[PATCH] allow src/tools/msvc/*.bat files to be called from the root of the source tree

Hello,

currently, on Windows/MSVC, src\tools\msvc\*.bat files mostly require 
being in that src\tools\msvc directory first.

I suggest an obvious fix:

diff --git a/src/tools/msvc/build.bat b/src/tools/msvc/build.bat
index 4001ac1d0d1..407b6559cfb 100755
--- a/src/tools/msvc/build.bat
+++ b/src/tools/msvc/build.bat
@@ -3,4 +3,4 @@ REM src/tools/msvc/build.bat
  REM all the logic for this now belongs in build.pl. This file really
  REM only exists so you don't have to type "perl build.pl"
  REM Resist any temptation to add any logic here.
-@perl build.pl %*
+@perl %~dp0\build.pl %*
diff --git a/src/tools/msvc/install.bat b/src/tools/msvc/install.bat
index d03277eff2b..98edf6bdffb 100644
--- a/src/tools/msvc/install.bat
+++ b/src/tools/msvc/install.bat
@@ -3,4 +3,4 @@ REM src/tools/msvc/install.bat
  REM all the logic for this now belongs in install.pl. This file really
  REM only exists so you don't have to type "perl install.pl"
  REM Resist any temptation to add any logic here.
-@perl install.pl %*
+@perl %~dp0\install.pl %*
diff --git a/src/tools/msvc/vcregress.bat b/src/tools/msvc/vcregress.bat
index a981d3a6aa1..0d65c823e13 100644
--- a/src/tools/msvc/vcregress.bat
+++ b/src/tools/msvc/vcregress.bat
@@ -3,4 +3,4 @@ REM src/tools/msvc/vcregress.bat
  REM all the logic for this now belongs in vcregress.pl. This file really
  REM only exists so you don't have to type "perl vcregress.pl"
  REM Resist any temptation to add any logic here.
-@perl vcregress.pl %*
+@perl %~dp0\vcregress.pl %*

This patch uses standard windows cmd's %~dp0 to get the complete path 
(drive, "d", and path, "p") of the currently executing .bat file to get 
proper path of a .pl file to execute. I find the following link useful 
whenever I need to remember details on cmd's %-substitution rules: 
https://ss64.com/nt/syntax-args.html

With this change, one can call those .bat files, e.g. 
src\tools\msvc\build.bat, without leaving the root of the source tree.

Not sure if similar change should be applied to pgflex.bat and 
pgbison.bat -- never used them on Windows and they seem to require being 
called from the root, but perhaps they deserve a similar change.

If accepted, do you think this change is worthy of back-porting?

Please advise if you think this change is a beneficial one.

P.S. Yes, I am aware of very probable upcoming move to meson, but until 
then this little patch really helps me whenever I have to deal with 
Windows and MSVC from the command line. Besides, it could help old 
branches as well.

-- 
Anton Voloshin

https://postgrespro.ru
Postgres Professional, The Russian Postgres Company