diff --git a/compiler/rustc_ast_lowering/src/format.rs b/compiler/rustc_ast_lowering/src/format.rs
index 0de0319c66763..17b443b8ecc2c 100644
--- a/compiler/rustc_ast_lowering/src/format.rs
+++ b/compiler/rustc_ast_lowering/src/format.rs
@@ -6,7 +6,7 @@ use rustc_ast::*;
use rustc_data_structures::fx::FxIndexMap;
use rustc_hir as hir;
use rustc_session::config::FmtDebug;
-use rustc_span::{Ident, Span, Symbol, kw, sym};
+use rustc_span::{Ident, Span, Symbol, sym};
use super::LoweringContext;
@@ -418,7 +418,7 @@ fn expand_format_args<'hir>(
&FormatArgsPiece::Placeholder(_) => {
// Inject empty string before placeholders when not already preceded by a literal piece.
if i == 0 || matches!(fmt.template[i - 1], FormatArgsPiece::Placeholder(_)) {
- Some(ctx.expr_str(fmt.span, kw::Empty))
+ Some(ctx.expr_str(fmt.span, sym::empty))
} else {
None
}
diff --git a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
index 5924c8991ad64..f731613d67e8a 100644
--- a/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
+++ b/compiler/rustc_codegen_ssa/src/mir/debuginfo.rs
@@ -10,7 +10,7 @@ use rustc_middle::ty::layout::{LayoutOf, TyAndLayout};
use rustc_middle::ty::{Instance, Ty};
use rustc_middle::{bug, mir, ty};
use rustc_session::config::DebugInfo;
-use rustc_span::{BytePos, Span, Symbol, hygiene, kw};
+use rustc_span::{BytePos, Span, Symbol, hygiene, sym};
use super::operand::{OperandRef, OperandValue};
use super::place::{PlaceRef, PlaceValue};
@@ -283,7 +283,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
// (after #67586 gets fixed).
None
} else {
- let name = kw::Empty;
+ let name = sym::empty;
let decl = &self.mir.local_decls[local];
let dbg_var = if full_debug_info {
self.adjusted_span_and_dbg_scope(decl.source_info).map(
@@ -318,7 +318,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
None
} else {
Some(match whole_local_var.or(fallback_var.clone()) {
- Some(var) if var.name != kw::Empty => var.name.to_string(),
+ Some(var) if var.name != sym::empty => var.name.to_string(),
_ => format!("{local:?}"),
})
};
diff --git a/compiler/rustc_hir/src/hir.rs b/compiler/rustc_hir/src/hir.rs
index fa1d1ec0a8601..f63ab30368914 100644
--- a/compiler/rustc_hir/src/hir.rs
+++ b/compiler/rustc_hir/src/hir.rs
@@ -85,7 +85,7 @@ impl From<Ident> for LifetimeSyntax {
fn from(ident: Ident) -> Self {
let name = ident.name;
- if name == kw::Empty {
+ if name == sym::empty {
unreachable!("A lifetime name should never be empty");
} else if name == kw::UnderscoreLifetime {
LifetimeSyntax::Anonymous
diff --git a/compiler/rustc_passes/src/check_attr.rs b/compiler/rustc_passes/src/check_attr.rs
index 5c0d0cf47969a..1d0246940499f 100644
--- a/compiler/rustc_passes/src/check_attr.rs
+++ b/compiler/rustc_passes/src/check_attr.rs
@@ -35,7 +35,7 @@ use rustc_session::lint::builtin::{
UNKNOWN_OR_MALFORMED_DIAGNOSTIC_ATTRIBUTES, UNUSED_ATTRIBUTES,
};
use rustc_session::parse::feature_err;
-use rustc_span::{BytePos, DUMMY_SP, Span, Symbol, edition, kw, sym};
+use rustc_span::{BytePos, DUMMY_SP, Span, Symbol, edition, sym};
use rustc_trait_selection::error_reporting::InferCtxtErrorExt;
use rustc_trait_selection::infer::{TyCtxtInferExt, ValuePairs};
use rustc_trait_selection::traits::ObligationCtxt;
@@ -936,7 +936,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
let span = meta.name_value_literal_span().unwrap_or_else(|| meta.span());
let attr_str =
&format!("`#[doc(alias{})]`", if is_list { "(\"...\")" } else { " = \"...\"" });
- if doc_alias == kw::Empty {
+ if doc_alias == sym::empty {
tcx.dcx().emit_err(errors::DocAliasEmpty { span, attr_str });
return;
}
@@ -1068,7 +1068,7 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
}
let doc_keyword = match meta.value_str() {
- Some(value) if value != kw::Empty => value,
+ Some(value) if value != sym::empty => value,
_ => return self.doc_attr_str_error(meta, "keyword"),
};
diff --git a/compiler/rustc_resolve/src/rustdoc.rs b/compiler/rustc_resolve/src/rustdoc.rs
index a32fe6990160c..d701410e4dc2e 100644
--- a/compiler/rustc_resolve/src/rustdoc.rs
+++ b/compiler/rustc_resolve/src/rustdoc.rs
@@ -12,7 +12,7 @@ use rustc_data_structures::fx::FxIndexMap;
use rustc_data_structures::unord::UnordSet;
use rustc_middle::ty::TyCtxt;
use rustc_span::def_id::DefId;
-use rustc_span::{DUMMY_SP, InnerSpan, Span, Symbol, kw, sym};
+use rustc_span::{DUMMY_SP, InnerSpan, Span, Symbol, sym};
use thin_vec::ThinVec;
use tracing::{debug, trace};
@@ -157,7 +157,7 @@ pub fn unindent_doc_fragments(docs: &mut [DocFragment]) {
};
for fragment in docs {
- if fragment.doc == kw::Empty {
+ if fragment.doc == sym::empty {
continue;
}
@@ -177,7 +177,7 @@ pub fn unindent_doc_fragments(docs: &mut [DocFragment]) {
///
/// Note: remove the trailing newline where appropriate
pub fn add_doc_fragment(out: &mut String, frag: &DocFragment) {
- if frag.doc == kw::Empty {
+ if frag.doc == sym::empty {
out.push('\n');
return;
}
diff --git a/compiler/rustc_span/src/symbol.rs b/compiler/rustc_span/src/symbol.rs
index fbe3b4ca6f5f6..befc5bbff52c8 100644
--- a/compiler/rustc_span/src/symbol.rs
+++ b/compiler/rustc_span/src/symbol.rs
@@ -34,17 +34,8 @@ symbols! {
// unnamed method parameters, crate root module, error recovery etc.
// Matching predicates: `is_special`/`is_reserved`
//
- // Notes about `kw::Empty`:
- // - Its use can blur the lines between "empty symbol" and "no symbol".
- // Using `Option<Symbol>` is preferable, where possible, because that
- // is unambiguous.
- // - For dummy symbols that are never used and absolutely must be
- // present, it's better to use `sym::dummy` than `kw::Empty`, because
- // it's clearer that it's intended as a dummy value, and more likely
- // to be detected if it accidentally does get used.
// tidy-alphabetical-start
DollarCrate: "$crate",
- Empty: "",
PathRoot: "{{root}}",
Underscore: "_",
// tidy-alphabetical-end
@@ -864,7 +855,7 @@ symbols! {
drop_types_in_const,
dropck_eyepatch,
dropck_parametricity,
- dummy: "<!dummy!>", // use this instead of `kw::Empty` for symbols that won't be used
+ dummy: "<!dummy!>", // use this instead of `sym::empty` for symbols that won't be used
dummy_cgu_name,
dylib,
dyn_compatible_for_dispatch,
@@ -883,6 +874,14 @@ symbols! {
emit_enum_variant_arg,
emit_struct,
emit_struct_field,
+ // Notes about `sym::empty`:
+ // - It should only be used when it genuinely means "empty symbol". Use
+ // `Option<Symbol>` when "no symbol" is a possibility.
+ // - For dummy symbols that are never used and absolutely must be
+ // present, it's better to use `sym::dummy` than `sym::empty`, because
+ // it's clearer that it's intended as a dummy value, and more likely
+ // to be detected if it accidentally does get used.
+ empty: "",
emscripten_wasm_eh,
enable,
encode,
@@ -2362,7 +2361,7 @@ impl Ident {
#[inline]
/// Constructs a new identifier from a symbol and a span.
pub fn new(name: Symbol, span: Span) -> Ident {
- debug_assert_ne!(name, kw::Empty);
+ debug_assert_ne!(name, sym::empty);
Ident { name, span }
}
@@ -2584,7 +2583,7 @@ impl Symbol {
}
pub fn is_empty(self) -> bool {
- self == kw::Empty
+ self == sym::empty
}
/// This method is supposed to be used in error messages, so it's expected to be
@@ -2593,7 +2592,7 @@ impl Symbol {
/// or edition, so we have to guess the rawness using the global edition.
pub fn to_ident_string(self) -> String {
// Avoid creating an empty identifier, because that asserts in debug builds.
- if self == kw::Empty { String::new() } else { Ident::with_dummy_span(self).to_string() }
+ if self == sym::empty { String::new() } else { Ident::with_dummy_span(self).to_string() }
}
}
@@ -2773,7 +2772,7 @@ impl Symbol {
/// Returns `true` if this symbol can be a raw identifier.
pub fn can_be_raw(self) -> bool {
- self != kw::Empty && self != kw::Underscore && !self.is_path_segment_keyword()
+ self != sym::empty && self != kw::Underscore && !self.is_path_segment_keyword()
}
/// Was this symbol predefined in the compiler's `symbols!` macro
diff --git a/compiler/rustc_symbol_mangling/src/v0.rs b/compiler/rustc_symbol_mangling/src/v0.rs
index 4a99ce09b39ab..644031af8597a 100644
--- a/compiler/rustc_symbol_mangling/src/v0.rs
+++ b/compiler/rustc_symbol_mangling/src/v0.rs
@@ -20,7 +20,7 @@ use rustc_middle::ty::{
self, FloatTy, GenericArg, GenericArgKind, Instance, IntTy, ReifyReason, Ty, TyCtxt,
TypeVisitable, TypeVisitableExt, UintTy,
};
-use rustc_span::kw;
+use rustc_span::sym;
pub(super) fn mangle<'tcx>(
tcx: TyCtxt<'tcx>,
@@ -902,7 +902,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
print_prefix,
ns,
disambiguated_data.disambiguator as u64,
- name.unwrap_or(kw::Empty).as_str(),
+ name.unwrap_or(sym::empty).as_str(),
)
}
diff --git a/src/tools/clippy/clippy_lints/src/manual_string_new.rs b/src/tools/clippy/clippy_lints/src/manual_string_new.rs
index 7ca3b71206671..73ee1c3c78abc 100644
--- a/src/tools/clippy/clippy_lints/src/manual_string_new.rs
+++ b/src/tools/clippy/clippy_lints/src/manual_string_new.rs
@@ -5,7 +5,7 @@ use rustc_hir::{Expr, ExprKind, PathSegment, QPath, TyKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::ty;
use rustc_session::declare_lint_pass;
-use rustc_span::{Span, sym, symbol};
+use rustc_span::{Span, sym};
declare_clippy_lint! {
/// ### What it does
@@ -67,7 +67,7 @@ impl LateLintPass<'_> for ManualStringNew {
fn is_expr_kind_empty_str(expr_kind: &ExprKind<'_>) -> bool {
if let ExprKind::Lit(lit) = expr_kind
&& let LitKind::Str(value, _) = lit.node
- && value == symbol::kw::Empty
+ && value == sym::empty
{
return true;
}
diff --git a/src/tools/clippy/clippy_lints/src/methods/or_fun_call.rs b/src/tools/clippy/clippy_lints/src/methods/or_fun_call.rs
index c74c42e9e5bd5..38cb4d51ca0f4 100644
--- a/src/tools/clippy/clippy_lints/src/methods/or_fun_call.rs
+++ b/src/tools/clippy/clippy_lints/src/methods/or_fun_call.rs
@@ -12,7 +12,7 @@ use rustc_errors::Applicability;
use rustc_lint::LateContext;
use rustc_middle::ty;
use rustc_span::Span;
-use rustc_span::symbol::{self, Symbol};
+use rustc_span::Symbol;
use {rustc_ast as ast, rustc_hir as hir};
use super::{OR_FUN_CALL, UNWRAP_OR_DEFAULT};
@@ -265,7 +265,7 @@ fn closure_body_returns_empty_to_string(cx: &LateContext<'_>, e: &hir::Expr<'_>)
&& ident.name == sym::to_string
&& let hir::Expr { kind, .. } = self_arg
&& let hir::ExprKind::Lit(lit) = kind
- && let ast::LitKind::Str(symbol::kw::Empty, _) = lit.node
+ && let ast::LitKind::Str(rustc_span::sym::empty, _) = lit.node
{
return true;
}