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c++: is_specialization_of_friend confusion [PR109923]

Message ID 20230602142920.1793173-1-ppalka@redhat.com
State New
Headers
Series c++: is_specialization_of_friend confusion [PR109923] |

Checks

Context Check Description
linaro-tcwg-bot/tcwg_gcc_build--master-arm success Testing passed
linaro-tcwg-bot/tcwg_gcc_build--master-aarch64 success Testing passed
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linaro-tcwg-bot/tcwg_gcc_check--master-arm success Testing passed

Commit Message

Patrick Palka June 2, 2023, 2:29 p.m. UTC 
  Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
trunk?

-- >8 --

The check for a non-template member function of a class template in
is_specialization_of_friend is overbroad, and accidentally holds for a
non-template hidden friend too, which causes the predicate to return
true for

  decl = void non_templ_friend(A<int>, A<void>)
  friend_decl = void non_templ_friend(A<void>, A<void>)

This patch refines the check appropriately.

	PR c++/109923

gcc/cp/ChangeLog:

	* pt.cc (is_specialization_of_friend): Fix overbroad check for
	a non-template member function of a class template.

gcc/testsuite/ChangeLog:

	* g++.dg/template/friend79.C: New test.
---
 gcc/cp/pt.cc                             |  1 +
 gcc/testsuite/g++.dg/template/friend79.C | 20 ++++++++++++++++++++
 2 files changed, 21 insertions(+)
 create mode 100644 gcc/testsuite/g++.dg/template/friend79.C

Comments

Jason Merrill June 2, 2023, 4:33 p.m. UTC | #1 
On 6/2/23 10:29, Patrick Palka wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk?

OK.

> -- >8 --
> 
> The check for a non-template member function of a class template in
> is_specialization_of_friend is overbroad, and accidentally holds for a
> non-template hidden friend too, which causes the predicate to return
> true for
> 
>    decl = void non_templ_friend(A<int>, A<void>)
>    friend_decl = void non_templ_friend(A<void>, A<void>)
> 
> This patch refines the check appropriately.
> 
> 	PR c++/109923
> 
> gcc/cp/ChangeLog:
> 
> 	* pt.cc (is_specialization_of_friend): Fix overbroad check for
> 	a non-template member function of a class template.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/template/friend79.C: New test.
> ---
>   gcc/cp/pt.cc                             |  1 +
>   gcc/testsuite/g++.dg/template/friend79.C | 20 ++++++++++++++++++++
>   2 files changed, 21 insertions(+)
>   create mode 100644 gcc/testsuite/g++.dg/template/friend79.C
> 
> diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
> index 7c2a5647665..a15d1d062c6 100644
> --- a/gcc/cp/pt.cc
> +++ b/gcc/cp/pt.cc
> @@ -1319,6 +1319,7 @@ is_specialization_of_friend (tree decl, tree friend_decl)
>        of a template class, we want to check if DECL is a specialization
>        if this.  */
>     if (TREE_CODE (friend_decl) == FUNCTION_DECL
> +      && DECL_CLASS_SCOPE_P (friend_decl)
>         && DECL_TEMPLATE_INFO (friend_decl)
>         && !DECL_USE_TEMPLATE (friend_decl))
>       {
> diff --git a/gcc/testsuite/g++.dg/template/friend79.C b/gcc/testsuite/g++.dg/template/friend79.C
> new file mode 100644
> index 00000000000..cd2030df019
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/template/friend79.C
> @@ -0,0 +1,20 @@
> +// PR c++/109923
> +
> +template<class T>
> +struct A {
> +private:
> +  int x;
> +
> +public:
> +  A() : x(0) { }
> +
> +  friend void non_templ_friend(A val, A<void> weird) {
> +    val.x++;   // always works
> +    weird.x++; // { dg-error "private" } should only work when T=void
> +  }
> +};
> +
> +int main() {
> +  non_templ_friend(A<void>(), A<void>()); // { dg-bogus "" }
> +  non_templ_friend(A<int>(), A<void>());  // { dg-message "required from here" }
> +}
diff mbox series

Patch

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 7c2a5647665..a15d1d062c6 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -1319,6 +1319,7 @@  is_specialization_of_friend (tree decl, tree friend_decl)
      of a template class, we want to check if DECL is a specialization
      if this.  */
   if (TREE_CODE (friend_decl) == FUNCTION_DECL
+      && DECL_CLASS_SCOPE_P (friend_decl)
       && DECL_TEMPLATE_INFO (friend_decl)
       && !DECL_USE_TEMPLATE (friend_decl))
     {
diff --git a/gcc/testsuite/g++.dg/template/friend79.C b/gcc/testsuite/g++.dg/template/friend79.C
new file mode 100644
index 00000000000..cd2030df019
--- /dev/null
+++ b/gcc/testsuite/g++.dg/template/friend79.C
@@ -0,0 +1,20 @@ 
+// PR c++/109923
+
+template<class T>
+struct A {
+private:
+  int x;
+
+public:
+  A() : x(0) { }
+
+  friend void non_templ_friend(A val, A<void> weird) {
+    val.x++;   // always works
+    weird.x++; // { dg-error "private" } should only work when T=void
+  }
+};
+
+int main() {
+  non_templ_friend(A<void>(), A<void>()); // { dg-bogus "" }
+  non_templ_friend(A<int>(), A<void>());  // { dg-message "required from here" }
+}