blob: f7a000935caf0e05c7d7e71551a2efe7b9e8099c [file] [log] [blame]
//! Parsing and validation of builtin attributes
use crate::ast::{self, Attribute, MetaItem, Name, NestedMetaItemKind};
use crate::feature_gate::{Features, GatedCfg};
use crate::parse::ParseSess;
use errors::{Applicability, Handler};
use syntax_pos::{symbol::Symbol, Span};
use super::{mark_used, MetaItemKind};
enum AttrError {
MultipleItem(Name),
UnknownMetaItem(Name, &'static [&'static str]),
MissingSince,
MissingFeature,
MultipleStabilityLevels,
UnsupportedLiteral(&'static str, /* is_bytestr */ bool),
}
fn handle_errors(sess: &ParseSess, span: Span, error: AttrError) {
let diag = &sess.span_diagnostic;
match error {
AttrError::MultipleItem(item) => span_err!(diag, span, E0538,
"multiple '{}' items", item),
AttrError::UnknownMetaItem(item, expected) => {
let expected = expected
.iter()
.map(|name| format!("`{}`", name))
.collect::<Vec<_>>();
struct_span_err!(diag, span, E0541, "unknown meta item '{}'", item)
.span_label(span, format!("expected one of {}", expected.join(", ")))
.emit();
}
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(
msg,
is_bytestr,
) => {
let mut err = struct_span_err!(diag, span, E0565, "{}", msg);
if is_bytestr {
if let Ok(lint_str) = sess.source_map().span_to_snippet(span) {
err.span_suggestion(
span,
"consider removing the prefix",
format!("{}", &lint_str[1..]),
Applicability::MaybeIncorrect,
);
}
}
err.emit();
}
}
}
#[derive(Copy, Clone, Hash, PartialEq, RustcEncodable, RustcDecodable)]
pub enum InlineAttr {
None,
Hint,
Always,
Never,
}
#[derive(Copy, Clone, Hash, PartialEq, RustcEncodable, RustcDecodable)]
pub enum OptimizeAttr {
None,
Speed,
Size,
}
#[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> {
attrs.iter().fold(None, |ia, attr| {
if attr.check_name("unwind") {
if let Some(meta) = attr.meta() {
if let MetaItemKind::List(items) = meta.node {
if items.len() == 1 {
if items[0].check_name("allowed") {
return Some(UnwindAttr::Allowed);
} else if items[0].check_name("aborts") {
return Some(UnwindAttr::Aborts);
}
}
diagnostic.map(|d| {
span_err!(d, attr.span, E0633, "malformed `#[unwind]` attribute");
});
}
}
}
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>,
/// `None` means the function is stable but needs to be a stable const fn, too
/// `Some` contains the feature gate required to be able to use the function
/// as const fn
pub const_stability: Option<Symbol>,
/// whether the function has a `#[rustc_promotable]` attribute
pub promotable: bool,
}
/// 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,
/// A text snippet used to completely replace any use of the deprecated item in an expression.
pub suggestion: Option<Symbol>,
}
/// Checks 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)
})
}
/// Finds the first stability attribute. `None` if none exists.
pub fn find_stability(sess: &ParseSess, attrs: &[Attribute],
item_sp: Span) -> Option<Stability> {
find_stability_generic(sess, attrs.iter(), item_sp)
}
fn find_stability_generic<'a, I>(sess: &ParseSess,
attrs_iter: I,
item_sp: Span)
-> Option<Stability>
where I: Iterator<Item = &'a Attribute>
{
use StabilityLevel::*;
let mut stab: Option<Stability> = None;
let mut rustc_depr: Option<RustcDeprecation> = None;
let mut rustc_const_unstable: Option<Symbol> = None;
let mut promotable = false;
let diagnostic = &sess.span_diagnostic;
'outer: for attr in attrs_iter {
if ![
"rustc_deprecated",
"rustc_const_unstable",
"unstable",
"stable",
"rustc_promotable",
].iter().any(|&s| attr.path == s) {
continue // not a stability level
}
mark_used(attr);
let meta = attr.meta();
if attr.path == "rustc_promotable" {
promotable = true;
}
// attributes with data
else 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(sess, 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 },
)+
_ => {
let expected = &[ $( stringify!($name) ),+ ];
handle_errors(
sess,
mi.span,
AttrError::UnknownMetaItem(mi.name(), expected),
);
continue 'outer
}
}
} else {
handle_errors(
sess,
meta.span,
AttrError::UnsupportedLiteral(
"unsupported literal",
false,
),
);
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, suggestion);
match (since, reason) {
(Some(since), Some(reason)) => {
rustc_depr = Some(RustcDeprecation {
since,
reason,
suggestion,
})
}
(None, _) => {
handle_errors(sess, 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(feature);
} else {
span_err!(diagnostic, attr.span(), E0629, "missing 'feature'");
continue
}
}
"unstable" => {
if stab.is_some() {
handle_errors(sess, 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(
sess,
meta.span,
AttrError::UnknownMetaItem(
mi.name(),
&["feature", "reason", "issue"]
),
);
continue 'outer
}
}
} else {
handle_errors(
sess,
meta.span,
AttrError::UnsupportedLiteral(
"unsupported literal",
false,
),
);
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,
const_stability: None,
promotable: false,
})
}
(None, _, _) => {
handle_errors(sess, attr.span(), AttrError::MissingFeature);
continue
}
_ => {
span_err!(diagnostic, attr.span(), E0547, "missing 'issue'");
continue
}
}
}
"stable" => {
if stab.is_some() {
handle_errors(sess, attr.span(), AttrError::MultipleStabilityLevels);
break
}
let mut feature = None;
let mut since = None;
for meta in metas {
match &meta.node {
NestedMetaItemKind::MetaItem(mi) => {
match &*mi.name().as_str() {
"feature" => if !get(mi, &mut feature) { continue 'outer },
"since" => if !get(mi, &mut since) { continue 'outer },
_ => {
handle_errors(
sess,
meta.span,
AttrError::UnknownMetaItem(
mi.name(), &["since", "note"],
),
);
continue 'outer
}
}
},
NestedMetaItemKind::Literal(lit) => {
handle_errors(
sess,
lit.span,
AttrError::UnsupportedLiteral(
"unsupported literal",
false,
),
);
continue 'outer
}
}
}
match (feature, since) {
(Some(feature), Some(since)) => {
stab = Some(Stability {
level: Stable {
since,
},
feature,
rustc_depr: None,
const_stability: None,
promotable: false,
})
}
(None, _) => {
handle_errors(sess, attr.span(), AttrError::MissingFeature);
continue
}
_ => {
handle_errors(sess, attr.span(), AttrError::MissingSince);
continue
}
}
}
_ => unreachable!()
}
}
}
// 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(feature) = rustc_const_unstable {
if let Some(ref mut stab) = stab {
stab.const_stability = Some(feature);
} else {
span_err!(diagnostic, item_sp, E0630,
"rustc_const_unstable attribute must be paired with \
either stable or unstable attribute");
}
}
// Merge the const-unstable info into the stability info
if promotable {
if let Some(ref mut stab) = stab {
stab.promotable = true;
} else {
span_err!(diagnostic, item_sp, E0717,
"rustc_promotable 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);
}
let error = |span, msg| { sess.span_diagnostic.span_err(span, msg); true };
if cfg.ident.segments.len() != 1 {
return error(cfg.ident.span, "`cfg` predicate key must be an identifier");
}
match &cfg.node {
MetaItemKind::List(..) => {
error(cfg.span, "unexpected parentheses after `cfg` predicate key")
}
MetaItemKind::NameValue(lit) if !lit.node.is_str() => {
handle_errors(
sess,
lit.span,
AttrError::UnsupportedLiteral(
"literal in `cfg` predicate value must be a string",
lit.node.is_bytestr()
),
);
true
}
MetaItemKind::NameValue(..) | MetaItemKind::Word => {
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,
mi.span,
AttrError::UnsupportedLiteral(
"unsupported literal",
false
),
);
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>,
}
/// Finds the deprecation attribute. `None` if none exists.
pub fn find_deprecation(sess: &ParseSess, attrs: &[Attribute],
item_sp: Span) -> Option<Deprecation> {
find_deprecation_generic(sess, attrs.iter(), item_sp)
}
fn find_deprecation_generic<'a, I>(sess: &ParseSess,
attrs_iter: I,
item_sp: Span)
-> Option<Deprecation>
where I: Iterator<Item = &'a Attribute>
{
let mut depr: Option<Deprecation> = None;
let diagnostic = &sess.span_diagnostic;
'outer: for attr in attrs_iter {
if !attr.check_name("deprecated") {
continue;
}
if depr.is_some() {
span_err!(diagnostic, item_sp, E0550, "multiple deprecated attributes");
break
}
let meta = attr.meta().unwrap();
depr = match &meta.node {
MetaItemKind::Word => Some(Deprecation { since: None, note: None }),
MetaItemKind::NameValue(..) => {
meta.value_str().map(|note| {
Deprecation { since: None, note: Some(note) }
})
}
MetaItemKind::List(list) => {
let get = |meta: &MetaItem, item: &mut Option<Symbol>| {
if item.is_some() {
handle_errors(sess, meta.span, AttrError::MultipleItem(meta.name()));
return false
}
if let Some(v) = meta.value_str() {
*item = Some(v);
true
} else {
if let Some(lit) = meta.name_value_literal() {
handle_errors(
sess,
lit.span,
AttrError::UnsupportedLiteral(
"literal in `deprecated` \
value must be a string",
lit.node.is_bytestr()
),
);
} else {
span_err!(diagnostic, meta.span, E0551, "incorrect meta item");
}
false
}
};
let mut since = None;
let mut note = None;
for meta in list {
match &meta.node {
NestedMetaItemKind::MetaItem(mi) => {
match &*mi.name().as_str() {
"since" => if !get(mi, &mut since) { continue 'outer },
"note" => if !get(mi, &mut note) { continue 'outer },
_ => {
handle_errors(
sess,
meta.span,
AttrError::UnknownMetaItem(mi.name(), &["since", "note"]),
);
continue 'outer
}
}
}
NestedMetaItemKind::Literal(lit) => {
handle_errors(
sess,
lit.span,
AttrError::UnsupportedLiteral(
"item in `deprecated` must be a key/value pair",
false,
),
);
continue 'outer
}
}
}
Some(Deprecation { since, note })
}
};
}
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 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(sess: &ParseSess, attr: &Attribute) -> Vec<ReprAttr> {
use ReprAttr::*;
let mut acc = Vec::new();
let diagnostic = &sess.span_diagnostic;
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(
sess,
item.span,
AttrError::UnsupportedLiteral(
"meta item in `repr` must be an identifier",
false,
),
);
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(
item.span,
"use parentheses instead",
format!("align({})", int),
Applicability::MachineApplicable
);
}
ast::LitKind::Str(s, _) => {
err.span_suggestion(
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 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
}
}