On 6/3/25 4:53 AM, Iain Sandoe wrote:
gcc/cp/ChangeLog:
* pt.cc (lookup_template_class): Honour provided namespace contexts
when looking up class templates.
This is good, but I'd also expect namespace context to take priority over
innermost_non_namespace_value just above?
So the attached version is more aggressive - it now asserts that the
combination of an identifier + a provided context implies that we want a
namespace lookup only. Since the function header content mentioned
FUNCTION_CONTEXT - but there is no such parameter I was a little concerned
that a non-namespace decl could be passed for CONTEXT; so I have added a
checking assert that CONTEXT is a namespace decl - that did not fire on
a bootstrap + testsuite (but without Ada or D).
Hmm, it looks like make_typename_type wants to call
lookup_template_class with a class as CONTEXT. But it first does the
lookup separately. So I guess it makes sense to say that passing an
identifier and context is only supported if context is a namespace.
+ If D1 is an identifier and CONTEXT is non-NULL, then the lookup is
+ carried out in the CONTEXT namespace, otherwise CONTEXT is ignored and
+ lookup is carried out with default priority.
This "otherwise" blurs two different cases: D1 is an id and CONTEXT is
NULL (in which case lookup selects the innermost non-namespace binding),
or D1 is not an id (in which case CONTEXT is ignored and no lookup is
performed).
Let's also remove the FUNCTION_CONTEXT paragraph.
I guess we should stop passing the CONTEXT argument in non-id+ns cases
such as make_typename_type and tsubst...
IN_DECL, if non-NULL, is the template declaration we are trying to
instantiate.
@@ -10079,20 +10083,24 @@ lookup_template_class (tree d1, tree arglist, tree in_decl, tree context,
spec_entry **slot;
spec_entry *entry;
- if (identifier_p (d1))
+ if (identifier_p (d1) && context)
+ {
+ gcc_checking_assert (TREE_CODE (context) == NAMESPACE_DECL);
+ push_decl_namespace (context);
+ templ = lookup_name (d1, LOOK_where::NAMESPACE, LOOK_want::NORMAL);
+ templ = maybe_get_template_decl_from_type_decl (templ);
This line is unnecessary for namespace lookup, it's just for the
injected-class-name.
+ pop_decl_namespace ();
+ }
+ else if (identifier_p (d1))
{
tree value = innermost_non_namespace_value (d1);
if (value && DECL_TEMPLATE_TEMPLATE_PARM_P (value))
templ = value;
else
- {
- if (context)
- push_decl_namespace (context);
+ {
templ = lookup_name (d1);
templ = maybe_get_template_decl_from_type_decl (templ);
- if (context)
- pop_decl_namespace ();
- }
+ }
}
else if (TREE_CODE (d1) == TYPE_DECL && MAYBE_CLASS_TYPE_P (TREE_TYPE (d1)))
{
diff --git a/gcc/testsuite/g++.dg/coroutines/pr120495.C
b/gcc/testsuite/g++.dg/coroutines/pr120495.C
new file mode 100644
index 00000000000..f59c34a8676
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr120495.C
@@ -0,0 +1,55 @@
+// { dg-additional-options "-fsyntax-only" }
+
+#include <coroutine>
+#include <exception>
+
+struct fire_and_forget {
+};
+
+template <typename... Args>
+struct std::coroutine_traits<fire_and_forget, Args...>
+{
+ struct promise_type
+ {
+ fire_and_forget get_return_object() const noexcept
+ {
+ return{};
+ }
+
+ void return_void() const noexcept
+ {
+ }
+
+ suspend_never initial_suspend() const noexcept
+ {
+ return{};
+ }
+
+ suspend_never final_suspend() const noexcept
+ {
+ return{};
+ }
+
+ void unhandled_exception() const noexcept
+ {
+ std::terminate();
+ }
+ };
+};
+
+struct foo
+{
+ fire_and_forget bar()
+ {
+ co_await std::suspend_always{ };
+ }
+
+private:
+ // The line below triggered the error.
+ using coroutine_handle = std::coroutine_handle<>;
+};
+
+int main()
+{
+ foo{}.bar();
+}
diff --git a/gcc/testsuite/g++.dg/pr115605.C b/gcc/testsuite/g++.dg/pr115605.C
new file mode 100644
index 00000000000..9e342555c89
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr115605.C
@@ -0,0 +1,10 @@
+// { dg-do compile { target c++20 } }
+
+#include <array>
+
+int foo() {
+ int const tuple_size = 5;
+ std::array<int, 3> array {1, 2, 3};
+ auto [a, b, c] = array;
+ return c;
+}
