Re: [PATCH] c++: visibility wrt template and ptrmem targs [PR70413]

[Jason Merrill <jason@redhat.com>]

On 9/15/23 12:03, Patrick Palka wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk?

OK.

> -- >8 --
> 
> When constraining the visibility of an instantiation, we weren't
> properly considering the visibility of PTRMEM_CST and TEMPLATE_DECL
> template arguments.
> 
> 	PR c++/70413
> 
> gcc/cp/ChangeLog:
> 
> 	* decl2.cc (min_vis_expr_r): Handle PTRMEM_CST and TEMPLATE_DECL.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/abi/no-linkage-expr2.C: New test.
> 	* g++.dg/abi/no-linkage-expr3.C: New test.
> ---
>   gcc/cp/decl2.cc                             | 18 ++++++++++++++----
>   gcc/testsuite/g++.dg/abi/no-linkage-expr2.C | 15 +++++++++++++++
>   gcc/testsuite/g++.dg/abi/no-linkage-expr3.C | 17 +++++++++++++++++
>   3 files changed, 46 insertions(+), 4 deletions(-)
>   create mode 100644 gcc/testsuite/g++.dg/abi/no-linkage-expr2.C
>   create mode 100644 gcc/testsuite/g++.dg/abi/no-linkage-expr3.C
> 
> diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
> index b402befba6d..5006372a646 100644
> --- a/gcc/cp/decl2.cc
> +++ b/gcc/cp/decl2.cc
> @@ -2582,7 +2582,10 @@ min_vis_expr_r (tree *tp, int */*walk_subtrees*/, void *data)
>     int *vis_p = (int *)data;
>     int tpvis = VISIBILITY_DEFAULT;
>   
> -  switch (TREE_CODE (*tp))
> +  tree t = *tp;
> +  if (TREE_CODE (t) == PTRMEM_CST)
> +    t = PTRMEM_CST_MEMBER (t);
> +  switch (TREE_CODE (t))
>       {
>       case CAST_EXPR:
>       case IMPLICIT_CONV_EXPR:
> @@ -2593,15 +2596,22 @@ min_vis_expr_r (tree *tp, int */*walk_subtrees*/, void *data)
>       case NEW_EXPR:
>       case CONSTRUCTOR:
>       case LAMBDA_EXPR:
> -      tpvis = type_visibility (TREE_TYPE (*tp));
> +      tpvis = type_visibility (TREE_TYPE (t));
>         break;
>   
> +    case TEMPLATE_DECL:
> +      t = DECL_TEMPLATE_RESULT (t);
> +      /* Fall through.  */
>       case VAR_DECL:
>       case FUNCTION_DECL:
> -      if (! TREE_PUBLIC (*tp))
> +      if (! TREE_PUBLIC (t))
>   	tpvis = VISIBILITY_ANON;
>         else
> -	tpvis = DECL_VISIBILITY (*tp);
> +	tpvis = DECL_VISIBILITY (t);
> +      break;
> +
> +    case FIELD_DECL:
> +      tpvis = type_visibility (DECL_CONTEXT (t));
>         break;
>   
>       default:
> diff --git a/gcc/testsuite/g++.dg/abi/no-linkage-expr2.C b/gcc/testsuite/g++.dg/abi/no-linkage-expr2.C
> new file mode 100644
> index 00000000000..db23570bb08
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/abi/no-linkage-expr2.C
> @@ -0,0 +1,15 @@
> +// PR c++/70413
> +// { dg-do compile { target c++11 } }
> +// { dg-final { scan-assembler-not "weak.*_Z" } }
> +
> +namespace {
> +  template<class> struct A;
> +  template<class> using B = int;
> +}
> +
> +template<template<class> class Q> void f() { }
> +
> +int main() {
> +  f<A>();
> +  f<B>();
> +}
> diff --git a/gcc/testsuite/g++.dg/abi/no-linkage-expr3.C b/gcc/testsuite/g++.dg/abi/no-linkage-expr3.C
> new file mode 100644
> index 00000000000..a2db1a45c74
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/abi/no-linkage-expr3.C
> @@ -0,0 +1,17 @@
> +// PR c++/70413
> +// { dg-final { scan-assembler-not "weak.*_Z" } }
> +
> +namespace {
> +  struct A {
> +    void f();
> +    int m;
> +  };
> +}
> +
> +template<void(A::*)()> void g() { }
> +template<int A::*> void h() { }
> +
> +int main() {
> +  g<&A::f>();
> +  h<&A::m>();
> +}