factor built-in attribute parsing into submodule

2 files changed, 1518 insertions, 0 deletions

diff --git a/src/libsyntax/attr/builtin.rs b/src/libsyntax/attr/builtin.rs
new file mode 100644
index 00000000000..7b626a0fc27
--- /dev/null
+++ b/src/libsyntax/attr/builtin.rs
@@ -0,0 +1,708 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Parsing and validation of builtin attributes
+
+use ast::{self, Attribute, MetaItem, Name, NestedMetaItemKind};
+use errors::{Applicability, Handler};
+use feature_gate::{Features, GatedCfg};
+use parse::ParseSess;
+use syntax_pos::{symbol::Symbol, Span};
+
+use super::{list_contains_name, mark_used, MetaItemKind};
+
+enum AttrError {
+    MultipleItem(Name),
+    UnknownMetaItem(Name),
+    MissingSince,
+    MissingFeature,
+    MultipleStabilityLevels,
+    UnsupportedLiteral
+}
+
+fn handle_errors(diag: &Handler, span: Span, error: AttrError) {
+    match error {
+        AttrError::MultipleItem(item) => span_err!(diag, span, E0538,
+                                                   "multiple '{}' items", item),
+        AttrError::UnknownMetaItem(item) => span_err!(diag, span, E0541,
+                                                      "unknown meta item '{}'", item),
+        AttrError::MissingSince => span_err!(diag, span, E0542, "missing 'since'"),
+        AttrError::MissingFeature => span_err!(diag, span, E0546, "missing 'feature'"),
+        AttrError::MultipleStabilityLevels => span_err!(diag, span, E0544,
+                                                        "multiple stability levels"),
+        AttrError::UnsupportedLiteral => span_err!(diag, span, E0565, "unsupported literal"),
+    }
+}
+
+#[derive(Copy, Clone, Hash, PartialEq, RustcEncodable, RustcDecodable)]
+pub enum InlineAttr {
+    None,
+    Hint,
+    Always,
+    Never,
+}
+
+#[derive(Copy, Clone, PartialEq)]
+pub enum UnwindAttr {
+    Allowed,
+    Aborts,
+}
+
+/// Determine what `#[unwind]` attribute is present in `attrs`, if any.
+pub fn find_unwind_attr(diagnostic: Option<&Handler>, attrs: &[Attribute]) -> Option<UnwindAttr> {
+    let syntax_error = |attr: &Attribute| {
+        mark_used(attr);
+        diagnostic.map(|d| {
+            span_err!(d, attr.span, E0633, "malformed `#[unwind]` attribute");
+        });
+        None
+    };
+
+    attrs.iter().fold(None, |ia, attr| {
+        if attr.path != "unwind" {
+            return ia;
+        }
+        let meta = match attr.meta() {
+            Some(meta) => meta.node,
+            None => return ia,
+        };
+        match meta {
+            MetaItemKind::Word => {
+                syntax_error(attr)
+            }
+            MetaItemKind::List(ref items) => {
+                mark_used(attr);
+                if items.len() != 1 {
+                    syntax_error(attr)
+                } else if list_contains_name(&items[..], "allowed") {
+                    Some(UnwindAttr::Allowed)
+                } else if list_contains_name(&items[..], "aborts") {
+                    Some(UnwindAttr::Aborts)
+                } else {
+                    syntax_error(attr)
+                }
+            }
+            _ => ia,
+        }
+    })
+}
+
+/// Represents the #[stable], #[unstable], #[rustc_{deprecated,const_unstable}] attributes.
+#[derive(RustcEncodable, RustcDecodable, Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Stability {
+    pub level: StabilityLevel,
+    pub feature: Symbol,
+    pub rustc_depr: Option<RustcDeprecation>,
+    pub rustc_const_unstable: Option<RustcConstUnstable>,
+}
+
+/// The available stability levels.
+#[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
+pub enum StabilityLevel {
+    // Reason for the current stability level and the relevant rust-lang issue
+    Unstable { reason: Option<Symbol>, issue: u32 },
+    Stable { since: Symbol },
+}
+
+impl StabilityLevel {
+    pub fn is_unstable(&self) -> bool {
+        if let StabilityLevel::Unstable {..} = *self {
+            true
+        } else {
+            false
+        }
+    }
+    pub fn is_stable(&self) -> bool {
+        if let StabilityLevel::Stable {..} = *self {
+            true
+        } else {
+            false
+        }
+    }
+}
+
+#[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
+pub struct RustcDeprecation {
+    pub since: Symbol,
+    pub reason: Symbol,
+}
+
+#[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
+pub struct RustcConstUnstable {
+    pub feature: Symbol,
+}
+
+/// Check if `attrs` contains an attribute like `#![feature(feature_name)]`.
+/// This will not perform any "sanity checks" on the form of the attributes.
+pub fn contains_feature_attr(attrs: &[Attribute], feature_name: &str) -> bool {
+    attrs.iter().any(|item| {
+        item.check_name("feature") &&
+        item.meta_item_list().map(|list| {
+            list.iter().any(|mi| {
+                mi.word().map(|w| w.name() == feature_name)
+                         .unwrap_or(false)
+            })
+        }).unwrap_or(false)
+    })
+}
+
+/// Find the first stability attribute. `None` if none exists.
+pub fn find_stability(diagnostic: &Handler, attrs: &[Attribute],
+                      item_sp: Span) -> Option<Stability> {
+    find_stability_generic(diagnostic, attrs.iter(), item_sp)
+}
+
+fn find_stability_generic<'a, I>(diagnostic: &Handler,
+                                 attrs_iter: I,
+                                 item_sp: Span)
+                                 -> Option<Stability>
+    where I: Iterator<Item = &'a Attribute>
+{
+    use self::StabilityLevel::*;
+
+    let mut stab: Option<Stability> = None;
+    let mut rustc_depr: Option<RustcDeprecation> = None;
+    let mut rustc_const_unstable: Option<RustcConstUnstable> = None;
+
+    'outer: for attr in attrs_iter {
+        if ![
+            "rustc_deprecated",
+            "rustc_const_unstable",
+            "unstable",
+            "stable",
+        ].iter().any(|&s| attr.path == s) {
+            continue // not a stability level
+        }
+
+        mark_used(attr);
+
+        let meta = attr.meta();
+        if let Some(MetaItem { node: MetaItemKind::List(ref metas), .. }) = meta {
+            let meta = meta.as_ref().unwrap();
+            let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
+                if item.is_some() {
+                    handle_errors(diagnostic, meta.span, AttrError::MultipleItem(meta.name()));
+                    return false
+                }
+                if let Some(v) = meta.value_str() {
+                    *item = Some(v);
+                    true
+                } else {
+                    span_err!(diagnostic, meta.span, E0539, "incorrect meta item");
+                    false
+                }
+            };
+
+            macro_rules! get_meta {
+                ($($name:ident),+) => {
+                    $(
+                        let mut $name = None;
+                    )+
+                    for meta in metas {
+                        if let Some(mi) = meta.meta_item() {
+                            match &*mi.name().as_str() {
+                                $(
+                                    stringify!($name)
+                                        => if !get(mi, &mut $name) { continue 'outer },
+                                )+
+                                _ => {
+                                    handle_errors(diagnostic, mi.span,
+                                                  AttrError::UnknownMetaItem(mi.name()));
+                                    continue 'outer
+                                }
+                            }
+                        } else {
+                            handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
+                            continue 'outer
+                        }
+                    }
+                }
+            }
+
+            match &*meta.name().as_str() {
+                "rustc_deprecated" => {
+                    if rustc_depr.is_some() {
+                        span_err!(diagnostic, item_sp, E0540,
+                                  "multiple rustc_deprecated attributes");
+                        continue 'outer
+                    }
+
+                    get_meta!(since, reason);
+
+                    match (since, reason) {
+                        (Some(since), Some(reason)) => {
+                            rustc_depr = Some(RustcDeprecation {
+                                since,
+                                reason,
+                            })
+                        }
+                        (None, _) => {
+                            handle_errors(diagnostic, attr.span(), AttrError::MissingSince);
+                            continue
+                        }
+                        _ => {
+                            span_err!(diagnostic, attr.span(), E0543, "missing 'reason'");
+                            continue
+                        }
+                    }
+                }
+                "rustc_const_unstable" => {
+                    if rustc_const_unstable.is_some() {
+                        span_err!(diagnostic, item_sp, E0553,
+                                  "multiple rustc_const_unstable attributes");
+                        continue 'outer
+                    }
+
+                    get_meta!(feature);
+                    if let Some(feature) = feature {
+                        rustc_const_unstable = Some(RustcConstUnstable {
+                            feature
+                        });
+                    } else {
+                        span_err!(diagnostic, attr.span(), E0629, "missing 'feature'");
+                        continue
+                    }
+                }
+                "unstable" => {
+                    if stab.is_some() {
+                        handle_errors(diagnostic, attr.span(), AttrError::MultipleStabilityLevels);
+                        break
+                    }
+
+                    let mut feature = None;
+                    let mut reason = None;
+                    let mut issue = None;
+                    for meta in metas {
+                        if let Some(mi) = meta.meta_item() {
+                            match &*mi.name().as_str() {
+                                "feature" => if !get(mi, &mut feature) { continue 'outer },
+                                "reason" => if !get(mi, &mut reason) { continue 'outer },
+                                "issue" => if !get(mi, &mut issue) { continue 'outer },
+                                _ => {
+                                    handle_errors(diagnostic, meta.span,
+                                                  AttrError::UnknownMetaItem(mi.name()));
+                                    continue 'outer
+                                }
+                            }
+                        } else {
+                            handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
+                            continue 'outer
+                        }
+                    }
+
+                    match (feature, reason, issue) {
+                        (Some(feature), reason, Some(issue)) => {
+                            stab = Some(Stability {
+                                level: Unstable {
+                                    reason,
+                                    issue: {
+                                        if let Ok(issue) = issue.as_str().parse() {
+                                            issue
+                                        } else {
+                                            span_err!(diagnostic, attr.span(), E0545,
+                                                      "incorrect 'issue'");
+                                            continue
+                                        }
+                                    }
+                                },
+                                feature,
+                                rustc_depr: None,
+                                rustc_const_unstable: None,
+                            })
+                        }
+                        (None, _, _) => {
+                            handle_errors(diagnostic, attr.span(), AttrError::MissingFeature);
+                            continue
+                        }
+                        _ => {
+                            span_err!(diagnostic, attr.span(), E0547, "missing 'issue'");
+                            continue
+                        }
+                    }
+                }
+                "stable" => {
+                    if stab.is_some() {
+                        handle_errors(diagnostic, attr.span(), AttrError::MultipleStabilityLevels);
+                        break
+                    }
+
+                    let mut feature = None;
+                    let mut since = None;
+                    for meta in metas {
+                        if let NestedMetaItemKind::MetaItem(ref mi) = meta.node {
+                            match &*mi.name().as_str() {
+                                "feature" => if !get(mi, &mut feature) { continue 'outer },
+                                "since" => if !get(mi, &mut since) { continue 'outer },
+                                _ => {
+                                    handle_errors(diagnostic, meta.span,
+                                                  AttrError::UnknownMetaItem(mi.name()));
+                                    continue 'outer
+                                }
+                            }
+                        } else {
+                            handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
+                            continue 'outer
+                        }
+                    }
+
+                    match (feature, since) {
+                        (Some(feature), Some(since)) => {
+                            stab = Some(Stability {
+                                level: Stable {
+                                    since,
+                                },
+                                feature,
+                                rustc_depr: None,
+                                rustc_const_unstable: None,
+                            })
+                        }
+                        (None, _) => {
+                            handle_errors(diagnostic, attr.span(), AttrError::MissingFeature);
+                            continue
+                        }
+                        _ => {
+                            handle_errors(diagnostic, attr.span(), AttrError::MissingSince);
+                            continue
+                        }
+                    }
+                }
+                _ => unreachable!()
+            }
+        } else {
+            span_err!(diagnostic, attr.span(), E0548, "incorrect stability attribute type");
+            continue
+        }
+    }
+
+    // Merge the deprecation info into the stability info
+    if let Some(rustc_depr) = rustc_depr {
+        if let Some(ref mut stab) = stab {
+            stab.rustc_depr = Some(rustc_depr);
+        } else {
+            span_err!(diagnostic, item_sp, E0549,
+                      "rustc_deprecated attribute must be paired with \
+                       either stable or unstable attribute");
+        }
+    }
+
+    // Merge the const-unstable info into the stability info
+    if let Some(rustc_const_unstable) = rustc_const_unstable {
+        if let Some(ref mut stab) = stab {
+            stab.rustc_const_unstable = Some(rustc_const_unstable);
+        } else {
+            span_err!(diagnostic, item_sp, E0630,
+                      "rustc_const_unstable attribute must be paired with \
+                       either stable or unstable attribute");
+        }
+    }
+
+    stab
+}
+
+pub fn find_crate_name(attrs: &[Attribute]) -> Option<Symbol> {
+    super::first_attr_value_str_by_name(attrs, "crate_name")
+}
+
+/// Tests if a cfg-pattern matches the cfg set
+pub fn cfg_matches(cfg: &ast::MetaItem, sess: &ParseSess, features: Option<&Features>) -> bool {
+    eval_condition(cfg, sess, &mut |cfg| {
+        if let (Some(feats), Some(gated_cfg)) = (features, GatedCfg::gate(cfg)) {
+            gated_cfg.check_and_emit(sess, feats);
+        }
+        sess.config.contains(&(cfg.name(), cfg.value_str()))
+    })
+}
+
+/// Evaluate a cfg-like condition (with `any` and `all`), using `eval` to
+/// evaluate individual items.
+pub fn eval_condition<F>(cfg: &ast::MetaItem, sess: &ParseSess, eval: &mut F)
+                         -> bool
+    where F: FnMut(&ast::MetaItem) -> bool
+{
+    match cfg.node {
+        ast::MetaItemKind::List(ref mis) => {
+            for mi in mis.iter() {
+                if !mi.is_meta_item() {
+                    handle_errors(&sess.span_diagnostic, mi.span, AttrError::UnsupportedLiteral);
+                    return false;
+                }
+            }
+
+            // The unwraps below may look dangerous, but we've already asserted
+            // that they won't fail with the loop above.
+            match &*cfg.name().as_str() {
+                "any" => mis.iter().any(|mi| {
+                    eval_condition(mi.meta_item().unwrap(), sess, eval)
+                }),
+                "all" => mis.iter().all(|mi| {
+                    eval_condition(mi.meta_item().unwrap(), sess, eval)
+                }),
+                "not" => {
+                    if mis.len() != 1 {
+                        span_err!(sess.span_diagnostic, cfg.span, E0536, "expected 1 cfg-pattern");
+                        return false;
+                    }
+
+                    !eval_condition(mis[0].meta_item().unwrap(), sess, eval)
+                },
+                p => {
+                    span_err!(sess.span_diagnostic, cfg.span, E0537, "invalid predicate `{}`", p);
+                    false
+                }
+            }
+        },
+        ast::MetaItemKind::Word | ast::MetaItemKind::NameValue(..) => {
+            eval(cfg)
+        }
+    }
+}
+
+
+#[derive(RustcEncodable, RustcDecodable, PartialEq, PartialOrd, Clone, Debug, Eq, Hash)]
+pub struct Deprecation {
+    pub since: Option<Symbol>,
+    pub note: Option<Symbol>,
+}
+
+/// Find the deprecation attribute. `None` if none exists.
+pub fn find_deprecation(diagnostic: &Handler, attrs: &[Attribute],
+                        item_sp: Span) -> Option<Deprecation> {
+    find_deprecation_generic(diagnostic, attrs.iter(), item_sp)
+}
+
+fn find_deprecation_generic<'a, I>(diagnostic: &Handler,
+                                   attrs_iter: I,
+                                   item_sp: Span)
+                                   -> Option<Deprecation>
+    where I: Iterator<Item = &'a Attribute>
+{
+    let mut depr: Option<Deprecation> = None;
+
+    'outer: for attr in attrs_iter {
+        if attr.path != "deprecated" {
+            continue
+        }
+
+        mark_used(attr);
+
+        if depr.is_some() {
+            span_err!(diagnostic, item_sp, E0550, "multiple deprecated attributes");
+            break
+        }
+
+        depr = if let Some(metas) = attr.meta_item_list() {
+            let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
+                if item.is_some() {
+                    handle_errors(diagnostic, meta.span, AttrError::MultipleItem(meta.name()));
+                    return false
+                }
+                if let Some(v) = meta.value_str() {
+                    *item = Some(v);
+                    true
+                } else {
+                    span_err!(diagnostic, meta.span, E0551, "incorrect meta item");
+                    false
+                }
+            };
+
+            let mut since = None;
+            let mut note = None;
+            for meta in metas {
+                if let NestedMetaItemKind::MetaItem(ref mi) = meta.node {
+                    match &*mi.name().as_str() {
+                        "since" => if !get(mi, &mut since) { continue 'outer },
+                        "note" => if !get(mi, &mut note) { continue 'outer },
+                        _ => {
+                            handle_errors(diagnostic, meta.span,
+                                          AttrError::UnknownMetaItem(mi.name()));
+                            continue 'outer
+                        }
+                    }
+                } else {
+                    handle_errors(diagnostic, meta.span, AttrError::UnsupportedLiteral);
+                    continue 'outer
+                }
+            }
+
+            Some(Deprecation {since: since, note: note})
+        } else {
+            Some(Deprecation{since: None, note: None})
+        }
+    }
+
+    depr
+}
+
+#[derive(PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
+pub enum ReprAttr {
+    ReprInt(IntType),
+    ReprC,
+    ReprPacked(u32),
+    ReprSimd,
+    ReprTransparent,
+    ReprAlign(u32),
+}
+
+#[derive(Eq, Hash, PartialEq, Debug, RustcEncodable, RustcDecodable, Copy, Clone)]
+pub enum IntType {
+    SignedInt(ast::IntTy),
+    UnsignedInt(ast::UintTy)
+}
+
+impl IntType {
+    #[inline]
+    pub fn is_signed(self) -> bool {
+        use self::IntType::*;
+
+        match self {
+            SignedInt(..) => true,
+            UnsignedInt(..) => false
+        }
+    }
+}
+
+/// Parse #[repr(...)] forms.
+///
+/// Valid repr contents: any of the primitive integral type names (see
+/// `int_type_of_word`, below) to specify enum discriminant type; `C`, to use
+/// the same discriminant size that the corresponding C enum would or C
+/// structure layout, `packed` to remove padding, and `transparent` to elegate representation
+/// concerns to the only non-ZST field.
+pub fn find_repr_attrs(diagnostic: &Handler, attr: &Attribute) -> Vec<ReprAttr> {
+    use self::ReprAttr::*;
+
+    let mut acc = Vec::new();
+    if attr.path == "repr" {
+        if let Some(items) = attr.meta_item_list() {
+            mark_used(attr);
+            for item in items {
+                if !item.is_meta_item() {
+                    handle_errors(diagnostic, item.span, AttrError::UnsupportedLiteral);
+                    continue
+                }
+
+                let mut recognised = false;
+                if let Some(mi) = item.word() {
+                    let word = &*mi.name().as_str();
+                    let hint = match word {
+                        "C" => Some(ReprC),
+                        "packed" => Some(ReprPacked(1)),
+                        "simd" => Some(ReprSimd),
+                        "transparent" => Some(ReprTransparent),
+                        _ => match int_type_of_word(word) {
+                            Some(ity) => Some(ReprInt(ity)),
+                            None => {
+                                None
+                            }
+                        }
+                    };
+
+                    if let Some(h) = hint {
+                        recognised = true;
+                        acc.push(h);
+                    }
+                } else if let Some((name, value)) = item.name_value_literal() {
+                    let parse_alignment = |node: &ast::LitKind| -> Result<u32, &'static str> {
+                        if let ast::LitKind::Int(literal, ast::LitIntType::Unsuffixed) = node {
+                            if literal.is_power_of_two() {
+                                // rustc::ty::layout::Align restricts align to <= 2^29
+                                if *literal <= 1 << 29 {
+                                    Ok(*literal as u32)
+                                } else {
+                                    Err("larger than 2^29")
+                                }
+                            } else {
+                                Err("not a power of two")
+                            }
+                        } else {
+                            Err("not an unsuffixed integer")
+                        }
+                    };
+
+                    let mut literal_error = None;
+                    if name == "align" {
+                        recognised = true;
+                        match parse_alignment(&value.node) {
+                            Ok(literal) => acc.push(ReprAlign(literal)),
+                            Err(message) => literal_error = Some(message)
+                        };
+                    }
+                    else if name == "packed" {
+                        recognised = true;
+                        match parse_alignment(&value.node) {
+                            Ok(literal) => acc.push(ReprPacked(literal)),
+                            Err(message) => literal_error = Some(message)
+                        };
+                    }
+                    if let Some(literal_error) = literal_error {
+                        span_err!(diagnostic, item.span, E0589,
+                                  "invalid `repr(align)` attribute: {}", literal_error);
+                    }
+                } else {
+                    if let Some(meta_item) = item.meta_item() {
+                        if meta_item.name() == "align" {
+                            if let MetaItemKind::NameValue(ref value) = meta_item.node {
+                                recognised = true;
+                                let mut err = struct_span_err!(diagnostic, item.span, E0693,
+                                    "incorrect `repr(align)` attribute format");
+                                match value.node {
+                                    ast::LitKind::Int(int, ast::LitIntType::Unsuffixed) => {
+                                        err.span_suggestion_with_applicability(
+                                            item.span,
+                                            "use parentheses instead",
+                                            format!("align({})", int),
+                                            Applicability::MachineApplicable
+                                        );
+                                    }
+                                    ast::LitKind::Str(s, _) => {
+                                        err.span_suggestion_with_applicability(
+                                            item.span,
+                                            "use parentheses instead",
+                                            format!("align({})", s),
+                                            Applicability::MachineApplicable
+                                        );
+                                    }
+                                    _ => {}
+                                }
+                                err.emit();
+                            }
+                        }
+                    }
+                }
+                if !recognised {
+                    // Not a word we recognize
+                    span_err!(diagnostic, item.span, E0552,
+                              "unrecognized representation hint");
+                }
+            }
+        }
+    }
+    acc
+}
+
+fn int_type_of_word(s: &str) -> Option<IntType> {
+    use self::IntType::*;
+
+    match s {
+        "i8" => Some(SignedInt(ast::IntTy::I8)),
+        "u8" => Some(UnsignedInt(ast::UintTy::U8)),
+        "i16" => Some(SignedInt(ast::IntTy::I16)),
+        "u16" => Some(UnsignedInt(ast::UintTy::U16)),
+        "i32" => Some(SignedInt(ast::IntTy::I32)),
+        "u32" => Some(UnsignedInt(ast::UintTy::U32)),
+        "i64" => Some(SignedInt(ast::IntTy::I64)),
+        "u64" => Some(UnsignedInt(ast::UintTy::U64)),
+        "i128" => Some(SignedInt(ast::IntTy::I128)),
+        "u128" => Some(UnsignedInt(ast::UintTy::U128)),
+        "isize" => Some(SignedInt(ast::IntTy::Isize)),
+        "usize" => Some(UnsignedInt(ast::UintTy::Usize)),
+        _ => None
+    }
+}
diff --git a/src/libsyntax/attr/mod.rs b/src/libsyntax/attr/mod.rs
new file mode 100644
index 00000000000..4e27d6c1525
--- /dev/null
+++ b/src/libsyntax/attr/mod.rs
@@ -0,0 +1,810 @@
+// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+//! Functions dealing with attributes and meta items
+
+mod builtin;
+
+pub use self::builtin::{
+    cfg_matches, contains_feature_attr, eval_condition, find_crate_name, find_deprecation,
+    find_repr_attrs, find_stability, find_unwind_attr, Deprecation, InlineAttr, IntType, ReprAttr,
+    RustcConstUnstable, RustcDeprecation, Stability, StabilityLevel, UnwindAttr,
+};
+pub use self::IntType::*;
+pub use self::ReprAttr::*;
+pub use self::StabilityLevel::*;
+
+use ast;
+use ast::{AttrId, Attribute, Name, Ident, Path, PathSegment};
+use ast::{MetaItem, MetaItemKind, NestedMetaItem, NestedMetaItemKind};
+use ast::{Lit, LitKind, Expr, ExprKind, Item, Local, Stmt, StmtKind, GenericParam};
+use codemap::{BytePos, Spanned, respan, dummy_spanned};
+use syntax_pos::Span;
+use parse::lexer::comments::{doc_comment_style, strip_doc_comment_decoration};
+use parse::parser::Parser;
+use parse::{self, ParseSess, PResult};
+use parse::token::{self, Token};
+use ptr::P;
+use symbol::Symbol;
+use tokenstream::{TokenStream, TokenTree, Delimited};
+use util::ThinVec;
+use GLOBALS;
+
+use std::iter;
+
+pub fn mark_used(attr: &Attribute) {
+    debug!("Marking {:?} as used.", attr);
+    let AttrId(id) = attr.id;
+    GLOBALS.with(|globals| {
+        let mut slot = globals.used_attrs.lock();
+        let idx = (id / 64) as usize;
+        let shift = id % 64;
+        if slot.len() <= idx {
+            slot.resize(idx + 1, 0);
+        }
+        slot[idx] |= 1 << shift;
+    });
+}
+
+pub fn is_used(attr: &Attribute) -> bool {
+    let AttrId(id) = attr.id;
+    GLOBALS.with(|globals| {
+        let slot = globals.used_attrs.lock();
+        let idx = (id / 64) as usize;
+        let shift = id % 64;
+        slot.get(idx).map(|bits| bits & (1 << shift) != 0)
+            .unwrap_or(false)
+    })
+}
+
+pub fn mark_known(attr: &Attribute) {
+    debug!("Marking {:?} as known.", attr);
+    let AttrId(id) = attr.id;
+    GLOBALS.with(|globals| {
+        let mut slot = globals.known_attrs.lock();
+        let idx = (id / 64) as usize;
+        let shift = id % 64;
+        if slot.len() <= idx {
+            slot.resize(idx + 1, 0);
+        }
+        slot[idx] |= 1 << shift;
+    });
+}
+
+pub fn is_known(attr: &Attribute) -> bool {
+    let AttrId(id) = attr.id;
+    GLOBALS.with(|globals| {
+        let slot = globals.known_attrs.lock();
+        let idx = (id / 64) as usize;
+        let shift = id % 64;
+        slot.get(idx).map(|bits| bits & (1 << shift) != 0)
+            .unwrap_or(false)
+    })
+}
+
+const RUST_KNOWN_TOOL: &[&str] = &["clippy", "rustfmt"];
+
+pub fn is_known_tool(attr: &Attribute) -> bool {
+    let tool_name =
+        attr.path.segments.iter().next().expect("empty path in attribute").ident.name;
+    RUST_KNOWN_TOOL.contains(&tool_name.as_str().as_ref())
+}
+
+impl NestedMetaItem {
+    /// Returns the MetaItem if self is a NestedMetaItemKind::MetaItem.
+    pub fn meta_item(&self) -> Option<&MetaItem> {
+        match self.node {
+            NestedMetaItemKind::MetaItem(ref item) => Some(item),
+            _ => None
+        }
+    }
+
+    /// Returns the Lit if self is a NestedMetaItemKind::Literal.
+    pub fn literal(&self) -> Option<&Lit> {
+        match self.node {
+            NestedMetaItemKind::Literal(ref lit) => Some(lit),
+            _ => None
+        }
+    }
+
+    /// Returns the Span for `self`.
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    /// Returns true if this list item is a MetaItem with a name of `name`.
+    pub fn check_name(&self, name: &str) -> bool {
+        self.meta_item().map_or(false, |meta_item| meta_item.check_name(name))
+    }
+
+    /// Returns the name of the meta item, e.g. `foo` in `#[foo]`,
+    /// `#[foo="bar"]` and `#[foo(bar)]`, if self is a MetaItem
+    pub fn name(&self) -> Option<Name> {
+        self.meta_item().and_then(|meta_item| Some(meta_item.name()))
+    }
+
+    /// Gets the string value if self is a MetaItem and the MetaItem is a
+    /// MetaItemKind::NameValue variant containing a string, otherwise None.
+    pub fn value_str(&self) -> Option<Symbol> {
+        self.meta_item().and_then(|meta_item| meta_item.value_str())
+    }
+
+    /// Returns a name and single literal value tuple of the MetaItem.
+    pub fn name_value_literal(&self) -> Option<(Name, &Lit)> {
+        self.meta_item().and_then(
+            |meta_item| meta_item.meta_item_list().and_then(
+                |meta_item_list| {
+                    if meta_item_list.len() == 1 {
+                        let nested_item = &meta_item_list[0];
+                        if nested_item.is_literal() {
+                            Some((meta_item.name(), nested_item.literal().unwrap()))
+                        } else {
+                            None
+                        }
+                    }
+                    else {
+                        None
+                    }}))
+    }
+
+    /// Returns a MetaItem if self is a MetaItem with Kind Word.
+    pub fn word(&self) -> Option<&MetaItem> {
+        self.meta_item().and_then(|meta_item| if meta_item.is_word() {
+            Some(meta_item)
+        } else {
+            None
+        })
+    }
+
+    /// Gets a list of inner meta items from a list MetaItem type.
+    pub fn meta_item_list(&self) -> Option<&[NestedMetaItem]> {
+        self.meta_item().and_then(|meta_item| meta_item.meta_item_list())
+    }
+
+    /// Returns `true` if the variant is MetaItem.
+    pub fn is_meta_item(&self) -> bool {
+        self.meta_item().is_some()
+    }
+
+    /// Returns `true` if the variant is Literal.
+    pub fn is_literal(&self) -> bool {
+        self.literal().is_some()
+    }
+
+    /// Returns `true` if self is a MetaItem and the meta item is a word.
+    pub fn is_word(&self) -> bool {
+        self.word().is_some()
+    }
+
+    /// Returns `true` if self is a MetaItem and the meta item is a ValueString.
+    pub fn is_value_str(&self) -> bool {
+        self.value_str().is_some()
+    }
+
+    /// Returns `true` if self is a MetaItem and the meta item is a list.
+    pub fn is_meta_item_list(&self) -> bool {
+        self.meta_item_list().is_some()
+    }
+}
+
+fn name_from_path(path: &Path) -> Name {
+    path.segments.last().expect("empty path in attribute").ident.name
+}
+
+impl Attribute {
+    pub fn check_name(&self, name: &str) -> bool {
+        let matches = self.path == name;
+        if matches {
+            mark_used(self);
+        }
+        matches
+    }
+
+    /// Returns the **last** segment of the name of this attribute.
+    /// E.g. `foo` for `#[foo]`, `skip` for `#[rustfmt::skip]`.
+    pub fn name(&self) -> Name {
+        name_from_path(&self.path)
+    }
+
+    pub fn value_str(&self) -> Option<Symbol> {
+        self.meta().and_then(|meta| meta.value_str())
+    }
+
+    pub fn meta_item_list(&self) -> Option<Vec<NestedMetaItem>> {
+        match self.meta() {
+            Some(MetaItem { node: MetaItemKind::List(list), .. }) => Some(list),
+            _ => None
+        }
+    }
+
+    pub fn is_word(&self) -> bool {
+        self.path.segments.len() == 1 && self.tokens.is_empty()
+    }
+
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    pub fn is_meta_item_list(&self) -> bool {
+        self.meta_item_list().is_some()
+    }
+
+    /// Indicates if the attribute is a Value String.
+    pub fn is_value_str(&self) -> bool {
+        self.value_str().is_some()
+    }
+
+    pub fn is_scoped(&self) -> bool {
+        self.path.segments.len() > 1
+    }
+}
+
+impl MetaItem {
+    pub fn name(&self) -> Name {
+        name_from_path(&self.ident)
+    }
+
+    pub fn value_str(&self) -> Option<Symbol> {
+        match self.node {
+            MetaItemKind::NameValue(ref v) => {
+                match v.node {
+                    LitKind::Str(ref s, _) => Some(*s),
+                    _ => None,
+                }
+            },
+            _ => None
+        }
+    }
+
+    pub fn meta_item_list(&self) -> Option<&[NestedMetaItem]> {
+        match self.node {
+            MetaItemKind::List(ref l) => Some(&l[..]),
+            _ => None
+        }
+    }
+
+    pub fn is_word(&self) -> bool {
+        match self.node {
+            MetaItemKind::Word => true,
+            _ => false,
+        }
+    }
+
+    pub fn span(&self) -> Span { self.span }
+
+    pub fn check_name(&self, name: &str) -> bool {
+        self.name() == name
+    }
+
+    pub fn is_value_str(&self) -> bool {
+        self.value_str().is_some()
+    }
+
+    pub fn is_meta_item_list(&self) -> bool {
+        self.meta_item_list().is_some()
+    }
+}
+
+impl Attribute {
+    /// Extract the MetaItem from inside this Attribute.
+    pub fn meta(&self) -> Option<MetaItem> {
+        let mut tokens = self.tokens.trees().peekable();
+        Some(MetaItem {
+            ident: self.path.clone(),
+            node: if let Some(node) = MetaItemKind::from_tokens(&mut tokens) {
+                if tokens.peek().is_some() {
+                    return None;
+                }
+                node
+            } else {
+                return None;
+            },
+            span: self.span,
+        })
+    }
+
+    pub fn parse<'a, T, F>(&self, sess: &'a ParseSess, mut f: F) -> PResult<'a, T>
+        where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
+    {
+        let mut parser = Parser::new(sess, self.tokens.clone(), None, false, false);
+        let result = f(&mut parser)?;
+        if parser.token != token::Eof {
+            parser.unexpected()?;
+        }
+        Ok(result)
+    }
+
+    pub fn parse_list<'a, T, F>(&self, sess: &'a ParseSess, mut f: F) -> PResult<'a, Vec<T>>
+        where F: FnMut(&mut Parser<'a>) -> PResult<'a, T>,
+    {
+        if self.tokens.is_empty() {
+            return Ok(Vec::new());
+        }
+        self.parse(sess, |parser| {
+            parser.expect(&token::OpenDelim(token::Paren))?;
+            let mut list = Vec::new();
+            while !parser.eat(&token::CloseDelim(token::Paren)) {
+                list.push(f(parser)?);
+                if !parser.eat(&token::Comma) {
+                   parser.expect(&token::CloseDelim(token::Paren))?;
+                    break
+                }
+            }
+            Ok(list)
+        })
+    }
+
+    pub fn parse_meta<'a>(&self, sess: &'a ParseSess) -> PResult<'a, MetaItem> {
+        Ok(MetaItem {
+            ident: self.path.clone(),
+            node: self.parse(sess, |parser| parser.parse_meta_item_kind())?,
+            span: self.span,
+        })
+    }
+
+    /// Convert self to a normal #[doc="foo"] comment, if it is a
+    /// comment like `///` or `/** */`. (Returns self unchanged for
+    /// non-sugared doc attributes.)
+    pub fn with_desugared_doc<T, F>(&self, f: F) -> T where
+        F: FnOnce(&Attribute) -> T,
+    {
+        if self.is_sugared_doc {
+            let comment = self.value_str().unwrap();
+            let meta = mk_name_value_item_str(
+                Ident::from_str("doc"),
+                dummy_spanned(Symbol::intern(&strip_doc_comment_decoration(&comment.as_str()))));
+            let mut attr = if self.style == ast::AttrStyle::Outer {
+                mk_attr_outer(self.span, self.id, meta)
+            } else {
+                mk_attr_inner(self.span, self.id, meta)
+            };
+            attr.is_sugared_doc = true;
+            f(&attr)
+        } else {
+            f(self)
+        }
+    }
+}
+
+/* Constructors */
+
+pub fn mk_name_value_item_str(ident: Ident, value: Spanned<Symbol>) -> MetaItem {
+    let value = respan(value.span, LitKind::Str(value.node, ast::StrStyle::Cooked));
+    mk_name_value_item(ident.span.to(value.span), ident, value)
+}
+
+pub fn mk_name_value_item(span: Span, ident: Ident, value: ast::Lit) -> MetaItem {
+    MetaItem { ident: Path::from_ident(ident), span, node: MetaItemKind::NameValue(value) }
+}
+
+pub fn mk_list_item(span: Span, ident: Ident, items: Vec<NestedMetaItem>) -> MetaItem {
+    MetaItem { ident: Path::from_ident(ident), span, node: MetaItemKind::List(items) }
+}
+
+pub fn mk_word_item(ident: Ident) -> MetaItem {
+    MetaItem { ident: Path::from_ident(ident), span: ident.span, node: MetaItemKind::Word }
+}
+
+pub fn mk_nested_word_item(ident: Ident) -> NestedMetaItem {
+    respan(ident.span, NestedMetaItemKind::MetaItem(mk_word_item(ident)))
+}
+
+pub fn mk_attr_id() -> AttrId {
+    use std::sync::atomic::AtomicUsize;
+    use std::sync::atomic::Ordering;
+
+    static NEXT_ATTR_ID: AtomicUsize = AtomicUsize::new(0);
+
+    let id = NEXT_ATTR_ID.fetch_add(1, Ordering::SeqCst);
+    assert!(id != ::std::usize::MAX);
+    AttrId(id)
+}
+
+/// Returns an inner attribute with the given value.
+pub fn mk_attr_inner(span: Span, id: AttrId, item: MetaItem) -> Attribute {
+    mk_spanned_attr_inner(span, id, item)
+}
+
+/// Returns an inner attribute with the given value and span.
+pub fn mk_spanned_attr_inner(sp: Span, id: AttrId, item: MetaItem) -> Attribute {
+    Attribute {
+        id,
+        style: ast::AttrStyle::Inner,
+        path: item.ident,
+        tokens: item.node.tokens(item.span),
+        is_sugared_doc: false,
+        span: sp,
+    }
+}
+
+/// Returns an outer attribute with the given value.
+pub fn mk_attr_outer(span: Span, id: AttrId, item: MetaItem) -> Attribute {
+    mk_spanned_attr_outer(span, id, item)
+}
+
+/// Returns an outer attribute with the given value and span.
+pub fn mk_spanned_attr_outer(sp: Span, id: AttrId, item: MetaItem) -> Attribute {
+    Attribute {
+        id,
+        style: ast::AttrStyle::Outer,
+        path: item.ident,
+        tokens: item.node.tokens(item.span),
+        is_sugared_doc: false,
+        span: sp,
+    }
+}
+
+pub fn mk_sugared_doc_attr(id: AttrId, text: Symbol, span: Span) -> Attribute {
+    let style = doc_comment_style(&text.as_str());
+    let lit = respan(span, LitKind::Str(text, ast::StrStyle::Cooked));
+    Attribute {
+        id,
+        style,
+        path: Path::from_ident(Ident::from_str("doc").with_span_pos(span)),
+        tokens: MetaItemKind::NameValue(lit).tokens(span),
+        is_sugared_doc: true,
+        span,
+    }
+}
+
+pub fn list_contains_name(items: &[NestedMetaItem], name: &str) -> bool {
+    items.iter().any(|item| {
+        item.check_name(name)
+    })
+}
+
+pub fn contains_name(attrs: &[Attribute], name: &str) -> bool {
+    attrs.iter().any(|item| {
+        item.check_name(name)
+    })
+}
+
+pub fn find_by_name<'a>(attrs: &'a [Attribute], name: &str) -> Option<&'a Attribute> {
+    attrs.iter().find(|attr| attr.check_name(name))
+}
+
+pub fn first_attr_value_str_by_name(attrs: &[Attribute], name: &str) -> Option<Symbol> {
+    attrs.iter()
+        .find(|at| at.check_name(name))
+        .and_then(|at| at.value_str())
+}
+
+impl MetaItem {
+    fn tokens(&self) -> TokenStream {
+        let mut idents = vec![];
+        let mut last_pos = BytePos(0 as u32);
+        for (i, segment) in self.ident.segments.iter().enumerate() {
+            let is_first = i == 0;
+            if !is_first {
+                let mod_sep_span = Span::new(last_pos,
+                                             segment.ident.span.lo(),
+                                             segment.ident.span.ctxt());
+                idents.push(TokenTree::Token(mod_sep_span, Token::ModSep).into());
+            }
+            idents.push(TokenTree::Token(segment.ident.span,
+                                         Token::from_ast_ident(segment.ident)).into());
+            last_pos = segment.ident.span.hi();
+        }
+        idents.push(self.node.tokens(self.span));
+        TokenStream::concat(idents)
+    }
+
+    fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<MetaItem>
+        where I: Iterator<Item = TokenTree>,
+    {
+        // FIXME: Share code with `parse_path`.
+        let ident = match tokens.next() {
+            Some(TokenTree::Token(span, Token::Ident(ident, _))) => {
+                if let Some(TokenTree::Token(_, Token::ModSep)) = tokens.peek() {
+                    let mut segments = vec![PathSegment::from_ident(ident.with_span_pos(span))];
+                    tokens.next();
+                    loop {
+                        if let Some(TokenTree::Token(span,
+                                                     Token::Ident(ident, _))) = tokens.next() {
+                            segments.push(PathSegment::from_ident(ident.with_span_pos(span)));
+                        } else {
+                            return None;
+                        }
+                        if let Some(TokenTree::Token(_, Token::ModSep)) = tokens.peek() {
+                            tokens.next();
+                        } else {
+                            break;
+                        }
+                    }
+                    let span = span.with_hi(segments.last().unwrap().ident.span.hi());
+                    Path { span, segments }
+                } else {
+                    Path::from_ident(ident.with_span_pos(span))
+                }
+            }
+            Some(TokenTree::Token(_, Token::Interpolated(ref nt))) => match nt.0 {
+                token::Nonterminal::NtIdent(ident, _) => Path::from_ident(ident),
+                token::Nonterminal::NtMeta(ref meta) => return Some(meta.clone()),
+                token::Nonterminal::NtPath(ref path) => path.clone(),
+                _ => return None,
+            },
+            _ => return None,
+        };
+        let list_closing_paren_pos = tokens.peek().map(|tt| tt.span().hi());
+        let node = MetaItemKind::from_tokens(tokens)?;
+        let hi = match node {
+            MetaItemKind::NameValue(ref lit) => lit.span.hi(),
+            MetaItemKind::List(..) => list_closing_paren_pos.unwrap_or(ident.span.hi()),
+            _ => ident.span.hi(),
+        };
+        let span = ident.span.with_hi(hi);
+        Some(MetaItem { ident, node, span })
+    }
+}
+
+impl MetaItemKind {
+    pub fn tokens(&self, span: Span) -> TokenStream {
+        match *self {
+            MetaItemKind::Word => TokenStream::empty(),
+            MetaItemKind::NameValue(ref lit) => {
+                TokenStream::concat(vec![TokenTree::Token(span, Token::Eq).into(), lit.tokens()])
+            }
+            MetaItemKind::List(ref list) => {
+                let mut tokens = Vec::new();
+                for (i, item) in list.iter().enumerate() {
+                    if i > 0 {
+                        tokens.push(TokenTree::Token(span, Token::Comma).into());
+                    }
+                    tokens.push(item.node.tokens());
+                }
+                TokenTree::Delimited(span, Delimited {
+                    delim: token::Paren,
+                    tts: TokenStream::concat(tokens).into(),
+                }).into()
+            }
+        }
+    }
+
+    fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<MetaItemKind>
+        where I: Iterator<Item = TokenTree>,
+    {
+        let delimited = match tokens.peek().cloned() {
+            Some(TokenTree::Token(_, token::Eq)) => {
+                tokens.next();
+                return if let Some(TokenTree::Token(span, token)) = tokens.next() {
+                    LitKind::from_token(token)
+                        .map(|lit| MetaItemKind::NameValue(Spanned { node: lit, span: span }))
+                } else {
+                    None
+                };
+            }
+            Some(TokenTree::Delimited(_, ref delimited)) if delimited.delim == token::Paren => {
+                tokens.next();
+                delimited.stream()
+            }
+            _ => return Some(MetaItemKind::Word),
+        };
+
+        let mut tokens = delimited.into_trees().peekable();
+        let mut result = Vec::new();
+        while let Some(..) = tokens.peek() {
+            let item = NestedMetaItemKind::from_tokens(&mut tokens)?;
+            result.push(respan(item.span(), item));
+            match tokens.next() {
+                None | Some(TokenTree::Token(_, Token::Comma)) => {}
+                _ => return None,
+            }
+        }
+        Some(MetaItemKind::List(result))
+    }
+}
+
+impl NestedMetaItemKind {
+    fn span(&self) -> Span {
+        match *self {
+            NestedMetaItemKind::MetaItem(ref item) => item.span,
+            NestedMetaItemKind::Literal(ref lit) => lit.span,
+        }
+    }
+
+    fn tokens(&self) -> TokenStream {
+        match *self {
+            NestedMetaItemKind::MetaItem(ref item) => item.tokens(),
+            NestedMetaItemKind::Literal(ref lit) => lit.tokens(),
+        }
+    }
+
+    fn from_tokens<I>(tokens: &mut iter::Peekable<I>) -> Option<NestedMetaItemKind>
+        where I: Iterator<Item = TokenTree>,
+    {
+        if let Some(TokenTree::Token(span, token)) = tokens.peek().cloned() {
+            if let Some(node) = LitKind::from_token(token) {
+                tokens.next();
+                return Some(NestedMetaItemKind::Literal(respan(span, node)));
+            }
+        }
+
+        MetaItem::from_tokens(tokens).map(NestedMetaItemKind::MetaItem)
+    }
+}
+
+impl Lit {
+    fn tokens(&self) -> TokenStream {
+        TokenTree::Token(self.span, self.node.token()).into()
+    }
+}
+
+impl LitKind {
+    fn token(&self) -> Token {
+        use std::ascii;
+
+        match *self {
+            LitKind::Str(string, ast::StrStyle::Cooked) => {
+                let escaped = string.as_str().escape_default();
+                Token::Literal(token::Lit::Str_(Symbol::intern(&escaped)), None)
+            }
+            LitKind::Str(string, ast::StrStyle::Raw(n)) => {
+                Token::Literal(token::Lit::StrRaw(string, n), None)
+            }
+            LitKind::ByteStr(ref bytes) => {
+                let string = bytes.iter().cloned().flat_map(ascii::escape_default)
+                    .map(Into::<char>::into).collect::<String>();
+                Token::Literal(token::Lit::ByteStr(Symbol::intern(&string)), None)
+            }
+            LitKind::Byte(byte) => {
+                let string: String = ascii::escape_default(byte).map(Into::<char>::into).collect();
+                Token::Literal(token::Lit::Byte(Symbol::intern(&string)), None)
+            }
+            LitKind::Char(ch) => {
+                let string: String = ch.escape_default().map(Into::<char>::into).collect();
+                Token::Literal(token::Lit::Char(Symbol::intern(&string)), None)
+            }
+            LitKind::Int(n, ty) => {
+                let suffix = match ty {
+                    ast::LitIntType::Unsigned(ty) => Some(Symbol::intern(ty.ty_to_string())),
+                    ast::LitIntType::Signed(ty) => Some(Symbol::intern(ty.ty_to_string())),
+                    ast::LitIntType::Unsuffixed => None,
+                };
+                Token::Literal(token::Lit::Integer(Symbol::intern(&n.to_string())), suffix)
+            }
+            LitKind::Float(symbol, ty) => {
+                Token::Literal(token::Lit::Float(symbol), Some(Symbol::intern(ty.ty_to_string())))
+            }
+            LitKind::FloatUnsuffixed(symbol) => Token::Literal(token::Lit::Float(symbol), None),
+            LitKind::Bool(value) => Token::Ident(Ident::with_empty_ctxt(Symbol::intern(if value {
+                "true"
+            } else {
+                "false"
+            })), false),
+        }
+    }
+
+    fn from_token(token: Token) -> Option<LitKind> {
+        match token {
+            Token::Ident(ident, false) if ident.name == "true" => Some(LitKind::Bool(true)),
+            Token::Ident(ident, false) if ident.name == "false" => Some(LitKind::Bool(false)),
+            Token::Interpolated(ref nt) => match nt.0 {
+                token::NtExpr(ref v) | token::NtLiteral(ref v) => match v.node {
+                    ExprKind::Lit(ref lit) => Some(lit.node.clone()),
+                    _ => None,
+                },
+                _ => None,
+            },
+            Token::Literal(lit, suf) => {
+                let (suffix_illegal, result) = parse::lit_token(lit, suf, None);
+                if suffix_illegal && suf.is_some() {
+                    return None;
+                }
+                result
+            }
+            _ => None,
+        }
+    }
+}
+
+pub trait HasAttrs: Sized {
+    fn attrs(&self) -> &[ast::Attribute];
+    fn map_attrs<F: FnOnce(Vec<ast::Attribute>) -> Vec<ast::Attribute>>(self, f: F) -> Self;
+}
+
+impl<T: HasAttrs> HasAttrs for Spanned<T> {
+    fn attrs(&self) -> &[ast::Attribute] { self.node.attrs() }
+    fn map_attrs<F: FnOnce(Vec<ast::Attribute>) -> Vec<ast::Attribute>>(self, f: F) -> Self {
+        respan(self.span, self.node.map_attrs(f))
+    }
+}
+
+impl HasAttrs for Vec<Attribute> {
+    fn attrs(&self) -> &[Attribute] {
+        self
+    }
+    fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
+        f(self)
+    }
+}
+
+impl HasAttrs for ThinVec<Attribute> {
+    fn attrs(&self) -> &[Attribute] {
+        self
+    }
+    fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
+        f(self.into()).into()
+    }
+}
+
+impl<T: HasAttrs + 'static> HasAttrs for P<T> {
+    fn attrs(&self) -> &[Attribute] {
+        (**self).attrs()
+    }
+    fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
+        self.map(|t| t.map_attrs(f))
+    }
+}
+
+impl HasAttrs for StmtKind {
+    fn attrs(&self) -> &[Attribute] {
+        match *self {
+            StmtKind::Local(ref local) => local.attrs(),
+            StmtKind::Item(..) => &[],
+            StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => expr.attrs(),
+            StmtKind::Mac(ref mac) => {
+                let (_, _, ref attrs) = **mac;
+                attrs.attrs()
+            }
+        }
+    }
+
+    fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(self, f: F) -> Self {
+        match self {
+            StmtKind::Local(local) => StmtKind::Local(local.map_attrs(f)),
+            StmtKind::Item(..) => self,
+            StmtKind::Expr(expr) => StmtKind::Expr(expr.map_attrs(f)),
+            StmtKind::Semi(expr) => StmtKind::Semi(expr.map_attrs(f)),
+            StmtKind::Mac(mac) => StmtKind::Mac(mac.map(|(mac, style, attrs)| {
+                (mac, style, attrs.map_attrs(f))
+            })),
+        }
+    }
+}
+
+impl HasAttrs for Stmt {
+    fn attrs(&self) -> &[ast::Attribute] { self.node.attrs() }
+    fn map_attrs<F: FnOnce(Vec<ast::Attribute>) -> Vec<ast::Attribute>>(self, f: F) -> Self {
+        Stmt { id: self.id, node: self.node.map_attrs(f), span: self.span }
+    }
+}
+
+impl HasAttrs for GenericParam {
+    fn attrs(&self) -> &[ast::Attribute] {
+        &self.attrs
+    }
+
+    fn map_attrs<F: FnOnce(Vec<Attribute>) -> Vec<Attribute>>(mut self, f: F) -> Self {
+        self.attrs = self.attrs.map_attrs(f);
+        self
+    }
+}
+
+macro_rules! derive_has_attrs {
+    ($($ty:path),*) => { $(
+        impl HasAttrs for $ty {
+            fn attrs(&self) -> &[Attribute] {
+                &self.attrs
+            }
+
+            fn map_attrs<F>(mut self, f: F) -> Self
+                where F: FnOnce(Vec<Attribute>) -> Vec<Attribute>,
+            {
+                self.attrs = self.attrs.map_attrs(f);
+                self
+            }
+        }
+    )* }
+}
+
+derive_has_attrs! {
+    Item, Expr, Local, ast::ForeignItem, ast::StructField, ast::ImplItem, ast::TraitItem, ast::Arm,
+    ast::Field, ast::FieldPat, ast::Variant_
+}