Re: [PATCH] c++: non-dependent .* folding [PR112427]

[Jason Merrill <jason@redhat.com>]

On 11/8/23 16:59, Patrick Palka wrote:
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk?
> 
> -- >8 --
> 
> Here when building up the non-dependent .* expression, we crash from
> fold_convert on 'b.a' due to this (templated) COMPONENT_REF having an
> IDENTIFIER_NODE instead of FIELD_DECL operand that middle-end routines
> expect.  Like in r14-4899-gd80a26cca02587, this patch fixes this by
> replacing the problematic piecemeal folding with a single call to
> cp_fully_fold.
> 
> 	PR c++/112427
> 
> gcc/cp/ChangeLog:
> 
> 	* typeck2.cc (build_m_component_ref): Use cp_convert, build2 and
> 	cp_fully_fold instead of fold_build_pointer_plus and fold_convert.

> gcc/testsuite/ChangeLog:
> 
> 	* g++.dg/template/non-dependent29.C: New test.
> ---
>   gcc/cp/typeck2.cc                               |  5 ++++-
>   gcc/testsuite/g++.dg/template/non-dependent29.C | 13 +++++++++++++
>   2 files changed, 17 insertions(+), 1 deletion(-)
>   create mode 100644 gcc/testsuite/g++.dg/template/non-dependent29.C
> 
> diff --git a/gcc/cp/typeck2.cc b/gcc/cp/typeck2.cc
> index 309903afed8..208004221da 100644
> --- a/gcc/cp/typeck2.cc
> +++ b/gcc/cp/typeck2.cc
> @@ -2378,7 +2378,10 @@ build_m_component_ref (tree datum, tree component, tsubst_flags_t complain)
>         /* Build an expression for "object + offset" where offset is the
>   	 value stored in the pointer-to-data-member.  */
>         ptype = build_pointer_type (type);
> -      datum = fold_build_pointer_plus (fold_convert (ptype, datum), component);
> +      datum = cp_convert (ptype, datum, complain);
> +      datum = build2 (POINTER_PLUS_EXPR, ptype,
> +		      datum, convert_to_ptrofftype (component));

We shouldn't need to build the POINTER_PLUS_EXPR at all in template 
context.  OK with that change.

Jason