Avoid ICE by accounting for missing type

Fix #105330

Author: estebank

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1607,7 +1607,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                         | ObligationCauseCode::ObjectCastObligation(..)
                         | ObligationCauseCode::OpaqueType
                 );
-                let expected_ty = data.term.ty().unwrap();
+                let expected_ty = data.term.ty().unwrap_or_else(|| self.tcx.ty_error());
 
                 // constrain inference variables a bit more to nested obligations from normalize so
                 // we can have more helpful errors.

src/test/ui/issues/issue-105330.rs

@@ -0,0 +1,21 @@
+pub trait TraitWAssocConst {
+    const A:   usize;
+}
+pub struct Demo {}
+
+impl TraitWAssocConst for impl Demo { //~ ERROR E0404
+    //~^ ERROR E0562
+    pubconst A: str = 32; //~ ERROR expected one of
+}
+
+fn foo<A: TraitWAssocConst<A=32>>() { //~ ERROR E0658
+    foo::<Demo>()(); //~ ERROR E0271
+    //~^ ERROR E0618
+    //~| ERROR E0277
+}
+
+fn main<A: TraitWAssocConst<A=32>>() { //~ ERROR E0131
+    //~^ ERROR E0658
+    foo::<Demo>(); //~ ERROR E0277
+    //~^ ERROR E0271
+}

src/test/ui/issues/issue-105330.stderr

@@ -0,0 +1,109 @@
+error: expected one of `!` or `::`, found `A`
+  --> $DIR/issue-105330.rs:8:14
+   |
+LL | impl TraitWAssocConst for impl Demo {
+   |                                     - while parsing this item list starting here
+LL |
+LL |     pubconst A: str = 32;
+   |              ^ expected one of `!` or `::`
+LL | }
+   | - the item list ends here
+
+error[E0404]: expected trait, found struct `Demo`
+  --> $DIR/issue-105330.rs:6:32
+   |
+LL | impl TraitWAssocConst for impl Demo {
+   |                                ^^^^ not a trait
+
+error[E0658]: associated const equality is incomplete
+  --> $DIR/issue-105330.rs:11:28
+   |
+LL | fn foo<A: TraitWAssocConst<A=32>>() {
+   |                            ^^^^
+   |
+   = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
+   = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
+
+error[E0658]: associated const equality is incomplete
+  --> $DIR/issue-105330.rs:17:29
+   |
+LL | fn main<A: TraitWAssocConst<A=32>>() {
+   |                             ^^^^
+   |
+   = note: see issue #92827 <https://github.com/rust-lang/rust/issues/92827> for more information
+   = help: add `#![feature(associated_const_equality)]` to the crate attributes to enable
+
+error[E0562]: `impl Trait` only allowed in function and inherent method return types, not in type
+  --> $DIR/issue-105330.rs:6:27
+   |
+LL | impl TraitWAssocConst for impl Demo {
+   |                           ^^^^^^^^^
+
+error[E0277]: the trait bound `Demo: TraitWAssocConst` is not satisfied
+  --> $DIR/issue-105330.rs:12:11
+   |
+LL |     foo::<Demo>()();
+   |           ^^^^ the trait `TraitWAssocConst` is not implemented for `Demo`
+   |
+note: required by a bound in `foo`
+  --> $DIR/issue-105330.rs:11:11
+   |
+LL | fn foo<A: TraitWAssocConst<A=32>>() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `foo`
+
+error[E0271]: type mismatch resolving `<Demo as TraitWAssocConst>::A == 32`
+  --> $DIR/issue-105330.rs:12:11
+   |
+LL |     foo::<Demo>()();
+   |           ^^^^ types differ
+   |
+note: required by a bound in `foo`
+  --> $DIR/issue-105330.rs:11:28
+   |
+LL | fn foo<A: TraitWAssocConst<A=32>>() {
+   |                            ^^^^ required by this bound in `foo`
+
+error[E0618]: expected function, found `()`
+  --> $DIR/issue-105330.rs:12:5
+   |
+LL | fn foo<A: TraitWAssocConst<A=32>>() {
+   | ----------------------------------- `foo::<Demo>` defined here returns `()`
+LL |     foo::<Demo>()();
+   |     ^^^^^^^^^^^^^--
+   |     |
+   |     call expression requires function
+
+error[E0277]: the trait bound `Demo: TraitWAssocConst` is not satisfied
+  --> $DIR/issue-105330.rs:19:11
+   |
+LL |     foo::<Demo>();
+   |           ^^^^ the trait `TraitWAssocConst` is not implemented for `Demo`
+   |
+note: required by a bound in `foo`
+  --> $DIR/issue-105330.rs:11:11
+   |
+LL | fn foo<A: TraitWAssocConst<A=32>>() {
+   |           ^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `foo`
+
+error[E0271]: type mismatch resolving `<Demo as TraitWAssocConst>::A == 32`
+  --> $DIR/issue-105330.rs:19:11
+   |
+LL |     foo::<Demo>();
+   |           ^^^^ types differ
+   |
+note: required by a bound in `foo`
+  --> $DIR/issue-105330.rs:11:28
+   |
+LL | fn foo<A: TraitWAssocConst<A=32>>() {
+   |                            ^^^^ required by this bound in `foo`
+
+error[E0131]: `main` function is not allowed to have generic parameters
+  --> $DIR/issue-105330.rs:17:8
+   |
+LL | fn main<A: TraitWAssocConst<A=32>>() {
+   |        ^^^^^^^^^^^^^^^^^^^^^^^^^^^ `main` cannot have generic parameters
+
+error: aborting due to 11 previous errors
+
+Some errors have detailed explanations: E0131, E0271, E0277, E0404, E0562, E0618, E0658.
+For more information about an error, try `rustc --explain E0131`.