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

[Jason Merrill via Gcc-patches]

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);