[PATCH] c++: Keep DECL_SAVED_TREE of destructor instantiations in modules [PR104040]

[Nathaniel Shead <nathanieloshead@gmail.com>]

Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk?

-- >8 --

A template instantiation still needs to have its DECL_SAVED_TREE so that
its definition is emitted into the CMI. This way it can be emitted in
the object file of any importers that use it, in case it doesn't end up
getting emitted in this TU.

	PR c++/104040

gcc/cp/ChangeLog:

	* semantics.cc (expand_or_defer_fn_1): Also keep DECL_SAVED_TREE
	for template instantiations.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/pr104040_a.C: New test.
	* g++.dg/modules/pr104040_b.C: New test.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
---
 gcc/cp/semantics.cc                       |  7 +++++--
 gcc/testsuite/g++.dg/modules/pr104040_a.C | 14 ++++++++++++++
 gcc/testsuite/g++.dg/modules/pr104040_b.C |  8 ++++++++
 3 files changed, 27 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/modules/pr104040_a.C
 create mode 100644 gcc/testsuite/g++.dg/modules/pr104040_b.C

diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index adb1ba48d29..84e9901509a 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -5033,9 +5033,12 @@ expand_or_defer_fn_1 (tree fn)
       /* We don't want to process FN again, so pretend we've written
 	 it out, even though we haven't.  */
       TREE_ASM_WRITTEN (fn) = 1;
-      /* If this is a constexpr function, keep DECL_SAVED_TREE.  */
+      /* If this is a constexpr function, or the body might need to be
+	 exported from a module CMI, keep DECL_SAVED_TREE.  */
       if (!DECL_DECLARED_CONSTEXPR_P (fn)
-	  && !(modules_p () && DECL_DECLARED_INLINE_P (fn)))
+	  && !(modules_p ()
+	       && (DECL_DECLARED_INLINE_P (fn)
+		   || DECL_TEMPLATE_INSTANTIATION (fn))))
 	DECL_SAVED_TREE (fn) = NULL_TREE;
       return false;
     }
diff --git a/gcc/testsuite/g++.dg/modules/pr104040_a.C b/gcc/testsuite/g++.dg/modules/pr104040_a.C
new file mode 100644
index 00000000000..ea36ce0a798
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr104040_a.C
@@ -0,0 +1,14 @@
+// PR c++/104040
+// { dg-additional-options "-fmodules-ts" }
+// { dg-module-cmi test }
+
+export module test;
+
+export template <typename T>
+struct test {
+  ~test() {}
+};
+
+test<bool> use() {
+  return {};
+}
diff --git a/gcc/testsuite/g++.dg/modules/pr104040_b.C b/gcc/testsuite/g++.dg/modules/pr104040_b.C
new file mode 100644
index 00000000000..efe014673fb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/pr104040_b.C
@@ -0,0 +1,8 @@
+// PR c++/104040
+// { dg-additional-options "-fmodules-ts" }
+
+import test;
+
+int main() {
+  test<bool> t{};
+}
-- 
2.43.2