43 lines
996 B
Makefile
43 lines
996 B
Makefile
# $NetBSD: envfirst.mk,v 1.2 2020/07/27 18:57:42 rillig Exp $
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#
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# The -e option makes environment variables stronger than global variables.
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.if ${FROM_ENV} != value-from-env
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.error ${FROM_ENV}
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.endif
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# Try to override the variable; this does not have any effect.
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FROM_ENV= value-from-mk
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.if ${FROM_ENV} != value-from-env
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.error ${FROM_ENV}
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.endif
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# Try to append to the variable; this also doesn't have any effect.
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FROM_ENV+= appended
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.if ${FROM_ENV} != value-from-env
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.error ${FROM_ENV}
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.endif
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# The default assignment also cannot change the variable.
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FROM_ENV?= default
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.if ${FROM_ENV} != value-from-env
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.error ${FROM_ENV}
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.endif
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# Neither can the assignment modifiers.
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.if ${FROM_ENV::=from-condition}
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.endif
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.if ${FROM_ENV} != value-from-env
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.error ${FROM_ENV}
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.endif
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# Even .undef doesn't work since it only affects the global context,
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# which is independent from the environment variables.
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.undef FROM_ENV
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.if ${FROM_ENV} != value-from-env
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.error ${FROM_ENV}
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.endif
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all:
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@: nothing
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