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use session::Session;
use syntax::ast;
use syntax::visit;
use syntax::visit::Visitor;
#[derive(Copy, Clone, PartialEq)]
enum Target {
Fn,
Struct,
Union,
Enum,
Other,
}
impl Target {
fn from_item(item: &ast::Item) -> Target {
match item.node {
ast::ItemKind::Fn(..) => Target::Fn,
ast::ItemKind::Struct(..) => Target::Struct,
ast::ItemKind::Union(..) => Target::Union,
ast::ItemKind::Enum(..) => Target::Enum,
_ => Target::Other,
}
}
}
struct CheckAttrVisitor<'a> {
sess: &'a Session,
}
impl<'a> CheckAttrVisitor<'a> {
fn check_inline(&self, attr: &ast::Attribute, target: Target) {
if target != Target::Fn {
struct_span_err!(self.sess, attr.span, E0518, "attribute should be applied to function")
.span_label(attr.span, &format!("requires a function"))
.emit();
}
}
fn check_repr(&self, attr: &ast::Attribute, target: Target) {
let words = match attr.meta_item_list() {
Some(words) => words,
None => {
return;
}
};
let mut conflicting_reprs = 0;
for word in words {
let name = match word.name() {
Some(word) => word,
None => continue,
};
let (message, label) = match &*name.as_str() {
"C" => {
conflicting_reprs += 1;
if target != Target::Struct &&
target != Target::Union &&
target != Target::Enum {
("attribute should be applied to struct, enum or union",
"a struct, enum or union")
} else {
continue
}
}
"packed" => {
if target != Target::Struct &&
target != Target::Union {
("attribute should be applied to struct or union",
"a struct or union")
} else {
continue
}
}
"simd" => {
conflicting_reprs += 1;
if target != Target::Struct {
("attribute should be applied to struct",
"a struct")
} else {
continue
}
}
"i8" | "u8" | "i16" | "u16" |
"i32" | "u32" | "i64" | "u64" |
"isize" | "usize" => {
conflicting_reprs += 1;
if target != Target::Enum {
("attribute should be applied to enum",
"an enum")
} else {
continue
}
}
_ => continue,
};
struct_span_err!(self.sess, attr.span, E0517, "{}", message)
.span_label(attr.span, &format!("requires {}", label))
.emit();
}
if conflicting_reprs > 1 {
span_warn!(self.sess, attr.span, E0566,
"conflicting representation hints");
}
}
fn check_attribute(&self, attr: &ast::Attribute, target: Target) {
let name: &str = &attr.name().as_str();
match name {
"inline" => self.check_inline(attr, target),
"repr" => self.check_repr(attr, target),
_ => (),
}
}
}
impl<'a> Visitor<'a> for CheckAttrVisitor<'a> {
fn visit_item(&mut self, item: &'a ast::Item) {
let target = Target::from_item(item);
for attr in &item.attrs {
self.check_attribute(attr, target);
}
visit::walk_item(self, item);
}
}
pub fn check_crate(sess: &Session, krate: &ast::Crate) {
visit::walk_crate(&mut CheckAttrVisitor { sess: sess }, krate);
}