[PATCH] Fix variable assignments in function invocations

[Harald van Dijk <harald@xxxxxxxxxxx>]

Hello all,

A long-standing problem with dash has been how it deals with variable 
assignments in function invocations, and several packages are affected 
by it, two I've come across recently being autogen and pkg-config (only 
their test suites, luckily).

A short test script:

  f() {
    echo inside f, VAR is $VAR
    sh -c 'echo inside sh called from f, VAR is $VAR'
  }

  VAR=value f
  echo after returning from f, VAR is $VAR

Assuming VAR was not already set, this should print (and does with bash):

  inside f, VAR is value
  inside sh called from f, VAR is value
  after returning from f, VAR is

With dash, this actually prints:

  inside f, VAR is value
  inside sh called from f, VAR is
  after returning from f, VAR is value

The first problem with that is that VAR does not get exported, the 
second is that VAR's assigned value is kept after the function has returned.

Quoting SUSv4 Shell Command Language 2.9.1 Simple Commands:

  If no command name results, variable assignments shall affect the
  current execution environment. Otherwise, the variable assignments
  shall be exported for the execution environment of the command and
  shall not affect the current execution environment (except for
  special built-ins).

In `VAR=value f`, f is found as the command name. No exception is made 
for function invocations, so I believe this disallows dash's current 
behaviour, and requires it to print the same thing bash does.

Fixing this seems trivial, see the attachment, and the test suites of 
both autogen and pkg-config pass with this change. Does this look correct?

Cheers,
Harald van Dijk

--- a/src/eval.c
+++ b/src/eval.c
@@ -875,7 +875,7 @@ raise:
 		break;
 
 	case CMDFUNCTION:
-		poplocalvars(1);
+		listsetvar(varlist.list, VEXPORT|VSTACK);
 		if (evalfun(cmdentry.u.func, argc, argv, flags))
 			goto raise;
 		break;