https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108238
--- Comment #2 from Barnabás Pőcze <pobrn at protonmail dot com> ---
Here is a change that I believe might address this. It seems to work but I have
never done anything in gcc, so probably has shortcomings.
The error points to the return expression, like this:
asd2.cpp: In function ‘auto f2()’:
asd2.cpp:9:20: error: ‘returns_nonnull’ attribute on a function not returning
a pointer
9 | auto f2() { return 42; }
| ^~
---
diff --git a/gcc/c-family/c-attribs.cc b/gcc/c-family/c-attribs.cc
index 4667f6de311..50f5ad6b8f1 100644
--- a/gcc/c-family/c-attribs.cc
+++ b/gcc/c-family/c-attribs.cc
@@ -5761,8 +5761,9 @@ static tree
handle_returns_nonnull_attribute (tree *node, tree name, tree, int,
bool *no_add_attrs)
{
+ auto type_code = TREE_CODE (TREE_TYPE (*node));
// Even without a prototype we still have a return type we can check.
- if (TREE_CODE (TREE_TYPE (*node)) != POINTER_TYPE)
+ if (type_code != POINTER_TYPE && type_code != TEMPLATE_TYPE_PARM)
{
error ("%qE attribute on a function not returning a pointer", name);
*no_add_attrs = true;
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 1656d02d6d1..b3ae608b350 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12305,6 +12305,10 @@ apply_deduced_return_type (tree fco, tree return_type)
if (return_type == error_mark_node)
return;
+ tree returns_nonnull = lookup_attribute("returns_nonnull", TYPE_ATTRIBUTES
(TREE_TYPE (fco)));
+ if (returns_nonnull && TREE_CODE (return_type) != POINTER_TYPE)
+ error ("%<returns_nonnull%> attribute on a function not returning a
pointer");
+
if (DECL_CONV_FN_P (fco))
DECL_NAME (fco) = make_conv_op_name (return_type);
