Fix unrooted_must_root lint to handle arguments/return types properly (…

…fixes #8022)

components/plugins/lints/unrooted_must_root.rs

@@ -4,12 +4,11 @@
 
 use rustc::front::map as ast_map;
 use rustc::lint::{LateContext, LintPass, LintArray, LateLintPass, LintContext};
-use rustc::middle::astconv_util::ast_ty_to_prim_ty;
 use rustc::middle::ty;
 use rustc_front::{hir, visit};
 use syntax::attr::AttrMetaMethods;
 use syntax::{ast, codemap};
-use utils::{match_def_path, unsafe_context};
+use utils::{match_def_path, unsafe_context, in_derive_expn};
 
 declare_lint!(UNROOTED_MUST_ROOT, Deny,
               "Warn and report usage of unrooted jsmanaged objects");
@@ -107,7 +106,7 @@ impl LateLintPass for UnrootedPass {
             match var.node.kind {
                 hir::TupleVariantKind(ref vec) => {
                     for ty in vec {
-                        ast_ty_to_prim_ty(cx.tcx, &*ty.ty).map(|t| {
+                        cx.tcx.ast_ty_to_ty_cache.borrow().get(&ty.id).map(|t| {
                             if is_unrooted_ty(cx, t, false) {
                                 cx.span_lint(UNROOTED_MUST_ROOT, ty.ty.span,
                                              "Type must be rooted, use #[must_root] on \
@@ -122,7 +121,7 @@ impl LateLintPass for UnrootedPass {
     }
     /// Function arguments that are #[must_root] types are not allowed
     fn check_fn(&mut self, cx: &LateContext, kind: visit::FnKind, decl: &hir::FnDecl,
-                block: &hir::Block, _span: codemap::Span, id: ast::NodeId) {
+                block: &hir::Block, span: codemap::Span, id: ast::NodeId) {
         match kind {
             visit::FnKind::ItemFn(n, _, _, _, _, _) |
             visit::FnKind::Method(n, _, _) if n.as_str() == "new"
@@ -145,12 +144,25 @@ impl LateLintPass for UnrootedPass {
         match block.rules {
             hir::DefaultBlock => {
                 for arg in &decl.inputs {
-                    ast_ty_to_prim_ty(cx.tcx, &*arg.ty).map(|t| {
+                    cx.tcx.ast_ty_to_ty_cache.borrow().get(&arg.ty.id).map(|t| {
                         if is_unrooted_ty(cx, t, false) {
+                            if in_derive_expn(cx, span) {
+                                return;
+                            }
                             cx.span_lint(UNROOTED_MUST_ROOT, arg.ty.span, "Type must be rooted")
                         }
                     });
                 }
+                if let hir::Return(ref ty) = decl.output {
+                    cx.tcx.ast_ty_to_ty_cache.borrow().get(&ty.id).map(|t| {
+                        if is_unrooted_ty(cx, t, false) {
+                            if in_derive_expn(cx, span) {
+                                return;
+                            }
+                            cx.span_lint(UNROOTED_MUST_ROOT, ty.span, "Type must be rooted")
+                        }
+                    });
+                }
             }
             _ => () // fn is `unsafe`
         }

components/plugins/utils.rs

@@ -3,12 +3,13 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use rustc::front::map as ast_map;
-use rustc::lint::LateContext;
+use rustc::lint::{LateContext, LintContext};
 use rustc::middle::def;
 use rustc::middle::def_id::DefId;
 use rustc_front::hir;
 use syntax::ast;
 use syntax::attr::mark_used;
+use syntax::codemap::{ExpnFormat, Span};
 use syntax::ptr::P;
 
 
@@ -100,3 +101,16 @@ pub fn match_def_path(cx: &LateContext, def_id: DefId, path: &[&str]) -> bool {
     cx.tcx.with_path(def_id, |iter| iter.map(|elem| elem.name())
         .zip(path.iter()).all(|(nm, p)| &nm.as_str() == p))
 }
+
+pub fn in_derive_expn(cx: &LateContext, span: Span) -> bool {
+    cx.sess().codemap().with_expn_info(span.expn_id,
+            |info| {
+                if let Some(i) = info {
+                    if let ExpnFormat::MacroAttribute(n) = i.callee.format {
+                        if n.as_str().contains("derive") {
+                            true
+                        } else { false }
+                    } else { false }
+                } else { false }
+            })
+}