Re: [PATCH 1/2] c++: Harden *_PACK_EXPANSION and *_ARGUMENT_PACK macros

[Jason Merrill <jason@redhat.com>]

On 5/10/22 09:40, Patrick Palka wrote:
> The accessor macros for TYPE_PACK_EXPANSION/EXPR_PACK_EXPANSION
> and TYPE_ARGUMENT_PACK/NONTYPE_ARGUMENT_PACK should check the
> tree code of the argument.
> 
> Bootstrapped and regtested on x86_64-pc-linux-gnu, does this look OK for
> trunk?

OK.

> gcc/cp/ChangeLog:
> 
> 	* cp-tree.h (PACK_EXPANSION_CHECK): Define.
> 	(PACK_EXPANSION_PATTERN): Use PACK_EXPANSION_CHECK.
> 	(SET_PACK_EXPANSION_PATTERN): Likewise.
> 	(PACK_EXPANSION_PARAMETER_PACKS): Likewise.
> 	(PACK_EXPANSION_EXTRA_ARGS): Likewise.
> 	(PACK_EXPANSION_LOCAL_P): Likewise.
> 	(PACK_EXPANSION_SIZEOF_P): Likewise.
> 	(PACK_EXPANSION_AUTO_P): Likewise.
> 	(PACK_EXPANSION_FORCE_EXTRA_ARGS_P): Likewise.
> 	(ARGUMENT_PACK_CHECK): Define.
> 	(ARGUMENT_PACK_ARGS): Use ARGUMENT_PACK_CHECK.
> 	(SET_ARGUMENT_PACK_ARGS): Likewise.
> 	* parser.c (cp_parser_sizeof_pack): Check for error_mark_node
> 	before setting PACK_EXPANSION_SIZEOF_P.
> ---
>   gcc/cp/cp-tree.h | 34 ++++++++++++++++++++++------------
>   gcc/cp/parser.cc |  3 ++-
>   2 files changed, 24 insertions(+), 13 deletions(-)
> 
> diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
> index 8a5057a4dff..29fc0e5f829 100644
> --- a/gcc/cp/cp-tree.h
> +++ b/gcc/cp/cp-tree.h
> @@ -3894,16 +3894,19 @@ struct GTY(()) lang_decl {
>     (TREE_CODE (NODE) == TYPE_PACK_EXPANSION     \
>      || TREE_CODE (NODE) == EXPR_PACK_EXPANSION)
>   
> +#define PACK_EXPANSION_CHECK(NODE) \
> +  TREE_CHECK2 (NODE, TYPE_PACK_EXPANSION, EXPR_PACK_EXPANSION)
> +
>   /* Extracts the type or expression pattern from a TYPE_PACK_EXPANSION or
>      EXPR_PACK_EXPANSION.  */
>   #define PACK_EXPANSION_PATTERN(NODE)                            \
> -  (TREE_CODE (NODE) == TYPE_PACK_EXPANSION ? TREE_TYPE (NODE)    \
> -   : TREE_OPERAND (NODE, 0))
> +  (TREE_CODE (PACK_EXPANSION_CHECK (NODE)) == TYPE_PACK_EXPANSION \
> +   ? TREE_TYPE (NODE) : TREE_OPERAND (NODE, 0))
>   
>   /* Sets the type or expression pattern for a TYPE_PACK_EXPANSION or
>      EXPR_PACK_EXPANSION.  */
>   #define SET_PACK_EXPANSION_PATTERN(NODE,VALUE)  \
> -  if (TREE_CODE (NODE) == TYPE_PACK_EXPANSION)  \
> +  if (TREE_CODE (PACK_EXPANSION_CHECK (NODE)) == TYPE_PACK_EXPANSION)  \
>       TREE_TYPE (NODE) = VALUE;                   \
>     else                                          \
>       TREE_OPERAND (NODE, 0) = VALUE
> @@ -3911,7 +3914,7 @@ struct GTY(()) lang_decl {
>   /* The list of parameter packs used in the PACK_EXPANSION_* node. The
>      TREE_VALUE of each TREE_LIST contains the parameter packs.  */
>   #define PACK_EXPANSION_PARAMETER_PACKS(NODE)		\
> -  *(TREE_CODE (NODE) == EXPR_PACK_EXPANSION		\
> +  *(TREE_CODE (PACK_EXPANSION_CHECK (NODE)) == EXPR_PACK_EXPANSION \
>       ? &TREE_OPERAND (NODE, 1)				\
>       : &TYPE_MIN_VALUE_RAW (TYPE_PACK_EXPANSION_CHECK (NODE)))
>   
> @@ -3922,22 +3925,26 @@ struct GTY(()) lang_decl {
>      are enclosing functions that provided function parameter packs we'll need
>      to map appropriately.  */
>   #define PACK_EXPANSION_EXTRA_ARGS(NODE)		\
> -  *(TREE_CODE (NODE) == TYPE_PACK_EXPANSION	\
> +  *(TREE_CODE (PACK_EXPANSION_CHECK (NODE)) == TYPE_PACK_EXPANSION \
>       ? &TYPE_MAX_VALUE_RAW (NODE)			\
>       : &TREE_OPERAND ((NODE), 2))
>   
>   /* True iff this pack expansion is within a function context.  */
> -#define PACK_EXPANSION_LOCAL_P(NODE) TREE_LANG_FLAG_0 (NODE)
> +#define PACK_EXPANSION_LOCAL_P(NODE) \
> +  TREE_LANG_FLAG_0 (PACK_EXPANSION_CHECK (NODE))
>   
>   /* True iff this pack expansion is for sizeof....  */
> -#define PACK_EXPANSION_SIZEOF_P(NODE) TREE_LANG_FLAG_1 (NODE)
> +#define PACK_EXPANSION_SIZEOF_P(NODE) \
> +  TREE_LANG_FLAG_1 (PACK_EXPANSION_CHECK (NODE))
>   
>   /* True iff this pack expansion is for auto... in lambda init-capture.  */
> -#define PACK_EXPANSION_AUTO_P(NODE) TREE_LANG_FLAG_2 (NODE)
> +#define PACK_EXPANSION_AUTO_P(NODE) \
> +  TREE_LANG_FLAG_2 (PACK_EXPANSION_CHECK (NODE))
>   
>   /* True if we must use PACK_EXPANSION_EXTRA_ARGS and avoid partial
>      instantiation of this pack expansion.  */
> -#define PACK_EXPANSION_FORCE_EXTRA_ARGS_P(NODE) TREE_LANG_FLAG_3 (NODE)
> +#define PACK_EXPANSION_FORCE_EXTRA_ARGS_P(NODE) \
> +  TREE_LANG_FLAG_3 (PACK_EXPANSION_CHECK (NODE))
>   
>   /* True iff the wildcard can match a template parameter pack.  */
>   #define WILDCARD_PACK_P(NODE) TREE_LANG_FLAG_0 (NODE)
> @@ -3947,16 +3954,19 @@ struct GTY(()) lang_decl {
>     (TREE_CODE (NODE) == TYPE_ARGUMENT_PACK              \
>      || TREE_CODE (NODE) == NONTYPE_ARGUMENT_PACK)
>   
> +#define ARGUMENT_PACK_CHECK(NODE) \
> +  TREE_CHECK2 (NODE, TYPE_ARGUMENT_PACK, NONTYPE_ARGUMENT_PACK)
> +
>   /* The arguments stored in an argument pack. Arguments are stored in a
>      TREE_VEC, which may have length zero.  */
>   #define ARGUMENT_PACK_ARGS(NODE)                               \
> -  (TREE_CODE (NODE) == TYPE_ARGUMENT_PACK? TREE_TYPE (NODE)    \
> -   : TREE_OPERAND (NODE, 0))
> +  (TREE_CODE (ARGUMENT_PACK_CHECK (NODE)) == TYPE_ARGUMENT_PACK \
> +   ? TREE_TYPE (NODE) : TREE_OPERAND (NODE, 0))
>   
>   /* Set the arguments stored in an argument pack. VALUE must be a
>      TREE_VEC.  */
>   #define SET_ARGUMENT_PACK_ARGS(NODE,VALUE)     \
> -  if (TREE_CODE (NODE) == TYPE_ARGUMENT_PACK)  \
> +  if (TREE_CODE (ARGUMENT_PACK_CHECK (NODE)) == TYPE_ARGUMENT_PACK)  \
>       TREE_TYPE (NODE) = VALUE;                           \
>     else                                                  \
>       TREE_OPERAND (NODE, 0) = VALUE
> diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
> index 8da02de95fb..5071c030f53 100644
> --- a/gcc/cp/parser.cc
> +++ b/gcc/cp/parser.cc
> @@ -32563,7 +32563,8 @@ cp_parser_sizeof_pack (cp_parser *parser)
>     else if (TREE_CODE (expr) == CONST_DECL)
>       expr = DECL_INITIAL (expr);
>     expr = make_pack_expansion (expr);
> -  PACK_EXPANSION_SIZEOF_P (expr) = true;
> +  if (expr != error_mark_node)
> +    PACK_EXPANSION_SIZEOF_P (expr) = true;
>   
>     if (paren)
>       parens.require_close (parser);