[PATCH] coroutines: Do not assume parms are named [PR94752].

[Iain Sandoe]

Hi 

As pointed out in the PR, parameters to user-defined coroutines might be
unnamed.  In that case, we must synthesize a name for the coroutine
frame copy.

tested on x86_64-darwin16 so far,
OK if it passes regtest on x86_64-linux?
thanks
Iain

gcc/cp/ChangeLog:

2020-04-25  Iain Sandoe  <i...@sandoe.co.uk>

        * coroutines.cc (morph_fn_to_coro): Ensure that
        unnamed function params have a usable and distinct
        frame field name.

gcc/testsuite/ChangeLog:

2020-04-25  Iain Sandoe  <i...@sandoe.co.uk>

        * g++.dg/coroutines/pr94752.C: New test.
---
 gcc/cp/coroutines.cc                      | 11 +++++++++--
 gcc/testsuite/g++.dg/coroutines/pr94752.C | 17 +++++++++++++++++
 2 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/coroutines/pr94752.C

diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 137d87bf294..ab1bdb9bcdb 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -3797,6 +3797,7 @@ morph_fn_to_coro (tree orig, tree *resumer, tree 
*destroyer)
       param_uses = new hash_map<tree, param_info>;
       bool lambda_p = LAMBDA_TYPE_P (DECL_CONTEXT (orig));
 
+      unsigned no_name_parm = 0;
       for (tree arg = DECL_ARGUMENTS (orig); arg != NULL;
           arg = DECL_CHAIN (arg))
        {
@@ -3847,8 +3848,14 @@ morph_fn_to_coro (tree orig, tree *resumer, tree 
*destroyer)
            parm.lambda_cobj = false;
 
          parm.trivial_dtor = TYPE_HAS_TRIVIAL_DESTRUCTOR (parm.frame_type);
-         tree pname = DECL_NAME (arg);
-         char *buf = xasprintf ("__parm.%s", IDENTIFIER_POINTER (pname));
+         char *buf;
+         if (DECL_NAME (arg))
+           {
+             tree pname = DECL_NAME (arg);
+             buf = xasprintf ("__parm.%s", IDENTIFIER_POINTER (pname));
+           }
+         else
+           buf = xasprintf ("__unnamed_parm.%d", no_name_parm++);
          parm.field_id = coro_make_frame_entry
            (&field_list, buf, actual_type, DECL_SOURCE_LOCATION (arg));
          free (buf);
diff --git a/gcc/testsuite/g++.dg/coroutines/pr94752.C 
b/gcc/testsuite/g++.dg/coroutines/pr94752.C
new file mode 100644
index 00000000000..7aa48ae8900
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr94752.C
@@ -0,0 +1,17 @@
+#include <coroutine>
+using namespace std;
+
+struct task {
+    struct promise_type {
+        promise_type() {}
+        task get_return_object() { return {}; }
+        suspend_never initial_suspend() { return {}; }
+        suspend_never final_suspend() { return {}; }
+        void return_void() {}
+        void unhandled_exception() {}
+    };
+};
+
+task foo(int) {
+    co_return;
+}
-- 
2.24.1