[gcc r13-1830] c++: aggregate prvalue as for range [PR106230]

[Jason Merrill <jason@gcc.gnu.org>]

https://gcc.gnu.org/g:789c4b9bb015c361bc1a6adfcd0abadce555e562

commit r13-1830-g789c4b9bb015c361bc1a6adfcd0abadce555e562
Author: Jason Merrill <jason@redhat.com>
Date:   Mon Jul 25 11:13:31 2022 -0400

    c++: aggregate prvalue as for range [PR106230]
    
    Since my PR94041 work on temporary lifetime in aggregate initialization, we
    end up calling build_vec_init to initialize the reference-extended temporary
    for the artificial __for_range variable.  And build_vec_init uses
    finish_for_stmt to implement its loop.  That function assumes that if
    __for_range is in current_binding_level, we're finishing a range-for, and we
    should fix up the variable as it goes out of scope.  But when called from
    build_vec_init we aren't finishing a range-for, and do_poplevel doesn't
    remove the variable from scope because stmts_are_full_exprs_p is false.  So
    let's check that here as well, and leave the DECL_NAME alone.
    
            PR c++/106230
    
    gcc/cp/ChangeLog:
    
            * semantics.cc (finish_for_stmt): Check stmts_are_full_exprs_p.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/cpp0x/range-for38.C: New test.

Diff:
---
 gcc/cp/semantics.cc                      |  5 +++++
 gcc/testsuite/g++.dg/cpp0x/range-for38.C | 16 ++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 96037c21b85..16dea0593b0 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -1411,6 +1411,11 @@ finish_for_stmt (tree for_stmt)
 
   add_stmt (do_poplevel (scope));
 
+  /* If we're being called from build_vec_init, don't mess with the names of
+     the variables for an enclosing range-for.  */
+  if (!stmts_are_full_exprs_p ())
+    return;
+
   for (int i = 0; i < 3; i++)
     if (range_for_decl[i])
       DECL_NAME (range_for_decl[i])
diff --git a/gcc/testsuite/g++.dg/cpp0x/range-for38.C b/gcc/testsuite/g++.dg/cpp0x/range-for38.C
new file mode 100644
index 00000000000..39845b937c1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/range-for38.C
@@ -0,0 +1,16 @@
+// PR c++/106230
+// { dg-do compile { target c++11 } }
+
+struct A {
+  A();
+  operator int();
+};
+template <int N> struct array {
+  A elts[N];
+  A *begin();
+  A *end();
+};
+void fn() {
+  for (int i : array<4>{})
+    ;
+}