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//! Meta-syntax validation logic of attributes for post-expansion.
use crate::parse_in;
use rustc_ast::tokenstream::DelimSpan;
use rustc_ast::{self as ast, Attribute, MacArgs, MacArgsEq, MacDelimiter, MetaItem, MetaItemKind};
use rustc_ast_pretty::pprust;
use rustc_errors::{Applicability, FatalError, PResult};
use rustc_feature::{AttributeTemplate, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
use rustc_session::lint::builtin::ILL_FORMED_ATTRIBUTE_INPUT;
use rustc_session::parse::ParseSess;
use rustc_span::{sym, Symbol};
pub fn check_meta(sess: &ParseSess, attr: &Attribute) {
if attr.is_doc_comment() {
return;
}
let attr_info = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
// Check input tokens for built-in and key-value attributes.
match attr_info {
// `rustc_dummy` doesn't have any restrictions specific to built-in attributes.
Some(BuiltinAttribute { name, template, .. }) if *name != sym::rustc_dummy => {
check_builtin_attribute(sess, attr, *name, *template)
}
_ if let MacArgs::Eq(..) = attr.get_normal_item().args => {
// All key-value attributes are restricted to meta-item syntax.
parse_meta(sess, attr)
.map_err(|mut err| {
err.emit();
})
.ok();
}
_ => {}
}
}
pub fn parse_meta<'a>(sess: &'a ParseSess, attr: &Attribute) -> PResult<'a, MetaItem> {
let item = attr.get_normal_item();
Ok(MetaItem {
span: attr.span,
path: item.path.clone(),
kind: match &item.args {
MacArgs::Empty => MetaItemKind::Word,
MacArgs::Delimited(dspan, delim, t) => {
check_meta_bad_delim(sess, *dspan, *delim, "wrong meta list delimiters");
let nmis = parse_in(sess, t.clone(), "meta list", |p| p.parse_meta_seq_top())?;
MetaItemKind::List(nmis)
}
MacArgs::Eq(_, MacArgsEq::Ast(expr)) => {
if let ast::ExprKind::Lit(lit) = &expr.kind {
if !lit.kind.is_unsuffixed() {
let mut err = sess.span_diagnostic.struct_span_err(
lit.span,
"suffixed literals are not allowed in attributes",
);
err.help(
"instead of using a suffixed literal (`1u8`, `1.0f32`, etc.), \
use an unsuffixed version (`1`, `1.0`, etc.)",
);
return Err(err);
} else {
MetaItemKind::NameValue(lit.clone())
}
} else {
// The non-error case can happen with e.g. `#[foo = 1+1]`. The error case can
// happen with e.g. `#[foo = include_str!("non-existent-file.rs")]`; in that
// case we delay the error because an earlier error will have already been
// reported.
let msg = format!("unexpected expression: `{}`", pprust::expr_to_string(expr));
let mut err = sess.span_diagnostic.struct_span_err(expr.span, msg);
if let ast::ExprKind::Err = expr.kind {
err.downgrade_to_delayed_bug();
}
return Err(err);
}
}
MacArgs::Eq(_, MacArgsEq::Hir(lit)) => MetaItemKind::NameValue(lit.clone()),
},
})
}
pub fn check_meta_bad_delim(sess: &ParseSess, span: DelimSpan, delim: MacDelimiter, msg: &str) {
if let ast::MacDelimiter::Parenthesis = delim {
return;
}
sess.span_diagnostic
.struct_span_err(span.entire(), msg)
.multipart_suggestion(
"the delimiters should be `(` and `)`",
vec![(span.open, "(".to_string()), (span.close, ")".to_string())],
Applicability::MachineApplicable,
)
.emit();
}
/// Checks that the given meta-item is compatible with this `AttributeTemplate`.
fn is_attr_template_compatible(template: &AttributeTemplate, meta: &ast::MetaItemKind) -> bool {
match meta {
MetaItemKind::Word => template.word,
MetaItemKind::List(..) => template.list.is_some(),
MetaItemKind::NameValue(lit) if lit.kind.is_str() => template.name_value_str.is_some(),
MetaItemKind::NameValue(..) => false,
}
}
pub fn check_builtin_attribute(
sess: &ParseSess,
attr: &Attribute,
name: Symbol,
template: AttributeTemplate,
) {
// Some special attributes like `cfg` must be checked
// before the generic check, so we skip them here.
let should_skip = |name| name == sym::cfg;
match parse_meta(sess, attr) {
Ok(meta) => {
if !should_skip(name) && !is_attr_template_compatible(&template, &meta.kind) {
emit_malformed_attribute(sess, attr, name, template);
}
}
Err(mut err) => {
err.emit();
}
}
}
fn emit_malformed_attribute(
sess: &ParseSess,
attr: &Attribute,
name: Symbol,
template: AttributeTemplate,
) {
// Some of previously accepted forms were used in practice,
// report them as warnings for now.
let should_warn = |name| {
matches!(name, sym::doc | sym::ignore | sym::inline | sym::link | sym::test | sym::bench)
};
let error_msg = format!("malformed `{}` attribute input", name);
let mut msg = "attribute must be of the form ".to_owned();
let mut suggestions = vec![];
let mut first = true;
let inner = if attr.style == ast::AttrStyle::Inner { "!" } else { "" };
if template.word {
first = false;
let code = format!("#{}[{}]", inner, name);
msg.push_str(&format!("`{}`", &code));
suggestions.push(code);
}
if let Some(descr) = template.list {
if !first {
msg.push_str(" or ");
}
first = false;
let code = format!("#{}[{}({})]", inner, name, descr);
msg.push_str(&format!("`{}`", &code));
suggestions.push(code);
}
if let Some(descr) = template.name_value_str {
if !first {
msg.push_str(" or ");
}
let code = format!("#{}[{} = \"{}\"]", inner, name, descr);
msg.push_str(&format!("`{}`", &code));
suggestions.push(code);
}
if should_warn(name) {
sess.buffer_lint(&ILL_FORMED_ATTRIBUTE_INPUT, attr.span, ast::CRATE_NODE_ID, &msg);
} else {
sess.span_diagnostic
.struct_span_err(attr.span, &error_msg)
.span_suggestions(
attr.span,
if suggestions.len() == 1 {
"must be of the form"
} else {
"the following are the possible correct uses"
},
suggestions.into_iter(),
Applicability::HasPlaceholders,
)
.emit();
}
}
pub fn emit_fatal_malformed_builtin_attribute(
sess: &ParseSess,
attr: &Attribute,
name: Symbol,
) -> ! {
let template = BUILTIN_ATTRIBUTE_MAP.get(&name).expect("builtin attr defined").template;
emit_malformed_attribute(sess, attr, name, template);
// This is fatal, otherwise it will likely cause a cascade of other errors
// (and an error here is expected to be very rare).
FatalError.raise()
}
|
