kutner@vid.cpg.sony.co.jp (Mike Kutner) (10/02/90)
The following code fragment gives a "Suspicious pointer conversion"
warning message when compiled by Turbo C++ 1.0 (in C mode). It seems
that the structure member's type information is getting lost. An
explicit cast (enum day_t *) gets rid of the warning message. However,
am I being dense or has someone else seen this problem?
enum day_t {mon, tue, wed, thu};
struct date_t
{
enum day_t day;
};
void foo(enum day_t *dtp)
{
*dtp = tue;
}
void main(void)
{
struct date_t bar;
foo(&(bar.day)); /* <--- Suspicious pointer conversion */
}
kutner@vid.cpg.sony.co.jp
--
----
Mike Kutner From the US: kutner@vid.cpg.sony.co.jp
Sony Corporation Atsugi Technology Center Tel: +81-462-30-5705
4-14-1 Asahi-cho, Atsugi-shi, Kanagawa-ken 243 Japankdq@demott.COM (Kevin D. Quitt) (10/03/90)
In article <2019@cpgvgw.vid.cpg.sony.co.jp> kutner@vid.cpg.sony.co.jp (Mike Kutner) writes: >The following code fragment gives a "Suspicious pointer conversion" >warning message when compiled by Turbo C++ 1.0 (in C mode). It seems >that the structure member's type information is getting lost. An >explicit cast (enum day_t *) gets rid of the warning message. However, >am I being dense or has someone else seen this problem? > >enum day_t {mon, tue, wed, thu}; > >struct date_t >{ > enum day_t day; >}; > >void foo(enum day_t *dtp) >{ > *dtp = tue; >} > >void main(void) >{ > struct date_t bar; ^^^^^^_________________Shouldn't this be enum? > > foo(&(bar.day)); /* <--- Suspicious pointer conversion */ >} > -- _ Kevin D. Quitt demott!kdq kdq@demott.com DeMott Electronics Co. 14707 Keswick St. Van Nuys, CA 91405-1266 VOICE (818) 988-4975 FAX (818) 997-1190 MODEM (818) 997-4496 PEP last 96.37% of all statistics are made up.
russw@cs.utexas.edu (Russ Williams) (10/03/90)
Yes, there is a bug in TC++ 1.0 that gives a spurious Suspicious Pointer COnversion for pointer-to-enum parameters. --Russ
wallis@labc.enet.dec.com (Barry L. Wallis) (10/05/90)
In article <2019@cpgvgw.vid.cpg.sony.co.jp>, kutner@vid.cpg.sony.co.jp (Mike Kutner) writes...
!>The following code fragment gives a "Suspicious pointer conversion"
!>warning message when compiled by Turbo C++ 1.0 (in C mode). It seems
!>that the structure member's type information is getting lost. An
!>explicit cast (enum day_t *) gets rid of the warning message. However,
!>am I being dense or has someone else seen this problem?
!>
!>enum day_t {mon, tue, wed, thu};
!>
!>struct date_t
!>{
!> enum day_t day;
!>};
!>
!>void foo(enum day_t *dtp)
!>{
!> *dtp = tue;
!>}
!>
!>void main(void)
!>{
!> struct date_t bar;
!>
!> foo(&(bar.day)); /* <--- Suspicious pointer conversion */
!>}
!>
!>
Turbo C++ V1.0 is acting correctly (at least as far as C++ is concerned; I know
you are in C mode, but, this may help as the logic makes sense in either
language). According to the ARM (_Annotated C++ Reference Manual_ by Ellis and
Stroustrup) section 7.2 explains that "Each enumeration defines an integral
type that is different from all other integral types." It then goes on to
explain that although you cannot assign an int directly to an enum you can use
a cast to force the assignment. However, in this case you losethe C++ strong
type checking facility and can assign a "bad" value to the enum.
So, the structure member's type information is not getting lost, it is being
enforced. The only question I have is should this be happening in C mode?
---
Barry L. Wallis USENET: wallis@labc.dec.com
Database Consultant Prodigy (don't laugh): DNMX41A
U.S. DECtp Resource Center DECUServe: EISNER::WALLIS (not on the net yet)
Los Angeles, CA "No one voted for me, I represent myself"
---dfoster@jarthur.Claremont.EDU (Derek R. Foster) (10/07/90)
In article <640@demott.COM> kdq@demott.COM (Kevin D. Quitt) writes: >In article <2019@cpgvgw.vid.cpg.sony.co.jp> kutner@vid.cpg.sony.co.jp (Mike Kutner) writes: >>The following code fragment gives a "Suspicious pointer conversion" >>warning message when compiled by Turbo C++ 1.0 (in C mode). It seems >>that the structure member's type information is getting lost. An >>explicit cast (enum day_t *) gets rid of the warning message. However, >>am I being dense or has someone else seen this problem? I've seen this problem. And, to answer a couple of previous poster's suggestions, the problem is not merely dependant on whether the enum in question is a member of a struct/class or not. I've had this problem with global variables too. I think it's a bug in TC++. MSC v. 5.1 passed my code without complaint, but TC++ complains. Also: in reply to another poster's response that the difference is caused by the way C++ treats enums: I don't see any reason why the difference between enum and int which is enforced by C++ (but not C) should make any difference in whether a pointer to an enum type should be able to be passed via a function call to a pointer of the same type. I could see problems created if one or the other was a normal int perhaps, but that was not the case here. Perhaps I am misunderstanding you? Derek Riippa Foster