[gcc r13-8224] c++: non-dep array list-init w/ non-triv dtor [PR109899]

[Patrick Palka]

https://gcc.gnu.org/g:766ea9da8ccff3786ec5df414046f6b1640e7e01

commit r13-8224-g766ea9da8ccff3786ec5df414046f6b1640e7e01
Author: Patrick Palka <ppalka@redhat.com>
Date:   Mon Jan 15 16:49:19 2024 -0500

    c++: non-dep array list-init w/ non-triv dtor [PR109899]
    
    The get_target_expr call added in r12-7069-g119cea98f66476 causes us
    for the below testcase to call build_vec_delete in a template context,
    which builds a templated destructor call and checks expr_noexcept_p for
    it, which ICEs because the call has templated form.
    
    Much of the work of build_vec_delete however is code generation and thus
    will just get discarded in a template context, and that includes the
    code guarded by expr_noexcept_p.  So this patch narrowly fixes this ICE
    by eliding the expr_noexcept_p call when in a template context.
    
            PR c++/109899
    
    gcc/cp/ChangeLog:
    
            * init.cc (build_vec_delete_1): Assume expr_noexcept_p returns
            false in a template context.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp0x/initlist-array21.C: New test.
    
    Reviewed-by: Jason Merrill <jason@redhat.com>
    (cherry picked from commit d33c3b5ac9b9b3e314ae9118d483ade7e91a80a5)

Diff:
---
 gcc/cp/init.cc                                |  3 ++-
 gcc/testsuite/g++.dg/cpp0x/initlist-array21.C | 12 ++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index 52b33d48844..78e992af171 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -4159,7 +4159,8 @@ build_vec_delete_1 (location_t loc, tree base, tree maxindex, tree type,
 
   /* If one destructor throws, keep trying to clean up the rest, unless we're
      already in a build_vec_init cleanup.  */
-  if (flag_exceptions && !in_cleanup && !expr_noexcept_p (tmp, tf_none))
+  if (flag_exceptions && !in_cleanup && !processing_template_decl
+      && !expr_noexcept_p (tmp, tf_none))
     {
       loop = build2 (TRY_CATCH_EXPR, void_type_node, loop,
 		     unshare_expr (loop));
diff --git a/gcc/testsuite/g++.dg/cpp0x/initlist-array21.C b/gcc/testsuite/g++.dg/cpp0x/initlist-array21.C
new file mode 100644
index 00000000000..357d88e727b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/initlist-array21.C
@@ -0,0 +1,12 @@
+// PR c++/109899
+// { dg-do compile { target c++11 } }
+
+struct A { A(); ~A(); };
+
+template<class T>
+using array = T[42];
+
+template<class T>
+void f() {
+  array<A>{};
+}