Hi all,

While trying out David Simcha's std.rational (see: http://forum.dlang.org/post/mailman.1774.1380289646.1719.digitalmars-d@puremagic.com and please offer feedback if this is of interest to you...), I tried building the docs and ran into the following amusing error message:

$ dmd -D rational.d

/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 0 has invalid symbol index 11
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 1 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 2 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 3 has invalid symbol index 2
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 4 has invalid symbol index 11
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 5 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 6 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 7 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 8 has invalid symbol index 12
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 9 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 10 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 11 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 12 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 13 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 14 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 15 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 16 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 17 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 18 has invalid symbol index 13
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_info): relocation 19 has invalid symbol index 21
/usr/bin/ld: /usr/lib/debug/usr/lib/x86_64-linux-gnu/crt1.o(.debug_line): relocation 0 has invalid symbol index 2
/usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/crt1.o: In function `_start':
(.text+0x20): undefined reference to `main'
collect2: error: ld returned 1 exit status
--- errorlevel 1

Ouch, I think you'll agree!

Of course, it only took a second's thought to realize that I should have used

    dmd -o- -D rational.d

... but the error message is pretty opaque.  How feasible would it be to handle the case where the -D flag is passed with a nicer error message limiting itself to:

    (.text+0x20): undefined reference to `main'
    collect2: error: ld returned 1 exit status
    To build only documentation, use dmd -o- -D

(I'd ask for it to just build the docs without erroring, but that would surely make for overlooked errors in some cases where you _should_ find main.)

Thanks & best wishes,

    -- Joe

Hi,

From "The D Programming Language" by Andrei Alexandrescu: "If you forget about --main, don't worry; the linker will fluently and baroquely remind you of that in its native language, encrypted Klingon."

So I think that your issue is well known and not a development priority at the moment... :P

Cheers,
Damien


> ... but the error message is pretty opaque.  How feasible would it be to handle the case where the -D flag is passed with a nicer error message limiting itself to:
>
>     (.text+0x20): undefined reference to `main'
>     collect2: error: ld returned 1 exit status
>     To build only documentation, use dmd -o- -D

On 28/09/13 15:38, Damien wrote:
>  From "The D Programming Language" by Andrei Alexandrescu: "If you forget about
> --main, don't worry; the linker will fluently and baroquely remind you of that
> in its native language, encrypted Klingon."

If you ever forget why we all love Andrei, a quick read of his books quickly reminds you ... :-)

> So I think that your issue is well known and not a development priority at the
> moment... :P

My request is subtly different from a plea for a better error message when the user misses off -main ;-)

If the user calls dmd -D on a file where "main" is not defined, the likely intention is that they want to build the docs and only the docs, and the Klingon is therefore slightly more disconcerting than usual.  So, slightly more need for a "nice" error message.  It was obvious to me because I'm used to D -- for a novice it could be nasty.