Update mir-opt tests.

src/test/mir-opt/copy_propagation.rs

@@ -13,7 +13,10 @@ fn test(x: u32) -> u32 {
     y
 }
 
-fn main() { }
+fn main() {
+    // Make sure the function actually gets instantiated.
+    test(0);
+}
 
 // END RUST SOURCE
 // START rustc.node4.CopyPropagation.before.mir

src/test/mir-opt/deaggregator_test.rs

@@ -18,7 +18,10 @@ fn bar(a: usize) -> Baz {
     Baz { x: a, y: 0.0, z: false }
 }
 
-fn main() {}
+fn main() {
+    // Make sure the function actually gets instantiated.
+    bar(0);
+}
 
 // END RUST SOURCE
 // START rustc.node13.Deaggregator.before.mir

src/test/mir-opt/deaggregator_test_enum_2.rs

@@ -23,7 +23,10 @@ fn test1(x: bool, y: i32) -> Foo {
     }
 }
 
-fn main() {}
+fn main() {
+    // Make sure the function actually gets instantiated.
+    test1(false, 0);
+}
 
 // END RUST SOURCE
 // START rustc.node12.Deaggregator.before.mir

src/test/mir-opt/deaggregator_test_multiple.rs

@@ -19,7 +19,10 @@ fn test(x: i32) -> [Foo; 2] {
     [Foo::A(x), Foo::A(x)]
 }
 
-fn main() { }
+fn main() {
+    // Make sure the function actually gets instantiated.
+    test(0);
+}
 
 // END RUST SOURCE
 // START rustc.node10.Deaggregator.before.mir

src/test/mir-opt/issue-41110.rs

@@ -14,7 +14,10 @@ fn main() {
     let x = S.other(S.id());
 }
 
-pub fn test() {
+// no_mangle and extern C to make sure this gets instantiated even in an
+// executable.
+#[no_mangle]
+pub extern "C" fn test() {
     let u = S;
     let mut v = S;
     drop(v);