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?

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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.