From 070df9e676d8f32b424484cdabca612c8b392020 Mon Sep 17 00:00:00 2001 From: Aaron Hill Date: Wed, 14 Jul 2021 19:51:45 -0500 Subject: [PATCH 1/2] Warn on inert attributes used on bang macro invocation 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. --- compiler/rustc_expand/src/expand.rs | 49 ++++++++++++++++-------- compiler/rustc_lint/src/context.rs | 10 +++++ compiler/rustc_lint/src/lib.rs | 1 + compiler/rustc_lint_defs/src/lib.rs | 1 + src/test/ui/lint/inert-attr-macro.rs | 20 ++++++++++ src/test/ui/lint/inert-attr-macro.stderr | 44 +++++++++++++++++++++ 6 files changed, 109 insertions(+), 16 deletions(-) create mode 100644 src/test/ui/lint/inert-attr-macro.rs create mode 100644 src/test/ui/lint/inert-attr-macro.stderr diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs index dcd871c9d2050..03d2105e5cca5 100644 --- a/compiler/rustc_expand/src/expand.rs +++ b/compiler/rustc_expand/src/expand.rs @@ -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 = 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) diff --git a/compiler/rustc_lint/src/context.rs b/compiler/rustc_lint/src/context.rs index c44df407f6b3a..e5afc63a2a519 100644 --- a/compiler/rustc_lint/src/context.rs +++ b/compiler/rustc_lint/src/context.rs @@ -734,6 +734,16 @@ pub trait LintContext: Sized { Applicability::MachineApplicable, ); } + BuiltinLintDiagnostics::UnusedBuiltinAttribute { + attr_name, + macro_name, + invoc_span + } => { + db.span_note( + invoc_span, + &format!("the built-in attribute `{attr_name}` will be ignored, since it's applied to the macro invocation `{macro_name}`") + ); + } } // Rewrap `db`, and pass control to the user. decorate(LintDiagnosticBuilder::new(db)); diff --git a/compiler/rustc_lint/src/lib.rs b/compiler/rustc_lint/src/lib.rs index c9478016140b7..1786f1e70343a 100644 --- a/compiler/rustc_lint/src/lib.rs +++ b/compiler/rustc_lint/src/lib.rs @@ -32,6 +32,7 @@ #![feature(box_syntax)] #![feature(box_patterns)] #![feature(crate_visibility_modifier)] +#![feature(format_args_capture)] #![feature(iter_order_by)] #![feature(iter_zip)] #![feature(never_type)] diff --git a/compiler/rustc_lint_defs/src/lib.rs b/compiler/rustc_lint_defs/src/lib.rs index 4d85bf6b499d9..df09d04e72149 100644 --- a/compiler/rustc_lint_defs/src/lib.rs +++ b/compiler/rustc_lint_defs/src/lib.rs @@ -296,6 +296,7 @@ pub enum BuiltinLintDiagnostics { DeprecatedMacro(Option, Span), MissingAbi(Span, Abi), UnusedDocComment(Span), + UnusedBuiltinAttribute { attr_name: Symbol, macro_name: String, invoc_span: Span }, PatternsInFnsWithoutBody(Span, Ident), LegacyDeriveHelpers(Span), ExternDepSpec(String, ExternDepSpec), diff --git a/src/test/ui/lint/inert-attr-macro.rs b/src/test/ui/lint/inert-attr-macro.rs new file mode 100644 index 0000000000000..dc0bb8ac26593 --- /dev/null +++ b/src/test/ui/lint/inert-attr-macro.rs @@ -0,0 +1,20 @@ +// check-pass + +#![warn(unused)] + +macro_rules! foo { + () => {} +} + +fn main() { + #[inline] foo!(); //~ WARN unused attribute `inline` + + // This does nothing, since `#[allow(warnings)]` is itself + // an inert attribute on a macro call + #[allow(warnings)] #[inline] foo!(); //~ WARN unused attribute `allow` + //~^ WARN unused attribute `inline` + + // This does work, since the attribute is on a parent + // of the macro invocation. + #[allow(warnings)] { #[inline] foo!(); } +} diff --git a/src/test/ui/lint/inert-attr-macro.stderr b/src/test/ui/lint/inert-attr-macro.stderr new file mode 100644 index 0000000000000..3b3aa5d0bc04d --- /dev/null +++ b/src/test/ui/lint/inert-attr-macro.stderr @@ -0,0 +1,44 @@ +warning: unused attribute `inline` + --> $DIR/inert-attr-macro.rs:10:5 + | +LL | #[inline] foo!(); + | ^^^^^^^^^ + | +note: the lint level is defined here + --> $DIR/inert-attr-macro.rs:3:9 + | +LL | #![warn(unused)] + | ^^^^^^ + = note: `#[warn(unused_attributes)]` implied by `#[warn(unused)]` +note: the built-in attribute `inline` will be ignored, since it's applied to the macro invocation `foo` + --> $DIR/inert-attr-macro.rs:10:15 + | +LL | #[inline] foo!(); + | ^^^ + +warning: unused attribute `allow` + --> $DIR/inert-attr-macro.rs:14:5 + | +LL | #[allow(warnings)] #[inline] foo!(); + | ^^^^^^^^^^^^^^^^^^ + | +note: the built-in attribute `allow` will be ignored, since it's applied to the macro invocation `foo` + --> $DIR/inert-attr-macro.rs:14:34 + | +LL | #[allow(warnings)] #[inline] foo!(); + | ^^^ + +warning: unused attribute `inline` + --> $DIR/inert-attr-macro.rs:14:24 + | +LL | #[allow(warnings)] #[inline] foo!(); + | ^^^^^^^^^ + | +note: the built-in attribute `inline` will be ignored, since it's applied to the macro invocation `foo` + --> $DIR/inert-attr-macro.rs:14:34 + | +LL | #[allow(warnings)] #[inline] foo!(); + | ^^^ + +warning: 3 warnings emitted + From b41672eba8b0f06d2803cbd3bc2bd9ca7a8f2465 Mon Sep 17 00:00:00 2001 From: Aaron Hill Date: Mon, 19 Jul 2021 17:45:28 -0500 Subject: [PATCH 2/2] Fix incorrect use of `#[repr(no_niche)]` --- src/test/ui/repr/repr-no-niche.rs | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/src/test/ui/repr/repr-no-niche.rs b/src/test/ui/repr/repr-no-niche.rs index a7f0d509af521..2e6064aeb0074 100644 --- a/src/test/ui/repr/repr-no-niche.rs +++ b/src/test/ui/repr/repr-no-niche.rs @@ -73,8 +73,7 @@ mod enum_inline { // general; this test is relying on that.) two_fifty_six_variant_enum!(Visible2, N8); - #[repr(no_niche)] - two_fifty_six_variant_enum!(Cloaked2, N8); + two_fifty_six_variant_enum!(#[repr(no_niche)] Cloaked2, N8); } mod enum_param { @@ -96,8 +95,7 @@ mod enum_param { // here as above (assuming `T` is instantiated with `NonZeroU8`). two_fifty_six_variant_enum!(Visible2); - #[repr(no_niche)] - two_fifty_six_variant_enum!(Cloaked2); + two_fifty_six_variant_enum!(#[repr(no_niche)] Cloaked2); } fn main() { @@ -157,8 +155,8 @@ fn main() { } macro two_fifty_six_variant_enum { - ($name:ident<$param:ident>) => { - #[derive(Debug)] + ($(#[$attr:meta])* $name:ident<$param:ident>) => { + #[derive(Debug)] $(#[$attr])* pub enum $name<$param> { _V00($param, u16), _V01(u16, $param), _V02($param, u16), _V03(u16, $param), _V04($param, u16), _V05(u16, $param), _V06($param, u16), _V07(u16, $param), @@ -242,8 +240,8 @@ macro two_fifty_six_variant_enum { } }, - ($name:ident, $param:ty) => { - #[derive(Debug)] + ($(#[$attr:meta])* $name:ident, $param:ty) => { + #[derive(Debug)] $(#[$attr])* pub enum $name { _V00($param, u16), _V01(u16, $param), _V02($param, u16), _V03(u16, $param), _V04($param, u16), _V05(u16, $param), _V06($param, u16), _V07(u16, $param),