https://gcc.gnu.org/g:aa49bb9deb7e040679f184009f38c5027f1a8dc4
commit r15-9611-gaa49bb9deb7e040679f184009f38c5027f1a8dc4
Author: Nathaniel Shead <nathanielosh...@gmail.com>
Date: Fri Apr 25 22:45:41 2025 +1000
c++/modules: Fix imported CNTTPs being considered non-constant [PR119938]
When importing a CNTTP object, since r15-3031-g0b7904e274fbd6 we
shortcut the processing of the generated NTTP so that we don't attempt
to recursively load pendings. However, due to an oversight we do not
properly set TREE_CONSTANT or DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P
on the decl, which confuses later processing. This patch ensures that
this happens correctly.
PR c++/119938
gcc/cp/ChangeLog:
* pt.cc (get_template_parm_object): When !check_init, add assert
that expr really is constant and mark decl as such.
gcc/testsuite/ChangeLog:
* g++.dg/modules/tpl-nttp-2_a.H: New test.
* g++.dg/modules/tpl-nttp-2_b.C: New test.
Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
Reviewed-by: Jason Merrill <ja...@redhat.com>
(cherry picked from commit d613678c94f06809656e56b37f314501b37a5ddd)
Diff:
---
gcc/cp/pt.cc | 7 ++++++-
gcc/testsuite/g++.dg/modules/tpl-nttp-2_a.H | 14 ++++++++++++++
gcc/testsuite/g++.dg/modules/tpl-nttp-2_b.C | 10 ++++++++++
3 files changed, 30 insertions(+), 1 deletion(-)
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 1f972c79b998..96230b444c01 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -7492,8 +7492,13 @@ get_template_parm_object (tree expr, tree name, bool
check_init/*=true*/)
{
/* The EXPR is the already processed initializer, set it on the NTTP
object now so that cp_finish_decl doesn't do it again later. */
+ gcc_checking_assert (reduced_constant_expression_p (expr));
DECL_INITIAL (decl) = expr;
- DECL_INITIALIZED_P (decl) = 1;
+ DECL_INITIALIZED_P (decl) = true;
+ DECL_INITIALIZED_BY_CONSTANT_EXPRESSION_P (decl) = true;
+ /* FIXME setting TREE_CONSTANT on refs breaks the back end. */
+ if (!TYPE_REF_P (type))
+ TREE_CONSTANT (decl) = true;
}
pushdecl_top_level_and_finish (decl, expr);
diff --git a/gcc/testsuite/g++.dg/modules/tpl-nttp-2_a.H
b/gcc/testsuite/g++.dg/modules/tpl-nttp-2_a.H
new file mode 100644
index 000000000000..bfae11cd1857
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/tpl-nttp-2_a.H
@@ -0,0 +1,14 @@
+// PR c++/119938
+// { dg-additional-options "-fmodules -std=c++20" }
+// { dg-module-cmi {} }
+
+struct A { int x; };
+
+template <A a> struct B { static_assert(a.x == 1); };
+using C = B<A{1}>;
+
+template <A a> void D() { static_assert(a.x == 2); };
+inline void E() { D<A{2}>(); }
+
+template <A a> struct F { static constexpr int result = a.x; };
+template <int=0> constexpr int G() { return F<A{3}>::result; };
diff --git a/gcc/testsuite/g++.dg/modules/tpl-nttp-2_b.C
b/gcc/testsuite/g++.dg/modules/tpl-nttp-2_b.C
new file mode 100644
index 000000000000..7e661cbdef0f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/tpl-nttp-2_b.C
@@ -0,0 +1,10 @@
+// PR c++/119938
+// { dg-additional-options "-fmodules -std=c++20" }
+
+import "tpl-nttp-2_a.H";
+
+int main() {
+ C c;
+ E();
+ static_assert(G() == 3);
+}
