1 files changed, 72 insertions, 0 deletions
diff --git a/src/test/incremental/thinlto/cgu_keeps_identical_fn.rs b/src/test/incremental/thinlto/cgu_keeps_identical_fn.rs
new file mode 100644
index 000000000..31f329a7f
--- /dev/null
+++ b/src/test/incremental/thinlto/cgu_keeps_identical_fn.rs
@@ -0,0 +1,72 @@
+// This test is almost identical to `cgu_invalided_via_import`, except that
+// the two versions of `inline_fn` are identical. Neither version of `inlined_fn`
+// ends up with any spans in its LLVM bitecode, so LLVM is able to skip
+// re-building any modules which import 'inlined_fn'
+
+// revisions: cfail1 cfail2 cfail3 cfail4 cfail5 cfail6
+// [cfail4]compile-flags: -Zincremental-relative-spans
+// [cfail5]compile-flags: -Zincremental-relative-spans
+// [cfail6]compile-flags: -Zincremental-relative-spans
+// compile-flags: -Z query-dep-graph -O
+// build-pass (FIXME(62277): could be check-pass?)
+
+#![feature(rustc_attrs)]
+#![crate_type = "rlib"]
+#![rustc_expected_cgu_reuse(module = "cgu_keeps_identical_fn-foo", cfg = "cfail2", kind = "no")]
+#![rustc_expected_cgu_reuse(
+    module = "cgu_keeps_identical_fn-foo",
+    cfg = "cfail3",
+    kind = "post-lto"
+)]
+#![rustc_expected_cgu_reuse(
+    module = "cgu_keeps_identical_fn-foo",
+    cfg = "cfail5",
+    kind = "post-lto"
+)]
+#![rustc_expected_cgu_reuse(
+    module = "cgu_keeps_identical_fn-foo",
+    cfg = "cfail6",
+    kind = "post-lto"
+)]
+#![rustc_expected_cgu_reuse(
+    module = "cgu_keeps_identical_fn-bar",
+    cfg = "cfail2",
+    kind = "post-lto"
+)]
+#![rustc_expected_cgu_reuse(
+    module = "cgu_keeps_identical_fn-bar",
+    cfg = "cfail3",
+    kind = "post-lto"
+)]
+#![rustc_expected_cgu_reuse(
+    module = "cgu_keeps_identical_fn-bar",
+    cfg = "cfail5",
+    kind = "post-lto"
+)]
+#![rustc_expected_cgu_reuse(
+    module = "cgu_keeps_identical_fn-bar",
+    cfg = "cfail6",
+    kind = "post-lto"
+)]
+
+mod foo {
+
+    // Trivial functions like this one are imported very reliably by ThinLTO.
+    #[cfg(any(cfail1, cfail4))]
+    pub fn inlined_fn() -> u32 {
+        1234
+    }
+
+    #[cfg(not(any(cfail1, cfail4)))]
+    pub fn inlined_fn() -> u32 {
+        1234
+    }
+}
+
+pub mod bar {
+    use foo::inlined_fn;
+
+    pub fn caller() -> u32 {
+        inlined_fn()
+    }
+}