#1736 SetEnvironmentVariable() currupts list

[David Gravereaux]

Win32 specific!

Use of SetEnvironmentVariable() by an extension or an
application that embeds Tcl, puts the libc maintained
environ list out-of-sync. This in turn puts Tcl's env
array out-of-sync as well.

[Jeffrey Hobbs]

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This is why Tcl has the Tcl_PutEnv compatibility procedure
for extension authors to use to keep in sync.

[David Gravereaux]

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but in places where this is out of your control,
GetEnvironmentStrings() more accurately represents what the
OS maintains.

[David Gravereaux]

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This is not fixed, nor invalid. reopening.

[David Gravereaux]

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writing sync problems:

% tsetenv FOO baz
% wgetenv FOO
baz
% set env(FOO)
baz
% getenv FOO <- blank return
% wsetenv FOO pickle
% set env(FOO)
baz
% getenv FOO
%

reading sync prolems:

% set env(TEST) first
first
% load test
% set env(TEST) second
second
% getenv TEST
first
% wgetenv TEST
second
% tgetenv TEST
second

[David Gravereaux]

test extension that shows the problems.

[David Gravereaux]

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Just this, and everyone has the wrong answer:

% getenv FOO
% setenv FOO qwe
% set env(FOO)
baz
% wgetenv FOO
qwe
% tgetenv FOO
baz
% wsetenv FOO asd <- system
% tgetenv FOO
baz <- tcl
% getenv FOO
qwe <- c-runtime
%

[Jeffrey Hobbs]

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Hmmm, I just corrected this for unix with 979640. I'm not
sure how related they are, as we rely on putenv solely for
Windows.