1 files changed, 36 insertions, 0 deletions
diff --git a/samples/test/gcc5_codegen_bug.rs b/samples/test/gcc5_codegen_bug.rs
new file mode 100644
index 00000000..60a54ea9
--- /dev/null
+++ b/samples/test/gcc5_codegen_bug.rs
@@ -0,0 +1,36 @@
+// compile-flags: -O
+extern crate test;
+
+// A reduction of issue #63, where gcc5 (but not 6) will generate invalid code for the following iterator adapter's
+// `next` function (seen in librustc)
+// ::"core"::iter::Map<::"core"::iter::Chain<::"core"::iter::sources::Once<::"syntax"::ast::NodeId/*S*/,>/*S*/,::"core"::iter::Map<::"core"::slice::Iter<::"syntax"::codemap::Spanned<::"syntax"::ast::PathListItem_/*S*/,>/*S*/,>/*S*/,::"rustc"::closure_I_82<::"rustc"::hir::lowering::LoweringContext/*S*/,>/*S*/,>/*S*/,>/*S*/,::"rustc"::closure_I_83<::"rustc"::hir::lowering::LoweringContext/*S*/,>/*S*/,>
+//
+// Symptom is an abort due to bad enum tag on Option<u32> when handling the second call to `it.next()`
+
+fn main() {
+    let n = 0;
+    let list: &[u32] = &[1]; // List can be zero length, it's appears to be the _last_ result that leads to a bad tag.
+    // Has to have the second map - even if it's just identity, first map probably needs to exist
+    let mut it = Iterator::chain(
+            ::std::iter::once(0u32),
+            list.iter().map(|v| *v)
+        ).map(|id| id);
+
+    // First works, and Foo is printed
+    it.next();
+    println!("Foo");
+    // Second one will crash with an abort (used in condition to avoid it being optimised out)
+    if it.next().is_none() {
+        println!("Bar");
+    }
+    else {
+        println!("Not-Bar");
+    }
+    if it.next().is_none() {
+        println!("Bar");
+    }
+    else {
+        println!("Not-Bar");
+    }
+}
+