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Warn on inert attributes used on bang macro invocation

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These attributes are currently discarded.
This may change in the future (see #63221), but for now,
placing inert attributes on a macro invocation does nothing,
so we should warn users about it.

Technically, it's possible for there to be attribute macro
on the same macro invocation (or at a higher scope), which
inspects the inert attribute. For example:

```rust
#[look_for_inline_attr]
#[inline]
my_macro!()

#[look_for_nested_inline]
mod foo { #[inline] my_macro!() }
```

However, this would be a very strange thing to do.
Anyone running into this can manually suppress the warning.
This commit is contained in:
Aaron Hill 2021-07-14 19:51:45 -05:00
parent 8df945c471
commit 070df9e676
No known key found for this signature in database
GPG key ID: B4087E510E98B164
6 changed files with 109 additions and 16 deletions
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49
compiler/rustc_expand/src/expand.rs
View file

@ -12,7 +12,7 @@ use rustc_ast::ptr::P;
use rustc_ast::token;
use rustc_ast::tokenstream::TokenStream;
use rustc_ast::visit::{self, AssocCtxt, Visitor};
use rustc_ast::{AstLike, Block, Inline, ItemKind, Local, MacArgs};
use rustc_ast::{AstLike, Block, Inline, ItemKind, Local, MacArgs, MacCall};
use rustc_ast::{MacCallStmt, MacStmtStyle, MetaItemKind, ModKind, NestedMetaItem};
use rustc_ast::{NodeId, PatKind, Path, StmtKind, Unsafe};
use rustc_ast_pretty::pprust;
@ -26,7 +26,7 @@ use rustc_parse::parser::{
AttemptLocalParseRecovery, ForceCollect, Parser, RecoverColon, RecoverComma,
};
use rustc_parse::validate_attr;
use rustc_session::lint::builtin::UNUSED_DOC_COMMENTS;
use rustc_session::lint::builtin::{UNUSED_ATTRIBUTES, UNUSED_DOC_COMMENTS};
use rustc_session::lint::BuiltinLintDiagnostics;
use rustc_session::parse::{feature_err, ParseSess};
use rustc_session::Limit;
@ -1070,7 +1070,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
// Detect use of feature-gated or invalid attributes on macro invocations
// since they will not be detected after macro expansion.
fn check_attributes(&mut self, attrs: &[ast::Attribute]) {
fn check_attributes(&mut self, attrs: &[ast::Attribute], call: &MacCall) {
let features = self.cx.ecfg.features.unwrap();
let mut attrs = attrs.iter().peekable();
let mut span: Option<Span> = None;
@ -1085,14 +1085,31 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
continue;
}
if attr.doc_str().is_some() {
if attr.is_doc_comment() {
self.cx.sess.parse_sess.buffer_lint_with_diagnostic(
&UNUSED_DOC_COMMENTS,
current_span,
ast::CRATE_NODE_ID,
self.cx.current_expansion.lint_node_id,
"unused doc comment",
BuiltinLintDiagnostics::UnusedDocComment(attr.span),
);
} else if rustc_attr::is_builtin_attr(attr) {
let attr_name = attr.ident().unwrap().name;
// `#[cfg]` and `#[cfg_attr]` are special - they are
// eagerly evaluated.
if attr_name != sym::cfg && attr_name != sym::cfg_attr {
self.cx.sess.parse_sess.buffer_lint_with_diagnostic(
&UNUSED_ATTRIBUTES,
attr.span,
self.cx.current_expansion.lint_node_id,
&format!("unused attribute `{}`", attr_name),
BuiltinLintDiagnostics::UnusedBuiltinAttribute {
attr_name,
macro_name: pprust::path_to_string(&call.path),
invoc_span: call.path.span,
},
);
}
}
}
}
@ -1152,7 +1169,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
}
if let ast::ExprKind::MacCall(mac) = expr.kind {
self.check_attributes(&expr.attrs);
self.check_attributes(&expr.attrs, &mac);
self.collect_bang(mac, expr.span, AstFragmentKind::Expr).make_expr().into_inner()
} else {
assign_id!(self, &mut expr.id, || {
@ -1253,7 +1270,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
}
if let ast::ExprKind::MacCall(mac) = expr.kind {
self.check_attributes(&expr.attrs);
self.check_attributes(&expr.attrs, &mac);
self.collect_bang(mac, expr.span, AstFragmentKind::OptExpr)
.make_opt_expr()
.map(|expr| expr.into_inner())
@ -1296,7 +1313,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
if let StmtKind::MacCall(mac) = stmt.kind {
let MacCallStmt { mac, style, attrs, tokens: _ } = mac.into_inner();
self.check_attributes(&attrs);
self.check_attributes(&attrs, &mac);
let mut placeholder =
self.collect_bang(mac, stmt.span, AstFragmentKind::Stmts).make_stmts();
@ -1344,9 +1361,9 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
let span = item.span;
match item.kind {
ast::ItemKind::MacCall(..) => {
ast::ItemKind::MacCall(ref mac) => {
self.check_attributes(&attrs, &mac);
item.attrs = attrs;
self.check_attributes(&item.attrs);
item.and_then(|item| match item.kind {
ItemKind::MacCall(mac) => {
self.collect_bang(mac, span, AstFragmentKind::Items).make_items()
@ -1455,8 +1472,8 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
}
match item.kind {
ast::AssocItemKind::MacCall(..) => {
self.check_attributes(&item.attrs);
ast::AssocItemKind::MacCall(ref mac) => {
self.check_attributes(&item.attrs, &mac);
item.and_then(|item| match item.kind {
ast::AssocItemKind::MacCall(mac) => self
.collect_bang(mac, item.span, AstFragmentKind::TraitItems)
@ -1480,8 +1497,8 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
}
match item.kind {
ast::AssocItemKind::MacCall(..) => {
self.check_attributes(&item.attrs);
ast::AssocItemKind::MacCall(ref mac) => {
self.check_attributes(&item.attrs, &mac);
item.and_then(|item| match item.kind {
ast::AssocItemKind::MacCall(mac) => self
.collect_bang(mac, item.span, AstFragmentKind::ImplItems)
@ -1526,8 +1543,8 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
}
match foreign_item.kind {
ast::ForeignItemKind::MacCall(..) => {
self.check_attributes(&foreign_item.attrs);
ast::ForeignItemKind::MacCall(ref mac) => {
self.check_attributes(&foreign_item.attrs, &mac);
foreign_item.and_then(|item| match item.kind {
ast::ForeignItemKind::MacCall(mac) => self
.collect_bang(mac, item.span, AstFragmentKind::ForeignItems)