Handle type errors in closure/generator upvar_tys

Co-authored-by: Roxane Fruytier <roxane.fruytier@hotmail.com>

Cargo.lock

@@ -3883,6 +3883,7 @@ version = "0.0.0"
 dependencies = [
  "bitflags",
  "chalk-ir",
+ "either",
  "measureme 9.0.0",
  "polonius-engine",
  "rustc-rayon-core",

compiler/rustc_middle/Cargo.toml

@@ -8,6 +8,7 @@ edition = "2018"
 doctest = false
 
 [dependencies]
+either = "1.5.0"
 rustc_arena = { path = "../rustc_arena" }
 bitflags = "1.2.1"
 tracing = "0.1"

compiler/rustc_middle/src/ty/sty.rs

@@ -5,6 +5,8 @@
 use self::InferTy::*;
 use self::TyKind::*;
 
+use either::Either;
+
 use crate::infer::canonical::Canonical;
 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
 use crate::ty::{
@@ -388,9 +390,17 @@ impl<'tcx> ClosureSubsts<'tcx> {
         self.split().parent_substs
     }
 
+    /// Returns an iterator over the list of types of captured paths by the closure.
+    /// In case there was a type error in figuring out the types of the captured path, an
+    /// empty iterator is returned.
     #[inline]
     pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
-        self.tupled_upvars_ty().tuple_fields()
+        match self.tupled_upvars_ty().kind() {
+            TyKind::Error(_) => Either::Left(std::iter::empty()),
+            TyKind::Tuple(..) => Either::Right(self.tupled_upvars_ty().tuple_fields()),
+            TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
+            ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
+        }
     }
 
     /// Returns the tuple type representing the upvars for this closure.
@@ -515,9 +525,17 @@ impl<'tcx> GeneratorSubsts<'tcx> {
         self.split().witness.expect_ty()
     }
 
+    /// Returns an iterator over the list of types of captured paths by the generator.
+    /// In case there was a type error in figuring out the types of the captured path, an
+    /// empty iterator is returned.
     #[inline]
     pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
-        self.tupled_upvars_ty().tuple_fields()
+        match self.tupled_upvars_ty().kind() {
+            TyKind::Error(_) => Either::Left(std::iter::empty()),
+            TyKind::Tuple(..) => Either::Right(self.tupled_upvars_ty().tuple_fields()),
+            TyKind::Infer(_) => bug!("upvar_tys called before capture types are inferred"),
+            ty => bug!("Unexpected representation of upvar types tuple {:?}", ty),
+        }
     }
 
     /// Returns the tuple type representing the upvars for this generator.
@@ -660,13 +678,15 @@ pub enum UpvarSubsts<'tcx> {
 }
 
 impl<'tcx> UpvarSubsts<'tcx> {
+    /// Returns an iterator over the list of types of captured paths by the closure/generator.
+    /// In case there was a type error in figuring out the types of the captured path, an
+    /// empty iterator is returned.
     #[inline]
     pub fn upvar_tys(self) -> impl Iterator<Item = Ty<'tcx>> + 'tcx {
-        let tupled_upvars_ty = match self {
-            UpvarSubsts::Closure(substs) => substs.as_closure().split().tupled_upvars_ty,
-            UpvarSubsts::Generator(substs) => substs.as_generator().split().tupled_upvars_ty,
-        };
-        tupled_upvars_ty.expect_ty().tuple_fields()
+        match self {
+            UpvarSubsts::Closure(substs) => Either::Left(substs.as_closure().upvar_tys()),
+            UpvarSubsts::Generator(substs) => Either::Right(substs.as_generator().upvar_tys()),
+        }
     }
 
     #[inline]

src/test/ui/issues/issue-77993-1.rs

@@ -0,0 +1,12 @@
+#[derive(Clone)]
+struct InGroup<F> {
+    it: It,
+    //~^ ERROR cannot find type `It` in this scope
+    f: F,
+}
+fn dates_in_year() -> impl Clone {
+    InGroup { f: |d| d }
+    //~^ ERROR missing field `it` in initializer of `InGroup<_>`
+}
+
+fn main() {}

src/test/ui/issues/issue-77993-1.stderr

@@ -0,0 +1,16 @@
+error[E0412]: cannot find type `It` in this scope
+  --> $DIR/issue-77993-1.rs:3:9
+   |
+LL |     it: It,
+   |         ^^ not found in this scope
+
+error[E0063]: missing field `it` in initializer of `InGroup<_>`
+  --> $DIR/issue-77993-1.rs:8:5
+   |
+LL |     InGroup { f: |d| d }
+   |     ^^^^^^^ missing `it`
+
+error: aborting due to 2 previous errors
+
+Some errors have detailed explanations: E0063, E0412.
+For more information about an error, try `rustc --explain E0063`.

src/test/ui/issues/issue-77993-2.rs

@@ -0,0 +1,9 @@
+// edition:2018
+
+async fn test() -> Result<(), Box<dyn std::error::Error>> {
+    macro!();
+    //~^ ERROR expected identifier, found `!`
+    Ok(())
+}
+
+fn main() {}

src/test/ui/issues/issue-77993-2.stderr

@@ -0,0 +1,8 @@
+error: expected identifier, found `!`
+  --> $DIR/issue-77993-2.rs:4:10
+   |
+LL |     macro!();
+   |          ^ expected identifier
+
+error: aborting due to previous error
+