Jeff King <peff@xxxxxxxx> writes:
> filter-branch tries to restore "old" copies of some
> environment variables by using the construct:
>
> unset var
> test -z "$old_var" || var="$old_var" && export var
>
> However, by the short-circuit logic, we will always run
> 'export var'.
Thanks.
I was confused by this description ("short-circuit logic"), but I do not
think there is no short-circuit going on. This is a simple ignorance of
shell syntax.
In a shell scriptlet:
a || b && c
AND list operator (&&) and OR list operator (||) have the same precedence
and bind to the left. Because the second part of OR list is always true,
we always export.
I have a mild suspecion that this was simply an artifcat of a careless
conversion from export var="$val" form we did in the past. I should have
caught them back then.
The patch is fine, but I find this easier to read:
+test -z "$ORIG_GIT_DIR" || {
+ GIT_DIR="$ORIG_GIT_DIR" && export GIT_DIR
+}
+test -z "$ORIG_GIT_WORK_TREE" || {
+ GIT_WORK_TREE="$ORIG_GIT_WORK_TREE" &&
+ export GIT_WORK_TREE
+}
+test -z "$ORIG_GIT_INDEX_FILE" || {
+ GIT_INDEX_FILE="$ORIG_GIT_INDEX_FILE" &&
+ export GIT_INDEX_FILE
+}
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