Don't ICE when computing a layout of a generator tainted by errors

4 files changed, 13 insertions, 8 deletions

diff --git a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
index 36a21b38c03..b9ae7963250 100644
--- a/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
+++ b/compiler/rustc_codegen_llvm/src/debuginfo/metadata.rs
@@ -1832,8 +1832,9 @@ impl<'tcx> VariantInfo<'_, 'tcx> {
     fn source_info(&self, cx: &CodegenCx<'ll, 'tcx>) -> Option<SourceInfo<'ll>> {
         match self {
             VariantInfo::Generator { def_id, variant_index, .. } => {
-                let span =
-                    cx.tcx.generator_layout(*def_id).variant_source_info[*variant_index].span;
+                let span = cx.tcx.generator_layout(*def_id).unwrap().variant_source_info
+                    [*variant_index]
+                    .span;
                 if !span.is_dummy() {
                     let loc = cx.lookup_debug_loc(span.lo());
                     return Some(SourceInfo {
diff --git a/compiler/rustc_middle/src/ty/layout.rs b/compiler/rustc_middle/src/ty/layout.rs
index 4475d4e9f2d..195e840866a 100644
--- a/compiler/rustc_middle/src/ty/layout.rs
+++ b/compiler/rustc_middle/src/ty/layout.rs
@@ -1466,10 +1466,12 @@ impl<'tcx> LayoutCx<'tcx, TyCtxt<'tcx>> {
     ) -> Result<&'tcx Layout, LayoutError<'tcx>> {
         use SavedLocalEligibility::*;
         let tcx = self.tcx;
-
         let subst_field = |ty: Ty<'tcx>| ty.subst(tcx, substs);
 
-        let info = tcx.generator_layout(def_id);
+        let info = match tcx.generator_layout(def_id) {
+            None => return Err(LayoutError::Unknown(ty)),
+            Some(info) => info,
+        };
         let (ineligible_locals, assignments) = self.generator_saved_local_eligibility(&info);
 
         // Build a prefix layout, including "promoting" all ineligible
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 8068574a38f..1399fc76e02 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -3068,8 +3068,10 @@ impl<'tcx> TyCtxt<'tcx> {
         self.trait_def(trait_def_id).has_auto_impl
     }
 
-    pub fn generator_layout(self, def_id: DefId) -> &'tcx GeneratorLayout<'tcx> {
-        self.optimized_mir(def_id).generator_layout.as_ref().unwrap()
+    /// Returns layout of a generator. Layout might be unavailable if the
+    /// generator is tainted by errors.
+    pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
+        self.optimized_mir(def_id).generator_layout.as_ref()
     }
 
     /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 744c7a541a5..d43c5135d90 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -605,7 +605,7 @@ impl<'tcx> GeneratorSubsts<'tcx> {
     #[inline]
     pub fn variant_range(&self, def_id: DefId, tcx: TyCtxt<'tcx>) -> Range<VariantIdx> {
         // FIXME requires optimized MIR
-        let num_variants = tcx.generator_layout(def_id).variant_fields.len();
+        let num_variants = tcx.generator_layout(def_id).unwrap().variant_fields.len();
         VariantIdx::new(0)..VariantIdx::new(num_variants)
     }
 
@@ -666,7 +666,7 @@ impl<'tcx> GeneratorSubsts<'tcx> {
         def_id: DefId,
         tcx: TyCtxt<'tcx>,
     ) -> impl Iterator<Item = impl Iterator<Item = Ty<'tcx>> + Captures<'tcx>> {
-        let layout = tcx.generator_layout(def_id);
+        let layout = tcx.generator_layout(def_id).unwrap();
         layout.variant_fields.iter().map(move |variant| {
             variant.iter().map(move |field| layout.field_tys[*field].subst(tcx, self.substs))
         })