[patch] Make vector::at() assertion message more useful (try #2)

Paul Pluzhnikov ppluzhnikov@google.com
Fri Sep 13 00:02:00 GMT 2013


On Wed, Sep 4, 2013 at 9:55 PM, Daniel Krügler
<daniel.kruegler@gmail.com> wrote:

>> Did you mean "pessimises code size", or something else?
>
> Yes.

Daniel's idea proved a good one, and I now have a patch that I am
happy with, and that will be easy to extend to string::at(), and other
__throw_... functions.

I've added the new snprintf.cc to c++11/ rather than c++98/ as Paolo
suggested, because the only current caller is in c++11/functexcept.cc

Thanks,
-- 
Paul Pluzhnikov

libstdc++-v3/ChangeLog:

2013-09-12  Paul Pluzhnikov  <ppluzhnikov@google.com>

	* src/c++11/Makefile.am: Add snprintf.cc
	* src/c++11/Makefile.in: Regenerate.
	* include/bits/functexcept.h (__throw_out_of_range): Adjust.
	* src/c++11/functexcept.cc (__throw_out_of_range): New overload.
	* src/c++11/snprintf.cc: New.
	* config/abi/pre/gnu.ver: Add _ZSt20__throw_out_of_rangePKcz.
	* include/bits/stl_vector.h (_M_range_check): Print
	additional assertion details.
	* testsuite/23_containers/vector/requirements/dr438/assign_neg.cc:
	Adjust.
	* testsuite/23_containers/vector/requirements/dr438/insert_neg.cc:
	Likewise.
	* testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc:
	Likewise.
	* testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc:
	Likewise.
-------------- next part --------------
Index: libstdc++-v3/src/c++11/Makefile.am
===================================================================
--- libstdc++-v3/src/c++11/Makefile.am	(revision 202545)
+++ libstdc++-v3/src/c++11/Makefile.am	(working copy)
@@ -42,6 +42,7 @@
 	random.cc \
 	regex.cc  \
 	shared_ptr.cc \
+	snprintf.cc \
 	system_error.cc \
 	thread.cc
 
Index: libstdc++-v3/src/c++11/functexcept.cc
===================================================================
--- libstdc++-v3/src/c++11/functexcept.cc	(revision 202545)
+++ libstdc++-v3/src/c++11/functexcept.cc	(working copy)
@@ -31,6 +31,7 @@
 #include <future>
 #include <functional>
 #include <bits/regex_error.h>
+#include <stdarg.h>
 
 #ifdef _GLIBCXX_USE_NLS
 # include <libintl.h>
@@ -39,6 +40,12 @@
 # define _(msgid)   (msgid)
 #endif
 
+namespace __gnu_cxx
+{
+  int __snprintf_lite(char *__buf, size_t __bufsize, const char *__fmt,
+		      va_list __ap);
+}
+
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -75,11 +82,27 @@
   __throw_length_error(const char* __s __attribute__((unused)))
   { _GLIBCXX_THROW_OR_ABORT(length_error(_(__s))); }
 
+  // Left only to maintain backward-compatible ABI.
   void
   __throw_out_of_range(const char* __s __attribute__((unused)))
   { _GLIBCXX_THROW_OR_ABORT(out_of_range(_(__s))); }
 
   void
+  __throw_out_of_range(const char* __fmt, ...)
+  {
+    const size_t __len = __builtin_strlen(__fmt);
+    // enough for expanding up to 5 size_t's in the format.
+    const size_t __alloca_size = __len + 100;
+    char *const __s = static_cast<char*>(alloca(__alloca_size));
+    va_list __ap;
+
+    va_start(__ap, __fmt);
+    __gnu_cxx::__snprintf_lite(__s, __alloca_size, __fmt, __ap);
+    _GLIBCXX_THROW_OR_ABORT(out_of_range(_(__s)));
+    va_end(__ap);  // Not reached.
+  }
+
+  void
   __throw_runtime_error(const char* __s __attribute__((unused)))
   { _GLIBCXX_THROW_OR_ABORT(runtime_error(_(__s))); }
 
Index: libstdc++-v3/src/c++11/snprintf.cc
===================================================================
--- libstdc++-v3/src/c++11/snprintf.cc	(revision 0)
+++ libstdc++-v3/src/c++11/snprintf.cc	(revision 0)
@@ -0,0 +1,103 @@
+// Debugging support -*- C++ -*-
+
+// Copyright (C) 2013 Free Software Foundation, Inc.
+//
+// This file is part of GCC.
+//
+// GCC is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3, or (at your option)
+// any later version.
+//
+// GCC is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#include <stdarg.h>
+#include <bits/locale_facets.h>
+
+namespace std {
+  template<typename _CharT, typename _ValueT>
+  int
+  __int_to_char(_CharT* __bufend, _ValueT __v, const _CharT* __lit,
+                ios_base::fmtflags __flags, bool __dec);
+}
+
+namespace __gnu_cxx {
+
+  // Private routine to append decimal representation of VAL to the given
+  // BUFFER, but not more than BUFSIZE characters.
+  // Does not NUL-terminate the output buffer.
+  // Returns number of characters appended, or -1 if BUFSIZE is too small.
+  int __concat_size_t(char *__buf, size_t __bufsize, size_t __val)
+  {
+    // Long enough for decimal representation.
+    int __ilen = 3 * sizeof(__val);
+    char *__cs = static_cast<char*>(__builtin_alloca(__ilen));
+    size_t __len = std::__int_to_char(__cs + __ilen, __val,
+				      std::__num_base::_S_atoms_out,
+				      std::ios_base::dec, true);
+    if (__bufsize < __len)
+      return -1;
+
+    __builtin_memcpy(__buf, __cs + __ilen - __len, __len);
+    return __len;
+  }
+
+  // Private routine to print into __buf arguments according to format,
+  // not to exceed __bufsize.
+  // Only '%%' and '%zu' format specifiers are understood.
+  // Returns number of characters printed (excluding terminating NUL).
+  // Always NUL-terminates __buf.
+  int __snprintf_lite(char *__buf, size_t __bufsize, const char *__fmt,
+		      va_list __ap)
+  {
+    char *__d = __buf;
+    const char *__s = __fmt;
+    const char *const __limit = __d + __bufsize - 1;  // Leave space for NUL.
+
+    while (*__s != '\0' && __d < __limit)
+      {
+	if (*__s == '%')
+	  switch (__s[1])
+	    {
+	    default:  // Stray '%'. Just print it.
+	      break;
+	    case '%':  // '%%'
+	      __s += 1;
+	      break;
+	    case 'z':
+	      if (__s[2] == 'u')  // '%zu' -- expand next size_t arg.
+		{
+		  const int __len = __concat_size_t(__d, __limit - __d,
+						    va_arg(__ap, size_t));
+		  if (__len > 0)
+		    __d += __len;
+		  else
+		    goto __out;
+
+		  __s += 3;
+		  continue;
+		}
+	      // Stray '%zX'. Just print it.
+	      break;
+	    }
+	*__d++ = *__s++;
+      }
+
+  __out:
+    *__d = '\0';
+    return __d - __buf;
+  }
+
+}  // __gnu_cxx
Index: libstdc++-v3/include/bits/functexcept.h
===================================================================
--- libstdc++-v3/include/bits/functexcept.h	(revision 202545)
+++ libstdc++-v3/include/bits/functexcept.h	(working copy)
@@ -72,7 +72,7 @@
   __throw_length_error(const char*) __attribute__((__noreturn__));
 
   void
-  __throw_out_of_range(const char*) __attribute__((__noreturn__));
+  __throw_out_of_range(const char*, ...) __attribute__((__noreturn__));
 
   void
   __throw_runtime_error(const char*) __attribute__((__noreturn__));
Index: libstdc++-v3/include/bits/stl_vector.h
===================================================================
--- libstdc++-v3/include/bits/stl_vector.h	(revision 202545)
+++ libstdc++-v3/include/bits/stl_vector.h	(working copy)
@@ -791,7 +791,9 @@
       _M_range_check(size_type __n) const
       {
 	if (__n >= this->size())
-	  __throw_out_of_range(__N("vector::_M_range_check"));
+	  __throw_out_of_range(__N("vector::_M_range_check: __n (which is %zu) "
+				   ">= this->size() (which is %zu)"),
+			       __n, this->size());
       }
 
     public:
Index: libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/assign_neg.cc
===================================================================
--- libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/assign_neg.cc	(revision 202545)
+++ libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/assign_neg.cc	(working copy)
@@ -18,7 +18,7 @@
 // <http://www.gnu.org/licenses/>.
 
 // { dg-do compile }
-// { dg-error "no matching" "" { target *-*-* } 1308 }
+// { dg-error "no matching" "" { target *-*-* } 1310 }
 
 #include <vector>
 
Index: libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/insert_neg.cc
===================================================================
--- libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/insert_neg.cc	(revision 202545)
+++ libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/insert_neg.cc	(working copy)
@@ -18,7 +18,7 @@
 // <http://www.gnu.org/licenses/>.
 
 // { dg-do compile }
-// { dg-error "no matching" "" { target *-*-* } 1349 }
+// { dg-error "no matching" "" { target *-*-* } 1351 }
 
 #include <vector>
 
Index: libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc
===================================================================
--- libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc	(revision 202545)
+++ libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_1_neg.cc	(working copy)
@@ -18,7 +18,7 @@
 // <http://www.gnu.org/licenses/>.
 
 // { dg-do compile }
-// { dg-error "no matching" "" { target *-*-* } 1234 }
+// { dg-error "no matching" "" { target *-*-* } 1236 }
 
 #include <vector>
 
Index: libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc
===================================================================
--- libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc	(revision 202545)
+++ libstdc++-v3/testsuite/23_containers/vector/requirements/dr438/constructor_2_neg.cc	(working copy)
@@ -18,7 +18,7 @@
 // <http://www.gnu.org/licenses/>.
 
 // { dg-do compile }
-// { dg-error "no matching" "" { target *-*-* } 1234 }
+// { dg-error "no matching" "" { target *-*-* } 1236 }
 
 #include <vector>
 #include <utility>
Index: libstdc++-v3/config/abi/pre/gnu.ver
===================================================================
--- libstdc++-v3/config/abi/pre/gnu.ver	(revision 202545)
+++ libstdc++-v3/config/abi/pre/gnu.ver	(working copy)
@@ -1365,6 +1365,9 @@
     # std::get_unexpected()
     _ZSt14get_unexpectedv;
 
+    # std::__throw_out_of_range(char const*, ...)
+    _ZSt20__throw_out_of_rangePKcz;
+
 } GLIBCXX_3.4.19;
 
 # Symbols in the support library (libsupc++) have their own tag.
Index: libstdc++-v3/src/c++11/Makefile.in
===================================================================
--- libstdc++-v3/src/c++11/Makefile.in	(revision 202545)
+++ libstdc++-v3/src/c++11/Makefile.in	(working copy)
@@ -70,7 +70,8 @@
 am__objects_1 = chrono.lo condition_variable.lo debug.lo \
 	functexcept.lo functional.lo future.lo hash_c++0x.lo \
 	hashtable_c++0x.lo limits.lo mutex.lo placeholders.lo \
-	random.lo regex.lo shared_ptr.lo system_error.lo thread.lo
+	random.lo regex.lo shared_ptr.lo snprintf.lo system_error.lo \
+	thread.lo
 @ENABLE_EXTERN_TEMPLATE_TRUE@am__objects_2 = fstream-inst.lo \
 @ENABLE_EXTERN_TEMPLATE_TRUE@	string-inst.lo wstring-inst.lo
 am_libc__11convenience_la_OBJECTS = $(am__objects_1) $(am__objects_2)
@@ -324,6 +325,7 @@
 	random.cc \
 	regex.cc  \
 	shared_ptr.cc \
+	snprintf.cc \
 	system_error.cc \
 	thread.cc
 


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