Debugging Alpha BASIC for OpenVMS

Question

I am trying to take over some projects involving DEC BASIC, A.K.A. VAX BASIC, A.K.A. Alpha BASIC. I am really hoping to run into someone with experience here. I have been through the user manual for VAX/Alpha BASIC through and though but I can't figure out how to debug shareable code.

I can create, compile and link shareable code, I can debug the code that references the shareable code, but I can't debug the shareable code. Any help would be greatly appreciated.

The commands I am using to compile and link are:

$ BASIC/DEBUG/NOOPTIMIZE COMPARE_DATES_TEST.BAS,COMPARE_DATES.BAS
$ LINK/SHAREABLE/DEBUG COMPARE_DATES.OBJ,COMPARE_DATES_SUB/OPT
$ LINK/DEBUG COMPARE_DATES_TEST,COMPARE_DATES_MAIN/OPT
$ RUN COMPARE_DATES_TEST

The contents of the two option files are:

$ type COMPARE_DATES_SUB.OPT
! COMPARE_DATES_SUB.OPT
SYMBOL_VECTOR=(COMPARE_DATES=PROCEDURE)
$ type COMPARE_DATES_MAIN.OPT
! COMPARE_DATES_MAIN.OPT
COMPARE_DATES/SHAREABLE

My shareable code has a bug, but I don't know where, the debugger reports:

— SRC: module COMPARE_DATES_TEST$MAIN -scroll-source————————————————————————————
     1: EXTERNAL INTEGER FUNCTION COMPARE_DATES(STRING,STRING)
     2: DECLARE STRING A$, B$
     3: A$ = "01-APR-18"
     4: B$ = "15-MAY-2017"
     5:
->   6: PRINT COMPARE_DATES(A$, B$)
     7: END
— OUT -output———————————————————————————————————————————————————————————————————
stepped to COMPARE_DATES_TEST$MAIN\COMPARE_DATES_TEST$MAIN\%LINE 3
stepped to COMPARE_DATES_TEST$MAIN\COMPARE_DATES_TEST$MAIN\%LINE 4
stepped to COMPARE_DATES_TEST$MAIN\COMPARE_DATES_TEST$MAIN\%LINE 6
%BAS-F-SUBOUTRAN, Subscript out of range
-BAS-I-FROFUN, In external function COMPARE_DATES
-BAS-I-FROMOD, In module COMPARE_DATES_TEST
break on unhandled exception preceding 18446744071563830960
— PROMPT -error-program-prompt——————————————————————————————————————————————————
%DEBUG-I-SOURCESCOPE, source lines not available for %PC in scope number 0
        Displaying source for 6\%PC
DBG>

Answer 1

Too long for a comment: You compiled with /NOOPTIMIZE, so I would have expected that a STEP/INTO when at line 6, PRINT COMPARE_DATES(A$, B$), would have stepped to COMPARE_DATES in your shareable image. I don't know why that's not the case, here. The debugger is right, you don't have the sources for DEC$BASRTL. Your shareable image is not installed, it is in your address space. It seems PRINT has problems with the passed argument. I would try a SET IMAGE COMPARE_DATES; SET MODULE/ALL; SET BREAK COMPARE_DATES at the initial debugger prompt. That makes all debug symbols of the shareable image known and sets a breakpoint in your function. And then a GO should get you into your function. (I noticed, that you have the same names for the function, the source module and the shareable image. This shouldn't be a problem.)