libtool with mingw hangs building openocd in func_convert_core_msys_to_w32

[Dietmar May]

Thanks for submitting the bug report.

> I can now see what may be a duplicate report under:
>
> https://debbugs.gnu.org/cgi/bugreport.cgi?bug=10949
>
> responding that //c is deliberate so MSYS does not convert a posix path,
> so in the Cygwin Mingw build case, the response may be "Don't Do That"! 

I just re-installed msys2 and tried a few things, with interesting result.

First, "ls /usr//bin" as well as "ls /usr/////bin" complete successfully 
under both cygwin and msys2, demonstrating slash compaction.

However, "ls //usr/bin" hangs, as both apparently evaluate the leading 
// as a server path.

For testing libtool's construct, I tried:

$ cmd //c echo hello
hello

which works, and this, which doesn't:

$ cmd /c echo hello

Microsoft Windows [Version 10.0.blah]
(c) Microsoft Corporation. All rights reserved.

C:\msys64\home\myname>

Interestingly,

ls //c

hangs under msys2 (as well as cygwin),

whereas

cmd //c

does not; so it almost seems like msys2 has a hack to recognize that 
cmd.exe is being invoked ...

However, both of the following also complete successfully under msys2, 
WITHOUT the double-slash hack:

$ cmd /c "echo hello"
hello

$ cmd "/c" "echo hello"
hello

Both seem preferable to bad syntax.

Of course, there's always the question of why libtool is using cmd.exe 
instead of /bin/echo, which seems to work just fine ...

$ /bin/echo "hello world"
hello world

> On 2021-06-27 14:23, Brian Inglis wrote:
>>> Which you don't need to change if you configure properly, as JonY 
>>> replied on the list to your earlier post:
>>
>>>> On 2021-06-25 09:27, Jonathan Yong via Cygwin wrote:
>>>>> Don't set --build, you are building on Cygwin, not MSYS.
>>
>>> Jonathan Yong is correct - removing --build allows make to complete 
>>> without error using the unmodified ltmain.sh > There's still the 
>>> issue of generating a call to cmd.exe with an
>>> invalid switch (//c), which will cause it to hang indefinitely if
>>> ever invoked.
>>  > The risk of breaking anything by fixing this seems like nil.
>>
>> The issue exists in the package libtool upstream:
>>
>> https://git.savannah.gnu.org/cgit/libtool.git/tree/build-aux/ltmain.in#n963 
>>
>>
>> I submitted a bug report with link to this thread and patch to the 
>> upstream package maintainers; I will post any responses received.
>