Q44452: -Zg Won’t Handle Untagged Aggregate typedef Parameters

Article: Q44452
Product(s): See article
Version(s): 5.00 5.10 | 5.10
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | | mspl13_c
Last Modified: 1-JUN-1989

The -Zg switch causes the Microsoft C Version 5.10 Optimizing Compiler
to generate a list of function prototypes from the input file. This is
documented on Page 86 of the "Microsoft C for the MS-DOS Operating
System: User's Guide."

It is noted on Page 87 of the same manual that structure, enumerated,
and union types that are used as formal parameters must be tagged.
Using untagged aggregate types as formal parameters results in the
following message being generated for each instance of untagged
aggregate type parameters:

   warning C4032 : unnamed struct/union as parameter

Typedefs are expanded in the prototype listing. If an aggregate type
has no tag then the prototype is commented out and the type of the
parameter is labeled, in the case of a structure, as follows:

   struct UNNAMED

There is no way to prevent the compiler from expanding the typedefs
and from disliking the untagged aggregate types.

The program below, when compiled in the following manner

   cl -Zg whack.c

produces the following output:

    extern  void main(void );
    extern  int Woof(struct ure a);
    /* int Heave(struct UNNAMED a); */
    whack.c(29) : warning C4032 : unnamed struct/union as parameter

/* Demonstration of typedef expansion when compiling with /Zg
 */
typedef struct ure      // This one's tagged
{
    int     x;
    int     y;
} URE;

typedef struct          // This one's not tagged
{
    int     x;
    int     y;
} IME;

void main()
{
    URE     Ok;         // Tagged type variable
    IME     NotOk;      // Untagged type variable

    Woof( Ok );
    Heave( NotOk );
}

int Woof( URE a )
{
    return( 0 );
}

int Heave( IME a )
{
    return( 0 );
}

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