Re: [PATCH 2/2] c++: non-dep init folding and access checking [PR109480]

[Jason Merrill via Gcc-patches]

On 5/1/23 15:59, Patrick Palka wrote:

enforce_access currently inspects processing_template_decl to determine
whether to defer the given access check until instantiation time.  But
using this flag is unreliable because it gets cleared during e.g.
non-dependent initializer folding, and can lead to premature access
check failures as in the below testcase.  It seems better to inspect
current_template_parms instead.

Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK
for trunk?

OK.

        PR c++/109480

gcc/cp/ChangeLog:

        * semantics.cc (enforce_access): Check current_template_parms
        instead of processing_template_decl when determining whether
        to defer the access check.

gcc/testsuite/ChangeLog:

        * g++.dg/template/non-dependent25a.C: New test.
---
  gcc/cp/semantics.cc                             |  2 +-
  .../g++.dg/template/non-dependent25a.C          | 17 +++++++++++++++++
  2 files changed, 18 insertions(+), 1 deletion(-)
  create mode 100644 gcc/testsuite/g++.dg/template/non-dependent25a.C

diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 9ba316ab3be..474da71bff6 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -346,7 +346,7 @@ enforce_access (tree basetype_path, tree decl, tree 
diag_decl,
      }

tree cs = current_scope ();

-  if (processing_template_decl
+  if (current_template_parms
        && (CLASS_TYPE_P (cs) || TREE_CODE (cs) == FUNCTION_DECL))
      if (tree template_info = get_template_info (cs))
        {
diff --git a/gcc/testsuite/g++.dg/template/non-dependent25a.C 
b/gcc/testsuite/g++.dg/template/non-dependent25a.C
new file mode 100644
index 00000000000..902e537ec09
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/non-dependent25a.C
@@ -0,0 +1,17 @@
+// PR c++/109480
+// A version of non-dependent25.C where b's initializer is a constant
+// expression.
+// { dg-do compile { target c++11 } }
+
+template<class T>
+struct A {
+  void f() {
+    constexpr A<int> a;
+    const bool b = a.g(); // { dg-bogus "private" }
+  }
+
+private:
+  constexpr bool g() const { return true; }
+};
+
+template struct A<int>;