Re: [PATCH] c++: fix ICE on invalid attributes [PR96637]

[Jason Merrill via Gcc-patches]

On 5/25/22 14:49, Marek Polacek wrote:

On Tue, May 24, 2022 at 08:22:22AM -0400, Jason Merrill wrote:

On 4/29/22 10:12, Marek Polacek wrote:

This patch fixes crashes with invalid attributes.  Arguably it could
make sense to assert seen_error() too.

So in this testcase we have TREE_CHAIN of a TREE_LIST pointing to
error_mark_node?  Can we avoid that?

Yes and yes.  Sorry, my previous fix was lousy.  This one is better:

Bootstrapped/regtested on x86_64-pc-linux-gnu, ok for trunk?

OK, thanks.

-- >8 --
When chaining attributes, attr_chainon should be used rather than plain
chainon, so that we don't end up with a TREE_LIST where one of the elements
is error_mark_node, which causes problems.  parser.cc has already been
fixed to use attr_chainon, but decl.cc has not.  Until now.

        PR c++/96637

gcc/cp/ChangeLog:

        * cp-tree.h (attr_chainon): Declare.
        * decl.cc (start_decl): Use attr_chainon.
        (grokdeclarator): Likewise.
        * parser.cc (cp_parser_statement): No longer static.

gcc/testsuite/ChangeLog:

        * g++.dg/parse/error64.C: New test.
---
  gcc/cp/cp-tree.h                     |  1 +
  gcc/cp/decl.cc                       | 19 ++++++++++---------
  gcc/cp/parser.cc                     |  2 +-
  gcc/testsuite/g++.dg/parse/error64.C |  4 ++++
  4 files changed, 16 insertions(+), 10 deletions(-)
  create mode 100644 gcc/testsuite/g++.dg/parse/error64.C

diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h
index ba986e892b6..d77fd1eb8a9 100644
--- a/gcc/cp/cp-tree.h
+++ b/gcc/cp/cp-tree.h
@@ -7235,6 +7235,7 @@ extern void inject_this_parameter (tree, cp_cv_quals);
  extern location_t defparse_location (tree);
  extern void maybe_show_extern_c_location (void);
  extern bool literal_integer_zerop (const_tree);
+extern tree attr_chainon (tree, tree);

/* in pt.cc */

  extern tree canonical_type_parameter          (tree);
diff --git a/gcc/cp/decl.cc b/gcc/cp/decl.cc
index 381259cb9cf..b1ea838ce8b 100644
--- a/gcc/cp/decl.cc
+++ b/gcc/cp/decl.cc
@@ -5557,7 +5557,7 @@ start_decl (const cp_declarator *declarator,
    *pushed_scope_p = NULL_TREE;

if (prefix_attributes != error_mark_node)

-    attributes = chainon (attributes, prefix_attributes);
+    attributes = attr_chainon (attributes, prefix_attributes);

decl = grokdeclarator (declarator, declspecs, NORMAL, initialized,

                         &attributes);
@@ -12728,9 +12728,10 @@ grokdeclarator (const cp_declarator *declarator,
               as a whole.  */
            late_attrs = splice_template_attributes (&attrs, type);
          returned_attrs = decl_attributes (&type,
-                                           chainon (returned_attrs, attrs),
+                                           attr_chainon (returned_attrs,
+                                                         attrs),
                                            attr_flags);
-         returned_attrs = chainon (late_attrs, returned_attrs);
+         returned_attrs = attr_chainon (late_attrs, returned_attrs);
        }

inner_declarator = declarator->declarator;

@@ -12781,8 +12782,8 @@ grokdeclarator (const cp_declarator *declarator,

The optional attribute-specifier-seq appertains to the

               array.  */
-           returned_attrs = chainon (returned_attrs,
-                                     declarator->std_attributes);
+           returned_attrs = attr_chainon (returned_attrs,
+                                          declarator->std_attributes);
          break;

case cdk_function:

@@ -13122,9 +13123,9 @@ grokdeclarator (const cp_declarator *declarator,
                /* transaction_safe applies to the type, but
                   transaction_safe_dynamic applies to the function.  */
                if (is_attribute_p ("transaction_safe", tx_qual))
-                 attrs = chainon (attrs, att);
+                 attrs = attr_chainon (attrs, att);
                else
-                 returned_attrs = chainon (returned_attrs, att);
+                 returned_attrs = attr_chainon (returned_attrs, att);
              }
            if (attrs)
              /* [dcl.fct]/2:
@@ -13438,7 +13439,7 @@ grokdeclarator (const cp_declarator *declarator,
    if (returned_attrs)
      {
        if (attrlist)
-       *attrlist = chainon (returned_attrs, *attrlist);
+       *attrlist = attr_chainon (returned_attrs, *attrlist);
        else
        attrlist = &returned_attrs;
      }
@@ -13451,7 +13452,7 @@ grokdeclarator (const cp_declarator *declarator,
        /* [dcl.meaning]/1: The optional attribute-specifier-seq following
         a declarator-id appertains to the entity that is declared.  */
        if (declarator->std_attributes != error_mark_node)
-       *attrlist = chainon (*attrlist, declarator->std_attributes);
+       *attrlist = attr_chainon (*attrlist, declarator->std_attributes);
        else
        /* We should have already diagnosed the issue (c++/78344).  */
        gcc_assert (seen_error ());
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 868b8610d60..62aaccda23d 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -12557,7 +12557,7 @@ cp_parser_statement (cp_parser* parser, tree 
in_statement_expr,

/* Append ATTR to attribute list ATTRS. */ -static tree

+tree
  attr_chainon (tree attrs, tree attr)
  {
    if (attrs == error_mark_node)
diff --git a/gcc/testsuite/g++.dg/parse/error64.C 
b/gcc/testsuite/g++.dg/parse/error64.C
new file mode 100644
index 00000000000..87848a58c27
--- /dev/null
+++ b/gcc/testsuite/g++.dg/parse/error64.C
@@ -0,0 +1,4 @@
+// PR c++/96637
+// { dg-do compile }
+
+void foo(int[] alignas[1] alignas(1)){} // { dg-error "" }

base-commit: 850a9ce8bcca59c7efabcdeeca14c5bd905e8363