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digitalmars.D.learn - DMD -L Flag, maybe a bug?

reply Bubbasaur <bubba gmail.com> writes:
If you follow the link below:

https://dlang.org/dmd-windows.html#switch-L

It's written:

"
    -Llinkerflag

    pass linkerflag to the linker link.exe , for example, -L/ma/li
"

But at least on Windows, you need to put a space between -L and 
the PATH. Which It's weird, since with "-I" flag you don't need 
any space.

It took me 30 minutes until I find why my program wasn't 
compiling. (I found the tip on a forum elsewhere).

Is this a bug or a mistake?

Bubba.
Dec 25 2015
parent reply anonymous <anonymous example.com> writes:
On 25.12.2015 15:40, Bubbasaur wrote:

 But at least on Windows, you need to put a space between -L and the
 PATH. Which It's weird, since with "-I" flag you don't need any space.


I don't think that's right. Unless something awful is going in Windows 
dmd, that should be processed as two separate entities: "-L" passes 
nothing to the linker, and whatever you try to send the linker is 
interpreted independently by dmd.

You can try removing the "-L" entirely. If it still works, then dmd is 
apparently able to handle things for you, and you don't need to go the 
linker yourself.

What exactly are trying to pass to the linker?


 It took me 30 minutes until I find why my program wasn't compiling. (I
 found the tip on a forum elsewhere).


Can you give a link to that?
Dec 25 2015
parent reply Bubbasaur <bubba gmail.com> writes:
On Friday, 25 December 2015 at 15:06:27 UTC, anonymous wrote:

 ...
 You can try removing the "-L" entirely. If it still works...


In fact it works without the "-L". Which makes me wonder if I was 
using it wrongly?


 What exactly are trying to pass to the linker?


A lib: GtkD.


 Can you give a link to that?


Sure (It's the second from the last answer):
http://www.dsource.org/forums/viewtopic.php?t=4928&sid=e1caca2e12a14c49672a92126dc0922c

Bubba.
Dec 25 2015
parent reply anonymous <anonymous example.com> writes:
On 25.12.2015 19:32, Bubbasaur wrote:

 On Friday, 25 December 2015 at 15:06:27 UTC, anonymous wrote:
 In fact it works without the "-L". Which makes me wonder if I was using
 it wrongly?


I'm convinced that putting a space between "-L" and its argument is 
nonsense. The "-L" part just means "pass the empty string to the 
linker", which doesn't do anything. And the argument is interpreted by 
dmd then, not by the linker.


 What exactly are trying to pass to the linker?


 A lib: GtkD.


That means a .lib file, right?

dmd knows how to handle .lib files [1], so it's no surprise that things 
work when you pass the .lib file to dmd.

The GtkD docs say to use -L though [2], so I suppose that should work 
too. Maybe show your exact complete command line, if you want to find 
out why it doesn't work for you.


[1] http://dlang.org/dmd-windows.html#switches
[2] 
https://github.com/gtkd-developers/GtkD/wiki/Installing-on-Windows#testing-installation
Dec 25 2015
parent reply Bubbasaur <bubba gmail.com> writes:
On Friday, 25 December 2015 at 23:45:42 UTC, anonymous wrote:

 ...
 That means a .lib file, right?


Yes.


 The GtkD docs say to use -L though [2], so I suppose that 
 should work too.



 Maybe show your exact complete command line, if you want to 
 find out why it doesn't work for you.


It's almost like the example in the URL you showed:

dmd test.d -LC:/gtkd/src/build/GtkD.lib

Where the command above doesn't works, on the other hand the 2 
others below works:

dmd test.d -L C:/gtkd/src/build/GtkD.lib

dmd test.d C:/gtkd/src/build/GtkD.lib


But if you do a search for problems like: Linking problem or 
Symbol Undefined most command lines uses this: 
"-Lpath/to/whatever" (Without Space). And another thing... there 
is other flag commonly used "-I" with doesn't need space, so most 
people will assume the same for -L.

Well this problem took only 30 minutes, because luckily I found 
the answer on the second link, but it could take hours.

Bubba.
Dec 25 2015
next sibling parent reply anonymous <anonymous example.com> writes:
On 26.12.2015 02:04, Bubbasaur wrote:

 On Friday, 25 December 2015 at 23:45:42 UTC, anonymous wrote:
 It's almost like the example in the URL you showed:

 dmd test.d -LC:/gtkd/src/build/GtkD.lib


Note that in the docs I linked it's `dmd hello.d -L+gtkd.lib` with a 
plus sign. I'm not sure if it's significant, but it's a difference.

Also, and this may be it, the link.exe that's distributed with dmd 
doesn't like forward slashes as path separators. You can try it with 
backslashes instead:

dmd test.d -LC:\gtkd\src\build\GtkD.lib


 But if you do a search for problems like: Linking problem or Symbol
 Undefined most command lines uses this: "-Lpath/to/whatever" (Without
 Space). And another thing... there is other flag commonly used "-I" with
 doesn't need space, so most people will assume the same for -L.


-L doesn't take a space, either. Putting a space there isn't even 
optional, it's wrong. The stuff after the space is not passed to the 
linker, it's interpreted by dmd.
Dec 26 2015
parent Bubbasaur <bubba gmail.com> writes:
On Saturday, 26 December 2015 at 11:19:27 UTC, anonymous wrote:

 ...
 Note that in the docs I linked it's `dmd hello.d -L+gtkd.lib` 
 with a plus sign. I'm not sure if it's significant, but it's a 
 difference.


There are two ways in the doc you linked:

dmd hello.d -L+gtkd.lib
or
dmd hello.d -Lgtkd.lib -m64

The second doesn't uses "+" but it has "-m64". Anyway even the 
example with "+" it doesn't working here either.


 Also, and this may be it, the link.exe that's distributed with 
 dmd doesn't like forward slashes as path separators. You can 
 try it with backslashes instead:

 dmd test.d -LC:\gtkd\src\build\GtkD.lib


I had tried that before, without any success.


 -L doesn't take a space, either. Putting a space there isn't 
 even optional, it's wrong. The stuff after the space is not 
 passed to the linker, it's interpreted by dmd.


In fact I already had understood what happened after your first 
answer, which "-L" with space wasn't been "evaluated" because DMD 
was reading a flag without arguments. So I could omit it there, 
but like I said, many examples out there uses:
"-Lpath/to/whatever", and then you see many topics about people 
complaining about this.

Bubba.
Dec 26 2015
prev sibling parent reply Ivan Kazmenko <gassa mail.ru> writes:
On Saturday, 26 December 2015 at 01:04:57 UTC, Bubbasaur wrote:

 It's almost like the example in the URL you showed:

 dmd test.d -LC:/gtkd/src/build/GtkD.lib


Note that -L passes flags (options) but not necessarily arguments 
or paths.  For example, I use "dmd -L/STACK:268435456" by default 
along with other options to increase the default stack size to 
256Mb.  The "/STACK:268435456" part is an OPTLINK switch, not a 
path.  Here is the list of OPTLINK switches: 
http://www.digitalmars.com/ctg/ctgLinkSwitches.html

Clearly, the forward slash (/) is reserved for switches, so the 
program will have trouble parsing paths with forward slashes.
Dec 26 2015
parent Bubbasaur <bubba gmail.com> writes:
On Saturday, 26 December 2015 at 11:53:55 UTC, Ivan Kazmenko 
wrote:

 Note that -L passes flags (options) but not necessarily 
 arguments or paths.  For example, I use "dmd 
 -L/STACK:268435456" by default along with other options to 
 increase the default stack size to 256Mb.


Your comment is reasonable enough, but unfortunately the main 
problem is there are examples on the internet using this "-L" for 
this kind of thing.

If go here: 
http://wiki.dlang.org/Compiling_and_linking_with_DMD_on_Windows#Static_Libraries_and_Import_Paths

There is an example in: "Passing search directories for static 
library files to Optlink", which follows:

     C:\Project\main.d
     C:\Project\lib\mylib.lib

     where main.d depends on the mylib library, you can compile 
via:

     dmd -L+.\lib\ driver.d mylib.lib

Yes there is a "+" plus sign and a "." dot there, but I believe 
people gets confuse and uses it as "-I".



 Clearly, the forward slash (/) is reserved for switches, so the 
 program will have trouble parsing paths with forward slashes.


About this in fact this was my mistake, because originally I had 
tried "\" and since it wasn't working so I change to "/" and that 
remains.

Bubba.
Dec 26 2015