session: disable internal lints for rustdoc

If an internal lint uses `typeck_results` or similar queries then that
can result in rustdoc checking code that it shouldn't (e.g. from other
platforms) and emit compilation errors.

Signed-off-by: David Wood <david.wood@huawei.com>

compiler/rustc_driver/src/lib.rs

@@ -249,7 +249,7 @@ fn run_compiler(
                     if sopts.describe_lints {
                         let mut lint_store = rustc_lint::new_lint_store(
                             sopts.unstable_opts.no_interleave_lints,
-                            compiler.session().unstable_options(),
+                            compiler.session().enable_internal_lints(),
                         );
                         let registered_lints =
                             if let Some(register_lints) = compiler.register_lints() {

compiler/rustc_interface/src/passes.rs

@@ -210,7 +210,7 @@ pub fn register_plugins<'a>(
 
     let mut lint_store = rustc_lint::new_lint_store(
         sess.opts.unstable_opts.no_interleave_lints,
-        sess.unstable_options(),
+        sess.enable_internal_lints(),
     );
     register_lints(sess, &mut lint_store);
 

compiler/rustc_lint/src/internal.rs

@@ -51,20 +51,6 @@ fn typeck_results_of_method_fn<'tcx>(
     cx: &LateContext<'tcx>,
     expr: &Expr<'_>,
 ) -> Option<(Span, DefId, ty::subst::SubstsRef<'tcx>)> {
-    // FIXME(rustdoc): Lints which use this function use typecheck results which can cause
-    // `rustdoc` to error if there are resolution failures.
-    //
-    // As internal lints are currently always run if there are `unstable_options`, they are added
-    // to the lint store of rustdoc. Internal lints are also not used via the `lint_mod` query.
-    // Crate lints run outside of a query so rustdoc currently doesn't disable them.
-    //
-    // Instead of relying on this, either change crate lints to a query disabled by rustdoc, only
-    // run internal lints if the user is explicitly opting in or figure out a different way to
-    // avoid running lints for rustdoc.
-    if cx.tcx.sess.opts.actually_rustdoc {
-        return None;
-    }
-
     match expr.kind {
         ExprKind::MethodCall(segment, _, _)
             if let Some(def_id) = cx.typeck_results().type_dependent_def_id(expr.hir_id) =>

compiler/rustc_session/src/session.rs

@@ -589,6 +589,14 @@ impl Session {
     pub fn time_passes(&self) -> bool {
         self.opts.unstable_opts.time_passes || self.opts.unstable_opts.time
     }
+
+    /// Returns `true` if internal lints should be added to the lint store - i.e. if
+    /// `-Zunstable-options` is provided and this isn't rustdoc (internal lints can trigger errors
+    /// to be emitted under rustdoc).
+    pub fn enable_internal_lints(&self) -> bool {
+        self.unstable_options() && !self.opts.actually_rustdoc
+    }
+
     pub fn instrument_mcount(&self) -> bool {
         self.opts.unstable_opts.instrument_mcount
     }

src/librustdoc/lib.rs

@@ -788,7 +788,7 @@ fn main_options(options: config::Options) -> MainResult {
         if sess.opts.describe_lints {
             let mut lint_store = rustc_lint::new_lint_store(
                 sess.opts.unstable_opts.no_interleave_lints,
-                sess.unstable_options(),
+                sess.enable_internal_lints(),
             );
             let registered_lints = if let Some(register_lints) = compiler.register_lints() {
                 register_lints(sess, &mut lint_store);