Lint attributes on function arguments

Author: c410-f3r

src/librustc/hir/intravisit.rs

@@ -210,6 +210,10 @@ pub trait Visitor<'v> : Sized {
         }
     }
 
+    fn visit_arg(&mut self, arg: &'v Arg) {
+        walk_arg(self, arg)
+    }
+
     /// Visits the top-level item and (optionally) nested items / impl items. See
     /// `visit_nested_item` for details.
     fn visit_item(&mut self, i: &'v Item) {
@@ -396,10 +400,7 @@ pub fn walk_mod<'v, V: Visitor<'v>>(visitor: &mut V, module: &'v Mod, mod_hir_id
 }
 
 pub fn walk_body<'v, V: Visitor<'v>>(visitor: &mut V, body: &'v Body) {
-    for argument in &body.arguments {
-        visitor.visit_id(argument.hir_id);
-        visitor.visit_pat(&argument.pat);
-    }
+    walk_list!(visitor, visit_arg, &body.arguments);
     visitor.visit_expr(&body.value);
 }
 
@@ -452,6 +453,12 @@ pub fn walk_trait_ref<'v, V>(visitor: &mut V, trait_ref: &'v TraitRef)
     visitor.visit_path(&trait_ref.path, trait_ref.hir_ref_id)
 }
 
+pub fn walk_arg<'v, V: Visitor<'v>>(visitor: &mut V, arg: &'v Arg) {
+    visitor.visit_id(arg.hir_id);
+    visitor.visit_pat(&arg.pat);
+    walk_list!(visitor, visit_attribute, &arg.attrs);
+}
+
 pub fn walk_item<'v, V: Visitor<'v>>(visitor: &mut V, item: &'v Item) {
     visitor.visit_vis(&item.vis);
     visitor.visit_ident(item.ident);

src/librustc/hir/lowering.rs

@@ -2461,8 +2461,10 @@ impl<'a> LoweringContext<'a> {
 
     fn lower_arg(&mut self, arg: &Arg) -> hir::Arg {
         hir::Arg {
+            attrs: self.lower_attrs(&arg.attrs),
             hir_id: self.lower_node_id(arg.id),
             pat: self.lower_pat(&arg.pat),
+            span: arg.span,
         }
     }
 
@@ -3279,19 +3281,29 @@ impl<'a> LoweringContext<'a> {
                 //
                 // If this is the simple case, this argument will end up being the same as the
                 // original argument, but with a different pattern id.
+                let mut stmt_attrs = ThinVec::new();
+                stmt_attrs.extend(argument.attrs.iter().cloned());
                 let (new_argument_pat, new_argument_id) = this.pat_ident(desugared_span, ident);
                 let new_argument = hir::Arg {
+                    attrs: argument.attrs,
                     hir_id: argument.hir_id,
                     pat: new_argument_pat,
+                    span: argument.span,
                 };
 
+
                 if is_simple_argument {
                     // If this is the simple case, then we only insert one statement that is
                     // `let <pat> = <pat>;`. We re-use the original argument's pattern so that
                     // `HirId`s are densely assigned.
                     let expr = this.expr_ident(desugared_span, ident, new_argument_id);
                     let stmt = this.stmt_let_pat(
-                        desugared_span, Some(P(expr)), argument.pat, hir::LocalSource::AsyncFn);
+                        stmt_attrs,
+                        desugared_span,
+                        Some(P(expr)),
+                        argument.pat,
+                        hir::LocalSource::AsyncFn
+                    );
                     statements.push(stmt);
                 } else {
                     // If this is not the simple case, then we construct two statements:
@@ -3313,14 +3325,23 @@ impl<'a> LoweringContext<'a> {
                         desugared_span, ident, hir::BindingAnnotation::Mutable);
                     let move_expr = this.expr_ident(desugared_span, ident, new_argument_id);
                     let move_stmt = this.stmt_let_pat(
-                        desugared_span, Some(P(move_expr)), move_pat, hir::LocalSource::AsyncFn);
+                        ThinVec::new(),
+                        desugared_span,
+                        Some(P(move_expr)),
+                        move_pat,
+                        hir::LocalSource::AsyncFn
+                    );
 
                     // Construct the `let <pat> = __argN;` statement. We re-use the original
                     // argument's pattern so that `HirId`s are densely assigned.
                     let pattern_expr = this.expr_ident(desugared_span, ident, move_id);
                     let pattern_stmt = this.stmt_let_pat(
-                        desugared_span, Some(P(pattern_expr)), argument.pat,
-                        hir::LocalSource::AsyncFn);
+                        stmt_attrs,
+                        desugared_span,
+                        Some(P(pattern_expr)),
+                        argument.pat,
+                        hir::LocalSource::AsyncFn
+                    );
 
                     statements.push(move_stmt);
                     statements.push(pattern_stmt);
@@ -4910,6 +4931,7 @@ impl<'a> LoweringContext<'a> {
 
                 // `let mut __next`
                 let next_let = self.stmt_let_pat(
+                    ThinVec::new(),
                     desugared_span,
                     None,
                     next_pat,
@@ -4919,6 +4941,7 @@ impl<'a> LoweringContext<'a> {
                 // `let <pat> = __next`
                 let pat = self.lower_pat(pat);
                 let pat_let = self.stmt_let_pat(
+                    ThinVec::new(),
                     head_sp,
                     Some(next_expr),
                     pat,
@@ -5413,19 +5436,20 @@ impl<'a> LoweringContext<'a> {
 
     fn stmt_let_pat(
         &mut self,
+        attrs: ThinVec<Attribute>,
         span: Span,
         init: Option<P<hir::Expr>>,
         pat: P<hir::Pat>,
         source: hir::LocalSource,
     ) -> hir::Stmt {
         let local = hir::Local {
-            pat,
-            ty: None,
-            init,
+            attrs,
             hir_id: self.next_id(),
-            span,
+            init,
+            pat,
             source,
-            attrs: ThinVec::new()
+            span,
+            ty: None,
         };
         self.stmt(span, hir::StmtKind::Local(P(local)))
     }
@@ -5831,6 +5855,7 @@ impl<'a> LoweringContext<'a> {
             hir::BindingAnnotation::Mutable,
         );
         let pinned_let = self.stmt_let_pat(
+            ThinVec::new(),
             span,
             Some(expr),
             pinned_pat,

src/librustc/hir/map/collector.rs

@@ -363,6 +363,14 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
         self.currently_in_body = prev_in_body;
     }
 
+    fn visit_arg(&mut self, arg: &'hir Arg) {
+        let node = Node::Arg(arg);
+        self.insert(arg.pat.span, arg.hir_id, node);
+        self.with_parent(arg.hir_id, |this| {
+            intravisit::walk_arg(this, arg);
+        });
+    }
+
     fn visit_item(&mut self, i: &'hir Item) {
         debug!("visit_item: {:?}", i);
         debug_assert_eq!(i.hir_id.owner,

src/librustc/hir/map/mod.rs

@@ -360,6 +360,7 @@ impl<'hir> Map<'hir> {
             Node::Pat(_) |
             Node::Binding(_) |
             Node::Local(_) |
+            Node::Arg(_) |
             Node::Arm(_) |
             Node::Lifetime(_) |
             Node::Visibility(_) |
@@ -932,6 +933,7 @@ impl<'hir> Map<'hir> {
     pub fn attrs(&self, id: HirId) -> &'hir [ast::Attribute] {
         self.read(id); // reveals attributes on the node
         let attrs = match self.find_entry(id).map(|entry| entry.node) {
+            Some(Node::Arg(a)) => Some(&a.attrs[..]),
             Some(Node::Local(l)) => Some(&l.attrs[..]),
             Some(Node::Item(i)) => Some(&i.attrs[..]),
             Some(Node::ForeignItem(fi)) => Some(&fi.attrs[..]),
@@ -995,6 +997,7 @@ impl<'hir> Map<'hir> {
     pub fn span(&self, hir_id: HirId) -> Span {
         self.read(hir_id); // reveals span from node
         match self.find_entry(hir_id).map(|entry| entry.node) {
+            Some(Node::Arg(arg)) => arg.span,
             Some(Node::Item(item)) => item.span,
             Some(Node::ForeignItem(foreign_item)) => foreign_item.span,
             Some(Node::TraitItem(trait_method)) => trait_method.span,
@@ -1197,6 +1200,7 @@ impl<'hir> print::PpAnn for Map<'hir> {
 impl<'a> print::State<'a> {
     pub fn print_node(&mut self, node: Node<'_>) {
         match node {
+            Node::Arg(a)          => self.print_arg(&a),
             Node::Item(a)         => self.print_item(&a),
             Node::ForeignItem(a)  => self.print_foreign_item(&a),
             Node::TraitItem(a)    => self.print_trait_item(a),
@@ -1338,6 +1342,9 @@ fn hir_id_to_string(map: &Map<'_>, id: HirId, include_id: bool) -> String {
         Some(Node::Pat(_)) => {
             format!("pat {}{}", map.hir_to_pretty_string(id), id_str)
         }
+        Some(Node::Arg(_)) => {
+            format!("arg {}{}", map.hir_to_pretty_string(id), id_str)
+        }
         Some(Node::Arm(_)) => {
             format!("arm {}{}", map.hir_to_pretty_string(id), id_str)
         }

src/librustc/hir/mod.rs

@@ -2010,8 +2010,10 @@ pub struct InlineAsm {
 /// Represents an argument in a function header.
 #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]
 pub struct Arg {
-    pub pat: P<Pat>,
+    pub attrs: HirVec<Attribute>,
     pub hir_id: HirId,
+    pub pat: P<Pat>,
+    pub span: Span,
 }
 
 /// Represents the header (not the body) of a function declaration.
@@ -2701,6 +2703,7 @@ impl CodegenFnAttrs {
 
 #[derive(Copy, Clone, Debug)]
 pub enum Node<'hir> {
+    Arg(&'hir Arg),
     Item(&'hir Item),
     ForeignItem(&'hir ForeignItem),
     TraitItem(&'hir TraitItem),

src/librustc/hir/print.rs

@@ -1767,6 +1767,11 @@ impl<'a> State<'a> {
         self.ann.post(self, AnnNode::Pat(pat))
     }
 
+    pub fn print_arg(&mut self, arg: &hir::Arg) {
+        self.print_outer_attributes(&arg.attrs);
+        self.print_pat(&arg.pat);
+    }
+
     pub fn print_arm(&mut self, arm: &hir::Arm) {
         // I have no idea why this check is necessary, but here it
         // is :(

src/librustc/lint/context.rs

@@ -966,6 +966,13 @@ for LateContextAndPass<'a, 'tcx, T> {
         self.context.tables = old_tables;
     }
 
+    fn visit_arg(&mut self, arg: &'tcx hir::Arg) {
+        self.with_lint_attrs(arg.hir_id, &arg.attrs, |cx| {
+            lint_callback!(cx, check_arg, arg);
+            hir_visit::walk_arg(cx, arg);
+        });
+    }
+
     fn visit_body(&mut self, body: &'tcx hir::Body) {
         lint_callback!(self, check_body, body);
         hir_visit::walk_body(self, body);
@@ -1156,6 +1163,13 @@ for LateContextAndPass<'a, 'tcx, T> {
 }
 
 impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
+    fn visit_arg(&mut self, arg: &'a ast::Arg) {
+        self.with_lint_attrs(arg.id, &arg.attrs, |cx| {
+            run_early_pass!(cx, check_arg, arg);
+            ast_visit::walk_arg(cx, arg);
+        });
+    }
+
     fn visit_item(&mut self, it: &'a ast::Item) {
         self.with_lint_attrs(it.id, &it.attrs, |cx| {
             run_early_pass!(cx, check_item, it);

src/librustc/lint/mod.rs

@@ -206,6 +206,7 @@ macro_rules! declare_lint_pass {
 macro_rules! late_lint_methods {
     ($macro:path, $args:tt, [$hir:tt]) => (
         $macro!($args, [$hir], [
+            fn check_arg(a: &$hir hir::Arg);
             fn check_body(a: &$hir hir::Body);
             fn check_body_post(a: &$hir hir::Body);
             fn check_name(a: Span, b: ast::Name);
@@ -358,6 +359,7 @@ macro_rules! declare_combined_late_lint_pass {
 macro_rules! early_lint_methods {
     ($macro:path, $args:tt) => (
         $macro!($args, [
+            fn check_arg(a: &ast::Arg);
             fn check_ident(a: ast::Ident);
             fn check_crate(a: &ast::Crate);
             fn check_crate_post(a: &ast::Crate);
@@ -495,8 +497,6 @@ pub type EarlyLintPassObject = Box<dyn EarlyLintPass + sync::Send + sync::Sync +
 pub type LateLintPassObject = Box<dyn for<'a, 'tcx> LateLintPass<'a, 'tcx> + sync::Send
                                                                            + sync::Sync + 'static>;
 
-
-
 /// Identifies a lint known to the compiler.
 #[derive(Clone, Copy, Debug)]
 pub struct LintId {
@@ -812,6 +812,12 @@ impl intravisit::Visitor<'tcx> for LintLevelMapBuilder<'tcx> {
         intravisit::NestedVisitorMap::All(&self.tcx.hir())
     }
 
+    fn visit_arg(&mut self, arg: &'tcx hir::Arg) {
+        self.with_lint_attrs(arg.hir_id, &arg.attrs, |builder| {
+            intravisit::walk_arg(builder, arg);
+        });
+    }
+
     fn visit_item(&mut self, it: &'tcx hir::Item) {
         self.with_lint_attrs(it.hir_id, &it.attrs, |builder| {
             intravisit::walk_item(builder, it);