Subject: [PATCH] better suggestion for duplicated `where`
---
compiler/rustc_parse/src/parser/generics.rs | 18 ++++-
compiler/rustc_parse/src/parser/item.rs | 29 +++++--
.../ui/parser/bad-struct-following-where.rs | 2 +
.../parser/bad-struct-following-where.stderr | 8 ++
src/test/ui/parser/duplicate-where-clauses.rs | 19 +++++
.../ui/parser/duplicate-where-clauses.stderr | 80 +++++++++++++++++++
6 files changed, 147 insertions(+), 9 deletions(-)
create mode 100644 src/test/ui/parser/bad-struct-following-where.rs
create mode 100644 src/test/ui/parser/bad-struct-following-where.stderr
create mode 100644 src/test/ui/parser/duplicate-where-clauses.rs
create mode 100644 src/test/ui/parser/duplicate-where-clauses.stderr
diff --git a/compiler/rustc_parse/src/parser/generics.rs b/compiler/rustc_parse/src/parser/generics.rs
index 419ea9cced0d7..62ed104aef37c 100644
--- a/compiler/rustc_parse/src/parser/generics.rs
+++ b/compiler/rustc_parse/src/parser/generics.rs
@@ -4,7 +4,7 @@ use rustc_ast::token;
use rustc_ast::{
self as ast, Attribute, GenericBounds, GenericParam, GenericParamKind, WhereClause,
};
-use rustc_errors::PResult;
+use rustc_errors::{Applicability, PResult};
use rustc_span::symbol::kw;
impl<'a> Parser<'a> {
@@ -256,7 +256,21 @@ impl<'a> Parser<'a> {
break;
}
- if !self.eat(&token::Comma) {
+ let prev_token = self.prev_token.span;
+ let ate_comma = self.eat(&token::Comma);
+
+ if self.eat_keyword_noexpect(kw::Where) {
+ let msg = &format!("cannot define duplicate `where` clauses on an item");
+ let mut err = self.struct_span_err(self.token.span, msg);
+ err.span_label(lo, "previous `where` clause starts here");
+ err.span_suggestion_verbose(
+ prev_token.shrink_to_hi().to(self.prev_token.span),
+ "consider joining the two `where` clauses into one",
+ ",".to_owned(),
+ Applicability::MaybeIncorrect,
+ );
+ err.emit();
+ } else if !ate_comma {
break;
}
}
diff --git a/compiler/rustc_parse/src/parser/item.rs b/compiler/rustc_parse/src/parser/item.rs
index 06849b3125683..93f5d79c0db13 100644
--- a/compiler/rustc_parse/src/parser/item.rs
+++ b/compiler/rustc_parse/src/parser/item.rs
@@ -1221,7 +1221,7 @@ impl<'a> Parser<'a> {
let struct_def = if this.check(&token::OpenDelim(token::Brace)) {
// Parse a struct variant.
- let (fields, recovered) = this.parse_record_struct_body("struct")?;
+ let (fields, recovered) = this.parse_record_struct_body("struct", false)?;
VariantData::Struct(fields, recovered)
} else if this.check(&token::OpenDelim(token::Paren)) {
VariantData::Tuple(this.parse_tuple_struct_body()?, DUMMY_NODE_ID)
@@ -1275,7 +1275,8 @@ impl<'a> Parser<'a> {
VariantData::Unit(DUMMY_NODE_ID)
} else {
// If we see: `struct Foo<T> where T: Copy { ... }`
- let (fields, recovered) = self.parse_record_struct_body("struct")?;
+ let (fields, recovered) =
+ self.parse_record_struct_body("struct", generics.where_clause.has_where_token)?;
VariantData::Struct(fields, recovered)
}
// No `where` so: `struct Foo<T>;`
@@ -1283,7 +1284,8 @@ impl<'a> Parser<'a> {
VariantData::Unit(DUMMY_NODE_ID)
// Record-style struct definition
} else if self.token == token::OpenDelim(token::Brace) {
- let (fields, recovered) = self.parse_record_struct_body("struct")?;
+ let (fields, recovered) =
+ self.parse_record_struct_body("struct", generics.where_clause.has_where_token)?;
VariantData::Struct(fields, recovered)
// Tuple-style struct definition with optional where-clause.
} else if self.token == token::OpenDelim(token::Paren) {
@@ -1313,10 +1315,12 @@ impl<'a> Parser<'a> {
let vdata = if self.token.is_keyword(kw::Where) {
generics.where_clause = self.parse_where_clause()?;
- let (fields, recovered) = self.parse_record_struct_body("union")?;
+ let (fields, recovered) =
+ self.parse_record_struct_body("union", generics.where_clause.has_where_token)?;
VariantData::Struct(fields, recovered)
} else if self.token == token::OpenDelim(token::Brace) {
- let (fields, recovered) = self.parse_record_struct_body("union")?;
+ let (fields, recovered) =
+ self.parse_record_struct_body("union", generics.where_clause.has_where_token)?;
VariantData::Struct(fields, recovered)
} else {
let token_str = super::token_descr(&self.token);
@@ -1332,6 +1336,7 @@ impl<'a> Parser<'a> {
fn parse_record_struct_body(
&mut self,
adt_ty: &str,
+ parsed_where: bool,
) -> PResult<'a, (Vec<FieldDef>, /* recovered */ bool)> {
let mut fields = Vec::new();
let mut recovered = false;
@@ -1353,9 +1358,19 @@ impl<'a> Parser<'a> {
self.eat(&token::CloseDelim(token::Brace));
} else {
let token_str = super::token_descr(&self.token);
- let msg = &format!("expected `where`, or `{{` after struct name, found {}", token_str);
+ let msg = &format!(
+ "expected {}`{{` after struct name, found {}",
+ if parsed_where { "" } else { "`where`, or " },
+ token_str
+ );
let mut err = self.struct_span_err(self.token.span, msg);
- err.span_label(self.token.span, "expected `where`, or `{` after struct name");
+ err.span_label(
+ self.token.span,
+ format!(
+ "expected {}`{{` after struct name",
+ if parsed_where { "" } else { "`where`, or " }
+ ),
+ );
return Err(err);
}
diff --git a/src/test/ui/parser/bad-struct-following-where.rs b/src/test/ui/parser/bad-struct-following-where.rs
new file mode 100644
index 0000000000000..823880b1b42c6
--- /dev/null
+++ b/src/test/ui/parser/bad-struct-following-where.rs
@@ -0,0 +1,2 @@
+struct A where T: Sized !
+//~^ ERROR expected `{` after struct name, found
diff --git a/src/test/ui/parser/bad-struct-following-where.stderr b/src/test/ui/parser/bad-struct-following-where.stderr
new file mode 100644
index 0000000000000..bb79776dc8459
--- /dev/null
+++ b/src/test/ui/parser/bad-struct-following-where.stderr
@@ -0,0 +1,8 @@
+error: expected `{` after struct name, found `!`
+ --> $DIR/bad-struct-following-where.rs:1:25
+ |
+LL | struct A where T: Sized !
+ | ^ expected `{` after struct name
+
+error: aborting due to previous error
+
diff --git a/src/test/ui/parser/duplicate-where-clauses.rs b/src/test/ui/parser/duplicate-where-clauses.rs
new file mode 100644
index 0000000000000..9eb2ffb06f02d
--- /dev/null
+++ b/src/test/ui/parser/duplicate-where-clauses.rs
@@ -0,0 +1,19 @@
+struct A where (): Sized where (): Sized {}
+//~^ ERROR cannot define duplicate `where` clauses on an item
+
+fn b() where (): Sized where (): Sized {}
+//~^ ERROR cannot define duplicate `where` clauses on an item
+
+enum C where (): Sized where (): Sized {}
+//~^ ERROR cannot define duplicate `where` clauses on an item
+
+struct D where (): Sized, where (): Sized {}
+//~^ ERROR cannot define duplicate `where` clauses on an item
+
+fn e() where (): Sized, where (): Sized {}
+//~^ ERROR cannot define duplicate `where` clauses on an item
+
+enum F where (): Sized, where (): Sized {}
+//~^ ERROR cannot define duplicate `where` clauses on an item
+
+fn main() {}
diff --git a/src/test/ui/parser/duplicate-where-clauses.stderr b/src/test/ui/parser/duplicate-where-clauses.stderr
new file mode 100644
index 0000000000000..8250d4f1e0568
--- /dev/null
+++ b/src/test/ui/parser/duplicate-where-clauses.stderr
@@ -0,0 +1,80 @@
+error: cannot define duplicate `where` clauses on an item
+ --> $DIR/duplicate-where-clauses.rs:1:32
+ |
+LL | struct A where (): Sized where (): Sized {}
+ | - ^
+ | |
+ | previous `where` clause starts here
+ |
+help: consider joining the two `where` clauses into one
+ |
+LL | struct A where (): Sized, (): Sized {}
+ | ~
+
+error: cannot define duplicate `where` clauses on an item
+ --> $DIR/duplicate-where-clauses.rs:4:30
+ |
+LL | fn b() where (): Sized where (): Sized {}
+ | - ^
+ | |
+ | previous `where` clause starts here
+ |
+help: consider joining the two `where` clauses into one
+ |
+LL | fn b() where (): Sized, (): Sized {}
+ | ~
+
+error: cannot define duplicate `where` clauses on an item
+ --> $DIR/duplicate-where-clauses.rs:7:30
+ |
+LL | enum C where (): Sized where (): Sized {}
+ | - ^
+ | |
+ | previous `where` clause starts here
+ |
+help: consider joining the two `where` clauses into one
+ |
+LL | enum C where (): Sized, (): Sized {}
+ | ~
+
+error: cannot define duplicate `where` clauses on an item
+ --> $DIR/duplicate-where-clauses.rs:10:33
+ |
+LL | struct D where (): Sized, where (): Sized {}
+ | - ^
+ | |
+ | previous `where` clause starts here
+ |
+help: consider joining the two `where` clauses into one
+ |
+LL | struct D where (): Sized, (): Sized {}
+ | ~
+
+error: cannot define duplicate `where` clauses on an item
+ --> $DIR/duplicate-where-clauses.rs:13:31
+ |
+LL | fn e() where (): Sized, where (): Sized {}
+ | - ^
+ | |
+ | previous `where` clause starts here
+ |
+help: consider joining the two `where` clauses into one
+ |
+LL | fn e() where (): Sized, (): Sized {}
+ | ~
+
+error: cannot define duplicate `where` clauses on an item
+ --> $DIR/duplicate-where-clauses.rs:16:31
+ |
+LL | enum F where (): Sized, where (): Sized {}
+ | - ^
+ | |
+ | previous `where` clause starts here
+ |
+help: consider joining the two `where` clauses into one
+ |
+LL | enum F where (): Sized, (): Sized {}
+ | ~
+
+error: aborting due to 6 previous errors
+