Josh Conner - [PATCH] Fix c++/22153 (original) (raw)

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• From: Josh Conner
• To: gcc-patches
• Date: Tue, 20 Sep 2005 09:42:08 -0700
• Subject: [PATCH] Fix c++/22153

In the following invalid code:

template<int> void foo();

template<int> struct A
{
  template<> friend void foo<0>();
};

We are parsing the invalid member function declaration as if it were a member template declaration. So, it's being added to the unparsed_functions_queue for post-processing. However, the functions that perform this post-processing (starting with cp_parser_late_parsing_for_member) make the assumption that if DECL_TEMPLATE_INFO is set then this function will have valid template info in DECL_TI_TEMPLATE. In this case, however, even though DECL_TEMPLATE_INFO is set, DECL_TI_TEMPLATE represents the class template for this friend declaration and not the function template info. The function inline_needs_template_parms fails to handle this and dereferences a NULL pointer returned by most_general_template. Fixed by checking the value before dereferencing it.

I also considered instead not adding the invalid declaration to the unparsed_functions_queue, but thought that since we were attempting to parse the function as an invalid template function (instead of as an invalid specialization), allowing it to be post-processed would be most consistent (and provide some, possibly useful?, additional checking).

Note that the PR indicated this as a 3.4, 4.0, and 4.1 regression, however I only see a segfault on 4.1. On 3.4 and 4.0 I see the expected warnings followed by:

bad.c:6: confused by earlier errors, bailing out

Should I look for a patch for this, too, or is it acceptable?

Patch tested on arm-none-elf and i686-pc-linux-gnu with no regressions. OK for mainline?

• Josh

2005-09-20 Josh Conner jconner@apple.com

PR c++/22153
* pt.c (inline_needs_template_parms): Check result of
call to most_general_template before using it.

2005-09-20 Josh Conner jconner@apple.com

PR c++/22153
* g++.dg/template/crash38.C: New test.

Index: gcc/cp/pt.c

RCS file: /cvsroot/gcc/gcc/gcc/cp/pt.c,v retrieving revision 1.1038 diff -c -3 -p -r1.1038 pt.c *** gcc/cp/pt.c 16 Sep 2005 15:41:38 -0000 1.1038 --- gcc/cp/pt.c 20 Sep 2005 01:12:34 -0000 *************** template_class_depth (tree type) *** 322,331 **** static int inline_needs_template_parms (tree decl) { if (! DECL_TEMPLATE_INFO (decl)) return 0;

! return (TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (most_general_template (decl))) > (processing_template_decl + DECL_TEMPLATE_SPECIALIZATION (decl))); }

--- 322,338 ---- static int inline_needs_template_parms (tree decl) {

• tree tmpl;
• if (! DECL_TEMPLATE_INFO (decl)) return 0;

! tmpl = most_general_template (decl); ! ! if (tmpl == NULL_TREE) ! return 0; ! ! return (TMPL_PARMS_DEPTH (DECL_TEMPLATE_PARMS (tmpl)) > (processing_template_decl + DECL_TEMPLATE_SPECIALIZATION (decl))); }

// { dg-do compile }

// PR c++/22153

template void foo();

template struct A { template<> friend void foo<0>(); // { dg-error "" } };

• Follow-Ups:
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