[BUGS] ECPG: "char*" instead of "const char*" in ecpglib.h

[Tomasz Ostrowski]

Using "char*" as an argument type instead of "const char*" in ecpglib.h
causes that for example the following sample program, basically
copied from docmentation
http://www.postgresql.org/docs/8.1/interactive/ecpg-dynamic.html ,
does not compile using "gcc-4.0.1":

test.pgc

        #include <stdio.h>
        
        int main()
        {
                EXEC SQL BEGIN DECLARE SECTION;
                const char *select_version_sql = "select version()";
                char version[1000];
                EXEC SQL END DECLARE SECTION;
        
                EXEC SQL CONNECT TO template1 USER postgres;
                EXEC SQL PREPARE select_version FROM :select_version_sql;
                EXEC SQL EXECUTE select_version INTO :version;
                printf("%s\n", version);
                return 0;
        }

$ ecpg --version
ecpg (PostgreSQL 8.1.0) 4.1.1

$ecpg test.pgc 

$gcc test.c -lecpg
test.pgc: In function 'main':
test.pgc:11: warning: passing argument 3 of 'ECPGprepare' discards qualifiers 
from pointer target type

$g++ test.c -lecpg
test.pgc: In function 'int main()':
test.pgc:11: error: invalid conversion from 'const char*' to 'char*'
test.pgc:11: error:   initializing argument 3 of 'bool ECPGprepare(int, char*, 
char*)'

----------------------------------------------------------

This forces to use terrible workarounds like:

        const char *select_version_sql = "select version()";
        int select_version_sql_l = strlen(select_version_sql);
        EXEC SQL BEGIN DECLARE SECTION;
        char _select_version_sql[select_version_sql_l+1];
        EXEC SQL END DECLARE SECTION;
        strncpy(_select_version_sql, select_version_sql, 
select_version_sql_l+1);

        EXEC SQL PREPARE select_version FROM :_select_version_sql;

----------------------------------------------------------

This bug was present in 8.0.4 and is present in 8.1.0 - I haven't
checked other versions.


Is this just a function declaration bug or do ecpg functions really
change their arguments so they cannot be declared "const" (also a bug)?

Regards
Tometzky
-- 
...although Eating Honey was a very good thing to do, there was a
moment just before you began to eat it which was better than when you
were...
                                                      Winnie the Pooh

---------------------------(end of broadcast)---------------------------
TIP 9: In versions below 8.0, the planner will ignore your desire to
       choose an index scan if your joining column's datatypes do not
       match