[gcc r13-4879] c++: get_nsdmi in template context [PR108116]

[gcc r13-4879] c++: get_nsdmi in template context [PR108116]

[Patrick Palka]

https://gcc.gnu.org/g:cf59c8983ef6590f0d69014f8dc8778b5b7691c6

commit r13-4879-gcf59c8983ef6590f0d69014f8dc8778b5b7691c6
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Dec 23 11:17:45 2022 -0500

    c++: get_nsdmi in template context [PR108116]
    
    Here during ahead of time checking of C{}, we indirectly call get_nsdmi
    for C::m from finish_compound_literal, which in turn calls
    break_out_target_exprs for C::m's (non-templated) initializer, during
    which we build a call to A::~A and check expr_noexcept_p for it (from
    build_vec_delete_1).  But this is all done with processing_template_decl
    set, so the built A::~A call is templated (whose form was recently
    changed by r12-6897-gdec8d0e5fa00ceb2) which expr_noexcept_p doesn't
    expect, and we crash.
    
    This patch fixes this by clearing processing_template_decl before
    the call to break_out_target_exprs from get_nsdmi.  And since it more
    generally seems we shouldn't be seeing (or producing) non-templated
    trees in break_out_target_exprs, this patch also adds an assert to
    that effect.
    
            PR c++/108116
    
    gcc/cp/ChangeLog:
    
            * constexpr.cc (maybe_constant_value): Clear
            processing_template_decl before calling break_out_target_exprs.
            * init.cc (get_nsdmi): Likewise.
            * tree.cc (break_out_target_exprs): Assert processing_template_decl
            is cleared.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp0x/nsdmi-template24.C: New test.

Diff:
---
 gcc/cp/constexpr.cc                           |  4 ++++
 gcc/cp/init.cc                                |  4 ++++
 gcc/cp/tree.cc                                |  4 ++++
 gcc/testsuite/g++.dg/cpp0x/nsdmi-template24.C | 22 ++++++++++++++++++++++
 4 files changed, 34 insertions(+)

diff --git a/gcc/cp/constexpr.cc b/gcc/cp/constexpr.cc
index d99c49bdbe2..414af7a6d4c 100644
--- a/gcc/cp/constexpr.cc
+++ b/gcc/cp/constexpr.cc
@@ -8507,6 +8507,10 @@ maybe_constant_value (tree t, tree decl /* = NULL_TREE */,
       r = *cached;
       if (r != t)
 	{
+	  /* Clear processing_template_decl for sake of break_out_target_exprs;
+	     entries in the cv_cache are non-templated.  */
+	  processing_template_decl_sentinel ptds;
+
 	  r = break_out_target_exprs (r, /*clear_loc*/true);
 	  protected_set_expr_location (r, EXPR_LOCATION (t));
 	}
diff --git a/gcc/cp/init.cc b/gcc/cp/init.cc
index 73e6547c076..b49a7ca9169 100644
--- a/gcc/cp/init.cc
+++ b/gcc/cp/init.cc
@@ -670,6 +670,10 @@ get_nsdmi (tree member, bool in_ctor, tsubst_flags_t complain)
       current_class_ptr = build_address (current_class_ref);
     }
 
+  /* Clear processing_template_decl for sake of break_out_target_exprs;
+     INIT is always non-templated.  */
+  processing_template_decl_sentinel ptds;
+
   /* Strip redundant TARGET_EXPR so we don't need to remap it, and
      so the aggregate init code below will see a CONSTRUCTOR.  */
   bool simple_target = (init && SIMPLE_TARGET_EXPR_P (init));
diff --git a/gcc/cp/tree.cc b/gcc/cp/tree.cc
index 33bde16f128..faf01616f87 100644
--- a/gcc/cp/tree.cc
+++ b/gcc/cp/tree.cc
@@ -3342,6 +3342,10 @@ break_out_target_exprs (tree t, bool clear_location /* = false */)
   static int target_remap_count;
   static splay_tree target_remap;
 
+  /* We shouldn't be called on templated trees, nor do we want to
+     produce them.  */
+  gcc_checking_assert (!processing_template_decl);
+
   if (!target_remap_count++)
     target_remap = splay_tree_new (splay_tree_compare_pointers,
 				   /*splay_tree_delete_key_fn=*/NULL,
diff --git a/gcc/testsuite/g++.dg/cpp0x/nsdmi-template24.C b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template24.C
new file mode 100644
index 00000000000..202c67d7321
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/nsdmi-template24.C
@@ -0,0 +1,22 @@
+// PR c++/108116
+// { dg-do compile { target c++11 } }
+
+#include <initializer_list>
+
+struct A {
+  A(int);
+  ~A();
+};
+
+struct B {
+  B(std::initializer_list<A>);
+};
+
+struct C {
+  B m{0};
+};
+
+template<class>
+void f() {
+  C c = C{};
+};