On 7 Nov 2001, at 17:00, Shafiek Rasdien wrote:

In my attempt to compile the p4 interpreter, I came across the following.

Please note the new list address address: gpc@gnu.de. Also, when reporting problems with GPC, please give your GPC version and platform. Perhaps the easiest way to do this is to report the result of:

gpc -v

e.g.:

Reading specs from D:\Programming\Pascal\i486-pc-mingw32msvc\2.95.3\specs gpc version 20010604, based on 2.95.3 20010315 (release)

The program

################################# program pcode; label 1; begin end.

###################################

yields

---

test.p: In function `program_Pcode': test.p:2: label `1' used but not defined

---

causing a compile time error. Should this not be a warning.

The wording is perhaps confusing, but it is an error. From the ISO 10206 Extended Pascal Standard (and ISO 7185 Standard Pascal also):

6.2.1 Blocks

A block closest­containing a label­declaration­part in which a label occurs shall closest­contain exactly one statement in which that label occurs.

In other words, an "unused label" is not permitted, because once declared, a statement must exist that uses that label.

The error message has "used" as meaning "used in a label declaration" and "defined" as meaning "defining the location of the label." Perhaps:

label '1' declared but not used

or

label '1' declared but not defined

...would be clearer?

Also

#################################### program pcode (output); label 1;

procedure asm; begin 1: end; { asm }

begin 1: end. ######################################

Should say "Multiple label `1' instances"....

"asm" is a GPC keyword, and with gpc-20010604, I get:

pcode.pas:4: parse error before `Asm'

If I use:

gpc -c --extended-pascal pcode.pas

...to eliminate the GPC keyword extensions, I get:

pcode.pas: In main program: pcode.pas:10: duplicate label `1'

-- Dave