Обсуждение: Windows v readline

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Windows v readline

От
Andrew Dunstan
Дата:
The configure code currently has this:


# readline on MinGW has problems with backslashes in psql and other bugs.
# This is particularly a problem with non-US code pages.
# Therefore disable its use until we understand the cause. 2004-07-20
if test "$PORTNAME" = "win32"; then
  if test "$with_readline" = yes; then
    AC_MSG_WARN([*** Readline does not work on MinGW --- disabling])
    with_readline=no
  fi
fi


2004 is a very long time ago. Has anyone looked at this more recently?
It would certainly be nice to have readline-enabled psql on Windows if
possible.


cheers


andrew

-- 
Andrew Dunstan                https://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services




psql tab-complete

От
Victor Spirin
Дата:
I found some problem with tab-complete in the 12 version.  I checked 
this in the Windows.


Victor Spirin
Postgres Professional:http://www.postgrespro.com
The Russian Postgres Company



Вложения

Re: psql tab-complete

От
Victor Spirin
Дата:
Sorry for wrong place and contents of my message.

It seems that the VA_ARGS_NARGS (__ VA_ARGS__) macros always return 1 on 
Windows.

Victor Spirin
Postgres Professional:http://www.postgrespro.com
The Russian Postgres Company

24.10.2019 19:11, Victor Spirin пишет:
> I found some problem with tab-complete in the 12 version.  I checked 
> this in the Windows.
>
>
> Victor Spirin
> Postgres Professional:http://www.postgrespro.com
> The Russian Postgres Company
>
>



Re: psql tab-complete

От
Tom Lane
Дата:
Victor Spirin <v.spirin@postgrespro.ru> writes:
> I found some problem with tab-complete in the 12 version.  I checked 
> this in the Windows.

This change seems to break the case intended by the comment,
ie given the context

    SELECT * FROM tablename WHERE <tab>

we want to offer the columns of "tablename" as completions.

I'd be the first to agree that that's completely lame, as there
are any number of related cases it fails to cover ... but this
patch isn't making it better.

            regards, tom lane



Re: psql tab-complete

От
Victor Spirin
Дата:
Yes, I found, that VA_ARGS_NARGS(__ VA_ARGS__) macros always return 1 on 
Windows.

Victor Spirin
Postgres Professional:http://www.postgrespro.com
The Russian Postgres Company

25.10.2019 0:48, Tom Lane пишет:
> Victor Spirin <v.spirin@postgrespro.ru> writes:
>> I found some problem with tab-complete in the 12 version.  I checked
>> this in the Windows.
> This change seems to break the case intended by the comment,
> ie given the context
>
>     SELECT * FROM tablename WHERE <tab>
>
> we want to offer the columns of "tablename" as completions.
>
> I'd be the first to agree that that's completely lame, as there
> are any number of related cases it fails to cover ... but this
> patch isn't making it better.
>
>             regards, tom lane
>
>



Re: psql tab-complete

От
Victor Spirin
Дата:
This patch resolved one problem in the tab-complete.c on MSVC. The 
VA_ARGS_NARGS macros now work correctly on Windows.


Victor Spirin
Postgres Professional:http://www.postgrespro.com
The Russian Postgres Company

25.10.2019 0:53, Victor Spirin пишет:
> Yes, I found, that VA_ARGS_NARGS(__ VA_ARGS__) macros always return 1 
> on Windows.
>
> Victor Spirin
> Postgres Professional:http://www.postgrespro.com
> The Russian Postgres Company
>
> 25.10.2019 0:48, Tom Lane пишет:
>> Victor Spirin <v.spirin@postgrespro.ru> writes:
>>> I found some problem with tab-complete in the 12 version.  I checked
>>> this in the Windows.
>> This change seems to break the case intended by the comment,
>> ie given the context
>>
>>     SELECT * FROM tablename WHERE <tab>
>>
>> we want to offer the columns of "tablename" as completions.
>>
>> I'd be the first to agree that that's completely lame, as there
>> are any number of related cases it fails to cover ... but this
>> patch isn't making it better.
>>
>>             regards, tom lane
>>
>>
>
>

Вложения

Re: psql tab-complete

От
Michael Paquier
Дата:
On Fri, Oct 25, 2019 at 11:57:18AM +0300, Victor Spirin wrote:
> This patch resolved one problem in the tab-complete.c on MSVC. The
> VA_ARGS_NARGS macros now work correctly on Windows.

Can you explain why and in what the use of EXPAND() helps with MSVC
builds?  Any references which help to understand why this is better?
If this change is needed, this also surely needs a comment to explain
the difference.
--
Michael

Вложения

Re: Windows v readline

От
Peter Eisentraut
Дата:
On 2019-09-29 22:55, Andrew Dunstan wrote:
> 
> The configure code currently has this:
> 
> 
> # readline on MinGW has problems with backslashes in psql and other bugs.
> # This is particularly a problem with non-US code pages.
> # Therefore disable its use until we understand the cause. 2004-07-20
> if test "$PORTNAME" = "win32"; then
>    if test "$with_readline" = yes; then
>      AC_MSG_WARN([*** Readline does not work on MinGW --- disabling])
>      with_readline=no
>    fi
> fi
> 
> 
> 2004 is a very long time ago. Has anyone looked at this more recently?
> It would certainly be nice to have readline-enabled psql on Windows if
> possible.

I tried this out.  First, it doesn't build, because readline doesn't do 
the dllimport/dllexport dance on global variables, so all references to 
rl_* global variables in tab-complete.c fail (similar to [0]).  After 
patching those out, it builds, but it doesn't work.  It doesn't print a 
prompt, keys don't do anything sensible.  I can enter SQL commands and 
get results back, but the readline part doesn't do anything sensible AFAICT.

Perhaps I did something wrong.  You can still use readline without 
global variables, but it seems like a serious restriction and makes me 
wonder whether this has actually ever been used before.  It's curious 
that MSYS2 ships a readline build for mingw.  Is there other software 
that uses it on Windows?


[0]: 
https://www.postgresql.org/message-id/001101c3eb6a$3b275500$f800a8c0@kuczek.pl

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services



Re: Windows v readline

От
Tom Lane
Дата:
Peter Eisentraut <peter.eisentraut@2ndquadrant.com> writes:
> On 2019-09-29 22:55, Andrew Dunstan wrote:
>> It would certainly be nice to have readline-enabled psql on Windows if
>> possible.

> I tried this out.  First, it doesn't build, because readline doesn't do 
> the dllimport/dllexport dance on global variables, so all references to 
> rl_* global variables in tab-complete.c fail (similar to [0]).  After 
> patching those out, it builds, but it doesn't work.

What do you mean by "patching those out" --- you removed all of
tab-complete's external variable assignments?  That would certainly
disable tab completion, at a minimum.

> It doesn't print a 
> prompt, keys don't do anything sensible.  I can enter SQL commands and 
> get results back, but the readline part doesn't do anything sensible AFAICT.

I wonder if readline was confused about the terminal type, or if it
decided that the input file was not-a-tty for some reason.

            regards, tom lane



Re: Windows v readline

От
Peter Eisentraut
Дата:
On 2019-12-30 14:28, Tom Lane wrote:
> Peter Eisentraut <peter.eisentraut@2ndquadrant.com> writes:
>> On 2019-09-29 22:55, Andrew Dunstan wrote:
>>> It would certainly be nice to have readline-enabled psql on Windows if
>>> possible.
> 
>> I tried this out.  First, it doesn't build, because readline doesn't do
>> the dllimport/dllexport dance on global variables, so all references to
>> rl_* global variables in tab-complete.c fail (similar to [0]).  After
>> patching those out, it builds, but it doesn't work.
> 
> What do you mean by "patching those out" --- you removed all of
> tab-complete's external variable assignments?  That would certainly
> disable tab completion, at a minimum.

Yeah, basically remove tab completion altogether.  But readline would 
still be useful without that for line editing and history.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services



Re: psql tab-complete

От
Thomas Munro
Дата:
On Sat, Oct 26, 2019 at 4:59 PM Michael Paquier <michael@paquier.xyz> wrote:
> On Fri, Oct 25, 2019 at 11:57:18AM +0300, Victor Spirin wrote:
> > This patch resolved one problem in the tab-complete.c on MSVC. The
> > VA_ARGS_NARGS macros now work correctly on Windows.
>
> Can you explain why and in what the use of EXPAND() helps with MSVC
> builds?  Any references which help to understand why this is better?
> If this change is needed, this also surely needs a comment to explain
> the difference.

Since I really want to be able to use VA_ARGS_NARGS() elsewhere, I
looked into this.  There are various derivatives of that macro, some
using GCC/Clang-only syntax and that work on GCC and MSVC, splattered
all over the internet, but the original, coming as it does from a C
standards newsgroup[1], does not.  There are also lots of complaints
that the original standard version doesn't work on MSVC, with
analysis:

https://stackoverflow.com/questions/5134523/msvc-doesnt-expand-va-args-correctly
https://stackoverflow.com/questions/32399191/va-args-expansion-using-msvc
https://learn.microsoft.com/en-us/cpp/build/reference/zc-preprocessor?view=msvc-170

The short version is that __VA_ARGS__ is not tokenized the way the
standard requires (it's considered to be a single token unless you
shove it back through the preprocessor again, which is what EXPAND()
does), but you can fix that with /Zc:preprocessor.  That switch only
works in Visual Studio 2019 and up, and maybe also 2017 if you spell
it /experimental:preprocessor.  We still claim to support older
compilers.  Assuming those switches actually work as claimed, I see
two choices: commit this hack with a comment reminding us to clean it
up later, or drop 2015.

[1] https://groups.google.com/g/comp.std.c/c/d-6Mj5Lko_s



Re: psql tab-complete

От
Tom Lane
Дата:
Thomas Munro <thomas.munro@gmail.com> writes:
> Since I really want to be able to use VA_ARGS_NARGS() elsewhere,

+1, that'd be handy.

> ... Assuming those switches actually work as claimed, I see
> two choices: commit this hack with a comment reminding us to clean it
> up later, or drop 2015.

As long as we can hide the messiness inside a macro definition,
I'd vote for the former.

            regards, tom lane



Re: psql tab-complete

От
Michael Paquier
Дата:
On Wed, Dec 21, 2022 at 05:56:05PM -0500, Tom Lane wrote:
> Thomas Munro <thomas.munro@gmail.com> writes:
>> Since I really want to be able to use VA_ARGS_NARGS() elsewhere,
>
> +1, that'd be handy.
>
>> ... Assuming those switches actually work as claimed, I see
>> two choices: commit this hack with a comment reminding us to clean it
>> up later, or drop 2015.
>
> As long as we can hide the messiness inside a macro definition,
> I'd vote for the former.

Agreed, even if it is worth noting that all the buildfarm members
with MSVC use 2017 or newer.
--
Michael

Вложения

Re: psql tab-complete

От
Thomas Munro
Дата:
On Thu, Dec 22, 2022 at 3:25 PM Michael Paquier <michael@paquier.xyz> wrote:
> On Wed, Dec 21, 2022 at 05:56:05PM -0500, Tom Lane wrote:
> > Thomas Munro <thomas.munro@gmail.com> writes:
> >> Since I really want to be able to use VA_ARGS_NARGS() elsewhere,
> >
> > +1, that'd be handy.
> >
> >> ... Assuming those switches actually work as claimed, I see
> >> two choices: commit this hack with a comment reminding us to clean it
> >> up later, or drop 2015.
> >
> > As long as we can hide the messiness inside a macro definition,
> > I'd vote for the former.
>
> Agreed, even if it is worth noting that all the buildfarm members
> with MSVC use 2017 or newer.

Thanks.  Pushed.

PS is it a mistake that we still mention SDK 8.1 in the docs?