sizeof a function return value

[Steven Weintraub]

We recently received the following code in as a test case of our compiler.

---------------------------------------------------------------------------
         char   f_char()   { return (char)           1; }
unsigned char   f_uchar()  { return (unsigned char)  1; }
         short  f_short()  { return (short)          1; }
unsigned short  f_ushort() { return (unsigned short) 1; }
         int    f_int()    { return (int)            1; }
unsigned int    f_uint()   { return (unsigned int)   1; }
         long   f_long()   { return (long)           1; }
unsigned long   f_ulong()  { return (unsigned long)  1; }
         float  f_float()  { return (float)          1; }
         double f_double() { return (double)         1; }

#define SIZER(type,func) size = sizeof(f_##func()); \
                         printf("%-6s ",#func); \
                         if (size == sizeof(type)) \
                           printf("good"); \
                         else \
                           printf("bug "); \
                         printf(" size = %d should be %d\n",size,sizeof(type));

main()
  {
  int size;

  SIZER(char          ,char);
  SIZER(unsigned char ,uchar);
  SIZER(short         ,short);
  SIZER(unsigned short,ushort);
  SIZER(int           ,int);
  SIZER(unsigned int  ,uint);
  SIZER(long          ,long);
  SIZER(unsigned long ,ulong);
  SIZER(float         ,float);
  SIZER(double        ,double);
  }
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As can be seen is it prototypes several functions, and then takes the
sizeof the return value of that function (once one wades through the
define).  The results we get are :

char   bug  size = 4 should be 1    <-------------
uchar  bug  size = 4 should be 1    <-------------
short  bug  size = 4 should be 2    <-------------
ushort bug  size = 4 should be 2    <-------------
int    good size = 4 should be 4
uint   good size = 4 should be 4
long   good size = 4 should be 4
ulong  good size = 4 should be 4
float  bug  size = 8 should be 4    <-------------
double good size = 8 should be 8

As can be guessed, the compiler returns a promoted return value.  

We have two camps on this issue.  One camp here claims this behavior is
not incorrect, there is nothing in the standard which prevents this.  The
other camp claims that the standard requires that a char function returns
a char, thus having sizeof(char).

This all breaks down to an argument of semantics in the standard.  Even
parts some of us feel clearly point to the second explanation (like
3.3.3.4 in the rational), others claim does not constrain what is PASSED
back.  To fix it one way or another is easy, we just want to know which
way to fix it.
                   enough from this mooncalf - Steven
----------------------------------------------------------------------------
Steven R Weintraub                             | O Lord,
...!cs.utexas.edu!oakhill!stevenw              |   let me talk gently,
Motorola Inc.  Austin, Texas                   | for I might have to eat my
(512) 891-3023 (office) (512) 453-6953 (home)  |   words tomorrow.
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