https://gcc.gnu.org/g:70136bdc76ae1774162ccbeeedd33aa531950e68
commit r16-2698-g70136bdc76ae1774162ccbeeedd33aa531950e68
Author: Nathaniel Shead <nathanielosh...@gmail.com>
Date: Thu Jul 31 08:56:09 2025 +1000
c++/modules: Merge PARM_DECL properties from function definitions [PR121238]
When we merge a function definition, if there already exists a forward
declaration in the importing TU we use the PARM_DECLs belonging to that
decl. This usually works fine, except as noted in the linked PR there
are some flags (such as TREE_ADDRESSABLE) that only get set on a
PARM_DECL once a definition is provided.
This patch fixes the wrong-code issues by propagating any properties on
PARM_DECLs I could find that may affect codegen.
PR c++/121238
gcc/cp/ChangeLog:
* module.cc (trees_in::fn_parms_fini): Merge properties for
definitions.
gcc/testsuite/ChangeLog:
* g++.dg/modules/merge-19.h: New test.
* g++.dg/modules/merge-19_a.H: New test.
* g++.dg/modules/merge-19_b.C: New test.
Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
Reviewed-by: Jason Merrill <ja...@redhat.com>
Reviewed-by: Patrick Palka <ppa...@redhat.com>
Diff:
---
gcc/cp/module.cc | 14 ++++++++++++++
gcc/testsuite/g++.dg/modules/merge-19.h | 21 +++++++++++++++++++++
gcc/testsuite/g++.dg/modules/merge-19_a.H | 5 +++++
gcc/testsuite/g++.dg/modules/merge-19_b.C | 16 ++++++++++++++++
4 files changed, 56 insertions(+)
diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 2f6a8ab98fa9..e6dcace0fad3 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -11164,6 +11164,20 @@ trees_in::fn_parms_fini (int tag, tree fn, tree
existing, bool is_defn)
names of the parms from us. */
DECL_NAME (existing_parm) = DECL_NAME (parm);
DECL_SOURCE_LOCATION (existing_parm) = DECL_SOURCE_LOCATION
(parm);
+
+ /* And some other flags important for codegen are only set
+ by the definition. */
+ TREE_ADDRESSABLE (existing_parm) = TREE_ADDRESSABLE (parm);
+ DECL_BY_REFERENCE (existing_parm) = DECL_BY_REFERENCE (parm);
+ DECL_NONLOCAL (existing_parm) = DECL_NONLOCAL (parm);
+ DECL_ARG_TYPE (existing_parm) = DECL_ARG_TYPE (parm);
+
+ /* Invisiref parms had their types adjusted by cp_genericize. */
+ if (DECL_BY_REFERENCE (parm))
+ {
+ TREE_TYPE (existing_parm) = TREE_TYPE (parm);
+ relayout_decl (existing_parm);
+ }
}
back_refs[~tag] = existing_parm;
diff --git a/gcc/testsuite/g++.dg/modules/merge-19.h
b/gcc/testsuite/g++.dg/modules/merge-19.h
new file mode 100644
index 000000000000..c3faadce07ad
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/merge-19.h
@@ -0,0 +1,21 @@
+// PR c++/121238
+
+inline void inc(const char*& __first) {
+ ++__first;
+}
+
+template <typename = void>
+bool parse_integer(const char *first) {
+ const char *start = first;
+ inc(first);
+ return first != start;
+}
+template bool parse_integer<void>(const char*);
+
+
+struct S { ~S() {} int x; };
+template <typename = void>
+bool take_by_invisiref(S s) {
+ return s.x == 5;
+}
+template bool take_by_invisiref<void>(S);
diff --git a/gcc/testsuite/g++.dg/modules/merge-19_a.H
b/gcc/testsuite/g++.dg/modules/merge-19_a.H
new file mode 100644
index 000000000000..149a447f2660
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/merge-19_a.H
@@ -0,0 +1,5 @@
+// PR c++/121238
+// { dg-additional-options "-fmodule-header" }
+// { dg-module-cmi {} }
+
+#include "merge-19.h"
diff --git a/gcc/testsuite/g++.dg/modules/merge-19_b.C
b/gcc/testsuite/g++.dg/modules/merge-19_b.C
new file mode 100644
index 000000000000..345e7fe13421
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/merge-19_b.C
@@ -0,0 +1,16 @@
+// PR c++/121238
+// { dg-module-do run }
+// { dg-additional-options "-fmodules -fno-module-lazy" }
+
+#include "merge-19.h"
+import "merge-19_a.H";
+
+int main() {
+ const char fmt[] = "5";
+ if (!parse_integer<void>(fmt))
+ __builtin_abort();
+
+ S s{ 5 };
+ if (!take_by_invisiref(s))
+ __builtin_abort();
+}
