#467: quickfix for tilde expansion

[hohwille]

This is a "fix" for #467.
However, it currently only replaces the tilde (~) if the variable value starts with it and is not quoted. Further for such variables it reintroduces the bug #100 and #395. So assuming that we only have cases like

export M2_REPO=~/.m2/repository

Or

PROJECT_HOME=~

But not something like

FOO="~/path with whitespaces"

this PR could be merged.
If we want a clean solution, further investigation is required (and IMHO a real CMD guru is needed as I run out of ideas).

[hohwille]

Compared to the current state on master that is entirely nuts this change IMHO is already a reasonable improvement.

[hohwille]

So it more or less works now.
Input from devon.properties:

export M2_REPO=~/.m2/repository
M3_REPO=~
M4_REPO="~/path with whitespaces"
M5_REPO=~/path with whitespaces and many words

Output from set command after executing devon:

M2_REPO=C:\Users\hohwille/.m2/repository
M3_REPO=C:\Users\hohwille
M4_REPO=C:\Users\hohwille/path with whitespaces
M5_REPO=C:\Users\hohwille/path

We could fix the case with M5_REPO by using this code instead:

  set line=%replacement%%USERPROFILE%!value:~1! %~3 %~4 %~5 %~6 %~7 %~8 %~9

However, if the additional arguments are empty, trailing whitespaces are added to the variable value and I am unsure what other side-effects this may have. Preventing this with IF statements does not work as described in #467.
I think this is already "good enough" as people are used to quote paths containing whitespaces (even though bash prevents ~ expansion inside quotes what could confuse bash experts)...

[maybeec]

isn't here a % missing at the end?

[hohwille]

Nope. %2 is the second argument and %~2 expands it and unquotes.
https://ss64.com/nt/syntax-args.html

So your question might be why is there an extra percent sign after the first arg.
I can only reasonable answer for the %~1%= case as here the % sign is an escape for the equals sign.
In the other case (line 92) it may be obsolete to add the extra percent.
I can test that and can also not tell if I initially wrote this code as Rohit supported the fix #395

[hohwille]

So also the equals sign does not need to be escaped with percent sign.
To make you happy and avoid further confusion I removed the pointless percent signs.
According to my tests in Win VM it does not make any difference so fingers crossed that this will not break anything in this fragile CMD universe...
Can we resolve our conversations now and merge this PR?

[markusschuh]

Well done to remove the trailing percent here. They should not be used after positional parameters.

Only variables within scripts must be surrounded by percents - for positional parameters this is just accepted for "convenience". (The percent is no escape char here)
A "%1%2" still resolves to first pos. param followed by 2nd,

From today's view point it is easy to say, this was a bad design decision - but in the 80'ies this was not so easy to forsee.

[maybeec]

for me it's fine to just support ~ replacement at the first character of the value. Anyhow just in case you havent seen it, there are solutions to a more generic algorithm, which anyhow underlines how crappy batch is :( https://stackoverrun.com/de/q/9716479

[hohwille]

Thanks for the link. After rethinking it might even be wrong to resolve C:/data/file~name to C:/data/fileC:\users\hohwillename. So I would rather consider this as a feature :)