Re: [PATCH] c++ modules: stream non-trailing default targs [PR105045]

[Nathan Sidwell <nathan@acm.org>]

On 10/18/22 10:13, Patrick Palka wrote:
> This fixes the below testcase in which we neglect to stream the default
> argument for T only because the subsequent parameter U doesn't also have
> a default argument.

ok

> 
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk?
> 
> 	PR c++/105045
> 
> gcc/cp/ChangeLog:
> 
> 	* module.cc (trees_out::tpl_parms_fini): Don't assume default
> 	template arguments are all trailing.
> 	(trees_in::tpl_parms_fini): Likewise.
> 
> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/modules/pr105045_a.C: New test.
> 	* g++.dg/modules/pr105045_b.C: New test.
> ---
>   gcc/cp/module.cc                          | 20 ++++++--------------
>   gcc/testsuite/g++.dg/modules/pr105045_a.C |  7 +++++++
>   gcc/testsuite/g++.dg/modules/pr105045_b.C |  6 ++++++
>   3 files changed, 19 insertions(+), 14 deletions(-)
>   create mode 100644 gcc/testsuite/g++.dg/modules/pr105045_a.C
>   create mode 100644 gcc/testsuite/g++.dg/modules/pr105045_b.C
> 
> diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
> index 999ff3faafc..2c2f9a9a8cb 100644
> --- a/gcc/cp/module.cc
> +++ b/gcc/cp/module.cc
> @@ -10034,15 +10034,11 @@ trees_out::tpl_parms_fini (tree tmpl, unsigned tpl_levels)
>         tree vec = TREE_VALUE (parms);
>   
>         tree_node (TREE_TYPE (vec));
> -      tree dflt = error_mark_node;
>         for (unsigned ix = TREE_VEC_LENGTH (vec); ix--;)
>   	{
>   	  tree parm = TREE_VEC_ELT (vec, ix);
> -	  if (dflt)
> -	    {
> -	      dflt = TREE_PURPOSE (parm);
> -	      tree_node (dflt);
> -	    }
> +	  tree dflt = TREE_PURPOSE (parm);
> +	  tree_node (dflt);
>   
>   	  if (streaming_p ())
>   	    {
> @@ -10072,19 +10068,15 @@ trees_in::tpl_parms_fini (tree tmpl, unsigned tpl_levels)
>          tpl_levels--; parms = TREE_CHAIN (parms))
>       {
>         tree vec = TREE_VALUE (parms);
> -      tree dflt = error_mark_node;
>   
>         TREE_TYPE (vec) = tree_node ();
>         for (unsigned ix = TREE_VEC_LENGTH (vec); ix--;)
>   	{
>   	  tree parm = TREE_VEC_ELT (vec, ix);
> -	  if (dflt)
> -	    {
> -	      dflt = tree_node ();
> -	      if (get_overrun ())
> -		return false;
> -	      TREE_PURPOSE (parm) = dflt;
> -	    }
> +	  tree dflt = tree_node ();
> +	  if (get_overrun ())
> +	    return false;
> +	  TREE_PURPOSE (parm) = dflt;
>   
>   	  tree decl = TREE_VALUE (parm);
>   	  if (TREE_CODE (decl) == TEMPLATE_DECL)
> diff --git a/gcc/testsuite/g++.dg/modules/pr105045_a.C b/gcc/testsuite/g++.dg/modules/pr105045_a.C
> new file mode 100644
> index 00000000000..597f9294185
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr105045_a.C
> @@ -0,0 +1,7 @@
> +// PR c++/105045
> +// { dg-additional-options -fmodules-ts }
> +// { dg-module-cmi pr105045 }
> +
> +export module pr105045;
> +
> +export template<int T=0, class U> void f(U) { }
> diff --git a/gcc/testsuite/g++.dg/modules/pr105045_b.C b/gcc/testsuite/g++.dg/modules/pr105045_b.C
> new file mode 100644
> index 00000000000..77c94d4c473
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/modules/pr105045_b.C
> @@ -0,0 +1,6 @@
> +// PR c++/105045
> +// { dg-additional-options -fmodules-ts }
> +
> +import pr105045;
> +
> +int main() { f(0); }

-- 
Nathan Sidwell