1 files changed, 68 insertions, 0 deletions
diff --git a/tests/ui/consts/promote-not.rs b/tests/ui/consts/promote-not.rs
new file mode 100644
index 000000000..907617052
--- /dev/null
+++ b/tests/ui/consts/promote-not.rs
@@ -0,0 +1,68 @@
+// ignore-tidy-linelength
+// Test various things that we do not want to promote.
+#![allow(unconditional_panic)]
+
+use std::cell::Cell;
+
+// We do not promote mutable references.
+static mut TEST1: Option<&mut [i32]> = Some(&mut [1, 2, 3]); //~ ERROR temporary value dropped while borrowed
+
+static mut TEST2: &'static mut [i32] = {
+    let x = &mut [1,2,3]; //~ ERROR temporary value dropped while borrowed
+    x
+};
+
+// We do not promote fn calls in `fn`, including `const fn`.
+pub const fn promote_cal(b: bool) -> i32 {
+    const fn foo() { [()][42] }
+
+    if b {
+        let _x: &'static () = &foo(); //~ ERROR temporary value dropped while borrowed
+    }
+    13
+}
+
+// We do not promote union field accesses in `fn.
+union U { x: i32, y: i32 }
+pub const fn promote_union() {
+    let _x: &'static i32 = &unsafe { U { x: 0 }.x }; //~ ERROR temporary value dropped while borrowed
+}
+
+// We do not promote union field accesses in `const`, either.
+const TEST_UNION: () = {
+    let _x: &'static i32 = &unsafe { U { x: 0 }.x }; //~ ERROR temporary value dropped while borrowed
+};
+
+// In a `const`, we do not promote things with interior mutability. Not even if we "project it away".
+const TEST_INTERIOR_MUT: () = {
+    // The "0." case is already ruled out by not permitting any interior mutability in `const`.
+    let _val: &'static _ = &(Cell::new(1), 2).1; //~ ERROR temporary value dropped while borrowed
+};
+
+const TEST_DROP: String = String::new();
+
+fn main() {
+    // We must not promote things with interior mutability. Not even if we "project it away".
+    let _val: &'static _ = &(Cell::new(1), 2).0; //~ ERROR temporary value dropped while borrowed
+    let _val: &'static _ = &(Cell::new(1), 2).1; //~ ERROR temporary value dropped while borrowed
+
+    // No promotion of fallible operations.
+    let _val: &'static _ = &(1/0); //~ ERROR temporary value dropped while borrowed
+    let _val: &'static _ = &(1/(1-1)); //~ ERROR temporary value dropped while borrowed
+    let _val: &'static _ = &(1%0); //~ ERROR temporary value dropped while borrowed
+    let _val: &'static _ = &(1%(1-1)); //~ ERROR temporary value dropped while borrowed
+    let _val: &'static _ = &([1,2,3][4]+1); //~ ERROR temporary value dropped while borrowed
+
+    // No promotion of temporaries that need to be dropped.
+    let _val: &'static _ = &TEST_DROP;
+    //~^ ERROR temporary value dropped while borrowed
+    let _val: &'static _ = &&TEST_DROP;
+    //~^ ERROR temporary value dropped while borrowed
+    //~| ERROR temporary value dropped while borrowed
+    let _val: &'static _ = &(&TEST_DROP,);
+    //~^ ERROR temporary value dropped while borrowed
+    //~| ERROR temporary value dropped while borrowed
+    let _val: &'static _ = &[&TEST_DROP; 1];
+    //~^ ERROR temporary value dropped while borrowed
+    //~| ERROR temporary value dropped while borrowed
+}