Eliminate word_and_empty methods.

As part of this, streamline a bunch of related stuff:

- Introduce `PathParser::word_sym`, as an alternative to
  `PathParser::word`.
- Remove `MetaItemParser::path`, and just get the two parsers
  one at a time.
- Rename `MetaItemParser::path_without_args` as `MetaItemParser::path`,
  and avoid the clone.
- Inline and remove `MetaItemParser::word_without_args`, which has a
  single use.
- Remove `MetaItemParser::word_or_empty_without_args`, which has a
  single use.
- Remove `MetaItemParser::path_is`, which is unused.
- Remove `MetaItemListParser::all_{word,path}_list`, which are unused.

Author: nnethercote

compiler/rustc_attr_parsing/src/attributes/allow_unstable.rs

@@ -53,7 +53,7 @@ fn parse_unstable<'a>(
 
     for param in list.mixed() {
         let param_span = param.span();
-        if let Some(ident) = param.meta_item().and_then(|i| i.word_without_args()) {
+        if let Some(ident) = param.meta_item().and_then(|i| i.path().word()) {
             res.push(ident.name);
         } else {
             cx.emit_err(session_diagnostics::ExpectsFeatures {

compiler/rustc_attr_parsing/src/attributes/deprecation.rs

@@ -1,5 +1,4 @@
 use rustc_attr_data_structures::{AttributeKind, DeprecatedSince, Deprecation};
-use rustc_span::symbol::Ident;
 use rustc_span::{Span, Symbol, sym};
 
 use super::SingleAttributeParser;
@@ -13,16 +12,13 @@ pub(crate) struct DeprecationParser;
 
 fn get(
     cx: &AcceptContext<'_>,
-    ident: Ident,
+    name: Symbol,
     param_span: Span,
     arg: &ArgParser<'_>,
     item: &Option<Symbol>,
 ) -> Option<Symbol> {
     if item.is_some() {
-        cx.emit_err(session_diagnostics::MultipleItem {
-            span: param_span,
-            item: ident.to_string(),
-        });
+        cx.emit_err(session_diagnostics::MultipleItem { span: param_span, item: name.to_string() });
         return None;
     }
     if let Some(v) = arg.name_value() {
@@ -83,16 +79,16 @@ impl SingleAttributeParser for DeprecationParser {
                     return None;
                 };
 
-                let (ident, arg) = param.word_or_empty();
+                let ident_name = param.path().word_sym();
 
-                match ident.name {
-                    sym::since => {
-                        since = Some(get(cx, ident, param_span, arg, &since)?);
+                match ident_name {
+                    Some(name @ sym::since) => {
+                        since = Some(get(cx, name, param_span, param.args(), &since)?);
                     }
-                    sym::note => {
-                        note = Some(get(cx, ident, param_span, arg, &note)?);
+                    Some(name @ sym::note) => {
+                        note = Some(get(cx, name, param_span, param.args(), &note)?);
                     }
-                    sym::suggestion => {
+                    Some(name @ sym::suggestion) => {
                         if !features.deprecated_suggestion() {
                             cx.emit_err(session_diagnostics::DeprecatedItemSuggestion {
                                 span: param_span,
@@ -101,12 +97,12 @@ impl SingleAttributeParser for DeprecationParser {
                             });
                         }
 
-                        suggestion = Some(get(cx, ident, param_span, arg, &suggestion)?);
+                        suggestion = Some(get(cx, name, param_span, param.args(), &suggestion)?);
                     }
                     _ => {
                         cx.emit_err(session_diagnostics::UnknownMetaItem {
                             span: param_span,
-                            item: ident.to_string(),
+                            item: param.path().to_string(),
                             expected: if features.deprecated_suggestion() {
                                 &["since", "note", "suggestion"]
                             } else {

compiler/rustc_attr_parsing/src/attributes/repr.rs

@@ -96,57 +96,65 @@ fn parse_repr(cx: &AcceptContext<'_>, param: &MetaItemParser<'_>) -> Option<Repr
 
     // FIXME(jdonszelmann): invert the parsing here to match on the word first and then the
     // structure.
-    let (ident, args) = param.word_or_empty();
-
-    match (ident.name, args) {
-        (sym::align, ArgParser::NoArgs) => {
-            cx.emit_err(session_diagnostics::InvalidReprAlignNeedArg { span: ident.span });
+    let ident = param.path().word();
+    let ident_span = ident.map_or(rustc_span::DUMMY_SP, |ident| ident.span);
+    let name = ident.map(|ident| ident.name);
+    let args = param.args();
+
+    match (name, args) {
+        (Some(sym::align), ArgParser::NoArgs) => {
+            cx.emit_err(session_diagnostics::InvalidReprAlignNeedArg { span: ident_span });
             None
         }
-        (sym::align, ArgParser::List(l)) => parse_repr_align(cx, l, param.span(), AlignKind::Align),
+        (Some(sym::align), ArgParser::List(l)) => {
+            parse_repr_align(cx, l, param.span(), AlignKind::Align)
+        }
 
-        (sym::packed, ArgParser::NoArgs) => Some(ReprPacked(Align::ONE)),
-        (sym::packed, ArgParser::List(l)) => {
+        (Some(sym::packed), ArgParser::NoArgs) => Some(ReprPacked(Align::ONE)),
+        (Some(sym::packed), ArgParser::List(l)) => {
             parse_repr_align(cx, l, param.span(), AlignKind::Packed)
         }
 
-        (sym::align | sym::packed, ArgParser::NameValue(l)) => {
+        (Some(sym::align | sym::packed), ArgParser::NameValue(l)) => {
             cx.emit_err(session_diagnostics::IncorrectReprFormatGeneric {
                 span: param.span(),
                 // FIXME(jdonszelmann) can just be a string in the diag type
-                repr_arg: &ident.to_string(),
+                repr_arg: &ident.unwrap().to_string(),
                 cause: IncorrectReprFormatGenericCause::from_lit_kind(
                     param.span(),
                     &l.value_as_lit().kind,
-                    ident.name.as_str(),
+                    ident.unwrap().as_str(),
                 ),
             });
             None
         }
 
-        (sym::Rust, ArgParser::NoArgs) => Some(ReprRust),
-        (sym::C, ArgParser::NoArgs) => Some(ReprC),
-        (sym::simd, ArgParser::NoArgs) => Some(ReprSimd),
-        (sym::transparent, ArgParser::NoArgs) => Some(ReprTransparent),
-        (i @ int_pat!(), ArgParser::NoArgs) => {
+        (Some(sym::Rust), ArgParser::NoArgs) => Some(ReprRust),
+        (Some(sym::C), ArgParser::NoArgs) => Some(ReprC),
+        (Some(sym::simd), ArgParser::NoArgs) => Some(ReprSimd),
+        (Some(sym::transparent), ArgParser::NoArgs) => Some(ReprTransparent),
+        (Some(i @ int_pat!()), ArgParser::NoArgs) => {
             // int_pat!() should make sure it always parses
             Some(ReprInt(int_type_of_word(i).unwrap()))
         }
 
         (
-            sym::Rust | sym::C | sym::simd | sym::transparent | int_pat!(),
+            Some(sym::Rust | sym::C | sym::simd | sym::transparent | int_pat!()),
             ArgParser::NameValue(_),
         ) => {
             cx.emit_err(session_diagnostics::InvalidReprHintNoValue {
                 span: param.span(),
-                name: ident.to_string(),
+                name: ident.unwrap().to_string(),
             });
             None
         }
-        (sym::Rust | sym::C | sym::simd | sym::transparent | int_pat!(), ArgParser::List(_)) => {
+        (
+            Some(sym::Rust | sym::C | sym::simd | sym::transparent | int_pat!()),
+            ArgParser::List(_),
+        ) => {
             cx.emit_err(session_diagnostics::InvalidReprHintNoParen {
                 span: param.span(),
-                name: ident.to_string(),
+                name: ident.unwrap().to_string(),
             });
             None
         }

compiler/rustc_attr_parsing/src/attributes/stability.rs

@@ -204,7 +204,7 @@ fn insert_value_into_option_or_error(
     if item.is_some() {
         cx.emit_err(session_diagnostics::MultipleItem {
             span: param.span(),
-            item: param.path_without_args().to_string(),
+            item: param.path().to_string(),
         });
         None
     } else if let Some(v) = param.args().name_value()
@@ -242,13 +242,13 @@ pub(crate) fn parse_stability(
             return None;
         };
 
-        match param.word_or_empty_without_args().name {
-            sym::feature => insert_value_into_option_or_error(cx, &param, &mut feature)?,
-            sym::since => insert_value_into_option_or_error(cx, &param, &mut since)?,
+        match param.path().word_sym() {
+            Some(sym::feature) => insert_value_into_option_or_error(cx, &param, &mut feature)?,
+            Some(sym::since) => insert_value_into_option_or_error(cx, &param, &mut since)?,
             _ => {
                 cx.emit_err(session_diagnostics::UnknownMetaItem {
                     span: param_span,
-                    item: param.path_without_args().to_string(),
+                    item: param.path().to_string(),
                     expected: &["feature", "since"],
                 });
                 return None;
@@ -310,11 +310,10 @@ pub(crate) fn parse_unstability(
             return None;
         };
 
-        let (word, args) = param.word_or_empty();
-        match word.name {
-            sym::feature => insert_value_into_option_or_error(cx, &param, &mut feature)?,
-            sym::reason => insert_value_into_option_or_error(cx, &param, &mut reason)?,
-            sym::issue => {
+        match param.path().word_sym() {
+            Some(sym::feature) => insert_value_into_option_or_error(cx, &param, &mut feature)?,
+            Some(sym::reason) => insert_value_into_option_or_error(cx, &param, &mut reason)?,
+            Some(sym::issue) => {
                 insert_value_into_option_or_error(cx, &param, &mut issue)?;
 
                 // These unwraps are safe because `insert_value_into_option_or_error` ensures the meta item
@@ -328,7 +327,7 @@ pub(crate) fn parse_unstability(
                                 session_diagnostics::InvalidIssueString {
                                     span: param.span(),
                                     cause: session_diagnostics::InvalidIssueStringCause::from_int_error_kind(
-                                        args.name_value().unwrap().value_span,
+                                        param.args().name_value().unwrap().value_span,
                                         err.kind(),
                                     ),
                                 },
@@ -338,17 +337,19 @@ pub(crate) fn parse_unstability(
                     },
                 };
             }
-            sym::soft => {
-                if !args.no_args() {
+            Some(sym::soft) => {
+                if !param.args().no_args() {
                     cx.emit_err(session_diagnostics::SoftNoArgs { span: param.span() });
                 }
                 is_soft = true;
             }
-            sym::implied_by => insert_value_into_option_or_error(cx, &param, &mut implied_by)?,
+            Some(sym::implied_by) => {
+                insert_value_into_option_or_error(cx, &param, &mut implied_by)?
+            }
             _ => {
                 cx.emit_err(session_diagnostics::UnknownMetaItem {
                     span: param.span(),
-                    item: param.path_without_args().to_string(),
+                    item: param.path().to_string(),
                     expected: &["feature", "reason", "issue", "soft", "implied_by"],
                 });
                 return None;

compiler/rustc_attr_parsing/src/context.rs

@@ -260,7 +260,8 @@ impl<'sess> AttributeParser<'sess> {
                 // }
                 ast::AttrKind::Normal(n) => {
                     let parser = MetaItemParser::from_attr(n, self.dcx());
-                    let (path, args) = parser.deconstruct();
+                    let path = parser.path();
+                    let args = parser.args();
                     let parts = path.segments().map(|i| i.name).collect::<Vec<_>>();
 
                     if let Some(accepts) = ATTRIBUTE_MAPPING.0.get(parts.as_slice()) {

compiler/rustc_attr_parsing/src/parser.rs

@@ -78,8 +78,8 @@ impl<'a> PathParser<'a> {
         (self.len() == 1).then(|| **self.segments().next().as_ref().unwrap())
     }
 
-    pub fn word_or_empty(&self) -> Ident {
-        self.word().unwrap_or_else(Ident::empty)
+    pub fn word_sym(&self) -> Option<Symbol> {
+        self.word().map(|ident| ident.name)
     }
 
     /// Asserts that this MetaItem is some specific word.
@@ -253,71 +253,28 @@ impl<'a> MetaItemParser<'a> {
         }
     }
 
-    /// Gets just the path, without the args.
-    pub fn path_without_args(&self) -> PathParser<'a> {
-        self.path.clone()
-    }
-
-    /// Gets just the args parser, without caring about the path.
-    pub fn args(&self) -> &ArgParser<'a> {
-        &self.args
-    }
-
-    pub fn deconstruct(&self) -> (PathParser<'a>, &ArgParser<'a>) {
-        (self.path_without_args(), self.args())
-    }
-
-    /// Asserts that this MetaItem starts with a path. Some examples:
+    /// Gets a `PathParser` for a path. Some examples:
     ///
     /// - `#[rustfmt::skip]`: `rustfmt::skip` is a path
     /// - `#[allow(clippy::complexity)]`: `clippy::complexity` is a path
     /// - `#[inline]`: `inline` is a single segment path
-    pub fn path(&self) -> (PathParser<'a>, &ArgParser<'a>) {
-        self.deconstruct()
-    }
-
-    /// Asserts that this MetaItem starts with a word, or single segment path.
-    /// Doesn't return the args parser.
-    ///
-    /// For examples. see [`Self::word`]
-    pub fn word_without_args(&self) -> Option<Ident> {
-        Some(self.word()?.0)
+    pub fn path(&self) -> &PathParser<'a> {
+        &self.path
     }
 
-    /// Like [`word`](Self::word), but returns an empty symbol instead of None
-    pub fn word_or_empty_without_args(&self) -> Ident {
-        self.word_or_empty().0
+    /// Gets just the args parser, without caring about the path.
+    pub fn args(&self) -> &ArgParser<'a> {
+        &self.args
     }
 
-    /// Asserts that this MetaItem starts with a word, or single segment path.
+    /// Asserts that this MetaItem starts with some specific word.
     ///
     /// Some examples:
     /// - `#[inline]`: `inline` is a word
     /// - `#[rustfmt::skip]`: `rustfmt::skip` is a path,
     ///   and not a word and should instead be parsed using [`path`](Self::path)
-    pub fn word(&self) -> Option<(Ident, &ArgParser<'a>)> {
-        let (path, args) = self.deconstruct();
-        Some((path.word()?, args))
-    }
-
-    /// Like [`word`](Self::word), but returns an empty symbol instead of None
-    pub fn word_or_empty(&self) -> (Ident, &ArgParser<'a>) {
-        let (path, args) = self.deconstruct();
-        (path.word().unwrap_or(Ident::empty()), args)
-    }
-
-    /// Asserts that this MetaItem starts with some specific word.
-    ///
-    /// See [`word`](Self::word) for examples of what a word is.
     pub fn word_is(&self, sym: Symbol) -> Option<&ArgParser<'a>> {
-        self.path_without_args().word_is(sym).then(|| self.args())
-    }
-
-    /// Asserts that this MetaItem starts with some specific path.
-    ///
-    /// See [`word`](Self::path) for examples of what a word is.
-    pub fn path_is(&self, segments: &[Symbol]) -> Option<&ArgParser<'a>> {
-        self.path_without_args().segments_is(segments).then(|| self.args())
+        self.path().word_is(sym).then(|| self.args())
     }
 }
 
@@ -560,7 +517,7 @@ impl<'a> MetaItemListParser<'a> {
     }
 
     /// Lets you pick and choose as what you want to parse each element in the list
-    pub fn mixed<'s>(&'s self) -> impl Iterator<Item = &'s MetaItemOrLitParser<'a>> + 's {
+    pub fn mixed(&self) -> impl Iterator<Item = &MetaItemOrLitParser<'a>> + '_ {
         self.sub_parsers.iter()
     }
 
@@ -572,20 +529,6 @@ impl<'a> MetaItemListParser<'a> {
         self.len() == 0
     }
 
-    /// Asserts that every item in the list is another list starting with a word.
-    ///
-    /// See [`MetaItemParser::word`] for examples of words.
-    pub fn all_word_list<'s>(&'s self) -> Option<Vec<(Ident, &'s ArgParser<'a>)>> {
-        self.mixed().map(|i| i.meta_item()?.word()).collect()
-    }
-
-    /// Asserts that every item in the list is another list starting with a full path.
-    ///
-    /// See [`MetaItemParser::path`] for examples of paths.
-    pub fn all_path_list<'s>(&'s self) -> Option<Vec<(PathParser<'a>, &'s ArgParser<'a>)>> {
-        self.mixed().map(|i| Some(i.meta_item()?.path())).collect()
-    }
-
     /// Returns Some if the list contains only a single element.
     ///
     /// Inside the Some is the parser to parse this single element.