gccrs: Fix ICE on copied array expressions

We need to check for errors on the number of copies expression before
trying to const fold it otherwise it will just fail in the const evaluator.

Fixes #4165

gcc/rust/ChangeLog:

	* typecheck/rust-hir-type-check-expr.cc (TypeCheckExpr::visit): check for error

gcc/testsuite/ChangeLog:

	* rust/compile/issue-4165.rs: New test.

Signed-off-by: Philip Herron <[email protected]>

Author: philberty

gcc/rust/typecheck/rust-hir-type-check-expr.cc

@@ -1096,11 +1096,13 @@ TypeCheckExpr::visit (HIR::ArrayExpr &expr)
 	context->insert_type (elems.get_num_copies_expr ().get_mappings (),
 			      expected_ty);
 
-	unify_site (
+	auto result = unify_site (
 	  expr.get_mappings ().get_hirid (), TyTy::TyWithLocation (expected_ty),
 	  TyTy::TyWithLocation (capacity_expr_ty,
 				elems.get_num_copies_expr ().get_locus ()),
 	  expr.get_locus ());
+	if (result->is<TyTy::ErrorType> ())
+	  return;
 
 	capacity_expr = &elems.get_num_copies_expr ();
 	capacity_type = expected_ty;

gcc/testsuite/rust/compile/issue-4165.rs

@@ -0,0 +1,12 @@
+const N: usize = 2;
+const ARR: [i32; N] = [42; X];
+// { dg-error {cannot find value .X. in this scope \[E0425\]} "" { target *-*-* } .-1 }
+// { dg-error {mismatched types, expected .\[i32; 2]. but got .<tyty::error>. \[E0308\]} "" { target *-*-* } .-2 }
+// { dg-error {mismatched types, expected .usize. but got .bool. \[E0308\]} "" { target *-*-* } .-3 }
+const X: bool = (N[0] == 99) && (ARR[0] == 0);
+// { dg-error {the type .usize. cannot be indexed by .<integer>. \[E0277\]} "" { target *-*-* } .-1 }
+// { dg-error {mismatched types, expected .<tyty::error>. but got .<integer>. \[E0308\]} "" { target *-*-* } .-2 }
+
+fn main() {
+    let _ = X;
+}