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Detect empty leading where-clauses on type aliases
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fmease committed Feb 29, 2024
1 parent 2b80605 commit cce8128
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Showing 11 changed files with 177 additions and 67 deletions.
3 changes: 2 additions & 1 deletion compiler/rustc_ast_passes/messages.ftl
Original file line number Diff line number Diff line change
Expand Up @@ -280,4 +280,5 @@ ast_passes_where_clause_after_type_alias = where clauses are not allowed after t
ast_passes_where_clause_before_type_alias = where clauses are not allowed before the type for type aliases
.note = see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information
.suggestion = move it to the end of the type declaration
.remove_suggestion = remove this `where`
.move_suggestion = move it to the end of the type declaration
63 changes: 35 additions & 28 deletions compiler/rustc_ast_passes/src/ast_validation.rs
Original file line number Diff line number Diff line change
Expand Up @@ -138,38 +138,42 @@ impl<'a> AstValidator<'a> {
&mut self,
ty_alias: &TyAlias,
) -> Result<(), errors::WhereClauseBeforeTypeAlias> {
let before_predicates =
ty_alias.generics.where_clause.predicates.split_at(ty_alias.where_clauses.split).0;

if ty_alias.ty.is_none() || before_predicates.is_empty() {
if ty_alias.ty.is_none() || !ty_alias.where_clauses.before.has_where_token {
return Ok(());
}

let mut state = State::new();
if !ty_alias.where_clauses.after.has_where_token {
state.space();
state.word_space("where");
} else {
state.word_space(",");
}
let mut first = true;
for p in before_predicates {
if !first {
state.word_space(",");
let (before_predicates, after_predicates) =
ty_alias.generics.where_clause.predicates.split_at(ty_alias.where_clauses.split);
let span = ty_alias.where_clauses.before.span;

let sugg = if !before_predicates.is_empty() || !ty_alias.where_clauses.after.has_where_token
{
let mut state = State::new();

if !ty_alias.where_clauses.after.has_where_token {
state.space();
state.word_space("where");
}
first = false;
state.print_where_predicate(p);
}

let span = ty_alias.where_clauses.before.span;
Err(errors::WhereClauseBeforeTypeAlias {
span,
sugg: errors::WhereClauseBeforeTypeAliasSugg {
let mut first = after_predicates.is_empty();
for p in before_predicates {
if !first {
state.word_space(",");
}
first = false;
state.print_where_predicate(p);
}

errors::WhereClauseBeforeTypeAliasSugg::Move {
left: span,
snippet: state.s.eof(),
right: ty_alias.where_clauses.after.span.shrink_to_hi(),
},
})
}
} else {
errors::WhereClauseBeforeTypeAliasSugg::Remove { span }
};

Err(errors::WhereClauseBeforeTypeAlias { span, sugg })
}

fn with_impl_trait(&mut self, outer: Option<Span>, f: impl FnOnce(&mut Self)) {
Expand Down Expand Up @@ -1476,15 +1480,18 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
if let AssocItemKind::Type(ty_alias) = &item.kind
&& let Err(err) = self.check_type_alias_where_clause_location(ty_alias)
{
let sugg = match err.sugg {
errors::WhereClauseBeforeTypeAliasSugg::Remove { .. } => None,
errors::WhereClauseBeforeTypeAliasSugg::Move { snippet, right, .. } => {
Some((right, snippet))
}
};
self.lint_buffer.buffer_lint_with_diagnostic(
DEPRECATED_WHERE_CLAUSE_LOCATION,
item.id,
err.span,
fluent::ast_passes_deprecated_where_clause_location,
BuiltinLintDiagnostics::DeprecatedWhereclauseLocation(
err.sugg.right,
err.sugg.snippet,
),
BuiltinLintDiagnostics::DeprecatedWhereclauseLocation(sugg),
);
}

Expand Down
30 changes: 19 additions & 11 deletions compiler/rustc_ast_passes/src/errors.rs
Original file line number Diff line number Diff line change
Expand Up @@ -515,17 +515,25 @@ pub struct WhereClauseBeforeTypeAlias {
}

#[derive(Subdiagnostic)]
#[multipart_suggestion(
ast_passes_suggestion,
applicability = "machine-applicable",
style = "verbose"
)]
pub struct WhereClauseBeforeTypeAliasSugg {
#[suggestion_part(code = "")]
pub left: Span,
pub snippet: String,
#[suggestion_part(code = "{snippet}")]
pub right: Span,

pub enum WhereClauseBeforeTypeAliasSugg {
#[suggestion(ast_passes_remove_suggestion, applicability = "machine-applicable", code = "")]
Remove {
#[primary_span]
span: Span,
},
#[multipart_suggestion(
ast_passes_move_suggestion,
applicability = "machine-applicable",
style = "verbose"
)]
Move {
#[suggestion_part(code = "")]
left: Span,
snippet: String,
#[suggestion_part(code = "{snippet}")]
right: Span,
},
}

#[derive(Diagnostic)]
Expand Down
25 changes: 16 additions & 9 deletions compiler/rustc_lint/src/context/diagnostics.rs
Original file line number Diff line number Diff line change
Expand Up @@ -428,15 +428,22 @@ pub(super) fn builtin(sess: &Session, diagnostic: BuiltinLintDiagnostics, diag:
diag.note("see <https://doc.rust-lang.org/nightly/unstable-book/compiler-flags/check-cfg.html> for more information about checking conditional configuration");
}
}
BuiltinLintDiagnostics::DeprecatedWhereclauseLocation(new_span, suggestion) => {
diag.multipart_suggestion(
"move it to the end of the type declaration",
vec![(diag.span.primary_span().unwrap(), "".to_string()), (new_span, suggestion)],
Applicability::MachineApplicable,
);
diag.note(
"see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information",
);
BuiltinLintDiagnostics::DeprecatedWhereclauseLocation(sugg) => {
let left_sp = diag.span.primary_span().unwrap();
match sugg {
Some((right_sp, sugg)) => diag.multipart_suggestion(
"move it to the end of the type declaration",
vec![(left_sp, String::new()), (right_sp, sugg)],
Applicability::MachineApplicable,
),
None => diag.span_suggestion(
left_sp,
"remove this `where`",
"",
Applicability::MachineApplicable,
),
};
diag.note("see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information");
}
BuiltinLintDiagnostics::SingleUseLifetime {
param_span,
Expand Down
2 changes: 1 addition & 1 deletion compiler/rustc_lint_defs/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -597,7 +597,7 @@ pub enum BuiltinLintDiagnostics {
UnicodeTextFlow(Span, String),
UnexpectedCfgName((Symbol, Span), Option<(Symbol, Span)>),
UnexpectedCfgValue((Symbol, Span), Option<(Symbol, Span)>),
DeprecatedWhereclauseLocation(Span, String),
DeprecatedWhereclauseLocation(Option<(Span, String)>),
SingleUseLifetime {
/// Span of the parameter which declares this lifetime.
param_span: Span,
Expand Down
18 changes: 13 additions & 5 deletions tests/ui/lazy-type-alias/leading-where-clause.fixed
Original file line number Diff line number Diff line change
Expand Up @@ -2,14 +2,22 @@

#![feature(lazy_type_alias)]
#![allow(incomplete_features)]
#![crate_type = "lib"]

// Check that we *reject* leading where-clauses on lazy type aliases.

type Alias<T>
pub type Leading0<T>

= T where String: From<T>;
//~^^^ ERROR where clauses are not allowed before the type for type aliases

fn main() {
let _: Alias<&str>;
}
pub type Leading1<T, U>

= (T, U)
where
U: Copy, String: From<T>;

pub type EmptyLeading0 = () where;
//~^ ERROR where clauses are not allowed before the type for type aliases

pub type EmptyLeading1<T> = T where T: Copy;
//~^ ERROR where clauses are not allowed before the type for type aliases
21 changes: 15 additions & 6 deletions tests/ui/lazy-type-alias/leading-where-clause.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2,15 +2,24 @@

#![feature(lazy_type_alias)]
#![allow(incomplete_features)]
#![crate_type = "lib"]

// Check that we *reject* leading where-clauses on lazy type aliases.

type Alias<T>
where
pub type Leading0<T>
where //~ ERROR where clauses are not allowed before the type for type aliases
String: From<T>,
= T;
//~^^^ ERROR where clauses are not allowed before the type for type aliases

fn main() {
let _: Alias<&str>;
}
pub type Leading1<T, U>
where //~ ERROR where clauses are not allowed before the type for type aliases
String: From<T>,
= (T, U)
where
U: Copy;

pub type EmptyLeading0 where = ();
//~^ ERROR where clauses are not allowed before the type for type aliases

pub type EmptyLeading1<T> where = T where T: Copy;
//~^ ERROR where clauses are not allowed before the type for type aliases
41 changes: 39 additions & 2 deletions tests/ui/lazy-type-alias/leading-where-clause.stderr
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
error: where clauses are not allowed before the type for type aliases
--> $DIR/leading-where-clause.rs:9:1
--> $DIR/leading-where-clause.rs:10:1
|
LL | / where
LL | | String: From<T>,
Expand All @@ -12,5 +12,42 @@ LL +
LL ~ = T where String: From<T>;
|

error: aborting due to 1 previous error
error: where clauses are not allowed before the type for type aliases
--> $DIR/leading-where-clause.rs:15:1
|
LL | / where
LL | | String: From<T>,
| |____________________^
|
= note: see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information
help: move it to the end of the type declaration
|
LL +
LL | = (T, U)
LL | where
LL ~ U: Copy, String: From<T>;
|

error: where clauses are not allowed before the type for type aliases
--> $DIR/leading-where-clause.rs:21:24
|
LL | pub type EmptyLeading0 where = ();
| ^^^^^
|
= note: see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information
help: move it to the end of the type declaration
|
LL - pub type EmptyLeading0 where = ();
LL + pub type EmptyLeading0 = () where;
|

error: where clauses are not allowed before the type for type aliases
--> $DIR/leading-where-clause.rs:24:27
|
LL | pub type EmptyLeading1<T> where = T where T: Copy;
| ^^^^^ help: remove this `where`
|
= note: see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information

error: aborting due to 4 previous errors

Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,8 @@ trait Trait {
type Assoc where u32: Copy;
// Fine.
type Assoc2 where u32: Copy, i32: Copy;
//
type Assoc3;
}

impl Trait for u32 {
Expand All @@ -17,6 +19,8 @@ impl Trait for u32 {
// Not fine, suggests moving `u32: Copy`
type Assoc2 = () where i32: Copy, u32: Copy;
//~^ WARNING where clause not allowed here
type Assoc3 = () where;
//~^ WARNING where clause not allowed here
}

impl Trait for i32 {
Expand All @@ -25,6 +29,8 @@ impl Trait for i32 {
// Not fine, suggests moving both.
type Assoc2 = () where u32: Copy, i32: Copy;
//~^ WARNING where clause not allowed here
type Assoc3 = () where;
//~^ WARNING where clause not allowed here
}

fn main() {}
Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,8 @@ trait Trait {
type Assoc where u32: Copy;
// Fine.
type Assoc2 where u32: Copy, i32: Copy;
//
type Assoc3;
}

impl Trait for u32 {
Expand All @@ -17,6 +19,8 @@ impl Trait for u32 {
// Not fine, suggests moving `u32: Copy`
type Assoc2 where u32: Copy = () where i32: Copy;
//~^ WARNING where clause not allowed here
type Assoc3 where = ();
//~^ WARNING where clause not allowed here
}

impl Trait for i32 {
Expand All @@ -25,6 +29,8 @@ impl Trait for i32 {
// Not fine, suggests moving both.
type Assoc2 where u32: Copy, i32: Copy = ();
//~^ WARNING where clause not allowed here
type Assoc3 where = () where;
//~^ WARNING where clause not allowed here
}

fn main() {}
Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
warning: where clause not allowed here
--> $DIR/where-clause-placement-assoc-type-in-impl.rs:15:16
--> $DIR/where-clause-placement-assoc-type-in-impl.rs:17:16
|
LL | type Assoc where u32: Copy = ();
| ^^^^^^^^^^^^^^^
Expand All @@ -13,7 +13,7 @@ LL + type Assoc = () where u32: Copy;
|

warning: where clause not allowed here
--> $DIR/where-clause-placement-assoc-type-in-impl.rs:18:17
--> $DIR/where-clause-placement-assoc-type-in-impl.rs:20:17
|
LL | type Assoc2 where u32: Copy = () where i32: Copy;
| ^^^^^^^^^^^^^^^
Expand All @@ -26,7 +26,20 @@ LL + type Assoc2 = () where i32: Copy, u32: Copy;
|

warning: where clause not allowed here
--> $DIR/where-clause-placement-assoc-type-in-impl.rs:26:17
--> $DIR/where-clause-placement-assoc-type-in-impl.rs:22:17
|
LL | type Assoc3 where = ();
| ^^^^^
|
= note: see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information
help: move it to the end of the type declaration
|
LL - type Assoc3 where = ();
LL + type Assoc3 = () where;
|

warning: where clause not allowed here
--> $DIR/where-clause-placement-assoc-type-in-impl.rs:30:17
|
LL | type Assoc2 where u32: Copy, i32: Copy = ();
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
Expand All @@ -38,5 +51,13 @@ LL - type Assoc2 where u32: Copy, i32: Copy = ();
LL + type Assoc2 = () where u32: Copy, i32: Copy;
|

warning: 3 warnings emitted
warning: where clause not allowed here
--> $DIR/where-clause-placement-assoc-type-in-impl.rs:32:17
|
LL | type Assoc3 where = () where;
| ^^^^^ help: remove this `where`
|
= note: see issue #89122 <https://github.com/rust-lang/rust/issues/89122> for more information

warning: 5 warnings emitted

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