[PATCH] Fix PR c++/28284: ICE with invalid static const variable

[Simon Martin <simartin at users dot sourceforge dot net>]

Hello.

With the following invalid code, we currently have an ICE (stack trace at the 
very end of this mail).

=== cut here ===
template<int> struct A
{
  static const int i=x, j, k;
};

template<int N> const int A<N>::j = i;
template<int N> const int A<N>::k = j;

A<0> a;
=== cut here ===

The problem is that DECL_INITIAL for the declaration of j is NULL (because the 
declaration for i is not "initializer_constant_valid_p" in cp/typeck2.c:628, 
so DECL_INITIAL is not set), and yet in constant_value_1 we pass it to 
fold_non_dependent_expr, that dereferences it, hence the ICE.

The attached patch fixes it by checking that DECL_INITIAL (decl) is not NULL 
before calling fold_non_dependent_expr in constant_value_1.

This has been boostrapped (except for the error in libjava reported there: 
http://gcc.gnu.org/ml/java-patches/2006-q3/msg00268.html) and regtested on 
i686-pc-linux-gnu with no new failures.

Is it OK? If so, could someone commit it for me please?

Thanks in advance.

Best regards,
Simon

:ADDPATCH c++:

PS: Here's the stack trace we get without this patch:
(gdb) r pr28284.cpp
Starting program: /newdisk/data/dev/projects/gcc/build_bootstrap/gcc/cc1plus 
pr28284.cpp
pr28284.cpp:5: error: 'x' was not declared in this scope

Program received signal SIGSEGV, Segmentation fault.
type_dependent_expression_p (expression=0x0) at ../../trunk/gcc/cp/pt.c:12741
12741     if (TREE_CODE (expression) == IDENTIFIER_NODE)
(gdb) bt
#0  type_dependent_expression_p (expression=0x0) 
at ../../trunk/gcc/cp/pt.c:12741
#1  0x080a4048 in fold_non_dependent_expr (expr=0x0) 
at ../../trunk/gcc/cp/pt.c:3374
#2  0x081214c7 in constant_value_1 (decl=0x40171210, integral_p=0 '\0') 
at ../../trunk/gcc/cp/init.c:1473
#3  0x08053836 in convert_like_real (convs=0x87f55b8, expr=0x40171210, fn=0x0, 
argnum=0, inner=1, issue_conversion_warnings=0 '\0', c_cast_p=0 '\0')
    at ../../trunk/gcc/cp/call.c:4336
#4  0x08053917 in convert_like_real (convs=0x87f55d0, expr=0x40171210, fn=0x0, 
argnum=0, inner=0, issue_conversion_warnings=1 '\001', c_cast_p=0 '\0')
    at ../../trunk/gcc/cp/call.c:4349
#5  0x0805428b in perform_implicit_conversion (type=0x40179284, expr=Variable 
"expr" is not available.
) at ../../trunk/gcc/cp/call.c:6423
#6  0x080b196a in digest_init (type=0x4021c4ac, init=0x40171210) 
at ../../trunk/gcc/cp/typeck2.c:731
#7  0x080b2c55 in store_init_value (decl=0x40171268, init=0x40171210) 
at ../../trunk/gcc/cp/typeck2.c:622
#8  0x0807a526 in check_initializer (decl=0x40171268, init=0x0, flags=8, 
cleanup=0xbffff088) at ../../trunk/gcc/cp/decl.c:4819
#9  0x0807af0a in cp_finish_decl (decl=0x40171268, init=0x40171210, 
init_const_expr_p=1 '\001', asmspec_tree=0x0, flags=8) 
at ../../trunk/gcc/cp/decl.c:5183
#10 0x080ee12d in cp_parser_init_declarator (parser=0x4021f23c, 
decl_specifiers=0xbffff138, checks=0x0, function_definition_allowed_p=1 
'\001', member_p=0 '\0',
    declares_class_or_enum=Variable "declares_class_or_enum" is not available.
) at ../../trunk/gcc/cp/parser.c:11194
#11 0x080ee615 in cp_parser_single_declaration (parser=0x4021f23c, checks=0x0, 
member_p=0 '\0', friend_p=0xbffff1db "") at ../../trunk/gcc/cp/parser.c:15684
#12 0x080fb9b3 in cp_parser_template_declaration_after_export 
(parser=0x4021f23c, member_p=0 '\0') at ../../trunk/gcc/cp/parser.c:15543
#13 0x080fd759 in cp_parser_declaration (parser=0x4021f23c) 
at ../../trunk/gcc/cp/parser.c:7108
#14 0x080fdd9d in cp_parser_declaration_seq_opt (parser=0x4021f23c) 
at ../../trunk/gcc/cp/parser.c:7031
#15 0x080fe4a5 in c_parse_file () at ../../trunk/gcc/cp/parser.c:2755
#16 0x0819c79a in c_common_parse_file (set_yydebug=0) 
at ../../trunk/gcc/c-opts.c:1164
#17 0x084e545a in toplev_main (argc=2, argv=0xbffff3a4) 
at ../../trunk/gcc/toplev.c:999
#18 0x081ab53f in main (argc=0, argv=0x4017f000) at ../../trunk/gcc/main.c:35

Attachment: pr28284.patch
Description: Text document

Attachment: CL_28284
Description: Text document

Attachment: CL_28284_testsuite
Description: Text document

Attachment: pr28284.cpp
Description: Text document