[PATCH] c++/modules: Propagate DECL_ARGUMENTS when reading a function def [PR124485]

[Nathaniel Shead]

Bootstrapped and regtested on x86_64-pc-linux-gnu, OK for trunk/15?

-- >8 --

The crash in the given PR occurs because we've streamed the definition
of an anticipated builtin, but when processing the nonnull attribute we
find that its DECL_ARGUMENTS is null.

Back in r14-8196-g3471a61ed0ddef70de8f1bbba85cd1e945fc86fd I removed the
setting of DECL_ARGUMENTS as this was causing issues where we were
replacing the argument list for existing definitions.  But it looks like
really it should have been adjusted just to only do the replacement in
cases that a definition wasn't already available, i.e. if installing.

        PR c++/124485

gcc/cp/ChangeLog:

        * module.cc (trees_in::read_function_def): Set DECL_ARGUMENTS if
        installing.

gcc/testsuite/ChangeLog:

        * g++.dg/modules/builtin-10_a.C: New test.
        * g++.dg/modules/builtin-10_b.C: New test.

Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
---
 gcc/cp/module.cc                            |  1 +
 gcc/testsuite/g++.dg/modules/builtin-10_a.C | 24 +++++++++++++++++++++
 gcc/testsuite/g++.dg/modules/builtin-10_b.C |  9 ++++++++
 3 files changed, 34 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/modules/builtin-10_a.C
 create mode 100644 gcc/testsuite/g++.dg/modules/builtin-10_b.C

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 83d24a3267d..066afca874f 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -13216,6 +13216,7 @@ trees_in::read_function_def (tree decl, tree 
maybe_template)
       DECL_RESULT (decl) = result;
       DECL_INITIAL (decl) = initial;
       DECL_SAVED_TREE (decl) = saved;
+      DECL_ARGUMENTS (decl) = DECL_ARGUMENTS (maybe_dup);
 
       if (context)
        SET_DECL_FRIEND_CONTEXT (decl, context);
diff --git a/gcc/testsuite/g++.dg/modules/builtin-10_a.C 
b/gcc/testsuite/g++.dg/modules/builtin-10_a.C
new file mode 100644
index 00000000000..cbadede81df
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/builtin-10_a.C
@@ -0,0 +1,24 @@
+// PR c++/124485
+// { dg-additional-options "-fmodules -Wno-global-module -O3" }
+// { dg-module-cmi M }
+
+module;
+extern "C" {
+  typedef long unsigned int size_t;
+
+  extern void *memset (void *__s, int __c, size_t __n) noexcept (true) 
__attribute__ ((__nonnull__ (1)));
+
+  extern
+    __inline
+    __attribute__((__always_inline__))
+    __attribute__((__gnu_inline__))
+    __attribute__((__artificial__))
+  void *
+    __attribute__((__leaf__))
+  memset(void *__dest, int __ch, size_t __len) noexcept(true) {
+    return __builtin___memset_chk(__dest, __ch, __len,
+                                  __builtin_object_size(__dest, 0));
+  }
+}
+export module M;
+export using ::memset;
diff --git a/gcc/testsuite/g++.dg/modules/builtin-10_b.C 
b/gcc/testsuite/g++.dg/modules/builtin-10_b.C
new file mode 100644
index 00000000000..acb49bbbe8b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/builtin-10_b.C
@@ -0,0 +1,9 @@
+// PR c++/124485
+// { dg-additional-options "-fmodules -O3 -fdump-lang-module-alias" }
+
+import M;
+void foo(void *data) {
+  memset(data, 0xFF, 4);
+}
+
+// { dg-final { scan-lang-dump {Deduping '::memset'} module } }
-- 
2.51.0