Re: [PATCH 8/7] syntax-check: fix violations and implement sc_useless_quotes_in_case_branch.

[Gary V. Vaughan]

Hi Eric,

On 22 Nov 2011, at 12:09, Gary V. Vaughan wrote:
> On 21 Nov 2011, at 23:15, Eric Blake wrote:
>> On 11/21/2011 07:47 AM, Gary V. Vaughan wrote:
>>> Contrary to popular belief, Bourne shell does not resplit case
>>> expressions after expansion, so if there are no shell unquoted
>>> shell metacharacters or whitespace, the quotes are useless.
>>> @@ -568,7 +568,7 @@ func_resolve_sysroot ()
>>> # store the result into func_replace_sysroot_result.
>>> func_replace_sysroot ()
>>> {
>>> -  case "$lt_sysroot:$1" in
>>> +  case $lt_sysroot:$1 in
>>>  ?*:"$lt_sysroot"*)
>> 
>> Likewise in the pattern expression; you could further change this to:
>> 
>> case $lt_sysroot:$1 in
>> ?*:$lt_sysroot*)
> 
> Good call, although narrowing the search down to eliminate false positives
> is a lot trickier in this case!
> 
> I'm adding the following changeset to this series.  Thanks!

Actually, no, I take it back.  I won't apply that patch since it causes tests
to fail for at least dash, bash and ksh.

My reading of the opengroup specification agrees with us both that no 
resplitting
should be done in the branch expressions of a case, but there is definitely
something odd going on that I don't really understand:

  $ cat case.test
  for match in '\$\$' '\$'; do
  case $match in *$match*)   echo good ;; *) echo bad ;; esac
  case $match in *"$match"*) echo good ;; *) echo bad ;; esac
  done

  solaris10 /bin/sh$ sh case.test
  good
  good
  good
  good

  solaris10 xpg4$ /usr/xpg4/bin/sh case.test
  good
  good
  good
  good

  hpux10 /bin/sh$ sh case.test
  good
  good
  good
  good

  aix6 /bin/sh$ sh case.test
  good
  good
  good
  good

  zsh-4.3.10$ zsh case.test
  good
  good
  good
  good

  zsh-4.3.11$ /usr/local/Cellar/zsh-4.3.11/bin/zsh case.test
  good
  good
  good
  good

  zsh-4.3.12$ /usr/local/bin/zsh case.test
  good
  good
  good
  good

  dash-0.5.7$ dash case.test
  bad
  good
  good
  good

  bash-3.2.48$ bash case.test
  bad
  good
  good
  good

  bash-4.1.5$ /usr/local/Cellar/bash-4.1.5/bin/bash case.test
  bad
  good
  good
  good

  bash-4.2.10$ /usr/local/bin/bash case.test
  bad
  good
  good
  good

  ksh-93s+$ ksh case.test
  bad
  good
  good
  good

Confusing! It seems any backslash escaped character will do, same
results with '\S\S' and '\S' as with the dollars above.  Yet, with
the backslashes removed, all the above print 4 'good's.

If it weren't for the fact that ksh, bash and dash all independently
behave the same way, I'd have called it a bug...  any idea?

Cheers,
-- 
Gary V. Vaughan (gary AT gnu DOT org)