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diff --git a/src/test/incremental/thinlto/cgu_invalidated_when_import_added.rs b/src/test/incremental/thinlto/cgu_invalidated_when_import_added.rs
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+++ b/src/test/incremental/thinlto/cgu_invalidated_when_import_added.rs
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+// revisions: cfail1 cfail2
+// compile-flags: -O -Zhuman-readable-cgu-names -Cllvm-args=-import-instr-limit=10
+// build-pass
+
+// rust-lang/rust#59535:
+//
+// This is analogous to cgu_invalidated_when_import_removed.rs, but it covers
+// the other direction:
+//
+// We start with a call-graph like `[A] -> [B -> D] [C]` (where the letters are
+// functions and the modules are enclosed in `[]`), and add a new call `D <- C`,
+// yielding the new call-graph: `[A] -> [B -> D] <- [C]`
+//
+// The effect of this is that the compiler previously classfied `D` as internal
+// and the import-set of `[A]` to be just `B`. But after adding the `D <- C` call,
+// `D` is no longer classified as internal, and the import-set of `[A]` becomes
+// both `B` and `D`.
+//
+// We check this case because an early proposed pull request included an
+// assertion that the import-sets monotonically decreased over time, a claim
+// which this test case proves to be false.
+
+fn main() {
+    foo::foo();
+    bar::baz();
+}
+
+mod foo {
+
+    // In cfail1, ThinLTO decides that foo() does not get inlined into main, and
+    // instead bar() gets inlined into foo().
+    // In cfail2, foo() gets inlined into main.
+    pub fn foo(){
+        bar()
+    }
+
+    // This function needs to be big so that it does not get inlined by ThinLTO
+    // but *does* get inlined into foo() when it is declared `internal` in
+    // cfail1 (alone).
+    pub fn bar(){
+        println!("quux1");
+        println!("quux2");
+        println!("quux3");
+        println!("quux4");
+        println!("quux5");
+        println!("quux6");
+        println!("quux7");
+        println!("quux8");
+        println!("quux9");
+    }
+}
+
+mod bar {
+
+    #[inline(never)]
+    pub fn baz() {
+        #[cfg(cfail2)]
+        {
+            crate::foo::bar();
+        }
+    }
+}