Automake: Syntax of conditionals in Makefile.am

I am familiar with the 开发者_JS百科if VAR_NAME, where VAR_NAME is defined by an AM_CONDITIONAL clause inside of configure.ac.

Is there a corresponding "if not defined" construct in Makefile.am?

There is no "if not defined" construct. The configure.ac must be written so that the conditional is always defined. However, you can do "if ! VAR_NAME" if you want to test that the condition is false.