m4_set_contains cannot find key

[Petre Pircalabu]

Please disregard this question. The m4 preprocessing is done before
"configure", so the m4 preprocessor has no way of knowing about the
variable.

Many thanks,
Petre

Hello,
I'm getting a false negative when trying to test if a set contains a key.
The key is specified as a variable in configure.ac.
Can you please take a look at the following code snippet?
m4_set_add([food], [fish])
m4_set_add([food], [steak])
m4_set_add([food], [junk])
meal=junk
AC_MSG_CHECKING([whether we have junk food for dinner])
m4_set_contains([food], [$meal], [VAL="yes"], [VAL="no"])
AC_MSG_RESULT([${VAL}])
Unfortunately is says that I will be eating healthy food tonight and I
really don't know why.
Many thanks,
Petre

[Eric Blake]

Post by Petre Pircalabu
Please disregard this question. The m4 preprocessing is done before
"configure", so the m4 preprocessor has no way of knowing about the
variable.

Correct - you were mixing two languages (m4 and shell), and which gets
run when.

Post by Petre Pircalabu

m4_set_add([food], [fish])
m4_set_add([food], [steak])
m4_set_add([food], [junk])
meal=junk
AC_MSG_CHECKING([whether we have junk food for dinner])
m4_set_contains([food], [$meal], [VAL="yes"], [VAL="no"])

The literal string '$meal' (at m4-time) is NOT in the set, so the m4
result of the expansion is always going to trigger the 'VAL="no"'
branch. If you want to see if the contents of a shell variable are in a
shell set, then m4_set_* is not the right construct to be using.