gccrs: Fix ICE by adding check for enum candidate's in TypePath resolution

Fixes #2479

gcc/rust/ChangeLog:

	* typecheck/rust-hir-trait-resolve.cc (TraitItemReference::resolve_item):
	always resolve the type even when its an a mandatory trait item
	* typecheck/rust-hir-type-check-type.cc (TypeCheckType::resolve_root_path):
	Add check for enum candidates otherwise you get undefined behaviour

gcc/testsuite/ChangeLog:

	* rust/compile/issue-2479.rs: New test.

Signed-off-by: Philip Herron <herron.philip@googlemail.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/gcc/testsuite/rust/compile/issue-2479.rs b/gcc/testsuite/rust/compile/issue-2479.rs
new file mode 100644
index 0000000..4a0d354
--- /dev/null
+++ b/gcc/testsuite/rust/compile/issue-2479.rs
@@ -0,0 +1,22 @@
+#![allow(unused)]
+fn main() {
+enum Dragon {
+    Born,
+}
+
+fn oblivion() -> Dragon::Born {
+// { dg-error "expected type, found variant of Dragon" "" { target *-*-* } .-1 }
+// { dg-error "failed to resolve return type" "" { target *-*-* } .-2 }
+    Dragon::Born
+}
+
+enum Wizard {
+    Gandalf,
+    Saruman,
+}
+
+trait Isengard {
+    fn wizard(_: Wizard::Saruman);
+    // { dg-error "expected type, found variant of Wizard" "" { target *-*-* } .-1 }
+}
+}