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-rw-r--r--tests/ui/unboxed-closures/unboxed-closures-mutate-upvar.rs57
1 files changed, 57 insertions, 0 deletions
diff --git a/tests/ui/unboxed-closures/unboxed-closures-mutate-upvar.rs b/tests/ui/unboxed-closures/unboxed-closures-mutate-upvar.rs
new file mode 100644
index 000000000..c57312b43
--- /dev/null
+++ b/tests/ui/unboxed-closures/unboxed-closures-mutate-upvar.rs
@@ -0,0 +1,57 @@
+// Test that we cannot mutate an outer variable that is not declared
+// as `mut` through a closure. Also test that we CAN mutate a moved copy,
+// unless this is a `Fn` closure. Issue #16749.
+
+#![feature(unboxed_closures, tuple_trait)]
+
+use std::mem;
+
+fn to_fn<A:std::marker::Tuple,F:Fn<A>>(f: F) -> F { f }
+fn to_fn_mut<A:std::marker::Tuple,F:FnMut<A>>(f: F) -> F { f }
+
+fn a() {
+ let n = 0;
+ let mut f = to_fn_mut(|| {
+ n += 1; //~ ERROR cannot assign to `n`, as it is not declared as mutable
+ });
+}
+
+fn b() {
+ let mut n = 0;
+ let mut f = to_fn_mut(|| {
+ n += 1; // OK
+ });
+}
+
+fn c() {
+ let n = 0;
+ let mut f = to_fn_mut(move || {
+ // If we just did a straight-forward desugaring, this would
+ // compile, but we do something a bit more subtle, and hence
+ // we get an error.
+ n += 1; //~ ERROR cannot assign
+ });
+}
+
+fn d() {
+ let mut n = 0;
+ let mut f = to_fn_mut(move || {
+ n += 1; // OK
+ });
+}
+
+fn e() {
+ let n = 0;
+ let mut f = to_fn(move || {
+ n += 1; //~ ERROR cannot assign
+ });
+}
+
+fn f() {
+ let mut n = 0;
+ let mut f = to_fn(move || {
+ n += 1; //~ ERROR cannot assign
+ });
+}
+
+fn main() { }