[gcc r12-7277] c++: double non-dep folding from finish_compound_literal [PR104565]

[gcc r12-7277] c++: double non-dep folding from finish_compound_literal [PR104565]

[Patrick Palka]

https://gcc.gnu.org/g:6bbd8afee0036c274f5ebb5b48d6fdc2091bd046

commit r12-7277-g6bbd8afee0036c274f5ebb5b48d6fdc2091bd046
Author: Patrick Palka <ppalka@redhat.com>
Date:   Thu Feb 17 08:35:23 2022 -0500

    c++: double non-dep folding from finish_compound_literal [PR104565]
    
    In finish_compound_literal, we perform non-dependent expr folding before
    the call to check_narrowing ever since r9-5973.  But ever since r10-7096,
    check_narrowing also performs non-dependent expr folding of its own.
    This double folding means tsubst will see non-templated trees during the
    second folding, which causes a spurious error in the below testcase.
    
    This patch removes the former folding operation; it seems obviated by
    the latter one.
    
            PR c++/104565
    
    gcc/cp/ChangeLog:
    
            * semantics.cc (finish_compound_literal): Don't perform
            non-dependent expr folding before calling check_narrowing.
    
    gcc/testsuite/ChangeLog:
    
            * g++.dg/template/non-dependent22.C: New test.

Diff:
---
 gcc/cp/semantics.cc                             | 10 +++-------
 gcc/testsuite/g++.dg/template/non-dependent22.C | 12 ++++++++++++
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 0cb17a6a8ab..114baa48710 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -3203,13 +3203,9 @@ finish_compound_literal (tree type, tree compound_literal,
     return error_mark_node;
   compound_literal = reshape_init (type, compound_literal, complain);
   if (SCALAR_TYPE_P (type)
-      && !BRACE_ENCLOSED_INITIALIZER_P (compound_literal))
-    {
-      tree t = instantiate_non_dependent_expr_sfinae (compound_literal,
-						      complain);
-      if (!check_narrowing (type, t, complain))
-	return error_mark_node;
-    }
+      && !BRACE_ENCLOSED_INITIALIZER_P (compound_literal)
+      && !check_narrowing (type, compound_literal, complain))
+    return error_mark_node;
   if (TREE_CODE (type) == ARRAY_TYPE
       && TYPE_DOMAIN (type) == NULL_TREE)
     {
diff --git a/gcc/testsuite/g++.dg/template/non-dependent22.C b/gcc/testsuite/g++.dg/template/non-dependent22.C
new file mode 100644
index 00000000000..83a6a13f15b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/non-dependent22.C
@@ -0,0 +1,12 @@
+// PR c++/104565
+// { dg-do compile { target c++11 } }
+
+struct apa {
+  constexpr int n() const { return 3; }
+};
+
+template<class>
+int f() {
+  apa foo;
+  return int{foo.n()};  // no matching function for call to 'apa::n(apa*)'
+}