Bug 22344

The following code causes strcmp to return 0 when passed two
strings that are NOT equal:

#include <stdio.h>
#include <string.h>

class StrContainer
{
  public:

  StrContainer(char* str)
  {
      strVal = str;
  }

  const char* const& getStr()
  {
     return strVal;
  }

  private:

  char* strVal;
};

int main()
{
   char* str1 = "7000";
   char* str2 = "8000";

   StrContainer sc1(str1);
   StrContainer sc2(str2);
 
   if (0 == strcmp(sc1.getStr(), sc2.getStr()))
   {
     printf("Expression 1: Strings '%s' and '%s' are equal\n",
            sc1.getStr(),
            sc2.getStr());
   }
   else
   {
     printf("Expression 1: Strings '%s' and '%s' are Not equal\n",
            sc1.getStr(),
            sc2.getStr());
   }

   const char* s1 = sc1.getStr();
   const char* s2 = sc2.getStr();

   if (0 == strcmp(s1, s2))
   {
     printf("Expression 2: Strings '%s' and '%s' are equal\n",
            s1,
            s2);
   }
   else
   {
     
     printf("Expression 2: Strings '%s' and '%s' are Not equal\n",
            s1,
            s2);
   }
  
 return 0;
}


The first strcmp results in Strings '7000' and '8000' are equal while the second strcmp
properly returns that the two strings are not equal.  Initially I thought there was a 
code generation problem when invoking strcmp(sc1.getStr(), sc2.getStr()) since the
second strcmp is correct when passed local variables instead of two expressions.
After stepping through the code at the assembly level, the first strcmp fails because
the  result of sc1.getStr() is pulled from the stack for both arguments to strcmp.
However, if I create a strcmp wrapper such as

int strcmp2(const char* s1, const char* s1)
{
  printf("comparing '%s' to '%s'\n");
  return strcmp(s1, s2);
}

and call this instead of strcmp, the code functions properly.  This lead me to look
at the preprocessor output via g++ -E to see the strcmp prototype.  I noticed
that it has an attribute of __pure__.  I could not find any documentation for this
attribute and I assume it means the implementation is in assembly.

Another interesting aspect of this problem is that if StrContainer::getStr() is changed to return
const char* instead of const char* const& the code functions properly.  
I realize that this code is an example of bad programming and that the const& attribute of
getStr() is not necessary, but it still should work.  This code malfunctions only with gcc 2.96.
It operates properly with 2.95.2 and egcs-X

This code also functions properly with Sun's Forte C++, VC++ 6.0, and Borland C++.